Electrode material including surface-modified silicon oxide particles

Abstract

An active material for a lithium-ion secondary battery includes a core particle containing SiO or M-SiO material, where M is selected from Al, Cu, Fe, K, Li, Mg, Na, Ni, Sn, Ti, Zn, Zr, or any combination thereof, and an amorphous Group 13 or Group 15 material ("G13 / G15 material") that includes at least one element selected from boron (B), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), or bismuth (Bi) coated on the core particle.

Description

[Technical field]

[0001] Aspects of the present disclosure relate to electrode materials comprising the surface-modified silicon oxide particles, in particular anodes comprising the electrode materials, and lithium ion batteries comprising the anodes. [Background technology]

[0002] Lithium (Li) ion electrochemical batteries typically require materials that enable high energy density, high power density, and high cycling stability. Li-ion batteries are commonly used in a variety of applications including consumer electronics, wearable computing devices, military mobile devices, satellite communications, spacecraft devices, and electric vehicles, and are particularly common for use in large-scale energy applications such as low-emission electric vehicles, renewable power plants, and stationary electric grids. In addition, lithium-ion batteries are at the forefront of a new generation of wireless and portable communications applications. One or more lithium-ion cells may be used to construct a battery that serves as the power source for any of these applications. However, the explosive growth in the number of applications requiring higher energy has accelerated research into lithium-ion batteries with even higher energy density, higher power density, higher rate charge and discharge capabilities, and longer cycle life. Furthermore, the need to extend today's energy and power densities is growing as applications move to higher current requirements, longer operating times, wider and higher power ranges, and smaller form factors along with the increasing adoption of lithium-ion technology.

[0003] Anode active materials such as silicon are desirable alternatives to current graphite-based anodes due to their high lithium storage capacity, which can be more than seven times that of graphite (up to 3200 mAh / g). However, due to the large volume expansion of the alloy particles upon lithiation, these anode materials typically exhibit very poor cycle life due to mechanical stress, low coulombic efficiency, and electrical disconnection. Summary of the Invention

Problems to be Solved by the Invention

[0004] Therefore, there is a need for an advanced anode material for use in electrochemical cells that includes an improved silicon oxide active material.

Means for Solving the Problems

[0005] According to one embodiment of the present invention, an active material for a lithium-ion secondary battery is SiO x or M-SiO x [where 0 < x < 1.2 and M is selected from Al, Ca, Cu, Fe, K, Li, Mg, Na, Ni, Sn, Ti, Zn, Zr, or any combination thereof] and a coating of an amorphous G13 / G15 material containing at least one element on the core particles selected from boron (B), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), or bismuth (Bi), and at least one of boron or phosphorus diffused in the core particles.

[0006] In one embodiment, at least one of the G13 / 15 materials, such as boron or phosphorus, is diffused up to a depth of at most about 20 nm only in the surface region of the core particles. In another embodiment, an electrode material for a lithium-ion secondary battery includes an active material and a binder. In another embodiment, a lithium-ion secondary battery includes a cathode electrode, an electrolyte, and an anode electrode including an electrode material containing about 15 wt% to about 25 wt% of a binder, about 2 wt% to about 7 wt% of a conductive additive, and about 70 wt% to about 80 wt% of an active material.

[0007] In another embodiment, a method of forming an active material for a lithium-ion secondary battery coats core particles with a precursor material containing at least one of boron or phosphorus in an amount from about 1 wt% to about 7 wt% and SiO from about 90 wt% to about 95 wt% xor M-SiO x mixing with core particles [where 0 < x < 1.2 and M is selected from Li, Na, Mg, Cu, Ni, Zn, Fe, or any combination thereof]; and forming active material particles comprising the core particles and a coating of amorphous G13 / G15 material on the core particles, and sintering the coated core particles in an inert atmosphere so as to diffuse at least one of boron or phosphorus of the precursor material into the core particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] [Figure 1A] A cross-sectional view of active material particles 100 according to various embodiments of the present disclosure. [Figure 1B] A cross-sectional view showing modified active material particles 100A according to various embodiments of the present disclosure. [Figure 1C] A cross-sectional view showing composite active material particles according to various embodiments of the present disclosure. [Figure 1D] A cross-sectional view showing composite active material particles according to various embodiments of the present disclosure. [Figure 1E] A cross-sectional view of core particles according to various embodiments of the present disclosure. [Figure 1F] A cross-sectional view of core particles according to various embodiments of the present disclosure. [Figure 2A-2C] Showing Raman spectra of graphite and various graphene-based materials. [Diagram 3] A bar graph comparing the Raman spectrum ID / IG ratios of a typical carbon material and low-defect turbostratic carbon. [Figure 4A-4C] Showing Raman spectra of electrode active materials comprising SiOx core particles encapsulated by amorphous carbon, reduced graphene oxide (rGO), and low-defect turbostratic carbon, respectively. [Diagram 5] A graph showing anode capacity retention as a function of the number of cycles of an exemplary half-cell and a comparative half-cell. [Figure 6] A graph showing the pH of an exemplary active material and a comparative active material as a function of time. [Figure 7A] 1 is a graph showing X-ray diffraction (XRD) results of exemplary active materials compared to a control active material and a crystalline Li2B4O7 material. [Figure 7B] 1 is a graph showing XRD data for an exemplary active material and a crystalline B4C material. [Figure 8A] 1 is a graph showing the capacity retention of a half-cell including an anode including an exemplary active material, carbon black, and PAA binder in a weight ratio of 75:5:20, and a comparative half-cell including an anode including a comparative active material including Si nanoparticles and CSS, carbon black, and PAA binder in a weight ratio of 75:5:20. [Figure 8B] 1 is a graph showing XRD results for exemplary and comparative active materials. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Various embodiments will now be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. References to specific examples and implementations are for illustrative purposes only and are not intended to limit the scope of the invention or the claims.

[0010] When an element or layer is referred to as being "on" or "connected" to another element or layer, it will be understood that the element or layer can be directly on or "connected" to the other element or layer, or that there can be intervening elements or layers. In contrast, when an element is referred to as being "directly on" or "directly connected" to another element or layer, there are no intervening elements or layers. For purposes of this disclosure, it will be understood that "at least one of X, Y, and Z" can be interpreted as X only, Y only, Z only, or any combination of two or more items of X, Y, and Z (e.g., XYZ, XYY, YZ, ZZ).

[0011] For the description of a range of values, unless the context clearly dictates otherwise, it is understood that each intermediate value between the upper and lower limits of the range, to the tenth of the unit of the lower limit, as well as any other specified or intermediate value within the specified range, is encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included within the smaller ranges, and are also encompassed by the present invention, subject to any specifically excluded limit value within the specified range. Where a specified range includes one or both of the limits, ranges excluding one or both of these included limits are also encompassed by the present invention. It will also be understood that the term "about" may refer to a slight measurement error, for example, + / - 5% to 10%.

[0012] Words such as "then," "then," and "next" are not necessarily intended to limit the order of the steps, but rather these words may be used to guide the reader through the method description. Further, references to claim elements in the singular, for example, using the articles "a," "an," or "the," should not be construed as limiting the element to the singular.

[0013] An "electrode material" is defined as a material that can be configured for use as an electrode in an electrochemical cell, such as a lithium ion rechargeable battery. An "electrode" is defined as either the anode or the cathode of an electrochemical cell. A "composite electrode material" is also defined as including an active material particle that is a conductive material combined with one of a particle, flake, sphere, platelet, sheet, tube, fiber, or combination thereof. The particle, flake, sphere, platelet, sheet, tube, fiber, or combination thereof may further be flat, crushed, crimped, layered, woven, braided, or combination thereof.

[0014] 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 graphite, graphene, diamond, pyrolytic graphite, carbon black, low defect turbostratic carbon, fullerene, other carbonaceous materials, or combinations thereof. Herein, the other carbonaceous materials may include pyrolytic carbon materials. Pyrolytic carbon may be derived from carbonaceous precursor materials, such as hydrocarbons, such as pitch or tar; citric acid; polysaccharides, such as sucrose, glucose, or chitosan; polymers, such as polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyacrylic acid (PAA), polydopamine (PDA), or polyacrylonitrile (PAN); combinations thereof, and the like. An "electrode material mix" is defined as a combination of materials such as material particles (either electrochemically active and conductive composites or combinations thereof), binder(s), non-crosslinked and / or crosslinked polymer(s), etc., that are mixed together for use in forming an electrode of an electrochemical cell. An "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 electrical potential. Furthermore, the term "intercalation and release" may be understood as ions that intercalate and deintercalate or lithiate and delithiate. Thus, the process of ion insertion and release is also understood as intercalation and deintercalation or lithiate and delithiate. Thus, an "active material" or "electrochemically active material" or "active material particles" is defined as a material or particle that can repeatedly intercalate and deintercalate ions or lithiate and delithiate lithium.

[0015] 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 a battery, determined by the mass of active material contained within the battery, and represents the maximum amount of energy in ampere-hours (Ah) that can be extracted from the battery at rated voltage. Capacity can also be defined by the following equation: Capacity = Energy / Voltage or Current (A) x Time (h). "Energy" is defined mathematically by the following equation: Energy = Capacity (Ah) x Voltage (V). "Specific Capacity" is defined herein as the amount of charge that can be delivered in a specified time per unit mass or unit volume of active electrode material. Specific Capacity may be measured in weight units, e.g., (Ah) / g, or volume units, e.g., (Ah) / cc. Specific Capacity is defined by the following formula: Specific Capacity (Ah / kg) = Capacity (Ah) / Mass (kg). "Rate Capability" is the ability of an electrochemical cell to accept or deliver a certain amount of energy within a specified period of time. Alternatively, "rate capability" is the maximum continuous or pulsed energy a battery can provide per unit of time.

[0016] "C-rate" is defined herein as a measure of the rate at which a battery is discharged relative to its maximum nominal capacity. For example, a current rate of 1C means that the discharge current discharges the entire battery in 1 hour, a current rate of C / 2 will fully discharge the battery in 2 hours, and a 2C rate will fully discharge the battery in 0.5 hours. "Power" is defined as the time rate of energy transfer measured in watts (W). Power is the product of the voltage (V) across a battery or cell and the current (A) flowing through the battery or cell. Mathematically, "C-rate" is defined as C-rate (inverse time) = current (A) / capacity (Ah) or C-rate (inverse time) = 1 / discharge time (h). Power is defined by the following formula: Power (W) = energy (Wh) / time (h) or Power (W) = current (A) x voltage (V). Coulombic efficiency is the efficiency with which charge is transferred in an electrochemical cell. Coulombic efficiency is the ratio of charge output by a battery to charge input.

[0017] A great deal of development in both commercial and academic environments has focused on designing systems that minimize or accommodate the total volumetric swelling of alloy particles and the associated electrochemical losses. This has typically been approached on two fronts: at the particle level, by engineering particle structures that confine the swelling to small domains to prevent particle rupture and electrical disconnection, and at the electrode level, by engineering polymer matrices and conductive networks that can accommodate the volumetric swelling of the lithium storage material while maintaining their mechanical and electronic integrity during repeated charge-discharge cycles of Li-ion batteries.

[0018] A popular technique for stabilizing the cycle life of anode alloy active materials such as silicon is through blending, encapsulation, or other incorporation with various carbon materials to provide an electronically conductive surface and promote overall electronic conduction across the electrode particle network. These include CVD amorphous carbon coatings, graphene wrapping, and physical blending with graphite, conductive carbon, and carbon nanoplatelets. However, the active material can still swell due to its rigidity and lack of long-range order, and particles can still become isolated, leading to loss of storage capacity and trapped lithium.

[0019] Various embodiments of the present disclosure provide an anode material for a Li-ion battery comprising silicon oxide particles and an amorphous material comprising at least one of boron or phosphorous ("B / P material") coated on and diffused into the core particle, the amorphous material enhancing the cycle life stability of the anode material.

[0020] Silicon Oxide Materials Silicon can greatly increase the capacity of an electrochemical cell when incorporated into the electrode.Silicon and silicon oxide are often incorporated into electrodes that contain graphite, graphene, or other carbon-based active materials.Examples of electrodes that contain carbon-based materials and silicon are described in U.S. Patent Nos. 8,551,650, 8,778,538, and 9,728,773 to Kung et al., and U.S. Patent Nos. 10,135,059 and 10,135,063 to Huang et al., the contents of which are all fully incorporated herein by reference.

[0021] As used herein, "SiO material" may generally refer to silicon and oxygen-containing materials. SiO materials are of interest for use in the anode electrodes of lithium-ion batteries due to their high theoretical energy and power densities. However, current commercially available SiO materials, such as silicon oxides (e.g., SiO x The use of Li2O4 (where x ranges from 0.8 to 1.2, e.g., from 0.9 to 1.1) has been limited by its low first cycle efficiency and high irreversibility. This low first cycle efficiency is due to the high irreversibility of Li2O4 with the silicon oxide matrix. + It is due to a reaction.

[0022] Irreversible Li with SiO materials + To reduce the reaction, various embodiments include metallized (e.g., metal-doped) silicon oxide materials (M-SiO). As used herein, M-SiO materials refer to active materials that react directly with metal-containing precursors, such as lithium-containing precursors and / or magnesium-containing precursors, to form a metallized silicon oxide phase before being utilized as an active material in a battery and / or before undergoing charge and discharge reactions. In other words, the metallized metal remains in the active material and does not intercalate or deintercalate during charging and discharging of the battery. In some embodiments, the battery may be a lithium-ion secondary battery, such as a solid-state lithium-ion battery that includes a solid anode, a solid cathode, and a solid electrolyte.

[0023] In some embodiments, silicon oxide materials of the embodiments may include M-SiO that is metallized (i.e., doped) to include a metal such as Al, Ca, Cu, Fe, K, Li, Mg, Na, Ni, Sn, Ti, Zn, Zr, or any combination thereof. Preferably, M-SiO materials may include lithium-doped (i.e., lithium-metallized) SiO (Li-SiO) materials and / or Mg-doped (i.e., Mg-metallized) SiO (Mg-SiO) materials.

[0024] Electrode materials containing M-SiO active material have been found to provide increased first cycle efficiency (FCE) compared to non-metallized SiO materials. Unfortunately, some M-SiO materials have been found to suffer from particle fracture, severe electrical disconnection, and rapid capacity loss, often dropping more than 90% of capacity within 20 cycles.

[0025] Coating M-SiO materials with carbon and / or other materials and / or blending M-SiO materials with graphite has been found to slightly reduce the electrical disconnection and capacity loss of the active material, delaying the capacity fade by more than 50% by about 50 cycles, but the cycling stability is still very insufficient for commercial applications. Overall, current M-SiO materials do not exhibit sufficient electrical stability for commercialization.

[0026] In addition, Li-SiO xMany conventional M-SiO materials, such as the materials [where x ranges from 0.8 to 1.2, e.g., from 0.9 to 1.1], are not chemically stable. Impurities such as Li2CO3, LiOH, and LiHCO3 may be found on the surface of the Li-SiO anode materials after synthesis. The surface impurities may come from various sources, such as unreacted lithium during sintering of the lithium source precursor with the hydroxide precursor, ion exchange with moisture, and further reaction with CO2 during storage. These impurities may cause problems such as gelling of the slurry required for electrode coating, gassing during storage of Li-ion batteries, and shortened cycle life. In addition, active Si nanoparticles and SiO type materials are not stable when used in high pH environments, limiting some of the electrode or slurry coating procedures that can be used. Especially high pH can promote the dissolution of silicate species in the glass matrix of SiO materials when exposed to water. Conventional CVD carbon coatings cannot prevent this problem.

[0027] The high pH of Li-SiO materials can be of particular concern when used in lithium-ion batteries containing high nickel content cathode materials. High nickel content cathode materials are typically processed in dry rooms to minimize the formation of surface impurities during storage, and "finishing" processes are often used to remove surface impurities after synthesis.

[0028] Thus, there is a need for improved M-SiO materials that provide increased cycle life and improved pH stability.According to various embodiments, the silicon oxide active materials include inorganic surface modifications, coatings and / or dopants that can stabilize the SiO materials.

[0029] Figure 1A is a cross-sectional view of an active material particle 100 according to various embodiments of the present disclosure. Referring to Figure 1A, in various embodiments, the active material 100 may include a core particle 102 and a chemical stability structure (CSS) 110 configured to increase the usable cycle life of the core particle 102. The core particle 102 may include an M-SiO material including metallized silicon species and silicon (e.g., crystalline silicon and / or amorphous silicon). The metallized silicon species may include metallized silicides and metallized silicates. In some embodiments, the M-SiO material may also include silicon oxide (SiO x [wherein x ranges from 0.8 to 1.2, for example, from 0.9 to 1.1]). In various embodiments, the M-SiO material may include lithiated silicon species. As used herein, "lithiated silicon species" may include lithium silicide (Li x Si, 0 < x < 4.4), and / or one or more lithium silicates (such as Li2Si2O5, Li2SiO3, and / or Li4SiO4).

[0030] The active material particle 100 may have an average particle size in the range of about 500 nm to about 20 μm, for example, about 1 μm to about 20 μm, about 1 μm to about 10 μm, about 3 μm to about 7 μm, or about 5 μm. The active material particle 100 may have a surface area in the range of about 0.5 m 2 / g to about 30 m 2 / g, for example, about 1 m 2 / g to about 20 m 2 / g, including about 1.5 m 2 / g to about 15 m 2 / g.

[0031] Chemical stability structure In various embodiments, the CSS 110 may provide unexpected chemical stability to the core particle 102 during the cycling of an electrochemical cell. The usable cycle life of an electrochemical cell is defined as the number of cycles (cycle n) that the cell can cycle while maintaining at least 80% of the initial capacity (i.e., the capacity at 1 cycle).

[0032] The CSS 110 may include materials including one or more elements selected from Group 13 (e.g., boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl)) and / or one or more elements selected from Group 15 (e.g., nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), and bismuth (Bi)), which may be referred to herein as "G13 / G15 materials." In some embodiments, the G13 / G15 materials may include boron and / or phosphorus-containing materials, which may be referred to herein as "B / P materials." For example, the B / P materials may include boron compounds, such as boron oxides (e.g., boron trioxide, BO) and borates (e.g., lithium borate), borosilicates, and / or lithium borosilicates, and / or phosphate compounds, such as lithium phosphates, phosphate silicates, phosphorus oxides, and / or lithium phosphate silicates. For example, suitable boron compounds include boron trioxide (BO), lithium metaborate (LiBO), lithium tetraborate (LiBO), lithium trilithium borate (LiBO), lithium borosilicate (BO-SiO-LiSiO, BO-SiO-LiO, BO-SiO-LiSiO, BO-SiO-LiSiO, or BO-SiO-LiSiO), borosilicate (BO-SiO), and / or combinations of borosilicate with LiSiO, LiSiO, and / or LiSiO. Suitable phosphorus compounds include phosphates (PO), lithium phosphate (LiPO), lithium silicate-lithium phosphate (xLiSiO-(1-x)LiPO), xLiSiO-(1-x)LiPO, xLiSiO-(1-x)LiPO, lithium aluminum borate, lithium borosilicate, lithium phosphosilicate, combinations thereof, etc. In some embodiments, the CSS 110 may include lithium aluminum borosilicate, lithium zirconium borosilicate, lithium niobium borosilicate, combinations thereof, etc.

[0033] However, other boron and / or phosphorus compounds are also included within the scope of the present disclosure. For example, in some embodiments, CSS110 may include a G13 / G15 material that also contains Group 1 elements (e.g., Li, Na, K, Rb, Cs), Group 2 elements (e.g., Be, Mg, Ca, Sr, Ba), and / or Group 4 elements (e.g., Ti, Zr, Hf, Rf) of the periodic table. For example, G13 / G15 materials may include aluminum borosilicate, lithium zirconium borosilicate, lithium niobate borosilicate, and the like. In other embodiments, CSS110 may include a Group 13 (e.g., B, Al, Ga, In, Ti) compound that also contains Group 1 elements (e.g., Li, Na, K, Rb, Cs) and / or Group 2 elements (e.g., Be, Mg, Ca, Sr, Ba).

[0034] In some embodiments, during the formation of CSS110, the G13 / G15 material may react with the natural oxide layer of the core particles. For example, the G13 / G15 material may include B x O y , xLi2O - yB2O3, xSiO2 - yB2O3, and / or xLi2O - ySiO2 - zB2O3 (0 < x ≤ 2, 0 < y ≤ 3, 0 < z ≤ 3). CSS110 may include, consist of, or consist essentially of an amorphous material. In some embodiments, CSS110 may not include, or may be essentially free of, crystal seeds and / or phases. For example, CSS110 may include less than 5 wt% (e.g., 0 - 5 wt%), such as less than 3 wt%, less than 1 wt%, less than 0.5 wt%, or less than 0.25 wt% of crystalline G13 / G15 material. In various embodiments, CSS110 and / or the G13 / G15 material may constitute from about 0.1 wt% to about 10 wt% of the total weight of the active material particles 100, such as from about 1 wt% to about 4 wt%, from about 1.25 wt% to about 2.5 wt%, or from about 1.5 wt% to about 2.0 wt%, and the silicon oxide material of the core particles 102 may constitute from about 95 wt% to about 99.9 wt% of the total weight of the active material particles 100, such as from about 97.5 wt% to about 99 wt%, or from about 98 wt% to about 98.5 wt%.

[0035] In some embodiments, the CSS 110 may include a continuous or discontinuous amorphous coating 110A comprising a G13 / G15 material formed on the surface of the core particle 102. The coating 110A may cover from about 60% to about 100% of the surface area of ​​the core particle 102, for example, from about 60% to about 99%, or from about 61% to about 80% of the surface of the core particle 102. The coating 110A may have an average thickness of from about 0.5 to about 500 nm, for example, from about 0.75 to about 100 nm, or from about 1 nm to about 50 nm. The G13 / G15 material or coating 110A may be at least 50 atomic percent (at %), for example at least 90 at %, at least 95 at %, at least 97 at %, at least 99 at %, at least 99.5 at %, or at least 99.75 at % amorphous.

[0036] Coating 110A can include at least 60% by weight of at least one G13 / G15 material, such as a G13 / G15 material that includes boron or phosphorus. For example, coating 110A can include from about 60 to about 80% by weight of B or P, such as from about 61 to about 70% by weight of P or B.

[0037] In various embodiments, the CSS 110 may include a G13 / G15 material with dopants such as boron and / or phosphorus, which may optionally diffuse into the core particle 102 to form an optional diffusion layer 110B in the silicon oxide material of the core particle 102. The diffusion layer 110B may include a silicon oxide material and a relatively small amount of a G13 / G15 material, such as boron or phosphorus (e.g., less than 5% by weight of boron and / or phosphorus), which diffuses into the core particle 102 to form a silicon oxide layer 110B doped with the G13 / G15 material, such as a silicon oxide layer 110B doped with boron and / or phosphorus. Preferably, the majority of the G13 / G15 material may remain in the coating 110A on the surface of the core particle 102. For example, about 0.1 atomic % to about 5 atomic % of the G13 / G15 material, e.g., about 1 weight % to about 5 weight % of the G13 / G15 material may be diffused into the diffusion layer 110B of the core particle 102, and the coating 110A may contain about 95 to about 99 atomic % of the G13 / G15 material relative to the total amount of G13 / G15 material contained in the active material particle 100.

[0038] The diffusion layer 110B may have a thickness ranging from 0 to about 100 nm, such as from about 10 to about 50 nm, or from about 15 to about 30 nm. In other words, the thickness of the diffusion layer 110B may be comparable to the maximum diffusion depth of the G13 / G15 material.

[0039] According to various embodiments, the active material particles can be prepared by mixing core particles including SiO or M-SiO materials with G13 / G15 material precursors. The core particles can have a particle size as described above with respect to FIG. 1A.

[0040] Suitable G13 / G15 material precursors may include boric acid (HBO), metaboric acid (HBO), boron trioxide (BO), trihydroxyboroxine (BHO), lithium metaborate (LiBO), lithium tetraborate (LiBO), lithium triborate (LiBO), lithium borosilicate (BO-SiO-LiSiO, BO-SiO-LiO), borosilicate (BO-SiO), borates, phosphates, combinations thereof, and the like.

[0041] The mixture may include from about 90% to about 99% by weight, for example, from about 95% to about 98.5% by weight, from about 97% to about 98% by weight, or about 97.5% by weight of silicon oxide particles, based on the total weight of the mixture. The mixture may also include from about 1% to about 90% by weight, for example, from about 5% to about 2.5% by weight, from about 3% to about 2% by weight, or about 2.5% by weight of G13 / G15 material precursor, based on the total weight of the mixture.

[0042] The mixture may be gently mixed by any suitable low shear mixing process, such as mixing in a planetary mixer, for a period ranging from about 5 minutes to about 25 minutes, such as from about 8 minutes to about 15 minutes, or for about 10 minutes. In some embodiments, high shear mixing processes such as ball milling may be avoided to avoid damaging the active material particles. For example, ball milling may break the silicon oxide material particles, which may reduce their electrochemical performance.

[0043] The mixture can then be sintered in an inert atmosphere, such as an argon atmosphere, to form active material particles including a CSS coating on the silicon oxide material core particles. For example, depending on the G13 / G15 material precursor, the mixture can be sintered at a temperature of about 1200° C. or less, for example, about 300° C. to about 1200° C., about 300° C. to about 750° C., or about 300° C. to about 700° C., or about 300° C. to about 650° C., or about 800° C. to about 1200° C., or about 800° C. to about 1100° C., or about 800° C. to about 1000° C., for a period of time ranging from about 1 to about 20 hours, for example, from about 3 to about 7 hours, or from about 4 to about 6 hours. The CSS 110 can include a G13 / G15 material precursor and / or can include a G13 / G15 material formed by reacting a G13 / G15 precursor material with the core particles 102.

[0044] In some embodiments, temperatures up to about 900° C. may be used during the annealing process. However, the inventors have discovered that sintering at temperatures above about 800° C., such as above about 750° C. or above about 700° C., may increase the formation of unstable amounts of unstable residues with high alkalinity and / or may increase the particle size of the silicon, silicon oxide, and lithium silicate phases, making particle fracture more likely. Thus, the G13 / G15 material coating may not form properly on the surface of the core particles and may not provide the full benefits currently described.

[0045] 1B is a cross-sectional view of an active material particle 100A according to various embodiments of the present disclosure. The active material particle 100A may be similar to the active material particle 100. Therefore, only the differences between the two will be described in detail.

[0046] 1B, the active material particle 100A may include a core particle 102 and a CSS 110 disposed thereon. The active material particle 100A may also include a carbon layer 112 disposed between the CSS 110 and the core particle 102. The carbon layer 112 may be formed of a carbon material, such as activated carbon, carbon black, graphene material, and the like. The active material particle 100A may be formed using a similar method to the active material particle 100 of FIG. 1A, except that the carbon layer 112 is first formed on the core particle 102 using any suitable carbon layer coating method, and then the CSS 110 is formed on the carbon layer 112.

[0047] composite particles 1C is a cross-sectional view illustrating an active material encapsulated particle 120 according to various embodiments of the present disclosure. With reference to FIG. 1C, the encapsulated particle 120 may include active material particle 100 or active material particle 100A encapsulated within a graphene material shell 122. The shell 122 may include a flexible, highly conductive graphene material, such as graphene, graphene oxide, partially reduced graphene oxide, or a combination thereof. In some embodiments, the encapsulated particle 120 may further include carbon nanotubes (not shown) disposed on or within the shell 122.

[0048] In various embodiments, the shell 122 can completely encapsulate the active material particle 100 / 100A, as shown in FIG. 1C. However, in some embodiments, the shell 122 may only partially encapsulate the active material particle 100 / 100A. In some embodiments, the shell 122 can represent from about 0.5% to about 20% by weight, such as from about 1% to about 10% by weight, or from about 2% to about 5% by weight, of the total weight of the encapsulated particle 120.

[0049] Shell 122, due to its electrical conductivity, may ensure that active material particle 100 / 100A circulates uniformly in all three dimensions (movement of electrons and Li-ions in and out of the structure), thereby minimizing stress on and exerted by core particle 102 and minimizing particle fracture. Additionally, in the event that active material particle 100 / 100A fractures, flexible shell 122 may function to electrically connect the fractured silicon oxide material of active material particle 100 / 100A and maintain the overall integrity of encapsulated particle 120, thereby resulting in significantly improved electrochemical performance.

[0050] In various embodiments, the encapsulated particle 120 may comprise or consist of about 90 to about 99 wt. % active material, e.g., SiO or M-SiO material, about 0.1 to about 5 wt. %, e.g., about 0.5 to about 3 wt. % G13 / G15 material, 0 to about 5 wt. %, e.g., 0.5 to about 3 wt. % carbon material, about 2 to about 5 wt. % graphene material, and 0 to about 0.3 wt. % carbon nanotubes or other conductive additives, based on the total weight of the encapsulated particle 120. In some embodiments, the encapsulated particle 120 may comprise about 0.5 to about 1.5 wt. %, e.g., about 0.75 to about 1.25 wt. % G13 / G15 material.

[0051] Figure ID is a cross-sectional view illustrating an encapsulated particle 130 according to various embodiments of the present disclosure. With reference to Figure ID, the encapsulated particle 130 may include a core particle 102 and a CSS 110 disposed thereon, as described above with respect to Figure 1A. The encapsulated particle 130 may also include a carbon layer 113 disposed on the CSS 110. The carbon layer 113 may be formed of a carbon material, such as activated carbon, carbon black, graphene material, pyrolytic carbon material, and the like.

[0052] In some embodiments, the carbon layer 113 may be formed by coating the CSS 110-coated core particles 102 with a carbon material using any suitable coating method, such as mechanofusion, spheronization, low shear mixing, chemical vapor deposition, etc. In other embodiments, the carbon layer 113 may be formed by coating the CSS 110-coated core particles 102 with a carbonaceous precursor material including hydrocarbons such as pitch or tar; citric acid; polysaccharides such as sucrose, glucose, or chitosan; polymers such as polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyacrylic acid (PAA), polydopamine (PDA), or polyacrylonitrile (PAN); combinations thereof, etc., using any suitable coating method, such as spray drying, aerosol coating, droplet evaporation, etc. A pyrolysis step may then be performed to pyrolyze the precursor material to form the carbon layer 113. In some embodiments, the precursor material may be applied by spray pyrolysis to directly form the carbon layer 113, and a separate pyrolysis step may be omitted.

[0053] Core Particles 1E is a cross-sectional view of a core particle 102A according to various embodiments of the present disclosure. Referring to FIG. 1E, the core particle 102A can include heterogeneous silicon-containing phases 104, 106, 108. For example, the silicon-containing phases 104, 106, 108 can be, independently, crystalline and / or amorphous silicon, silicon oxide (e.g., SiO x [wherein x ranges from 0.8 to 1.2, e.g., from 0.9 to 1.1], and / or lithiated silicon species. In some embodiments, however, the core particle 102A material may be substantially homogeneous and may lack a distinct phase, but includes silicon, oxygen, and optionally Li and / or Mg.

[0054] FIG. 1F is a cross-sectional view of an active material core particle 102B according to various embodiments of the present disclosure. Referring to FIG. 1F, the core particle 102B may include a primary phase 103 with crystalline silicon regions 105 dispersed as secondary phases. For example, the primary phase 103 may include lithiated silicon species, such as lithium silicate species, and in particular Li2SiO3, Li4SiO4, and Li2Si2O5. In other embodiments, the primary phase 103 may include magnesium metal silicon species, magnesium silicate species, in particular MgSiO3, Mg2SiO4, or combinations thereof. The crystalline silicon regions 105 may include crystalline silicon nanoparticles having a particle size of less than 100 nm. For example, the crystalline silicon regions 105 may have an average particle size ranging from about 3 nm to about 60 nm. In one embodiment, the majority of the crystalline silicon regions 105 may have an average particle size ranging from about 5 nm to about 10 nm, and the remainder of the crystalline silicon regions 105 may have an average particle size ranging from about 10 nm to about 50 nm.

[0055] In some embodiments, the core particles 102B are optionally comprised of SiO 2 dispersed as a secondary phase in the primary phase 103. x Region 107 (e.g., SiO x where x ranges from 0.8 to 1.2, e.g., from 0.9 to 1.1. x Region 107 may have a grain size of less than about 100 nm. For example, SiO x Region 107 may have an average grain size ranging from about 3 nm to about 60 nm, for example, from about 5 nm to about 50 nm.

[0056] 1A-1F, core particles 102A, 102B may be utilized as the core particle 102 described above. In various embodiments, the core particle 102 may represent about 80% to about 99.5% by weight, such as about 90% to about 99% by weight, including about 90% to about 95% by weight, of the total weight of the composite particle 100. In some embodiments, the M-SiO material may include about 40 atomic % to about 5 atomic %, such as about 20 atomic % to about 10 atomic %, or about 15 atomic % of lithiated silicon species. In some embodiments, the M-SiO material of the core particle 102A may include about 60 atomic % to about 95 atomic %, such as about 80 atomic % to about 90 atomic %, or about 85 atomic % of silicon and SiO. x The M-SiO material of the core particle 102 may have a silicon to oxygen atomic weight ratio ranging from about 1.25:1 to about 1:1.25, such as from about 1.1:1 to about 1:1.1, or about 1:1. In some embodiments, the M-SiO material of the core particle 102 may comprise crystalline silicon and SiO of approximately equal atomic weight. x may include.

[0057] During the initial charging reaction and / or subsequent charging reactions, the composition of the M-SiO material of the core particle 102A may change due to lithiation and / or other reactions. For example, Si and SiO x Lithium is added to Li x A Si region can be formed. In addition, some SiO x can form inactive species such as lithium silicate and LiO.

[0058] Turbostratic carbon In various embodiments, the shell 122 may preferably comprise a flexible, highly conductive graphene material with low defect turbostratic properties, which may be referred to as turbostratic carbon. The low defect turbostratic carbon may be in the form of platelets comprising one to about ten layers of graphene material, such as graphene, graphene oxide, or reduced graphene oxide. In some embodiments, the low defect turbostratic carbon may comprise at least 90% by weight, e.g., from about 90% to about 100% by weight graphene. The graphene material may further comprise powders, particles, single layer sheets, multi-layer sheets, flakes, platelets, ribbons, quantum dots, tubes, fullerenes (hollow graphene spheres), or combinations thereof.

[0059] The turbostratic carbon may be in the form of sheets or platelets that overlap to replicate a single sheet structure of a larger size. In some embodiments, the platelets have two or more graphene-based material layers. In some embodiments, the platelets may have a sheet size that may be 15 μm or less on average. In some embodiments, the platelets may have a sheet size that may be 1 μm or less on average. In some embodiments, the turbostratic carbon-based material platelets may have a small thickness. In some embodiments, the small thickness of the turbostratic carbon-based material platelets may be 1 μm or less on average. In some embodiments, the small thickness of the turbostratic carbon-based material platelets may be 100 nm or less on average.

[0060] 2A, 2B, and 2C show the Raman spectra of graphite and various graphene-based materials. -1 , 1584cm -1 , and 2700 cm -1 It is well established that the ion exchange reaction has a characteristic peak at 1340 cm -1 The peak at 1584 cm is shown in Figure 2C and is characterized as the D band. -1 The peak at is shown in the spectra of Figures 2A and 2C and is characterized as the G band, which is due to the sp 2It arises from vibrational modes represented by the C=C bond stretching of every pair of hybridized carbon atoms. The D band originates from hybridized vibrational modes associated with the edges of graphene, indicating the presence of defects or broken symmetry in the graphene structure. 2700 cm -1 The peak at is shown in FIG. 2B and is characterized as a 2D band, which arises from a double resonance process based on the interaction between stacked graphene layers. The appearance of a double peak at the 2D wavenumber breaks the symmetry of the peak and indicates an AB stacking order between graphene planes, e.g., between nanoplatelets, in graphite and graphite derivatives. The 2D1 peak shown in FIG. 1B is suppressed when the AB stacking order of the turbostratic multilayer graphene particles is disturbed. The position of the G band and the 2D band is used to determine the number of layers in the material system. Thus, Raman spectroscopy provides scientific clarity and definition for electrochemical battery carbon material additives and provides a fingerprint for the correct selection as an additive for active material electrode compositions. As shown, the present definition provides a fingerprint for the low defect turbostratic carbon of the present application. It is this low defect turbostratic carbon that provides better electrochemical battery performance when used as an additive to electrochemical battery electrode active material mixes.

[0061] FIG. 3 shows the I of carbon additives (i.e., reduced graphene oxide or amorphous carbon) commonly used in electrode active material mixtures in the prior art. D / I G The ratios are given relative to low defect turbostratic carbon in this application.

[0062] Reduced graphene oxide (rGO) is another form of carbon often referred to in the industry as graphene, but its final structure and manufacturing process make it unique. Graphene oxide is typically manufactured using a modified Hummers process, in which the graphitic material is first oxidized and exfoliated into a single layer or platelet containing several carbon layers that may contain a variety of functional groups, including but not limited to hydroxyl, epoxide, carbonyl, and carboxyl. These functional groups are then removed by chemical or thermal treatments that convert the insulating graphene oxide into conductive reduced graphene oxide. Reduced graphene oxide is similar to graphene in that it consists of a single layer of a carbon atom lattice, but differs in that it has mixed sp2 and sp3 hybridization, residual functional groups, and often increased defect density resulting from the manufacturing and reduction process. Reduced graphene oxide is shown in the first bar of Figure 3 and has an I of 0.9. D / I G The ratio is:

[0063] Amorphous carbon is often used as an additive or surface coating for both anode and cathode material combinations in electrochemical cells to enhance the electrical conductivity of the electrodes. Typically, amorphous carbon is produced using a chemical vapor deposition (CVD) process, in which a hydrocarbon feed gas is flowed into a closed vessel and carbonized onto the surface of the desired powder material at high temperatures. This pyrolysis process can provide a thin amorphous carbon coating on the order of a few nanometers thick that is completely devoid of sp2 hybridization as found in crystalline graphene-based materials. Amorphous carbon is shown in the third bar of Figure 3 and has an I of greater than 1.2. D / I G The ratio is:

[0064] Low defect turbostratic carbon, also called graphene, has unique properties resulting from its manufacturing process. One common way to manufacture this material is by plasma-based CVD process, where a hydrocarbon feedstock gas is fed through an inert gas plasma in the presence of a catalyst that can nucleate graphene-like carbon structures. By controlling the manufacturing parameters, carbon materials with few layers and no AB stacking order between lattices can be manufactured. These carbon materials are typically highly ordered sp2 carbon lattices with low defect density.

[0065] The low defect turbostratic carbon of the present disclosure is shown in the second bar in the center of Figure 3. The Raman spectrum of the low defect turbostratic carbon additive of the present application shows the intensity ratio of the D band to the G band (I D / I G ) and the intensity ratio between the 2D band and the G band (I 2D / I G ) is derived from I D , I 2D , and I G are expressed by their respective integrated intensities. D / I G The ratio indicates a low defect material. The low defect turbostratic carbon material of the present invention has a peak at 1580 and 1600 cm -1 I at wave numbers in the range between G , 1330 and 1360cm -1 I at wave numbers in the range between D and an I of greater than 0 and less than or equal to about 0.8, as measured using an incident laser wavelength of 532 nm. D / I G Furthermore, the low defect turbostratic carbon material of the present disclosure has an I ratio of about 0.4 or more. 2D / I G Show the ratio. I 2D / I G As a reference for the ratio, typically, I is about 2. 2D / I G The ratio is related to single-layer graphene. I less than about 0.4 2D / I GThe ratio is usually associated with bulk graphite consisting of many AB-stacked graphene layers. Thus, an I of about 0.4 or greater for the low defect turbostratic carbon materials of the present disclosure. 2D / I G The ratio indicates a low layer count of 10 or less. Low-defect turbostratic carbon materials with low layer counts further lack the AB stacking order between the graphene layers (i.e., turbostratic). The turbostratic nature or lack of AB stacking in these graphene planes is due to the I 2D What distinguishes turbostratic and AB-stacked graphene layered materials is the symmetry of the 2D peaks, which indicates the disorder of the rotated stacking versus the order of the layered stacking.

[0066] Carbon materials with high AB stacking order still exhibit 2D peaks, but these 2D peaks exhibit doublets that break the symmetry of the peaks. This break in symmetry is exhibited in both few-layer AB-stacked graphene or many-layer graphite. Therefore, the 2D peak, which is a very strong indicator of the presence of stacking order, regardless of the number of graphene layers present in the material, is important when selecting graphene or graphene-based additives. It is the rotational disorder of stacking in this carbon that distinguishes the low-defect turbostratic carbon of the present disclosure from all other graphene or graphene-based additives used to date. Because the rotational disorder of the low-defect turbostratic carbon stacking of the present application provides flexibility to the carbon-based particles of the present application, thereby enabling them to provide and maintain contact with the active core particles of the composite particles that make up the electrodes of the electrochemical cell. The result is an electrochemical cell with increased cycle life, better cycle life stability, improved energy density, and better high-rate performance.

[0067] FIG. 4A is a graph of the Raman spectrum of an active material mix containing SiO material particles coated with an amorphous carbon material. FIG. 4B is a graph of the Raman spectrum of an active material mix containing SiO material core particles encapsulated by rGO. FIG. 4C is a graph showing the Raman spectrum of an active material mix containing SiO material core particles encapsulated by low defect turbostratic carbon. Layer thickness (wavelength 2700 cm -1 size, shape, and position of the 2D peak near 1340 cm -1 Each spectrum is different because the size of the nearby D peaks (the size of the peaks) is different.

[0068] Preparation of the Raman analysis samples involved taking small aliquots of powders such as active material powders, composite material powders, and carbon material powders, and placing these powders individually into clean glass vials. The sample powders are rinsed with methanol. The powder / methanol solution is then vortexed briefly and sonicated for approximately 10 minutes. The suspension is then transferred to a glass slide with a micropipette. The slide is then allowed to air dry completely before analysis is performed.

[0069] The Raman spectroscopy of this application is performed using confocal Raman spectroscopy on a Bruker Senterra Raman system under the following test conditions: 532 nm laser, 0.02 mW, 50x objective, 90 s integration time, 50 × 1000 μm aperture, and 9–18 cm -1 Three co-additions (three Raman spectroscopy sample runs) using a resolution of 100 nm. For reference, the D band is not active in Raman scattering in perfect crystals. The D band becomes Raman active in defective graphitic materials by a defect-induced double-resonance Raman scattering process involving π-π electronic transitions. The intensity of the D band relative to the G band increases with the degree of disorder. Thus, the intensity I D / I G The ratio can be used to characterize the graphene material.

[0070] Both the D and G bands of amorphous carbon shown in FIG. 4A are more intense than either the D and G bands of reduced graphene oxide (rGO) in FIG. 4B or the D and G bands of turbostratic carbon in FIG. 4C. Amorphous carbon has a significantly higher I D / I G The spectrum of amorphous carbon also exhibits a ratio (1.25). The suppressed intensity of the G band of amorphous carbon compared to that of the D band reflects the lack of crystallinity within its carbon structure (also known as the nature of graphitic). The higher D peak intensity than the G peak intensity is caused by a higher amount of defects in the amorphous carbon network. Thus, the spectrum of amorphous carbon exhibits a lower degree of crystallinity and a much higher degree of disorder in its graphitic network compared to more crystalline carbons such as graphene, graphene oxide, and rGO. Furthermore, its higher D peak intensity compared to the G peak of rGO, as well as the D and G peak intensities and I of turbostratic carbon, D / I G The I of rGO is higher compared to the ratio D / I G The ratio (almost double) indicates that rGO has more defects than the turbostratic carbon of the present application.

[0071] Table 1 below details the Raman spectra of Figures 4A-4C.

[0072] [Table 1]

[0073] Careful examination of these spectra indicates that increasing disorder broadens the D band and changes the relative intensities of the bands. For the amorphous carbon coated sample, the intense (6194.8) and broad D peak indicates a large amount of defects. The intensity of the G peak (4908.2) is lower than the D peak (6194.8), indicating a lack of crystallinity. The D peak intensities (9115.5) and G peak intensities (10033.3) for the rGO encapsulated sample are very similar. However, it is noteworthy that the D peak intensity (9115.5) of the rGO sample is much higher than the D peak intensity (2915.3) of the turbostratic carbon sample, indicating that the rGO sample has a much higher defect density than the turbostratic carbon sample. Also noteworthy is that the G bands of the amorphous carbon and rGO samples are at wavelengths of 1589.4 cm, respectively. -1 and 1597.82 cm -1 and wavelength 1584 cm -1 , and the G band of the turbostratic carbon sample is shifted to the right at 1581.32 cm -1 1584cm -1 Importantly, unlike the amorphous carbon and rGO samples, the turbostratic carbon (in this case the graphene sample) exhibits little, if any, position shift, reflecting fewer defects in it, making the turbostratic carbon sample more closely resemble a nearly "perfect" turbostratic carbon material.

[0074] electrode material Various embodiments of the present disclosure provide electrode materials, and in particular anode electrode compositions, for Li-ion batteries. The electrode materials may include the above-mentioned active materials, binders, and optionally single-walled carbon nanotubes (SWCNTs). The active materials may include the above-mentioned active material particles 100 or 100A, or encapsulated particles 120 (i.e., containing active material particles 100 or 100A encapsulated within a shell 122), and optionally additional graphite particles. In some embodiments, the electrode materials may optionally include conductive additives, such as carbon black. The active materials and graphite particles may be mixed together. The carbon black particles may be smaller (i.e., have a smaller diameter) than the silicon oxide particles and graphite particles, and may be located between and / or on the surface of the silicon oxide particles and / or graphite particles. The SWCNTs may extend between the mixture of silicon oxide particles and graphite particles to provide long-range conductivity across multiple active particles.

[0075] The electrode material may include an active material comprising a SiO or M-SiO material core particle, and a G13 / G15 material coated thereon, and optionally boron and / or phosphorus diffused into the core particle, as described above. Thus, the core particle may include silicon, metal silicate, and silicon oxide phases, and optional lithiated silicon species, and the coatings described above and / or diffusion layers comprising boron and / or phosphorus. The active material particles may include an optional carbon coating, or the carbon coating may be omitted.

[0076] The active material may have an average particle size ranging from about 1 μm to about 20 μm, for example, from about 1 μm to about 15 μm, from about 3 μm to about 10 μm, or from about 5 μm to about 8 μm. 2 / g to about 30m 2 / g, for example, about 1m 2 / g to about 20m 2 / g, including about 1.5 m 2 / g to about 15m2 / g is included.

[0077] The electrode material can include at least 65% by weight active material, such as from about 70% to about 98% by weight, from about 70% to about 90% by weight, or about 75% by weight active material.

[0078] The electrode material may optionally include graphite particles. For example, the electrode material may include about 0% to about 97% by weight, e.g., about 50% to about 95% by weight, about 5% to about 35% by weight, about 10% to about 30% by weight, or about 15% to about 25% by weight of graphite particles, and about 3% to about 100% by weight, e.g., about 5% to about 50% by weight, about 95% to about 65% by weight, 90% to about 70% by weight, or about 85% to about 75% by weight of active material particles. It should be noted that graphite may also function as an active material during battery operation. However, for clarity of description, the active material particles are described herein separately from the graphite particles.

[0079] The graphite may include graphite particles of synthetic or natural origin. The graphite may have an average particle size ranging from about 2 μm to about 30 μm, such as from about 10 μm to about 20 μm, including from about 12 μm to about 18 μm. In one embodiment, the average particle size of the graphite particles may be greater than the average particle size of the silicon oxide active material particles 100. The graphite particles may have an average particle size of about 0.5 μm to about 18 μm. 2 / g to about 2.5m 2 / g, for example, about 1m 2 / g to about 2m 2 The graphite particles 130 may be larger than the silicon oxide particles.

[0080] The electrode material may include any suitable electrode material binder. For example, the electrode material may include a polymer binder, such as polyvinylidene fluoride (PVDF), carboxymethylcellulose Na (CMC), styrene butadiene rubber (SBR), polyacrylic acid (PAA), lithium polyacrylate (LiPAA), combinations thereof, and the like. In some embodiments, the binder may include a combination of CMC and SBR, where the CMC has a molecular weight of 250 to 850 g / mol and a degree of substitution of 0.65 to 0.9.

[0081] In various embodiments, the electrode material may include from about 1% to about 12% by weight, such as from about 2% to about 10% by weight, or from about 2% to about 8% by weight of a binder. In some embodiments, the electrode material may include from about 95% to about 98% by weight of an active material, from about 1% to about 2% by weight of a conductive agent, and from about 2% to about 4% by weight of a binder, which may include CMC and SBR.

[0082] In some embodiments, the SWCNTs may have an average length greater than about 1 μm. For example, the SWCNTs may have an average length ranging from about 1 μm to about 500 μm, e.g., from about 1 μm to about 10 μm. The SWCNTs may have an average diameter ranging from about 0.5 nm to about 2.5 nm, e.g., from about 1 nm to about 2 nm.

[0083] SWCNTs have a wavelength of 1580-1600 cm -1 related to the Raman intensity at wavenumber I G , and 1330-1360 cm -1 related to the Raman intensity at wavenumber I D and an I of greater than about 5, e.g., greater than about 6 or greater than about 10, as measured using an incident laser wavelength of 633 nm. G / I D The ratio may be:

[0084] In various embodiments, the electrode material can include from about 0 to about 1 wt. % SWCTN, for example, from about 0.075 to about 0.9 wt. %, from about 0.08 to about 0.25 wt. %, or about 0.1 wt. %.

[0085] The conductive additive may include carbon black (e.g., KETJENBLACK or Super-P carbon black), low defect turbostratic carbon, acetylene black, channel black, furnace black, lamp black, thermal black, or a combination thereof. The conductive additive may optionally include 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 polyphenylene derivatives, conductive polymers, or a combination thereof.

[0086] In various embodiments, the electrode material may include 0 to about 10% by weight of a conductive additive, such as about 0.25% to about 7% by weight, about 2% to about 7% by weight, or about 5% by weight. In some embodiments, the conductive additive may preferably include carbon black.

[0087] Anode Formation According to various embodiments, the anode may be formed using any suitable method known to those skilled in the art. For example, active material particles (e.g., SiO material and / or M-SiO material particles with CSS as described above) may be mixed with graphite particles to form the active material. In one embodiment, the active material may include less than 50% silicon oxide and more than 50% graphite by weight. The active material may be mixed with a binder and optional SWCNTs and / or conductive additives to form a solid component. In some embodiments, the silicon oxide particles may be encapsulated with turbostratic carbon shells 122, for example, using a spray drying process, prior to forming the active material. Alternatively, the shell 122 may be omitted.

[0088] The solid components can be mixed in a polar solvent, such as water or N-methyl-2-pyrrolidone (NMP), at a solids loading of between about 20 and about 60% by weight to form the electrode slurry. For example, mixing can include using a planetary mixer and high shear dispersing blades under vacuum.

[0089] The electrode slurry can be coated onto a metal substrate, such as a copper or stainless steel substrate, at an appropriate mass loading to balance the lithium capacity of the anode and the lithium capacity of the cathode selected. Coating can be performed using a variety of equipment, such as a doctor blade, comma coater, gravure coater, slot die coater, etc.

[0090] After coating, the slurry can be dried to form the anode. For example, the slurry can be dried under forced air at a temperature ranging from room temperature to about 120° C. The dried slurry can be pressed to reduce internal porosity, and the electrode can be cut to the desired shape. Typical anode press densities can range from about 1.0 g / cc to about 1.7 g / cc, depending on the electrode composition and target application. Cathode press densities can range from about 2.7 to about 4.7 g / cc.

[0091] In some embodiments, the active material particles may be coated with turbostratic carbon prior to forming the active material. For example, a mixture of silicon oxide particles, turbostratic carbon and a solvent may be spray dried to form a powder, and the powder may then be heat treated in an inert atmosphere, such as argon gas, to carbonize any remaining surfactants or dispersants. In other embodiments, the silicon oxide particles may be coated with turbostratic carbon using a binder and a mechanofusion process.

[0092] Electrochemical Cell Assembly The construction of an electrochemical cell involves pairing a coated anode substrate and a coated cathode substrate, electronically insulated from each other by a polymeric and / or ceramic electrically insulating separator. The electrode assembly is sealed within a housing, which may be of various configurations, such as, but not limited to, a coin cell, a pouch cell, or a can cell, and contains a non-aqueous, ionically conductive electrolyte operatively associated with the anode and the cathode. The electrolyte consists of an inorganic salt dissolved in a non-aqueous solvent, more preferably an alkali metal salt dissolved in a mixture of a low viscosity solvent, including organic esters, ethers, and dialkyl carbonates, and a highly conductive solvent, including cyclic carbonates, cyclic esters, and cyclic amides. Non-limiting examples of electrolytes can include lithium hexafluorophosphate (LiPF6) or lithium bis(fluorosulfonyl)imide (LiFSi) salts in an organic solvent, including one of ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), fluoroethylene carbonate (FEC), or a combination thereof.

[0093] Additional solvents useful in embodiments of the present invention include dialkyl carbonates such as tetrahydrofuran (THF), methyl acetate (MA), diglyme, trigylum, tetragylum, 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), butylene carbonate, acetonitrile, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, gamma-valerolactone, gamma-butyrolactone (GBL), N-methyl-2-pyrrolidone (NMP), and combinations thereof.

[0094] The electrolyte may also include one or more additives, such as vinylene carbonate (VC), 1,3-propanesulfone (PS), prop-1-ene-1,3-sultone (PES), fluoroethylene carbonate (FEC), and / or propylene carbonate (PC). The electrolyte serves as a medium for the transfer of lithium ions between the anode and cathode during the electrochemical reactions of the battery, particularly during discharging and recharging of the battery. The electrochemical cell may also have positive and negative terminals and / or contact structures.

[0095] In some embodiments, the electrolyte may be a solid electrolyte including Li-B silicate and / or Li-silicate. EXAMPLES

[0096] Experimental Example The following experimental examples relate to anodes formed using various embodiment electrode materials and comparative electrode materials of the present disclosure and are provided by way of illustration and not by way of limitation, where % is weight percent, g is grams, CE is coulombic efficiency, and mAh / g is capacity.

[0097] Exemplary anode active material: 2.5 grams of boric acid powder is mixed gently with 97.5 grams of Li-SiO material powder in a planetary mixer for 10 minutes. The resulting mixture is then heated in a furnace in an Ar atmosphere for 5 hours to remove residual water, and the mixture is sintered to form an exemplary anode active material including Li-SiO material particles modified with chemically stable structures (CSS).

[0098] Control active material: Li-SiO anode powder without CSS is used as the control active material.

[0099] Exemplary Half-Cell: 0.75 grams of exemplary anode active material, 0.05 grams of conductive agent (C65 carbon black), and 0.20 grams of aqueous binder (10.1 wt% poly(acrylic acid)) are combined in a small mixing jar. The combined materials are then vigorously mixed in a planetary mixer for 30 minutes to form an anode slurry. This anode slurry is coated onto copper foil with a capacity of 3 mAh / cm2 and an electrode density of 1.4-1.5 g / cc. The coating is dried, calendared to a porosity of 40-45%, and then cut to form the anode. The anode is assembled into a half-cell (excess counter electrode material = lithium metal) and 100 microliters of electrolyte (1.2M LiPF6, EC:EMC=3:7, with 20 wt% FEC additive) is injected into the cell. The cell is electrochemically "formed" with charge-discharge cycles of C / 20, C / 10, and C / 5 to complete the exemplary half-cell.

[0100] Comparative half-cell: 0.75 grams of control Li-SiO anode active material, 0.05 grams of conductive agent (C65 carbon black), and 0.20 grams of aqueous binder (Li-poly(acrylic acid) 10.1 wt%) are combined in a small mixing jar. The combined materials are then vigorously mixed in a planetary mixer for 30 minutes to form an anode slurry. This anode slurry is coated onto copper foil with a capacity of 3 mAh / cm2 and an electrode density of 1.4-1.5 g / cc. The coating is dried and calendared to a porosity of 40-45%, then cut to form the anode. The anode is assembled into a half-cell (excess counter electrode material = lithium metal) and 100 μL of electrolyte (1.2 M LiPF6, EC:EMC=3:7, with 20 wt% FEC additive) is injected into the cell. The cell is electrochemically "formed" by cycling at C / 20, C / 10, and C / 5 to form a control half-cell.

[0101] The exemplary and comparative half-cells were characterized under a standard C / 2 charge-discharge protocol until the anode capacity of each cell decreased to 80% of its initial capacity. The cycling performance of the cells is shown in FIG. 5 and summarized in Table 2 below.

[0102] [Table 2]

[0103] As shown in FIG. 5 and Table 2, the exemplary half-cell containing the surface-modified Li—SiO active material has a higher first cycle efficiency and 640% higher 50th cycle capacity retention than the comparative half-cell.

[0104] 6 is a graph showing the pH of the exemplary and comparative active materials over time when dispersed in water. In particular, four mixtures are prepared containing 0.5 g of the exemplary or comparative active materials dispersed in 25 g of DI water (2 wt % solids) at room temperature. The pH values ​​of the mixtures are measured after 1, 2, 10, 30, and 60 minutes. Table 3 shows the results of the testing.

[0105] [Table 3]

[0106] As can be seen in FIG. 6 and Table 3, the exemplary active materials had significantly lower pH and significantly less pH change over time than the comparative active materials.

[0107] 7A is a graph showing X-ray diffraction (XRD) results for an exemplary active material compared to a control active material and crystalline Li2B4O7, and FIG 7B is a graph showing XRD data for an exemplary active material and crystalline B4C.

[0108] As seen in Figure 7A, the results show that the formation of CSS in the exemplary active material results in very little change in the crystallinity and structure of the particles. Furthermore, no lithium tetraborate phase was detected in either the exemplary or comparative active materials. As seen in Figure 7B, the results show no presence of boron carbide in the exemplary active material. Thus, the active material may contain less than 0.5 atomic %, such as less than 0.1 atomic %, of carbide material, for example, no carbide material at all.

[0109] Figure 8A is a graph showing the capacity retention of a half-cell including an anode with an exemplary active material, carbon black, and PAA binder in a weight ratio of 75:5:20, and a comparative half-cell including an anode with a comparative active material including Si nanoparticles and CSS, carbon black, and PAA binder in a weight ratio of 75:5:20. Figure 8B is a graph showing XRD results of the exemplary and comparative active materials.

[0110] As can be seen in Figure 8A, the exemplary half-cell has about 75% capacity retention after 50 charge / discharge cycles. In contrast, the comparative half-cell shows a rapid loss of capacity, with zero capacity retention after 25 charge / discharge cycles. Thus, the use of silicon oxide nanoparticles and CSS unexpectedly improves capacity retention compared to the use of an active material including silicon nanoparticles and CSS.

[0111] Referring to Figure 8B, it can be seen that the exemplary active material contains substantially less silicon phase than the comparative active material. Furthermore, there is no evidence of borate formation in the comparative active material. Therefore, it can be concluded that the CSS layers of both the exemplary and comparative active materials are amorphous.

[0112] Therefore, the active material of the present embodiment is believed to include amorphous G13 / G15 material that does not have a significant amount of crystallinity. Without wishing to be bound by any particular theory, the inventors believe that coating the active material with crystalline G13 / G15 material may hinder the diffusion of lithium during charging and discharging of the active material. If the diffusion of lithium is hindered, the fast charging and charging rate performance may be reduced. Furthermore, if the diffusion of lithium is hindered, the internal resistance in the battery may increase and the operating temperature of the battery may increase, which may also increase the risk of the battery exploding and significantly reduce the cycle life.

[0113] It is also believed that diffusion of boron and / or phosphorus from the G13 / G15 materials into the active material particles may unexpectedly result in improved electrical conductivity, potentially improving the charge rate capability of electrochemical cells.

[0114] Furthermore, by using prelithiated Li-SiO material core particles, it is not necessary to remove the native oxide from the core particles prior to lithiation. Finally, it is believed that the relatively high sintering temperatures ranging from about 300° C. to about 800° C. localize most of the G13 / G15 material at the surface of the core particles, and diffuse B and / or P into the surface region of the core particles.

[0115] Although the above content refers to certain preferred embodiments, it will be understood that the present invention is not so limited. Those skilled in the art will recognize that various modifications can be made to the disclosed embodiments and that such modifications are intended to be within the scope of the present invention. All publications, patent applications, and patents cited herein are incorporated herein by reference in their entirety.

Claims

1. 1. An active material for a lithium ion secondary battery, comprising: core particles comprising a SiO material or an M-SiOx material, where 0<x<1.2 and M is selected from Al, Ca, Cu, Fe, K, Li, Mg, Na, Ni, Sn, Ti, Zn, Zr, or any combination thereof; an amorphous Group 13 or Group 15 material ("G13 / G15 material") comprising at least one element selected from boron (B), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), or bismuth (Bi), coated on a core particle; An active material comprising:

2. each active material particle further comprises a shell, said shell encapsulating said core particle; 1330 cm －１ and 1360 cm －１ The peak intensity (I Ｄ ) D band having 1580 cm －１ and 1600 cm －１ The peak intensity (I Ｇ ) G band, and 2650 cm －１ and 2750 cm －１ The peak intensity (I ２Ｄ ) 2D bands having I Ｄ / I Ｇ the ratio is in the range of from greater than 0 to about 1.1; I ２Ｄ / I Ｇ The ratio is in the range of about 0.4 to about 2.

10. The active material of claim 1 comprising turbostratic carbon having a Raman spectrum.

3. 10. The active material of claim 1, further comprising a carbon layer disposed between the G13 / G15 material and the core particle, the carbon layer comprising pyrolytic carbon, activated carbon, or carbon black.

4. 4. The active material of claim 3, wherein the G13 / G15 material covers at least 60% of the surface of the core particle.

5. 2. The active material of claim 1, wherein about 0.1 atomic % to about 5 atomic % of the G13 / G15 material is diffused into the core particles and about 95 atomic % to about 99 atomic % of the G13 / G15 material remains on the surface of the core particles.

6. the G13 / G15 material is at least 50 atomic % amorphous; the active material comprises less than 0.5 atomic percent of a carbide material; and 10. The active material of claim 1, wherein the G13 / G15 material comprises boron oxide, borate, borosilicate, lithium borosilicate, lithium phosphate, phosphate silicate, phosphorus oxide, lithium phosphate silicate, or a combination thereof.

7. With respect to the total weight of the active material, from about 90% to about 99% by weight of said core particles; about 0.1% to about 10% by weight of said G13 / G15 material; 0 to about 5 wt. % carbon material disposed between the G13 / G15 material and the core particle; about 0 wt % to about 5 wt % graphene material encapsulating the core particles; 0 to about 3 wt. % of a conductive additive; The active material of claim 1 comprising:

8. the core particles have an average particle size ranging from about 500 nanometers to about 20 microns; 10. The active material of claim 1, wherein the G13 / G15 material is coated to a thickness ranging from about 0.5 nm to about 500 nm.

9. the core particle comprises M-SiO, M contains Li; 2. The active material of claim 1, wherein the M-SiO comprises at least one of crystalline or amorphous silicon regions, lithiated silicon species regions, and silicon oxide regions comprising SiO, where y is in the range of 0.8 to 1.

2.

10. the G13 / G15 material comprises boron oxide, borate, borosilicate, lithium borosilicate, or a combination thereof; The M-SiO ２ Si ２ O ５ , Li ２ SiO ３ , Li ４ SiO ４ 10. The active material of claim 9, comprising a lithiated silicon species domain comprising:

11. the G13 / G15 material comprises lithium phosphate, phosphate silicate, phosphorus oxide, lithium phosphate silicate, or a combination thereof; The M-SiO ２ Si ２ O ５ , Li ２ SiO ３ , Li ４ SiO ４ 10. The active material of claim 9, comprising a lithiated silicon species domain comprising:

12. The core particle comprises a crystalline or amorphous silicon region and a SiO ｙ 10. The active material of claim 1, comprising at least one silicon oxide region comprising: wherein y is in the range of from 0.8 to 1.

2.

13. an anode comprising an electrode material comprising the active material of claim 1 and a binder; A separator; a cathode; an electrolyte disposed between the anode and the cathode; Including, The electrode material contains, relative to the total weight of the active material, about 0.3% to about 30% by weight of said binder; from about 0.01 wt % to about 20 wt % of a conductive additive; about 0% to about 97% by weight of graphite particles; about 3% to about 100% by weight of active material; a lithium-ion secondary battery,

14. 1. A method of forming an active material for a lithium ion secondary battery, comprising: mixing about 1 wt. % to about 10 wt. % precursor material comprising at least one of boron or phosphorus with about 90 wt. % to about 99 wt. % SiO or M-SiO material core particles, where M is selected from Al, Cu, Fe, K, Li, Mg, Na, Ni, Sn, Ti, Zn, Zr, or any combination thereof, and coating the core particles with the precursor material; sintering the coated core particles in an inert atmosphere to form active material particles comprising the core particles and an amorphous Group 13 or Group 15 material ("G13 / G15 material") coated on the core particles, the amorphous Group 13 or Group 15 material comprising at least one element selected from boron (B), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), or bismuth (Bi); A method comprising:

15. the mixing step includes using a low shear mixing process; the G13 / G15 material comprises boron oxide, borate, borosilicate, lithium borosilicate, lithium phosphate, phosphate silicate, phosphorus oxide, lithium phosphate silicate, or a combination thereof; and The method comprises the steps of: mixing the active material particles with a solvent and a carbon precursor material to form a mixture; evaporating the mixture to encapsulate the active material particles within a shell comprising a carbon-based material; further comprising The method of claim 14 , wherein the sintering step comprises pyrolyzing the carbon precursor material.

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