Electroactive material for metal-ion battery

Abstract

To provide an electroactive material and a method for preparing the same.SOLUTION: Electroactive particles have a porous particle skeleton with a total pore volume of pores having pore diameters ranging from 3.5 to 100 nm ranging from 0.3 to 2.4 cm3 per gram of porous particle skeleton. The pores of the porous particles are at least partially occupied by a multilayer coating disposed on the interior pore surfaces of the porous particle skeleton. The multilayer coating includes at least a first electroactive material layer, a second electroactive material layer, and a first intermediate layer material disposed between the first and second electroactive material layers.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This application relates generally to electroactive materials suitable for use in electrodes for rechargeable metal-ion batteries, and more particularly to particulate materials having high electrochemical capacity suitable for use as anode active materials in rechargeable metal-ion batteries. [Background technology]

[0002] Rechargeable metal-ion batteries are widely used in portable electronic devices such as mobile phones and laptops, and are increasingly being applied to electric and hybrid vehicles. Rechargeable metal-ion batteries generally have an anode in the form of a metal current collector with a layer of electroactive material, which is defined as a material that can insert and release metal ions during charging and discharging of the battery. The terms "cathode" and "anode" are used to refer to a battery placed across a load, with the anode being the negative electrode. When a metal-ion battery is charged, metal ions are transported from the metal-ion-containing cathode layer to the anode through the electrolyte and inserted into the anode material. The term "battery" is used to refer to both devices containing a single anode and a single cathode, as well as devices containing multiple anodes and / or multiple cathodes.

[0003] There is considerable interest in improving the gravimetric and / or volumetric capacity of rechargeable metal-ion batteries. To date, commercially available lithium-ion batteries have been primarily limited to using graphite as the anode active material. When a graphite anode is charged, lithium intercalates between the graphite layers, forming a charge-discharge charge according to the empirical formula Li xC6 (where x is greater than 0 and less than or equal to 1). As a result, graphite exhibits a maximum theoretical capacity of 372 mAh / g in lithium-ion batteries, although actual capacities are somewhat lower (approximately 340-360 mAh / g). Other materials, such as silicon, tin, and germanium, can intercalate lithium at significantly higher capacities than graphite, but are not widely used commercially due to the difficulty of maintaining sufficient capacity over charge / discharge cycles.

[0004] In particular, silicon has been identified as a promising alternative to graphite for the production of rechargeable metal-ion batteries with high gravimetric and volumetric capacities due to its extremely high capacity for lithium (see, for example, Winter, M. et al., "Intercalation Electrode Materials for Rechargeable Lithium Batteries," Adv. Mater. 1998, 10, No. 10). At room temperature, silicon has a capacity of about 3,600 mAh / g (Li 15 Silicon anodes have the theoretical maximum specific capacity for lithium-ion batteries (based on silicon). However, the intercalation of lithium into bulk silicon results in the volume of the silicon material increasing to 400% of its original volume when the silicon is lithiated to its maximum capacity. Repeated charge-discharge cycles create significant mechanical stresses on the silicon material, resulting in fracture and delamination of the silicon anode material. The volumetric shrinkage of silicon particles during delithiation leads to loss of electrical contact between the anode material and the current collector. Another problem is that the solid electrolyte interphase (SEI) layer that forms on the silicon surface does not have sufficient mechanical tolerance to accommodate the expansion and contraction of silicon. As a result, the newly exposed silicon surface causes further electrolyte decomposition and an increase in the thickness of the SEI layer, resulting in irreversible consumption of lithium. These failure mechanisms collectively lead to unacceptable electrochemical capacity loss over successive charge-discharge cycles.

[0005] Many approaches have been proposed to overcome the problems associated with volume changes observed during charging of silicon-containing anodes. It has been reported that small silicon structures with cross sections of 150 nm or less, such as silicon films and silicon nanoparticles, are more resistant to volume changes during charging and discharging than micron-sized silicon particles. However, none of these, in their unmodified form, are suitable for commercial-scale applications; nanoscale particles are difficult to prepare and handle, and silicon thin films do not provide sufficient bulk capacitance.

[0006] WO 2007 / 083155 discloses that improved capacity retention can be achieved with silicon particles with high aspect ratios, i.e., silicon particles with a high ratio of the particle's maximum dimension to its minimum dimension. The small cross-section of such particles reduces structural stress on the material due to volume changes during charging and discharging. However, such particles are difficult, costly, and fragile to manufacture. Furthermore, the large surface area can lead to excessive SEI formation, resulting in excessive capacity loss during the first charge-discharge cycle.

[0007] It is also generally known that electroactive materials such as silicon can be deposited within the pores of porous carrier materials, such as activated carbon materials. These composite materials avoid the handling problems of nanoparticles while providing some of the beneficial charge-discharge properties of nanoscale silicon particles. Guo et al. (Journal of Materials Chemistry A, 2013, pp. 14075-14079) disclose silicon-carbon composite materials in which a porous carbon substrate provides a conductive framework with silicon nanoparticles deposited within the pore structure of the substrate with a uniform distribution. While the composite materials show improved capacity retention over multiple charge cycles, the initial capacity of the composites in mAh / g is shown to be significantly lower than that of silicon nanoparticles. Summary of the Invention [Problem to be solved by the invention]

[0008] The present inventors have previously reported the development of a class of electroactive materials having a composite structure in which a nanoscale electroactive material, such as silicon, is deposited within the pore network of a highly porosity porous, conductive particulate material, such as a porous carbon material.

[0009] For example, International Publication Nos. 2020 / 095067 and 2020 / 128495 report that the improved electrochemical properties of these materials are due to the way in which the electroactive material is arranged in the porous material in the form of small domains with dimensions of a few nanometers or less. These fine electroactive structures are believed to have lower resistance to elastic deformation and higher fracture resistance than larger electroactive structures, and therefore are capable of lithiation and delithiation in the absence of excessive structural stress. As a result, the electroactive materials exhibit good reversible capacity retention over multiple charge-discharge cycles. Second, by controlling the loading of silicon within the porous carbon framework, only a portion of the pore volume is occupied by silicon in the uncharged state, and the unoccupied pore volume of the porous particle framework can accommodate a significant expansion of the silicon. Furthermore, as mentioned above, by arranging nanoscale silicon domains within small mesopores and / or micropores, only a small area of ​​the silicon surface is accessible to the electrolyte, limiting the formation of an SEI. Further exposure of silicon during subsequent charge-discharge cycles is substantially prevented, and SEI formation is no longer a major failure mechanism leading to capacity loss, in stark contrast to the excessive SEI formation that characterizes the materials disclosed by, for example, Guo (see above).

[0010] The materials described in WO 2020 / 095067 and WO 2020 / 128495 are synthesized by chemical vapor infiltration (CVI) in different reactor systems (static, rotating, and FBR). Porous particles are contacted with a flow of silicon-containing precursor (CVI), typically silane gas, at atmospheric pressure and temperatures between 400 and 700 °C until the required amount of silicon is deposited in the micropores and small mesopores. The materials described in WO 2020 / 095067 and WO 2020 / 128495 require careful control of the pore distribution of the porous particles and the amount of deposited silicon to obtain a fine, electroactive structure capable of lithiation and delithiation with good reversible capacity retention over multiple charge-discharge cycles. In particular, the materials described in WO 2020 / 095067 and WO 2020 / 128495 comprise porous particle scaffolds in which a relatively high proportion of the pore volume is in the form of micropores (pore diameter <2 nm) or fine mesopores (e.g., pore diameter <20 nm or <10 nm). In particular, WO 2020 / 095067 and WO 2020 / 128495 disclose that optimal results are obtained when the volume fraction of micropores is at least 50 vol% of the total pore volume of micropores and mesopores.

[0011] It has been observed that the use of porous particles with a more open pore structure (i.e., a volumetric pore size distribution toward larger mesopores and macropores) to prepare this type of composite particle results in poor electrochemical properties. Larger pores are believed to result in the deposition of rougher silicon domains and a greater exposed surface area of ​​the deposited silicon. This leads to a decrease in initial capacity due to oxygenation of the exposed silicon surface, high initial cycle losses due to initial SEI formation, and poor reversible capacity retention due to excessive structural stress and uncontrolled SEI formation during subsequent charge-discharge cycles.

[0012] It would therefore be desirable to extend the techniques described in WO2020 / 095067 and WO2020 / 128495 to a wider range of porous particle scaffolds without the aforementioned drawbacks. It has been discovered that this problem can be addressed if the electroactive material is present within the pores of a multilayered porous particle, in which multiple layers of the electroactive material are interleaved with spacer layers of different chemical species. The intercalated multilayer structure is formed using a chemical vapor deposition (CVI) process, in which different chemical species are deposited layer-by-layer until the desired multilayer structure is formed. Within this general structure, a range of options are offered for the number of layers, the chemical composition of each layer, and the thickness of each layer. [Means for solving the problem]

[0013] In a first aspect, the present invention provides a particulate material comprising a plurality of composite particles, wherein the composite particles are: (a) a porous particulate scaffold, the total pore volume of pores having pore diameters in the range of 3.5 to 100 nm, as determined by nitrogen gas adsorption, being P per gram of porous particulate scaffold; 1 cm 3 where P 1 represents a number ranging from 0.3 to 2.4, and a porous particle skeleton; (b) a multilayer coating disposed on the interior pore surfaces of a porous particulate scaffold, the multilayer coating comprising at least: (i) a first electroactive material layer; (ii) a second electroactive material layer, and (iii) a first interlayer material disposed between the first and second electroactive material layers; a multi-layer coating comprising: It has. DETAILED DESCRIPTION OF THE INVENTION

[0014] While many different factors contribute to the improved properties of these materials compared to materials prepared using similar porous particle frameworks, the electroactive material is deposited as a single, homogeneous mass. The multilayer structure can also function as a filler, reducing residual surface area and thus minimizing SEI formation and oxygenation on the surface of the electroactive material. The layered structure of the electroactive material also inhibits volume expansion across the thickness of the layers through mechanical buffering by the interlayer material, allowing stress to be released in the longitudinal direction. The multilayer structure also inhibits SEI formation because the innermost layers of the electroactive material are not exposed to the electrolyte, effectively preventing SEI formation on these layers. The interlayer material in the multilayer structure may also act as a conductive component; for example, a conductive carbon layer may be used as an interlayer material. This is believed to improve the kinetic properties of the composite particles.

[0015] The terms "multilayer coating," "first electroactive material layer," "second electroactive material layer," and "first interlayer material" define a particle structure consistent with the sequential deposition of a first electroactive material, a first interlayer material, and a second electroactive material into the pore structure of a porous particle framework. Thus, the electroactive materials do not form a network extending throughout the pore space, but are interrupted by the interlayer material. Thus, within at least a portion of the pore volume, there is an assembly of materials according to the following sequence: [First Electroactive Materials Domain] ↓ [Interlayer material area] ↓ [Second Electroactive Materials Domain] This sequence may be suitably extended, both before and after, by additional electroactive material domains, and / or additional interlayer material domains as needed. Interlayer material domains located between adjacent electroactive material domains may act as barriers separating the electroactive material domains, limiting the length scale of successive electroactive material domains within the composite particle.

[0016] The electroactive material layer and the interlayer material may form separate domains with a sharp boundary between the two, or there may be a compositional gradient between the electroactive material layer and the interlayer material. The interlayer material may be chemically bonded (e.g., covalently, ionic, or metallically bonded) to the first and / or second electroactive material layers. For example, the interlayer material may have a passivation layer on the surface of the first electroactive material layer, or an alloy of the electroactive material on the surface of the electroactive material, or a doped electroactive material on the surface of the electroactive material. Alternatively, the interlayer material may not be chemically bonded to the electroactive material layer.

[0017] As a result of the manufacturing method, the layered structure may not be uniform throughout the particle, e.g., the thickness of the various layers may vary, and the layers need not be in phase, however, the composite particles exhibit an arrangement of layers / domains of electroactive material and interlayer material as described above resulting from the process of the present invention.

[0018] The porous particle skeleton is preferably a conductive porous particle skeleton that improves the kinetic properties of the composite particles by facilitating charge transfer during lithiation and delithiation of the electroactive material.

[0019] A preferred conductive porous particle skeleton is a conductive porous carbon particle skeleton. The conductive porous carbon particle skeleton preferably contains at least 80% by weight of carbon, more preferably at least 85% by weight of carbon, more preferably at least 90% by weight of carbon, more preferably at least 95% by weight of carbon, and if necessary, at least 98% by weight or at least 99% by weight of carbon. The carbon may be crystalline carbon or amorphous carbon, or a mixture of amorphous and crystalline carbon. The conductive porous carbon particle skeleton may be either a hard carbon particle skeleton or a soft carbon particle skeleton.

[0020] The term "hard carbon" describes a disordered carbon matrix in which carbon atoms are found primarily in the sp2 hybridized state (trigonal bonding) in nanoscale polyaromatic domains. The polyaromatic domains are cross-linked with chemical bonds, e.g., C-O-C bonds. Due to the chemical cross-linking between the polyaromatic domains, hard carbon cannot be converted to graphite at high temperatures. Hard carbons are characterized by a large G band in the Raman spectrum (~1600 cm -1 ), it has graphite-like properties. However, the D band in the Raman spectrum (~1350 cm -1 ) is evident, the carbon is not fully graphitized.

[0021] The term "soft carbon" also refers to a disordered carbon matrix in which carbon atoms are found primarily in sp2 hybridized (trigonal bonding) polyaromatic domains with dimensions ranging from 5 to 200 nm. In contrast to hard carbon, the polyaromatic domains of soft carbon are held together by intermolecular forces but are not cross-linked by chemical bonds. This means that they graphitize at high temperatures. The conductive porous carbon particle skeleton preferably contains at least 50% sp2 hybridized carbon, as measured by XPS. For example, the conductive porous carbon particle skeleton may suitably contain 50% to 98% sp2 hybridized carbon, 55% to 95% sp2 hybridized carbon, 60% to 90% sp2 hybridized carbon, or 70% to 85% sp2 hybridized carbon.

[0022] A variety of different materials may be used to prepare suitable conductive porous carbon particle scaffolds. Examples of organic materials that can be used include fossil carbon sources such as plant biomass and coal. Examples of resins and polymeric materials that produce porous carbon particles upon pyrolysis include phenolic resins, novolac resins, pitch, melamine, polyacrylates, polystyrene, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and various copolymers containing monomer units of acrylates, styrene, α-olefins, vinylpyrrolidone, and other ethylenically unsaturated monomers. Depending on the starting materials and pyrolysis process conditions, a variety of different carbon materials are available in the art. Porous carbon particles with various specifications are available from commercial suppliers.

[0023] Mesopores and macropores can be obtained by known templating processes, which use extractable pore-forming agents such as MgO and other colloidal or polymeric templates that can be removed by thermal or chemical means after pyrolysis or activation.

[0024] Alternatives to carbon-based particle skeletons include porous particle skeletons containing titanium nitride (TiN), titanium carbide (TiC), and boron nitride (BN). Titanium nitride (TiN) and boron nitride (BN) are preferred. Alternatively, the conductive porous particle skeleton may have a non-conductive porous particle skeleton, in which the internal pore surfaces of the porous particle skeleton are provided with a conductive coating, such as a conductive pyrolytic carbon coating.

[0025] The porous particle scaffold has a three-dimensional interconnected open pore network comprising macropores and / or mesopores, and optionally a small amount of micropores. Following conventional IUPAC terminology, the term "micropore" is used to refer to pores with a diameter of less than 2 nm, the term "mesopore" is used to refer to pores with a diameter of 2 to 50 nm, and the term "macropore" is used to refer to pores with a diameter of more than 50 nm.

[0026] In this application, references to the volume of micropores, mesopores, and macropores within a porous particulate scaffold, as well as the distribution of pore volumes within the porous particulate scaffold, should be understood to refer to the internal pore volume of the isolated porous particulate scaffold (i.e., prior to the deposition of a multilayer coating). References to the BET surface area of ​​a porous particulate scaffold should be understood to refer to the isolated BET surface area porous particulate scaffold.

[0027] The porous particle scaffold is characterized by a total volume of pores having a pore diameter in the range of 3.5 to 100 nm as determined by nitrogen gas adsorption. The total volume of pores in this range is P per gram of the conductive porous particle scaffold as determined by nitrogen gas adsorption. 1 cm 3 where P 1 represents a dimensionless number ranging from 0.3 to 2.4 (e.g., if the total volume of pores ranging from 3.5 to 100 nm is 1.2 cm 3 / g, P 1 =1.2). Preferably, P 1 is between 0.6 and 2.4.

[0028] Typically, the porous particle scaffold contains both macropores and mesopores. However, it is not excluded to use a porous particle scaffold having a pore diameter distribution that includes macropores but not mesopores, or that includes mesopores but not macropores. For purposes of this invention, measured pore volumes above 100 nm are considered to be interparticle porosity and are disregarded.

[0029] In this application, references to the volume of pores in the range of 0 to 100 nm in diameter (including subranges thereof) are based on nitrogen gas adsorption at 77 K and pore sizes between 1 and 10 nm, as determined by the Barrett-Joyner-Halenda (BJH) method in accordance with ISO 15901-2. -4The term "BJH method" should be understood to mean the pore volume measured using a relative pressure range of p / p (referred to herein as the "BJH method"). Nitrogen gas adsorption is a technique for characterizing the porosity and pore diameter distribution of a material by condensing a gas into the pores of a solid. As pressure is increased, the gas condenses first in the smallest diameter pores, until a saturation point is reached where all pores are filled with liquid. The nitrogen gas pressure is then gradually reduced, and the liquid is evaporated from the system. Analysis of the adsorption and desorption isotherms and the hysteresis between them allows the pore volume and pore diameter distribution to be determined. Suitable instruments for measuring pore volume and pore diameter distribution using the BJH method include the TriStar II and TriStar II Plus porosity analyzers available from Micromeritics, Inc., USA, and the Autosorb IQ porosity analyzer available from Quantachrome Instruments, Inc.

[0030] P 1 preferably has a value of at least 0.4, at least 0.5, at least 0.6, at least 0.7, at least 0.8, at least 0.85, at least 0.9, at least 0.95, at least 1, at least 1.05, at least 1.1, at least 1.15, or at least 1.2. The use of a porous particle scaffold with high porosity can be advantageous as it allows for the accommodation of large amounts of silicon within the pore structure.

[0031] The internal pore volume of the porous particle scaffold is suitably capped at a value where the increased fragility of the scaffold outweighs the benefit of the increased pore volume to accommodate more silicon. 1 is 2.3 or less, 2.2 or less, 2.1 or less, 2 or less, 1.95 or less, 1.9 or less, 1.85 or less, or 1.8 or less.

[0032] P 1is preferably in the range of 0.6 to 2.4, or 0.7 to 2.4, or 0.8 to 2.3, or 0.9 to 2.2, or 0.95 to 2.1, or 1 to 2, or 1.05 to 1.95, or 1.1 to 1.9, or 1.15 to 1.85, or 1.2 to 1.8.

[0033] PD of porous particle framework 50 The pore diameter is preferably at least 10 nm, at least 20 nm, at least 25 nm, at least 30 nm, at least 35 nm, at least 40 nm, at least 45 nm, or at least 50 nm. 50 The term "pore diameter" refers to the median pore diameter on a volume basis, based on the total volume of pores having a pore diameter of 3.5 to 100 nm within the porous particle scaffold. Thus, in the present invention, it is preferred that at least 50% of the total volume of pores having a pore diameter of 3.5 to 100 nm is in the form of pores having a diameter of at least 10 nm.

[0034] It is understood that gas adsorption is only useful for determining the pore volume of pores accessible to nitrogen from the outside of the porous material. It is understood that the porosity values ​​specified herein represent the volume of open pores, i.e., the volume of pores accessible to fluid from the outside of the porous particle. Completely enclosed pores that cannot be identified by nitrogen adsorption are not considered when determining the porosity value.

[0035] The pore diameter distribution within the porous particulate scaffold is preferably such that at least 50 vol% of the total volume of pores having pore diameters in the range of 3.5 to 100 nm is in pores having pore diameters in the range of 5 to 60 nm. Thus, the volume fraction of pores having pore diameters in the range of 5 to 60 nm is preferably at least 50 vol%, at least 55 vol%, at least 60 vol%, at least 65 vol%, at least 70 vol%, at least 75 vol%, at least 80 vol%, at least 85 vol%, or at least 90 vol%, based on the total pore volume of pores having pore diameters in the range of 3.5 to 100 nm in the porous particulate scaffold.

[0036] More preferably, at least 50 vol% of the total volume of pores having a pore diameter in the range of 3.5 to 100 nm is in the form of pores having a pore diameter in the range of 10 to 50 nm. Thus, the volume fraction of pores having a pore diameter in the range of 10 to 50 nm is preferably at least 50 vol%, at least 55 vol%, at least 60 vol%, at least 65 vol%, at least 70 vol%, at least 75 vol%, at least 80 vol%, at least 85 vol%, or at least 90 vol%, based on the total pore volume of pores having a pore diameter in the range of 3.5 to 100 nm in the porous particle scaffold.

[0037] The BJH method for analyzing pore volume and pore size distribution is valid for pores with diameters equal to or greater than 3.5 nm, but is inappropriate for pore sizes less than 3.5 nm. Reference to the volume of pores with diameters less than 3.5 nm (including subranges) is calculated using the quenched solid density functional theory (QSDFT) at a relative pressure p / p = 10, according to the standard method described in ISO 15901-2 and ISO 15901-3. -6 It is understood to mean the pore volume as measured by nitrogen gas adsorption at 77 K (referred to herein as the "QSDFT method") as follows: Suitable instruments for QSDFT measurements include the Autosorb IQ Porosity Analyzer available from Quantachrome Instruments.

[0038] The total volume of pores in the porous particle scaffold with a diameter of less than 3.5 nm is P per gram of porous particle scaffold. 2 cm 3 where P 2 represents a dimensionless number having a value of less than 0.5, less than 0.45, less than 0.4, less than 0.35, less than 0.3, less than 0.25, less than 0.2, less than 0.15, or less than 0.1, as determined by nitrogen gas adsorption (e.g., when the total volume of pores having a diameter of less than 3.5 nm is less than 0.1 cm). 3 / g, P 2 =0.1).

[0039] If necessary, P 2 The value of P 1 Preferably, P 2 is [1×P 1 ] and below, [0.8×P 1 ] and below, [0.6 × P 1 ] and below, [0.5 × P 1 ] and below, [0.4 × P 1 ] and below, [0.3 × P 1 ] and below, [0.2 × P 1 ] or less, or [0.1 × P 1 ] represents the following numerical values.

[0040] The porous particle framework is preferably at least 150 mm 2 / g, more preferably at least 250m 2 / g, optionally at least 500m 2 / g, or at least 750m 2 / g, or at least 1,000m 2 / g, or at least 1,250m 2 / g. The term "BET surface area" should be interpreted as meaning the surface area per unit mass calculated from measurements of the physical adsorption of gas molecules on a solid surface using the Brunauer-Emmett-Teller theory according to ISO 9277. Preferably, the BET surface area of ​​the porous particle framework is greater than 2,500 m 2 / g or less, preferably 2,000m 2 / g or less, or 1,750m 2 / g or less, or 1,500m 2 For example, the porous particle skeleton is 250 m 2 / g to 2,500m 2 / g, 500m 2 / g to 2,500m 2 / g, 750m 2 / g to 2,000m 2 / g, 750m 2 / g to 1,750m 2 / g, 750m 2 / g to 1,500m 2 / g, 1,000 to 2,000 m2 / g, 1,000m 2 / g to 1,750m 2 / g, 1,000m 2 / g to 1,500m 2 / g, 1,250m 2 / g to 2,000m 2 / g, 1,250m 2 / g to 1,750m 2 / g, 250m 2 / g to 2,000m 2 / g, 250m 2 / g to 1,750m 2 / g, 500m 2 / g to 1,500m 2 / g.

[0041] The electroactive materials of the first and second electroactive material layers may be the same or different and, if desired, may be selected independently from one another from elemental silicon, elemental tin, elemental germanium, elemental aluminum, and mixtures and alloys thereof.

[0042] Preferably, the electroactive materials in the first and second electroactive material layers are elemental silicon, elemental tin, elemental germanium, and mixtures and alloys thereof, which may optionally include aluminum.

[0043] A preferred electroactive material is silicon. Preferably, at least one of the first and second electroactive material layers comprises or consists of elemental silicon. More preferably, both the first and second electroactive material layers comprise or consist of elemental silicon.

[0044] The term "intermediate layer material" refers to a layer of material that is disposed between two adjacent electroactive material layers and has a distinct chemical composition different from the electroactive material layers. Thus, the multilayer coating has a periodic structure with alternating layers of electroactive material and intermediate layer material. The electroactive material layer and the intermediate layer material may be distinct layers having a sharp boundary therebetween, or there may be a composition gradient between the electroactive material layer and the intermediate layer material.

[0045] The first intermediate layer material preferably contains one or more of carbon, nitrogen, and / or oxygen.

[0046] The first intermediate layer material may include, or may be composed of, a passivation layer formed on the surface of the first electroactive material layer.

[0047] One type of passivation layer is a native oxide layer, which is formed, for example, by exposing the surface of the first electroactive material layer to air or another oxygen-containing gas prior to the deposition of the second electroactive material layer. When the first electroactive material layer is silicon, the first intermediate layer material may include silicon oxide having the general formula SiO x where 0 < x ≦ 2. The silicon oxide is preferably amorphous silicon oxide.

[0048] Another type of passivation layer is, for example, a nitride layer formed by exposing the surface of the first electroactive material layer to ammonia or another nitrogen-containing molecule prior to the deposition of the second electroactive material layer. When the first electroactive material layer is silicon, the first intermediate layer material may include silicon nitride having the general formula SiN x where 0 < x ≦ 4 / 3. The silicon nitride is preferably amorphous silicon nitride. The nitride intermediate layer material is more preferable than the oxide passivation layer. (SiN x : sub-stoichiometric nitrides such as 0 < x ≦ 4 / 3) are conductive, and the nitride intermediate layer functions as a conductive network, enabling faster charge and discharge of the electroactive material.

[0049] Another type of passivation layer is, for example, a oxynitride layer formed by exposing the surface of the first electroactive material layer to ammonia (or other nitrogen-containing molecules) and oxygen gas before forming the second electroactive material layer. When the first electroactive material layer is silicon, the first intermediate layer material may contain silicon oxynitride with the general formula SiO x N y where 0 < x < 2, 0 < y < 4 / 3, and 0 < (2x + 3y) ≤ 4. The silicon oxynitride is preferably amorphous silicon oxynitride.

[0050] Another type of passivation layer is a carbide layer. When the first electroactive material layer is silicon, the first intermediate layer may contain silicon carbide with the general formula SiC x where 0 < x ≤ 1. The silicon carbide is preferably amorphous silicon carbide. The silicon carbide layer may be formed by contacting the surface of the first electroactive material with a carbon-containing precursor, such as methane or ethylene, at a high temperature.

[0051] As a further alternative, the passivation layer may include a carbon-containing organic moiety covalently bonded to the surface of the first electroactive material layer. The covalently bonded organic intermediate layer may be formed by inserting an organic compound into the M-H groups (M represents an atom of the electroactive material) on the surface of the electroactive material to form a covalently passivated surface resistant to oxidation by air. When silicon is the electroactive material, the passivation reaction between the silicon surface and the passivating agent can be understood as a form of hydrosilylation, as schematically shown below:

[0052] [Chemical formula] Suitable organic compounds that can be used to form the first interlayer material via passivation of the surface of the first electroactive material layer include compounds having an alkene, alkyne, or carbonyl functional group, more preferably a terminal alkene, terminal alkyne, or aldehyde group. For example, the first interlayer material may be formed by passivating the surface of the first electroactive material layer with one or more compounds of the following formula: (i)R 1 -CH=CH-R 1 ; (ii)R 1 -C±CR 1 ; (iii) O=CH-R 1 ; Here, each R 1 independently represent H or an unsubstituted or substituted aliphatic or aromatic hydrocarbon group having 1 to 20 carbon atoms, preferably 2 to 10 carbon atoms, or two R groups in formula (i) form an unsubstituted or substituted hydrocarbon ring structure containing 3 to 8 carbon atoms in the ring.

[0053] Particularly preferred passivators include one or more compounds of the following formula: (i) CH2=CH-R 1 ; (ii) HC≡CR 1 ; where R 1 is as described above. Preferably, R 1 is non-substituted.

[0054] Specific examples of suitable organic compounds that can be used to form the first interlayer material through surface passivation of the first electroactive material layer include ethylene, propylene, 1-butene, butadiene, 1-pentene, 1,4-pentadiene, 1-hexene, 1-octene, styrene, divinylbenzene, acetylene, phenylacetylene, norbornene, norbornadiene, bicyclo[2.2.2]oct-2-ene, camphene, 3-carene, sabinene, tadiene, pinene, limonene, acetylene, phenylacetylene, anthraquinone, anthrone, and camphor. Mixtures of different passivating agents may also be used.

[0055] Other examples of organic compounds that can be used to form the first interlayer material through passivation of the surface of the first electroactive material layer include compounds with active hydrogen atoms bonded to oxygen, nitrogen, sulfur, or phosphorus. For example, the passivating agent may be an alcohol, amine, thiol, or phosphine. It is understood that the reaction of the -XH group with a hydride group on the surface of the electroactive material results in the elimination of H and the formation of a direct bond between X and the surface of the electroactive material.

[0056] Suitable passivators in this category include compounds of the formula: (iv) HX-R 2 , (v) HX-C(O)-R 1 , where X represents O, S, NR, or PR, where each R 1 are independently defined as above, and R 2 represents an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having from 1 to 20 carbon atoms, or R 1 and R 2 together form an unsubstituted or substituted hydrocarbyl ring structure containing from 3 to 8 carbon atoms in the ring.

[0057] Preferably, X represents O or NH.

[0058] Preferably, R 2 represents an optionally substituted aliphatic or aromatic group having 2 to 10 carbon atoms, and the amine group may also be incorporated into a 4- to 10-membered aliphatic or aromatic ring structure, such as pyrrolidine, pyrrole, imidazole, piperazine, indole, or purine.

[0059] The first interlayer material may comprise a conductive pyrolytic carbon material. The conductive pyrolytic carbon layer may be formed by CVI using a suitable carbon-containing precursor, as described in more detail below. Optionally, the first interlayer material may comprise a conductive pyrolytic carbon material layer on top of the aforementioned passivation layer.

[0060] The first interlayer material may include a conductive metal element or metal alloy. The conductive metal or metal alloy layer may be formed by chemical vapor deposition (CVI) using a suitable metal-containing precursor, as described in more detail below. An example of a suitable conductive metal interlayer material is silver metal. Optionally, the first interlayer material may include a conductive metal or metal alloy layer on a passivation layer, as described above.

[0061] The first interlayer material may comprise a lithium ion permeable solid electrolyte. Examples of suitable lithium permeable solid electrolytes include garnet-type solid electrolytes (Li7La3Zr2O 12 and Li 6.5 La3Ti 0.5 Zr 1.5 O 12 perovskite-type solid electrolytes (including "LLZO" electrolytes such as Li 0.33 La 0.57 including "LLTO" electrolytes such as TiO3); LISICON-type solid electrolytes, NaSICON-type solid electrolytes (L i1.3 Al 0.3 T i1.7 (PO4)3, etc.); lithium phosphate oxynitride (LiPON) solid electrolyte; Li3N type solid electrolyte, lithium phosphate (Li3PO4) solid electrolyte, lithium titanate (Li4Ti5O 12) solid electrolytes, lithium tantalate (LiTaO) solid electrolytes, sulfide-type solid electrolytes, argyrodite-type solid electrolytes, and antiperovskite-type solid electrolytes. Also included are variations (e.g., with dopants) and combinations of these electrolyte types. Optionally, the first interlayer material may include a lithium-permeable solid electrolyte layer over the aforementioned passivation layer.

[0062] The multilayer coating may include additional electroactive material layers and the aforementioned intermediate layers. For example, the multilayer coating may include n electroactive material layers and (n-1) intermediate layer materials disposed between each electroactive material layer, where n is an integer from 3 to 20, 3 to 15, 4 to 12, 4 to 10, 5 to 10, or 5 to 8. Preferably, each of the n electroactive materials is independent of the first and second electroactive materials, as described above. Preferably, each of the n electroactive materials is the same electroactive material, and more preferably, each of the n electroactive materials is elemental silicon. Preferably, each of the (n-1) intermediate layer materials is independent of the first interlayer material, as described above. If necessary, each of the (n-1) interlayer materials is the same interlayer material.

[0063] The thickness of the intermediate layer material is preferably less than 5 nm, more preferably less than 2 nm, and most preferably less than 1 nm. It is understood that a thicker intermediate layer reduces the amount of electroactive material that can be accommodated within the pore volume of the porous particle framework. Therefore, it is preferred that the average intermediate layer thickness is less than 20%, or less than 10%, or less than 5% of the average thickness of the electroactive material layer.

[0064] The multilayer coating disposed on the interior pore surfaces of the porous particle scaffold may optionally further comprise: (iv) A coating layer disposed on the surface of the outermost electroactive material layer (i.e., the last electroactive material layer to be formed and the electroactive material layer most distal from the pore walls of the porous particle scaffold).

[0065] If desired, coating layer (iv) may be formed from any of the materials used to form the aforementioned intermediate layer materials. Coating layer (iv) may be the same as or different from any intermediate layer material.

[0066] The particulate materials of the present invention may have a range of electroactive material contents. For example, the amount of silicon in the composite particles may be selected so that at least 25% and up to 80% or more of the internal pore volume of the porous particle skeleton is occupied by the electroactive material and the interlayer material. For example, the electroactive material may occupy 25% to 75%, 25% to 70%, 30% to 65%, 35% to 60%, 40% to 60%, 25% to 45%, or 30% to 40% of the internal pore volume of the porous particle skeleton. Within these preferred ranges, the pore volume of the porous particle skeleton is effective to accommodate expansion of the electroactive material during charge and discharge, while avoiding excess pore volume that does not contribute to the particle's volumetric capacity. However, the amount of electroactive material is not so high that effective lithiation is prevented by inadequate lithium ion diffusion rates or inadequate expansion volume that results in mechanical resistance to lithiation.

[0067] Preferably, at least 85 wt. % of the mass of the electroactive material in the composite particles is located within the interior pore volume of the porous particulate skeleton, more preferably at least 90 wt. %, more preferably at least 95 wt. %, and even more preferably at least 98 wt. %, with very little or no electroactive material located on the exterior surface of the composite particles. The kinetics of the CVI process ensure that preferential deposition of silicon occurs on the interior surface of the porous particulate skeleton.

[0068] When the electroactive material is silicon, the mass ratio of silicon to the porous particle skeleton is [0.5 × P 1 From 1.9 x P 1The amount of silicon in the composite particles can be correlated to the available pore volume, since the ratio of silicon to silicon content should be in the range of 0.01:1. This relationship takes into account the density of the silicon and the pore volume of the porous particle framework, and determines the weight ratio of silicon so that approximately 20% to 80% of the pore volume is occupied by silicon.

[0069] When the electroactive material is silicon, the composite particles preferably comprise 35% to 75% by weight silicon, 40% to 70% by weight silicon, or 45% to 65% by weight silicon.

[0070] Preferred composite particles comprise an electrically conductive porous carbon particle skeleton as described above, the composite particles comprising at least 80% by weight, or 80% to 98% by weight, of silicon and carbon combined.

[0071] The amount of silicon in the composite particles can be determined by elemental analysis. Preferably, elemental analysis is used to determine the weight percent of carbon (and optionally hydrogen, nitrogen, and oxygen) in the porous carbon particles alone and in the composite particles. Determining the weight percent of carbon in the porous carbon particles alone takes into account the possibility that the porous carbon particles may contain small amounts of heteroatoms, as well as any carbon present in the interlayer material. By performing both measurements together, the weight percentage of the electroactive material relative to the porous carbon particles can be reliably determined.

[0072] The silicon content of the composite particles is preferably measured by ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy). Many ICP-OES instruments are commercially available, such as the iCAP® 7000 series of ICP-OES analyzers available from ThermoFisher Scientific. The single elemental composition of the composite particles and porous particle skeleton (and optionally the hydrogen, nitrogen, and oxygen content) is preferably measured by IR absorption. Suitable instruments for measuring carbon, hydrogen, nitrogen, and oxygen content include the TruSpec® Micro elemental analyzer available from Leco.

[0073] The particulate materials of the present invention can be further characterized by their properties under thermogravimetric analysis (TGA) in air. Preferably, the particulate material contains 10% or less unoxidized silicon at 800°C when measured by TGA in air at a temperature ramp rate of 10°C / min. More preferably, the particulate material contains 5% or less or 2% or less unoxidized silicon at 800°C when measured by TGA in air at a temperature ramp rate of 10°C / min.

[0074] Determination of the amount of unoxidized silicon is derived from the characteristic TGA traces of these materials. A mass increase between about 300 and 500 °C corresponds to the initial oxidation of Si to SiO2, followed by a mass loss between about 500 and 600 °C due to the oxidation of carbon to CO2 gas. Above about 600 °C, there is a further mass increase corresponding to the continued conversion of silicon to SiO2, rising towards an asymptotic value above 1000 °C as the oxidation of silicon approaches completion.

[0075] In this analysis, we assume that the mass increase above 800 °C corresponds to the oxidation of Si to SiO2, and that the total mass at the completion of oxidation is due to SiO2. This allows us to determine the fraction of unoxidized silicon at 800 °C as a ratio to the total amount of silicon using the following formula: Z = 1.875 × [(M f -M 800 ) / M f ]×100% where Z is the fraction of unoxidized silicon at 800°C, M f is the mass of the sample at the end of oxidation, M 800 is the sample mass at 800°C.

[0076] Without being bound by theory, it is understood that the temperature at which silicon oxidizes under TGA broadly corresponds to the length scale of the oxide coating on silicon due to the diffusion of oxygen atoms through the thermally activated oxide layer. The size and arrangement of silicon nanostructures limit the length scale of the oxide coating thickness. Therefore, it is understood that silicon deposited within pores oxidizes at a lower temperature than silicon deposits on the particle surface due to the necessarily thinner oxide coating present in these structures. Therefore, preferred materials according to the present invention exhibit substantially complete oxidation of silicon at low temperatures consistent with the small scale of silicon nanostructures located within micropores and smaller mesopores. For purposes of the present invention, it is assumed that the oxidation of silicon at 800°C is silicon on the outer surface of the porous particle skeleton.

[0077] The composite particles preferably have a low total oxygen content. Oxygen may be present in the composite particles, for example, as part of the porous particle skeleton or as an oxide layer on any exposed silicon surfaces. Preferably, the surface of the electroactive material is passivated to inhibit or prevent oxide formation.

[0078] Preferably, the total oxygen content of the composite particles is less than 15% by weight, more preferably less than 10% by weight, more preferably less than 5% by weight, such as less than 2% by weight, or less than 1% by weight, or less than 0.5% by weight.

[0079] The composite particles preferably have a D in the range of 0.5 to 200 μm. 50 If necessary, the diameter of the composite particle 50 The particle diameter is at least 1 μm, at least 1.5 μm, at least 2 μm, at least 3 μm, at least 4 μm, or at least 5 μm. If desired, the D of the composite particles 50 The particle diameter may be 150 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 18 μm or less, 15 μm or less, 12 μm or less, 10 μm or less.

[0080] For example, the composite particles may have a D in the range of 0.5 to 200 μm, 0.5 to 150 μm, 0.5 to 100 μm, 0.5 to 50 μm, 0.5 to 30 μm, 1 to 25 μm, 1 to 20 μm, 2 to 25 μm, 2 to 20 μm, 2 to 18 μm, 3 to 20 μm, 3 to 18 μm, 3 to 15 μm, 4 to 18 μm, 4 to 15 μm, 4 to 12 μm, 5 to 15 μm, 5 to 12 μm, or 5 to 10 μm. 50 It may have a particle diameter.

[0081] Particles within these preferred size ranges, and having the porosity and pore diameter distributions described herein, are ideally suited for the preparation of composite particles for use in anodes for metal-ion batteries by fluidized-bed processes. In particular, particles with these properties have good dispersibility in slurries, structural robustness, and high capacity retention over repeated charge-discharge cycles, and are suitable for forming dense electrode layers of uniform thickness in the conventional thickness range of 20 to 50 μm.

[0082] D of composite particles 10 The particle diameter is preferably at least 0.5 μm, at least 0.8 μm, at least 1 μm, at least 1.5 μm, or at least 2 μm. 10 Maintaining particle diameters of 0.5 μm or greater reduces the likelihood of undesirable agglomeration of submicron-sized particles, thereby improving the dispersibility of the composite particles in the slurry used in electrode fabrication.

[0083] D of composite particles 90 The particle size is preferably 300 μm or less, 250 μm or less, 200 μm or less, 150 μm or less, 100 μm or less, 80 μm or less, 60 μm or less, 40 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less. The use of large composite particles can result in uneven packing of the composite particles in the electrode active layer, thereby inhibiting the formation of a dense electrode layer, particularly an electrode layer having a thickness in the range of 20 to 50 μm.

[0084] The composite particles preferably have a narrow size distribution span. For example, the particle size distribution span (D 90 -D 10 ) / D 50 ), defined as ), is preferably 5 or less, more preferably 4 or less, more preferably 3 or less, more preferably 2 or less, and most preferably 1.5 or less. By maintaining a narrow size distribution span, efficient packing of particles into a dense electrode layer can be more easily achieved.

[0085] For the avoidance of doubt, the term "particle diameter" refers to the equivalent spherical diameter (esd), i.e., the diameter of a sphere having the same volume as a given particle, where particle volume is understood to include the volume of any intra-particle pores. 50 " and "D 50 The term "particle diameter" refers to the volume-based median particle diameter, i.e., the diameter at which less than 50% by volume of the particle population is found. 10 " and "D 10 The term "particle diameter" refers to the median particle diameter on a 10% volume basis, i.e., the diameter at which less than 10% by volume of the particle population is found. As used herein, the terms "D90" and "D90 particle diameter" refer to the median particle diameter on a 90% volume basis, i.e., the diameter at which less than 90% by volume of the particle population is found.

[0086] Particle size and particle size distribution can be measured by standard laser diffraction methods in accordance with ISO 13320:2009. Laser diffraction is based on the principle that particles scatter light at angles that vary depending on the particle size, and that particles or aggregates thereof produce a pattern of scattered light defined by intensity and angle that can be correlated to particle size distribution. Numerous laser diffraction instruments are commercially available for rapid and reliable measurement of particle size distribution. Unless otherwise noted, particle size distribution measurements described or reported herein were measured using a conventional Malvern Mastersizer™ 3000 particle size analyzer manufactured by Malvern Instruments. The Malvern Mastersizer™ 3000 particle size analyzer operates by illuminating a transparent cell containing particles of interest suspended in an aqueous solution with a helium-neon gas laser beam. A light beam striking a particle is scattered through an angle inversely proportional to the particle size, and a photodetector array measures the light intensity at several predetermined angles. Using standard theoretical principles, the measured intensities at different angles are processed by a computer to determine the particle size distribution. The laser diffraction values ​​described herein are obtained using a wet dispersion of particles in 2-propanol with 5 vol% of the surfactant SPAN™-40 (sorbitan monopalmitate). The particle refractive index is taken to be 3.50, and a dispersant index of 1.378 is used. The particle size distribution is calculated using the Mie scattering model.

[0087] The composite particles are preferably 100m 2 / g or less, 80m 2 / g or less, 60m 2 / g or less, 40m 2 / g or less, 30m 2 / g or less, 25m 2 / g or less, 20m 2 / g or less, 15m 2 / g or less, or 10m 2 / g or less. Generally, a low BET surface area is preferred to minimize the formation of a solid electrolyte interphase (SEI) layer on the surface of the composite particles during the first charge-discharge cycle of the anode. However, an excessively low BET surface area can lead to unacceptably low charge rates and capacities due to the inaccessibility of the bulk metal ions of the electroactive material in the surrounding electrolyte. For example, the BET surface area of ​​the composite particles is preferably at least 0.1 m 2 / g, at least 1m 2 / g, at least 2m 2 / g, or at least 5m 2 / g. For example, the BET surface area is between 0.1 and 100 m 2 / g, 0.1 to 80m 2 / g, 0.5 to 60m 2 / g, 0.5 to 40m 2 / g, 1 to 30 m 2 / g, 1 to 25 m 2 / g, or 2 to 20m 2 / g.

[0088] The composite particles may optionally include a conductive coating. For example, the conductive coating may be a conductive pyrolytic carbon coating. When one or more intermediate layer materials are conductive pyrolytic carbon materials, the conductive carbon coating may be the same type of conductive pyrolytic carbon or a different type relative to the intermediate layer materials, for example, formed from a different carbon-containing precursor.

[0089] Preferably, the conductive pyrolytic carbon coating may be obtained by chemical vapor deposition (CVD). The thickness of the carbon coating may preferably be in the range of 2 to 30 nm. Optionally, the conductive pyrolytic carbon coating may be porous and / or may cover only a portion of the surface of the composite particles.

[0090] The carbon coating has the advantage of further reducing the BET surface area of ​​the particulate material by smoothing any surface defects and filling any remaining surface microporosity, thereby further reducing first cycle loss. The carbon coating also improves the electrical conductivity of the surface of the composite particles, reducing the need for conductive additives in the electrode composition, and provides an optimal surface for the formation of a stable SEI layer, resulting in improved capacity retention upon cycling.

[0091] The particulate material of the present invention preferably has a specific charge capacity of 1400 to 2340 mAh / g upon initial lithiation. Preferably, the silicon-containing particulate material of the present invention has a specific charge capacity of 1600 to 2340 mAh / g upon initial lithiation.

[0092] In a second aspect of the present invention, there is provided a method of preparing composite particles, the method comprising: (a) providing a plurality of porous particles, the total pore volume of pores having pore diameters in the range of 3.5 to 100 nm being P per gram of porous particles as measured by nitrogen gas adsorption; 1 cm 3 where P 1 represents a number ranging from 0.3 to 2.4, and (b) depositing a first electroactive material layer on the interior pore surfaces of the porous particles; (c) forming a first interlayer material on a surface of the first electroactive material layer; (d) depositing a second layer of electroactive material on the surface of the first interlayer material; It has.

[0093] Thus, in the method of the present invention, a composite particle as described above is provided, wherein the porous particle forms the skeleton of a multi-layer coating comprising at least first and second electroactive material layers and at least a first intermediate layer material disposed between said first and second electroactive material layers.

[0094] In the second aspect of the present invention, the porous particles used in step (a) form a porous particle skeleton in the particle of the first aspect of the present invention. Therefore, the porous particles in step (a) are considered to be equivalent to the porous particle skeleton in the composite particle described above. Therefore, the porous particle skeletons described above in relation to the first aspect (in particular the porous particle skeleton, the total pore volume of the porous particle skeleton, the PD of the porous particle skeleton) can be used. 50 It will be understood that any optional or preferred properties of the porous particles used in step (a) of the method according to the second aspect of the present invention (including the material that forms the pore diameter, the pore size distribution of the porous particle scaffold, and the BET surface area of ​​the porous particle scaffold) also apply to the porous particles used in step (a) of the method according to the second aspect of the present invention.

[0095] The porous particles used in step (a) have preferred dimensions which correspond to the preferred dimensions of the composite particles described in relation to the first aspect of the invention.

[0096] Therefore, the porous particles used in step (a) have a D in the range of 0.5 to 200 μm. 50 The particle diameter of the composite particle is appropriately 50 The particle diameter may be at least 1 μm, at least 1.5 μm, at least 2 μm, at least 3 μm, at least 4 μm, or at least 5 μm. If desired, the D of the porous particles 50 The particle diameter may be 150 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 18 μm or less, 15 μm or less, 12 μm or less, or 10 μm or less.

[0097] For example, the porous particles used in step (a) may have a D in the range of 0.5 to 200 μm, 0.5 to 150 μm, 0.5 to 100 μm, 0.5 to 50 μm, 0.5 to 30 μm, 1 to 25 μm, 2 to 25 μm, 2 to 20 μm, 2 to 18 μm, 3 to 20 μm, 3 to 18 μm, 3 to 15 μm, 4 to 18 μm, 4 to 15 μm, 4 to 12 μm, 5 to 15 μm, 5 to 12 μm, or 5 to 10 μm. 50 It may have a particle diameter.

[0098] D of the porous particles used in step (a) 10 The particle size is preferably at least 0.5 μm, at least 0.8 μm, at least 1 μm, at least 1.5 μm, or at least 2 μm. 10 Maintaining particle diameters of 0.5 μm or greater reduces the likelihood of undesirable agglomeration of submicron-sized particles, thereby improving the dispersibility of the composite particles in the slurry used in electrode fabrication.

[0099] D of the porous particles used in step (a) 90 The particle size is preferably 300 μm or less, 250 μm or less, 200 μm or less, 150 μm or less, 100 μm or less, 80 μm or less, 60 μm or less, 40 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

[0100] The porous particles used in step (a) preferably have a narrow size distribution span. For example, a particle size distribution span (D 90 -D 10 ) / D 50 ) is preferably 5 or less, more preferably 4 or less, more preferably 3 or less, more preferably 2 or less, and most preferably 1.5 or less.

[0101] In steps (b) and (d), chemical vapor infiltration (CVI) is preferably used to deposit the first and second electroactive material layers on the pore surfaces of the porous particles. As mentioned above, chemical vapor infiltration (CVI) is a process in which an additional phase is infiltrated into a porous material, typically by passing a mixture of an inert carrier gas and a gaseous precursor through a porous substrate at elevated temperatures. Decomposition / reaction of the gaseous precursor at the pore surfaces results in the deposition of a solid phase within the pore structure. References to gaseous precursors in this application are understood to include gaseous precursors that are liquid or solid at ambient temperatures but vaporize below the reaction temperature.

[0102] The electroactive materials in the first and second electroactive material layers deposited in steps (b) and (d) may be the same or different, and may optionally be selected independently from elemental silicon, elemental tin, elemental germanium, elemental aluminum, and mixtures and alloys thereof. A preferred electroactive material is silicon. Preferably, at least one of the first and second electroactive material layers is an elemental silicon layer. More preferably, both the first and second electroactive material layers are elemental silicon layers.

[0103] Suitable silicon-containing precursors include silane (SiH), disilane (SiH), trisilane (SiH), tetrasilane (SiH), 10 ), or chlorosilanes such as trichlorosilane (HSiCl), or methylchlorosilanes such as methyltrichlorosilane (CHSiCl) or dimethyldichlorosilane ((CH)SiCl). Preferably, the silicon-containing precursor is a silane.

[0104] Suitable tin-containing precursors include bis[bis(trimethylsilyl)amino]tin(II) ([(CH3)3Si]2N)2Sn), tetraallyltin (((HC=CHCH2)4Sn), tetrakis(diethylamido)tin(IV) ([(C2H5)2N]4Sn), tetrakis(dimethylamido)tin(IV) ([(CH3)2N]4Sn), tetramethyltin (Sn(CH3)4), tetravinyltin (Sn(CH=CH2)4), tin(II) acetylacetonate (C 10 H 14 0Sn), trimethyl(phenylethynyl)tin (C6H5C≡CSn(CH3)3), and trimethyl(phenyl)tin (C6H5Sn(CH3)3). Preferably, the tin-containing precursor is tetramethyltin.

[0105] Suitable aluminum-containing precursors include aluminum tris(2,2,6,6-tetramethyl-3,5-heptanedionate) (Al(OCC(CH)CHCOC(CH))), trimethylaluminum ((CH)Al), and tris(dimethylamido)aluminum(III) (Al(N(CH))). Preferably, the aluminum-containing precursor is trimethylaluminum.

[0106] Suitable germanium-containing precursors include germane (GeH), hexamethyldigermanium ((CH)GeGe(CH), tetramethylgermanium ((CH)Ge), tributylgermanium hydride ([CH(CH)]GeH), triethylgermanium hydride ((CH)GeH), and triphenylgermanium hydride ((CH)GeH). Preferably, the germanium-containing precursor is germane.

[0107] In the CVI process in steps (b) and (d), a gaseous precursor of the dopant material may be used, if necessary, to deposit the doped electroactive material in the micropores and / or mesopores of the porous particles. When the dopant is boron, suitable precursors include borane (BH), triisopropyl borate ([(CH)CHO]B), triphenylborane ((CH)B), and tris(pentafluorophenyl)borane (CF)B, with borane being preferred. When the dopant is phosphorus, a suitable precursor is phosphine (PH).

[0108] Preferably, the first and second electroactive materials are both silicon. More preferably, the gaseous precursors used in steps (b) and (d) are, independently of one another, silane (SiH), disilane (SiH), trisilane (SiH), tetrasilane (SiH). 10), trichlorosilane (HSiCl), methyltrichlorosilane (CHSiCl), and dimethyldichlorosilane ((CH)SiCl). More preferably, the gaseous precursor used to form the first and second electroactive material layers in steps (b) and (d) is silane (SiH).

[0109] The precursors in steps (b) and (d) may be used in pure form or, more commonly, as a dilute mixture with an inert carrier gas such as nitrogen or argon. For example, the precursors may be used in an amount ranging from 1 to 100 vol%, 1 to 50 vol%, 2 to 40 vol%, 5 to 30 vol%, or 5 to 25 vol%, based on the total volume of the precursors and inert carrier gas.

[0110] The CVI process in steps (b) and (d) is suitably carried out at low partial pressures of the gaseous precursors, with the total pressure at or near 101.3 kPa (i.e., atmospheric pressure, 1 atm), with the remaining partial pressure reaching atmospheric pressure using an inert padding gas such as hydrogen, nitrogen, or argon. The presence of oxygen should be minimized to prevent undesired oxidation of the deposited electroactive material, following conventional procedures for operating in an inert atmosphere. Preferably, the oxygen content is less than 0.01 vol%, more preferably less than 0.001 vol%, based on the total volume of gas used in step (b).

[0111] The temperature of the CVI process in steps (b) and (d) can in principle be any temperature effective for pyrolyzing the precursor to form the electroactive material. Preferably, the CVI process in steps (b) and (d) is carried out at a temperature in the range of 300 to 700°C, 350 to 700°C, 400 to 700°C, 400 to 650°C, 400 to 600°C, 400 to 550°C, 400 to 500°C, 400 to 450°C, or 450 to 500°C. More preferably, the CVI process in steps (b) and (d) is carried out at a temperature in the range of 400 to 500°C, preferably 450 to 500°C.

[0112] The surface of the first electroactive material layer formed in step (b) is reactive to oxygen and forms a native oxide layer when exposed to oxygen. In the case of silicon, an amorphous silicon dioxide film is formed when the silicon surface is exposed to oxygen. Therefore, the first intermediate layer material may be a native oxide layer formed in step (c) by passivating the surface of the first electroactive material with air or other oxygen-containing gases such as nitrous oxide. The native oxide layer on the surface of silicon has the chemical formula SiO x where 0>x≦2.

[0113] The formation of the native oxide layer is an exothermic reaction and therefore requires careful process control to prevent overheating or combustion of the particulate material during production. When the first intermediate layer material formed in step (c) is a native oxide layer, step (c) may include cooling the material formed in step (b) to a temperature below 300°C, preferably below 200°C, more preferably below 100°C, before contacting the surface of the first electroactive material with an oxygen-containing gas.

[0114] The first interlayer material formed in step (c) may be a nitride of the first electroactive material instead of an oxide layer. The nitride layer can be formed by passivating the surface of the first electroactive material with ammonia at a temperature in the range of 200 to 700°C, preferably 400 to 700°C, more preferably 400 to 600°C, to form a nitride surface (e.g., a nitride having the general formula SiN x where x≦4 / 3). For example, if the passivating agent is ammonia, step (c) may be performed at a temperature the same as or similar to the temperature used to deposit the first electroactive material in step (b). Because substoichiometric silicon nitride is electrically conductive, this step results in the formation of a conductive network, which allows for faster charging and discharging of the electroactive material.

[0115] The first intermediate layer material formed in step (c) may be an oxynitride layer formed on the surface of the first electroactive material layer. Step (c) may include the step of exposing the surface of the first electroactive material layer to ammonia (or other nitrogen-containing molecules) and oxygen gas. When the first electroactive material layer contains silicon, the intermediate layer material may contain silicon oxynitride with the general formula SiO x N y . Here, 0 < x < 2, 0 < y < 4 / 3, and 0 < (2x + 3y) ≤ 4. The silicon oxynitride is preferably amorphous silicon oxynitride.

[0116] The first intermediate layer material formed in step (c) may be an amorphous or nanocrystalline carbide layer formed on the surface of the first electroactive material layer. Step (c) may include the step of contacting the surface of the first electroactive material layer with a carbon-containing precursor, such as methane or ethylene, at a temperature in the range of 250 to 700 °C. At low temperatures, a covalent bond is formed between the surface of the electroactive material and the carbon-containing precursor, and as the temperature rises, this is converted into a single layer of crystalline carbide. When the first electroactive material layer contains silicon, the intermediate layer material may contain silicon carbide with the general formula SiC x . Here, 0 < x ≤ 1. The silicon carbide is preferably amorphous silicon carbide.

[0117] As a further option, the intermediate layer material formed in step (c) may include a carbon-containing organic moiety covalently bonded to the surface of the first electroactive material layer. Organic compounds containing certain functional groups, such as alkenes, alkynes, or carbonyl functional groups, more preferably terminal alkenes, terminal alkynes, or aldehyde groups, can passivate the surface of the first electroactive material layer and form covalent bonds on its surface. Also, compounds containing active hydrogen atoms, such as alcohols, thiols, amines, and phosphines, may be used as passivating agents. For example, step (c) may include the step of passivating the surface of the first electroactive material layer using a passivating agent selected from one or more compounds of the following formula: (i) R1 -CH=CH-R 1 ; (ii)R 1 -C≡CR 1 ; (iii) O=CH-R 1 ; Here, each R 1 represent, independently of each other, H or an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 carbon atoms, preferably 2 to 10 carbon atoms, or two R groups in general formula (i) form an unsubstituted or substituted hydrocarbyl ring structure containing 3 to 8 carbon atoms in the ring.

[0118] Particularly preferred passivators include one or more compounds of the following formula: (i) CH2=CH-R 1 ; (ii) HC≡CR 1 ; where R 1 is as described above. Preferably, R 1 is non-substituted.

[0119] Specific examples of suitable organic compounds that can be used to form modified material domains via surface passivation of electroactive material domains include ethylene, propylene, 1-butene, butadiene, 1-pentene, 1,4-pentadiene, 1-hexene, 1-octene, styrene, divinylbenzene, acetylene, phenylacetylene, norbornene, norbornadiene, bicyclo[2.2]oct-2-ene, camphene, 3-carene, sabinene, thujene, pinene, limonene, acetylene, phenylacetylene, anthraquinone, anthrone, and camphor. Mixtures of different passivating agents may also be used.

[0120] Other examples of organic compounds that can be used to form the first interlayer material through passivation of the surface of the first electroactive material layer include compounds containing active hydrogen atoms bonded to oxygen, nitrogen, sulfur, or phosphorus. For example, the passivating agent may be an alcohol, amine, thiol, or phosphine. It is understood that the reaction of the -XH group with the hydride group on the surface of the electroactive material results in the elimination of H and the formation of a direct bond between X and the surface of the electroactive material.

[0121] Suitable passivators in this category include compounds of the formula: (iv) HX-R 2 , (v) HX-C(O)-R 1 , where X represents O, S, NR, or PR, and each R 1 are independently defined as above, and R 2 represents an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having from 1 to 20 carbon atoms, or R 1 and R 2 together form an unsubstituted or substituted hydrocarbyl ring structure containing from 3 to 8 carbon atoms in the ring.

[0122] Preferably, X represents O or NH.

[0123] Preferably, R 2 represents an optionally substituted aliphatic or aromatic group having from 2 to 10 carbon atoms. The amine group may also be incorporated into a 4- to 10-membered aliphatic or aromatic ring structure, such as pyrrolidine, pyrrole, imidazole, piperazine, indole, or purine.

[0124] Examples of suitable compounds in this category include borneol, terpineol, sucrose, thiophenol, and aniline. Mixtures of different passivators may also be used.

[0125] The covalently bonded organic interlayer material may be formed by passivating the surface of the first electroactive material with an organic passivator, as described above, at a temperature ranging from 200 to 700° C., preferably from 400 to 700° C., and more preferably from 400 to 600° C. For example, if the first interlayer material is formed using an organic passivator, step (c) may be carried out at a temperature that is the same as or similar to the temperature used in depositing the first electroactive material in step (b).

[0126] As a further option, an amorphous or nanocrystalline carbide layer may be formed by contacting the surface of the first electroactive material with a carbon-containing precursor, such as methane or ethylene, at a temperature of 250 to 700° C. At low temperatures, covalent bonds are formed between the surface of the electroactive material and the carbon-containing precursor, which convert to a monolayer of crystalline silicon carbide as the temperature increases.

[0127] As a further option, step (c) may comprise forming a layer of electrically conductive pyrolytic carbon material as the first intermediate layer material, and the pyrolytic carbon may be obtained by chemical vapor infiltration (CVI), i.e., by pyrolysis of a volatile carbon-containing gas (such as a hydrocarbon) on the surface of the silicon-containing composite particles.

[0128] Suitable precursors for forming electrically conductive pyrolytic carbon materials include polycyclic hydrocarbons containing 10 to 25 carbon atoms and, optionally, 1 to 3 heteroatoms, selected from naphthalene, substituted naphthalenes such as dihydroxynaphthalene, anthracene, tetracene, pentacene, fluorene, acenaphthene, phenanthrene, fluoranthrene, pyrene, chrysene, perylene, coronene, fluorenone, anthraquinone, anthrone, and alkyl-substituted derivatives thereof. Further suitable pyrolytic carbon precursors include bicyclic monoterpenoids, optionally selected from camphor, borneol, eucalyptol, camphene, careen, sabinene, thujene, α-terpinene, and pinene. Other suitable pyrolytic carbon precursors include C2 to C6 10 Examples of suitable pyrolytic carbon precursors include hydrocarbons such as alkanes, alkenes, alkynes, cycloalkanes, cycloalkenes, and arenes, such as methane, ethylene, propylene, butane, butadiene, 1-pentene, 1,4-pentadiene, 1-hexene, 1-octene, limonene, styrene, cyclohexane, cyclohexene, and acetylenedivinbenzene, norbornene, norbornadiene, cyclopentadiene, dicyclopentadiene, and bicyclo[2.2.2]oct-2-ene. Other suitable pyrolytic carbon precursors include phthalocyanine, sucrose, starch, graphene oxide, reduced graphene oxide, pyrene, perhydropyrene, triphenylene, tetracene, benzopyrene, perylene, coronene, and chrysene. A preferred carbon precursor is acetylene.

[0129] The pyrolytic carbon precursor used in step (c) may be used in pure form or in a mixture diluted with an inert carrier gas such as nitrogen or argon. For example, the pyrolytic carbon precursor may be used in an amount ranging from 0.1 to 50 vol%, 0.5 to 20 vol%, 1 to 10 vol%, or 1 to 5 vol%, based on the total volume of the precursor and inert carrier gas.

[0130] The formation of the conductive pyrolytic carbon layer in step (c) may optionally be followed by passivation of the surface of the first electroactive material layer by one of the processes described above. Thus, the interlayer material formed in step (c) may include both a passivation layer on the surface of the first electroactive material layer and a conductive pyrolytic carbon layer.

[0131] The same compound as the pyrolytic carbon precursor may be used for the passivation step if the surface of the first electroactive material layer is passivated with an organic compound (particularly an alkene or alkyne) to form covalently bonded organic moieties on the surface of the first electroactive material layer. The covalently bonded organic moieties thus provide a substrate for the growth of the conductive pyrolytic carbon interlayer material.

[0132] Alternatively, step (c) may comprise forming a layer of conductive metal as the first intermediate layer material. The conductive metal layer may be obtained by chemical vapor infiltration (CVI). Examples of suitable conductive metals include silver, gold, copper, and titanium.

[0133] The formation of the conductive metal interlayer material in step (c) may optionally be carried out after passivation of the surface of the first electroactive material layer by one of the processes described above. Thus, the interlayer material formed in step (c) may include both a passivation layer on the surface of the first electroactive material layer and a conductive metal layer.

[0134] As another option, step (c) may include forming a layer of a lithium-ion permeable solid electrolyte as the first intermediate layer material. The lithium-ion permeable solid electrolyte may be deposited in step (c) by a CVI process similar to that used in step (b). For example, a lithium phosphate solid electrolyte may be deposited in step (c) using an atmosphere of tert-butyllithium and trimethylphosphate. The CVI of the lithium-ion permeable solid electrolyte in step (c) is preferably performed at a temperature of 700°C or less, 650°C or less, 600°C or less, 550°C or less, or 500°C or less. The minimum temperature in step (c) depends on the type of lithium-ion permeable solid electrolyte used. The temperature in step (c) is preferably 300°C or more, 350°C or more, 400°C or more, or 450°C or more. For example, the temperature in step (c) may be in the range of 400 to 500°C.

[0135] Steps (c) and (d) may be repeated one or more times, as needed, to form a particulate material having three or more electroactive material layers with multiple interlayer materials disposed between each adjacent electroactive material layer. For example, steps (c) and (d) may be repeated one or more times, as needed, to form a particulate material including n electroactive material layers and (n-1) interlayer materials disposed between each electroactive material layer, where n is an integer from 3 to 20, 3 to 15, 3 to 12, 3 to 10, 4 to 10, or 5 to 8.

[0136] Each repetition of step (d) forms an electrically active material layer, which may be the same or different from any other electrically active material layer, and each repetition may independently have any of the characteristics of step (d) as described above. Preferably, each of the n electroactive material layers comprises the same electroactive material. More preferably, each of the n electroactive material layers formed in each repetition of step (d) is a silicon layer.

[0137] Similarly, each repetition of step (c) is used to form an interlayer material, which may be the same or different from any other interlayer material. Each repetition may independently have any of the features of step (c), as described above. Preferably, each of the (n-1) electroactive material layers comprises the same interlayer material.

[0138] The method of the present invention may further include step (e) if necessary. Step (e) comprises forming a coating layer on the surface of the final electroactive material layer to be deposited (i.e., the layer formed in the final event of step (d)). The coating layer formed in step (e) may be formed in the same manner as the intermediate layer formed in step (c), and the coating layer may be formed in step (e) using any of the intermediate layer materials described above.

[0139] The method of the present invention may be carried out in any reactor capable of contacting the porous particles with a gas containing precursors of the electroactive material and the intermediate layer material. Suitable types of reactors include a static furnace, a rotary kiln, or a fluidized bed reactor (including a spouted bed reactor).

[0140] Preferably, each of steps (b), (c), (d) and optional step (e) is carried out by contacting the porous particles with a continuous stream of gas containing precursors of the electroactive material, the intermediate layer material, and any coating material for a time sufficient to form the desired layer thickness. By cycling the atmosphere in the reactor between different precursors, the multilayer structure may be formed layer by layer until the required number of layers is formed.

[0141] Alternatively, each of steps (b), (c), (d), and optional step (e) may be carried out by contacting the porous particles with a constant input charge of gas containing the respective precursor in a batch reactor. The use of a batch reactor has the advantage that the amounts of electroactive material, intermediate layer material, and coating material can be precisely controlled by controlling the volume of precursor gas supplied to the reactor in each input charge. The batch reactor may optionally have a means for agitating the porous particles.

[0142] The reactor is preferably flushed with a suitable inert gas between each successive CVI step, and the inert gas used to flush the reactor is preferably the same inert gas used as the carrier gas for the respective precursors of the electroactive material, the intermediate layer material, and any coating materials.

[0143] In a third aspect of the present invention, there is provided a composition comprising a particulate material according to the first aspect of the present invention and at least one other component, optionally selected from (i) a binder, (ii) a conductive additive, and (iii) an additional particulate electroactive material. The composition of the third aspect of the present invention is useful as an electrode composition and may therefore be used to form the active layer of an electrode.

[0144] Preferably the composition comprises from 1 to 95%, 2 to 90%, 5 to 85%, or 10 to 80% by weight of particulate material according to the first aspect of the invention, based on the total dry weight of the composition.

[0145] The composition may be a hybrid electrode composition comprising the composite particles and at least one additional particulate electroactive material. Examples of the additional particulate electroactive material include graphite, hard carbon, silicon, tin, germanium, aluminum, and lead. Preferably, the at least one additional particulate electroactive material is selected from graphite and hard carbon, and most preferably, the at least one additional particulate electroactive material is graphite.

[0146] In the case of hybrid electrode compositions, the composition preferably comprises from 3 to 60 wt%, 3 to 50 wt%, 5 to 50 wt%, 10 to 50 wt%, or 15 to 50 wt% composite particles, based on the total dry weight of the composition.

[0147] The at least one additional particulate electroactive material is suitably present in an amount of from 20 to 95%, from 25 to 90%, or from 30 to 75% by weight of the at least one additional particulate electroactive material.

[0148] The at least one additional particulate electroactive material preferably has a D in the range of 10 to 50 μm, preferably 10 to 40 μm, more preferably 10 to 30 μm, most preferably 10 to 25 μm, for example 15 to 25 μm. 50 It has a particle diameter.

[0149] D of at least one additional particulate electroactive material 10 The particle diameter is preferably at least 5 μm, more preferably at least 6 μm, more preferably at least 7 μm, more preferably at least 8 μm, more preferably at least 9 μm, and even more preferably at least 10 μm.

[0150] D of at least one additional particulate electroactive material 90 The particle diameter is preferably at most 100 μm, more preferably at most 80 μm, more preferably at most 60 μm, more preferably at most 50 μm, most preferably at most 40 μm.

[0151] The at least one additional particulate electroactive material is preferably selected from carbon-containing particles, graphite particles and / or hard carbon particles, the graphite and hard carbon particles having a D in the range of 10 to 50 μm. 50 More preferably, the at least one additional particulate electroactive material is selected from graphite particles, the graphite particles having a particle diameter D in the range of 10 to 50 μm. 50It has a particle diameter.

[0152] The composition may also be a non-hybrid (or "highly loaded") electrode composition that is substantially free of additional particulate electroactive material. In this context, the term "substantially free of additional particulate electroactive material" should be understood to mean that the composition contains less than 15 wt. %, preferably less than 10 wt. %, preferably less than 5 wt. %, preferably less than 2 wt. %, more preferably less than 1 wt. %, and more preferably less than 0.5 wt. % of any additional electroactive material (i.e., additional material capable of inserting and releasing metal ions during charging and discharging of the battery), based on the total dry weight of the composition.

[0153] "Highly loaded" electrode compositions of this type preferably comprise at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% by weight of composite particles obtained according to the first aspect of the invention, based on the total dry weight of the composition.

[0154] The composition may optionally contain a binder. The binder functions to adhere the composition to the current collector and maintain the integrity of the composition. Examples of binders that can be used in accordance with the present invention include polyvinylidene fluoride (PVDF), polyacrylic acid (PAA) and its alkali metal salts, modified polyacrylic acid (mPAA) and its alkali metal salts, carboxymethyl cellulose (CMC), modified carboxymethyl cellulose (mCMC), sodium carboxymethyl cellulose (Na-mCMC), polyvinyl alcohol (PVA), alginates and their alkali metal salts, styrene-butadiene rubber (SBR), and polyimides. The composition may also contain a mixture of binders. Preferably, the binder comprises a polymer selected from polyacrylic acid (PAA) and its alkali metal salts, modified polyacrylic acid (mPAA) and its alkali metal salts, SBR, and CMC.

[0155] The binder may suitably be present in an amount of from 0.5 to 20% by weight, preferably from 1 to 15% by weight, preferably from 2 to 10% by weight, most preferably from 5 to 10% by weight, based on the total dry weight of the composition.

[0156] The binder may optionally be present in combination with one or more additives that modify the properties of the binder, such as crosslinking promoters, coupling agents and / or adhesion promoters.

[0157] The composition may optionally contain one or more conductive additives. Preferred conductive additives are non-electroactive materials that are included to improve electrical conductivity between the electroactive components of the composition and between the electroactive components of the composition and the current collector. The conductive additive may be selected from carbon black, carbon fiber, carbon nanotubes, graphene, acetylene black, ketjen black, metal fiber, metal powder, and conductive metal oxide. Preferred conductive additives include carbon black and carbon nanotubes.

[0158] The one or more conductive additives may suitably be present in a total amount of from 0.5 to 20 wt %, preferably from 1 to 15 wt %, preferably from 2 to 10 wt %, most preferably from 5 to 10 wt %, based on the total dry weight of the composition.

[0159] In a fourth aspect, the present invention provides an electrode comprising a particulate material according to the first aspect of the invention in electrical contact with a current collector. The particulate material used to prepare the electrode of the fourth aspect of the invention may be in the form of a composition according to the third aspect of the invention.

[0160] The term "current collector" as used herein refers to any conductive substrate capable of carrying electrical current to or from the electroactive particles in the composition. Examples of materials that can be used as current collectors include copper, aluminum, stainless steel, nickel, titanium, and sintered carbon. Copper is a preferred material. The current collector is typically in the form of a thin film or mesh having a thickness of 3 to 500 μm. The particulate material of the present invention may be applied to one or both surfaces of the current collector, preferably to a thickness ranging from 10 μm to 1 mm, e.g., 20 to 500 μm, or 50 to 200 μm.

[0161] The electrode of the fourth aspect of the present invention may be manufactured by combining the particulate material of the present invention with a solvent and, optionally, one or more viscosity-modifying additives to form a slurry. The slurry is then cast onto the surface of a current collector and the solvent is removed, thereby forming an electrode layer on the surface of the current collector. Optionally, additional steps may be performed, such as heat treatment to cure any binder and / or calendering the electrode layer. Suitably, the electrode layer has a thickness of 20 μm to 2 mm, preferably 20 μm to 1 mm, preferably 20 μm to 500 μm, preferably 20 μm to 200 μm, preferably 20 μm to 100 μm, and preferably 20 μm to 50 μm.

[0162] Alternatively, the slurry may be formed into a free-standing film or mat comprising the particulate material of the present invention, for example, by casting the slurry onto a suitable casting template, removing the solvent, and then removing the casting template. The resulting film or mat is in the form of a coherent, free-standing mass, which may then be bonded to a current collector by conventional methods.

[0163] The electrode of the fourth aspect of the invention may be used as the anode of a metal-ion battery. Thus, in a fifth aspect, the present invention provides a rechargeable metal-ion battery having an anode, a cathode and an electrolyte therebetween, the anode comprising an electrode as described above and the cathode comprising a cathode active material capable of releasing and reabsorbing metal ions.

[0164] The metal ions are preferably lithium ions. More preferably, the rechargeable metal ion battery of the present invention is a lithium ion battery, and the cathode active material is capable of releasing and accepting lithium ions.

[0165] The cathode active material is preferably a metal oxide-based composite material. Examples of suitable cathode active materials include LiCoO, LiCo 0.99 Al 0.01 O2, LiNiO2, LiMnO2, LiCo 0.5 Ni 0.5 O2, LiCo 0.7 Ni 0.3 O2, LiCo 0.8 Ni 0.2 O2, LiCo 0.82 Ni 0.18 O2, LiCo 0.8 Ni 0.15 Al 0.05 O2, LiNi 0.4 Co 0.3 Mn 0.3 O2 and LiNi 0.33 Co 0.33 Mn 0.34 O2. The cathode current collector is generally 3 to 500 μm thick. Examples of materials that can be used as the cathode current collector include aluminum, stainless steel, nickel, titanium, and sintered carbon.

[0166] The electrolyte is preferably a non-aqueous electrolyte containing a metal salt, such as a lithium salt, and may include, but is not limited to, non-aqueous electrolyte solutions, solid electrolytes, and inorganic solid electrolytes. Examples of usable non-aqueous electrolyte solutions include aprotic organic solvents such as propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma butyrolactone, 1,2-dimethoxyethane, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxymethane, sulfolane, methyl sulfolane, and 1,3-dimethyl-2-imidazolidinone.

[0167] Examples of organic solid electrolytes include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate ester polymers, polyester sulfides, polyvinyl alcohol, polyvinylidine fluoride, and polymers containing ion-dissociating groups.

[0168] Examples of inorganic solid electrolytes include nitrides, halides and sulfides of lithium salts, such as Li5NI2, Li3N, LiI, LiSiO4, Li2SiS3, Li4SiO4, LiOH and Li3PO4.

[0169] The lithium salt is suitably soluble in the selected solvent or mixture of solvents. Examples of suitable lithium salts include LiCl, LiBr, LiI, LiClO4, LiBF4, LiBC4O8, LiPF6, LiCF3SO3, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, and CF3SO3Li.

[0170] When the electrolyte is a non-aqueous organic solution, the metal-ion battery is preferably provided with a separator interposed between the anode and the cathode. The separator is typically formed from an insulating material with high ion permeability and high mechanical strength. The separator typically has a pore diameter of 0.01 to 100 μm and a thickness of 5 to 300 μm. An example of a suitable electrode separator is a microporous polyethylene membrane.

[0171] The separator may be replaced with a polymer electrolyte material, in which case the polymer electrolyte material is present within both the composite anode layer and the composite cathode layer. The polymer electrolyte material may be a solid polymer electrolyte or a gel-type polymer electrolyte.

[0172] In a sixth aspect, the present invention provides the use of a particulate material according to the first aspect of the invention as an anode active material, optionally in the form of a composition according to the third aspect of the invention.

[0173] Further disclosure of the present invention is provided in the following numbered statements: 1. A particulate material composed of a plurality of composite particles, The composite particles are (a) a porous particulate scaffold, the total pore volume of pores having pore diameters in the range of 3.5 to 100 nm as determined by nitrogen gas adsorption is P per gram of said porous particulate scaffold; 1 cm 3 where P 1 represents a number ranging from 0.3 to 2.4, and a porous particle skeleton; (b) a multilayer coating disposed on the interior pore surfaces of the porous particulate scaffold, the multilayer coating comprising at least: (i) a first electroactive material layer; (ii) a second electroactive material layer; and (iii) a first interlayer material disposed between the first and second electroactive material layers; a multi-layer coating having 1. A particulate material having:

[0174] 2. The particulate material according to Disclosure 1, wherein the porous particle skeleton is an electrically conductive porous particle skeleton.

[0175] 3. The particulate material according to Disclosure 2, wherein the conductive porous particle skeleton is a conductive porous carbon particle skeleton.

[0176] 4. The particulate material of Disclosure 3, wherein the electrically conductive porous carbon particle skeleton comprises at least 80% by weight carbon, at least 85% by weight carbon, at least 90% by weight carbon, or at least 95% by weight carbon.

[0177] 5. The above P 1 is in the range of 0.6 to 2.4, 0.7 to 2.4, 0.8 to 2.3, 0.9 to 2.2, 0.95 to 2.1, 1 to 2, 1.05 to 1.95, 1.1 to 1.9, 1.15 to 1.85, or 1.2 to 1.8.

[0178] 6. A particulate material according to any one of Disclosures 1 to 5, wherein the volume fraction of pores having a pore diameter in the range of 5 to 60 nm is at least 50 vol%, at least 55 vol%, at least 60 vol%, at least 65 vol%, at least 70 vol%, at least 75 vol%, at least 80 vol%, at least 85 vol%, or at least 90 vol%, based on the total pore volume of pores having a pore diameter in the range of 3.5 to 100 nm in the porous particulate skeleton.

[0179] 7. The volume fraction of pores with pore diameters in the range of 10 to 50 nm is 7. The particulate material of Disclosure 6, wherein pores having pore diameters in the range of 3.5 to 100 nm in the porous particulate skeleton account for at least 50 vol%, at least 55 vol%, at least 60 vol%, at least 65 vol%, at least 70 vol%, at least 75 vol%, at least 80 vol%, at least 85 vol%, or at least 90 vol%, based on the total pore volume.

[0180] 8. The total pore volume of pores having a diameter of less than 3.5 nm in the porous particle skeleton as determined by nitrogen gas adsorption is P 2 cm 3 / g, The P 2 represents a number having a value of less than 0.5, less than 0.45, less than 0.4, less than 0.35, less than 0.3, less than 0.25, less than 0.2, less than 0.15, or less than 0.1.

[0181] 9. The total volume of pores having a diameter of less than 3.5 nm in the porous particle framework as determined by nitrogen gas adsorption is P 2 cm 3 / g, The P 2 is [1×P 1 ] and below, [0.8×P 1 ] and below, [0.6 × P 1 ] and below, [0.5 × P 1 ] and below, [0.4 × P 1 ] and below, [0.3 × P 1 ] and below, [0.2 × P 1 ] or less, or [0.1 × P 1 9. The particulate material according to any one of Disclosures 1 to 8, wherein:

[0182] 10. The porous particle framework is 250 mm 2 / g to 2,500m 2 / g, 500m 2 / g to 2,500m 2 / g, 750m 2 / g to 2,000m 2 / g, 750m 2 / g to 1,750m 2 / g, 750m 2 / g to 1,500m 2 / g, 1,000 to 2,000 m 2 / g, 1,000m 2 / g to 1,750m 2 / g, 1,000m 2 / g to 1,500m 2 / g, 1,250 m 2 / g to 2,000 m 2 / g, 1,250 m 2 / g to 1,750 m 2 / g, 2500 m 2 / g to 2,000 m 2 / g, 2500 m 2 / g to 1,750 m 2 / g, or 500 m 2 / g to 1,500 m 2 The particulate material according to any one of Disclosures 1 to 9, having a BET surface area in the range of / g.

[0183] [[ID=?]]

[0184] 12. The particulate material according to Disclosure 11, wherein the first electroactive material layer and the second electroactive material layer each independently have an electroactive material selected from elemental silicon, elemental tin, elemental germanium, elemental aluminum, and mixtures and alloys thereof.

[0185] 13. The particulate material according to any one of Disclosures 1 to 11, wherein the first intermediate layer material contains carbon, nitrogen, oxygen, or a conductive metal element or alloy.

[0186] 14. The first intermediate layer material has a passivation layer formed on the surface of the first electroactive material layer or is composed of a passivation layer. The passivation layer is an oxide, nitride, oxynitride, or carbide of the first electroactive material. Preferably, the first intermediate layer material is an oxide selected from SiO x where 0 < x ≦ 2, or a nitride selected from SiN x where 0 < x ≦ 4 / 3, or a carbide selected from SiC x where 0 < x ≦ 1, of the particulate material according to Disclosure 13. <??

[0187] It should be noted that there seems to be an issue with the "??0000959" tag in the original text. It might be a misprint or an incorrect tag. Also, the "?" in the "12." item's ID might be a mistake in the original input. Please double-check the source text for accuracy. 15. The first interlayer material has or consists of a passivation layer formed on a surface of the first electroactive material layer; 14. The particulate material of claim 13, wherein the passivation layer comprises a carbon-containing organic moiety covalently bonded to the surface of the first electroactive material layer.

[0188] 16. The particulate material of any one of Disclosures 1 to 15, wherein the first intermediate layer material comprises an electrically conductive pyrolytic carbon material.

[0189] 17. A particulate material according to any one of claims 1 to 15, wherein the first intermediate layer material comprises a conductive metal layer.

[0190] 18. The particulate material according to any one of Disclosures 1 to 15, wherein the first intermediate layer material comprises a lithium ion permeable solid electrolyte.

[0191] 19. The particulate material of any of Disclosures 1-18, wherein the multilayer coating comprises n electroactive material layers and (n-1) intermediate layer materials disposed between each of the electroactive material layers, where n is an integer from 3 to 20, 3 to 15, 4 to 12, 4 to 10, 5 to 10, or 5 to 8.

[0192] 20. The particulate material of Disclosure 19, wherein each of the n electroactive materials is independently defined as described in Disclosure 11, preferably each of the n electroactive materials is the same electroactive material, and more preferably each of the n electroactive materials is silicon.

[0193] 21. The particulate material of Disclosure 19 or 20, wherein each of the (n-1) intermediate layer materials is independently defined as described in any of Disclosures 13 to 18, and optionally, each of the (n-1) intermediate layer materials is the same intermediate layer material.

[0194] 22. Furthermore, (iv) a coating layer disposed on the outermost surface of the electroactive material layer; and A particulate material according to any one of Disclosures 1 to 21, wherein if necessary, the coating layer is formed from an intermediate layer material according to Disclosures 13 to 18.

[0195] 23. A particulate material according to any one of Disclosures 1 to 22, wherein the amount of the electroactive material in the composite particle is selected so that the internal pore volume of the porous particle skeleton is at least 25% and at most 80% is occupied by the electroactive material and the intermediate layer material.

[0196] 24. The particulate material of any one of claims 1 to 23, wherein the composite particles comprise 35% to 75% by weight silicon, 40% to 70% by weight silicon, or 45% to 65% by weight silicon.

[0197] 25. A particulate material according to any one of claims 1 to 24, wherein the composite particles contain at least 80% by weight or 80 to 98% by weight of silicon and carbon in total.

[0198] 26. A particulate material according to any one of claims 1 to 25, wherein at least 85% by weight, more preferably at least 90% by weight, more preferably at least 95% by weight, more preferably at least 98% by weight of the electroactive material within the composite particles is filled within the internal pore volume of the porous particle skeleton.

[0199] 27. A particulate material according to any one of Disclosures 1 to 26, wherein the total oxygen content of the composite particles is less than 15% by weight, less than 10% by weight, or less than 5% by weight, less than 2% by weight, less than 1% by weight, or less than 0.5% by weight.

[0200] 28. The composite particles have a D in the range of 0.5 to 200 μm, 0.5 to 150 μm, 0.5 to 100 μm, 0.5 to 50 μm, 0.5 to 30 μm, 1 to 25 μm, 1 to 20 μm, 2 to 25 μm, 2 to 20 μm, 2 to 18 μm, 3 to 20 μm, 3 to 18 μm, 3 to 15 μm, 4 to 18 μm, 4 to 15 μm, 4 to 12 μm, 5 to 15 μm, 5 to 12 μm, or 5 to 10 μm. 50 28. The particulate material of any one of Disclosures 1 to 27, having a particle diameter.

[0201] 29. The composite particles have a particle size of 0.1 to 100 m 2 / g, or 0.1 to 80m 2 / g, or 0.5 to 60m 2 / g, or 0.5 to 40m 2 / g, or 1 to 30m 2 / g, or 1 to 25m 2 / g, or 2 to 20m 2 29. The particulate material of any one of claims 1 to 28, having a BET surface area in the range of 1 / g.

[0202] 30. A particulate material according to any one of claims 1 to 29, having a specific capacity upon lithiation in the range of 1400 to 2340 mAh / g, preferably 1600 to 2340 mAh / g.

[0203] 31. A method for preparing composite particles, comprising: (a) providing a plurality of porous particles, the total pore volume of pores having pore diameters in the range of 3.5 to 100 nm as determined by nitrogen gas adsorption is P per gram of said porous particles; 1 cm 3 where P 1 represents a number ranging from 0.3 to 2.4, and (b) depositing a first electroactive material layer on the interior pore surfaces of the porous particle; (c) forming a first interlayer material on a surface of the first electroactive material layer; (d) depositing a second electroactive material layer on the surface of the first interlayer material; A method comprising:

[0204] 32. The method of Disclosure 31, wherein the porous particles are conductive porous particles.

[0205] 33. The method of Disclosure 32, wherein the conductive porous particles are conductive porous carbon particles.

[0206] 34. The method of Disclosure 33, wherein the conductive porous carbon particles comprise at least 80% by weight carbon, at least 85% by weight carbon, at least 90% by weight carbon, or at least 95% by weight carbon.

[0207] 35. The above P 1 35. The particulate material of any of Disclosures 31 to 34, wherein Mn is in the range of 0.6 to 2.4, 0.7 to 2.4, 0.8 to 2.3, 0.9 to 2.2, 0.95 to 2.1, 1 to 2, 1.05 to 1.95, 1.1 to 1.9, 1.15 to 1.85, or 1.2 to 1.8.

[0208] 36. A particulate material according to any one of Disclosures 31 to 35, wherein the volume fraction of pores having a pore diameter in the range of 5 to 60 nm is at least 50 vol%, at least 55 vol%, at least 60 vol%, at least 65 vol%, at least 70 vol%, at least 75 vol%, at least 80 vol%, at least 85 vol%, or at least 90 vol%, based on the total pore volume of pores having a pore diameter in the range of 3.5 to 100 nm in the porous particulate skeleton.

[0209] 37. The particulate material of Disclosure 36, wherein the volume fraction of pores having pore diameters in the range of 10 to 50 nm is at least 50 vol%, at least 55 vol%, at least 60 vol%, at least 65 vol%, at least 70 vol%, at least 75 vol%, at least 80 vol%, at least 85 vol%, or at least 90 vol%, based on the total pore volume of pores having pore diameters in the range of 3.5 to 100 nm in the porous particulate skeleton.

[0210] 38. The total pore volume of pores having a diameter of less than 3.5 nm in the porous particles as determined by nitrogen gas adsorption is P 2 cm 3 / g, The P 2 38. The particulate material of any one of Disclosures 31 to 37, wherein R represents a number having a value of less than 0.5, less than 0.45, less than 0.4, less than 0.35, less than 0.3, less than 0.25, less than 0.2, less than 0.15, or less than 0.1.

[0211] 39. The total volume of pores having a diameter of less than 3.5 nm in the porous particle as determined by nitrogen gas adsorption is P 2 cm 3 / g, The P 2 is [1×P 1 ] and below, [0.8×P 1 ] and below, [0.6 × P 1 ] and below, [0.5 × P 1 ] and below, [0.4 × P 1 ] and below, [0.3 × P 1 ] and below, [0.2 × P 1 ] or less, or [0.1 × P 1 39. The particulate material of any one of Disclosures 31 to 38, wherein:

[0212] 40. The porous particles are 250 mm 2 / g to 2,500m 2 / g, 500m 2 / g to 2,500m 2 / g, 750m 2 / g to 2,000m2 / g, 750m 2 / g to 1,750m 2 / g, 750m 2 / g to 1,500m 2 / g, 1,000 to 2,000 m 2 / g, 1,000m 2 / g to 1,750m 2 / g, 1,000m 2 / g to 1,500m 2 / g, 1,250m 2 / g to 2,000m 2 / g, 1,250m 2 / g to 1,750m 2 / g, 2500m 2 / g to 2,000m 2 / g, 2500m 2 / g to 1,750m 2 / g, or 500m 2 / g to 1,500m 2 40. The particulate material of any of Disclosures 31 to 39, having a BET surface area in the range of 1 / g.

[0213] 41. The porous particles have a D in the range of 0.5 to 200 μm, 0.5 to 150 μm, 0.5 to 100 μm, 0.5 to 50 μm, 0.5 to 30 μm, 1 to 25 μm, 1 to 20 μm, 2 to 25 μm, 2 to 20 μm, 2 to 18 μm, 3 to 20 μm, 3 to 18 μm, 3 to 15 μm, 4 to 18 μm, 4 to 15 μm, 4 to 12 μm, 5 to 15 μm, 5 to 12 μm, or 5 to 10 μm. 50 41. The particulate material of any one of Disclosures 31 to 40, having a particle diameter.

[0214] 42. A particulate material according to any one of Disclosures 31 to 41, wherein the first electroactive material and the second electroactive material are, independently of one another, selected from elemental silicon, elemental tin, elemental germanium, elemental aluminum, and mixtures and alloys thereof.

[0215] 43. The method of any of disclosures 31-42, wherein at least one of the first and / or second electroactive materials is deposited by a chemical vapor infiltration (CVI) process using a gaseous precursor of the first and / or second electroactive material.

[0216] 44. The gaseous precursors of the first and second electroactive materials are, independently of one another, silane (SiH4), disilane (Si2H6), trisilane (Si3H8), tetrasilane (Si4H 10 ), trichlorosilane (HSiCl3) such as methyltrichlorosilane (CH3SiCl3) or dimethyldichlorosilane ((CH3)2SiCl2), bis[bis(trimethylsilyl)amino]tin(II) ([[(CH3)3Si]2N]2Sn), tetraallyltin ((H2C=CHCH2)4Sn), tetrakis(diethylamido)tin(IV) ([(C2H5)2N]4Sn), tetrakis(dimethylamido)tin(IV) ([(CH3)2N]4Sn), tetramethyltin (Sn(CH3)4), tetravinyltin (Sn(CH=CH2)4), tin(II) acetylacetonate (C 10 H 14 O4Sn), trimethyl(phenylethynyl)tin (C6H5C)≡CSn(CH3)3), trimethyl(phenyl)tin (C6H5Sn(CH3)3), aluminum tris(2,2,6,6-tetramethyl-3,5-heptanedionate (Al(OCC(CH3)3CHCOC(CH3)3)3), trimethylaluminum ((CH3)3Al), tris(dimethylamido)aluminum(III) (Al( 44. The method of claim 43, wherein the hydride is selected from the group consisting of tetramethyl germanium ((CH)Ge), tetramethyl germanium ((CH)Ge), tetramethyl germanium ((CH)Ge), tributyl germanium hydride ([CH(CH)]GeH), triethyl germanium hydride ((CH)GeH), and triphenyl germanium hydride ((CH)GeH)).

[0217] 45. The first electroactive material and the second electroactive material are both elemental silicon; If desired, the gaseous precursors of the first and second electroactive materials may be, independently of one another, silane (SiH), disilane (SiH), trisilane (SiH), tetrasilane (SiH), 10 ), trichlorosilane (HSiCl3), methyltrichlorosilane (CH3SiCl3), and dimethyldichlorosilane ((CH3)2SiCl2); 45. The method of claim 42 or 44, wherein, if required, the gaseous precursor of the first and second electroactive materials is silane (SiH4).

[0218] 46. ​​The method of any of Disclosures 43-45, wherein steps (b) and (d) independently comprise contacting the plurality of porous particles with a gas comprising 1 to 100 vol%, 1 to 50 vol%, 2 to 40 vol%, 5 to 30 vol%, or 5 to 25 vol% of each of the gaseous precursors.

[0219] 47. The method of any of disclosures 31 to 46, wherein steps (b) and (d) are carried out, independently of one another, at a temperature in the range of 300 to 700°C, 350 to 700°C, 400 to 700°C, 400 to 650°C, 400 to 600°C, 400 to 550°C, 400 to 500°C, 400 to 450°C, or 450 to 500°C.

[0220] 48. The method of any of disclosures 31-47, wherein step (c) comprises passivating the surface of the first electroactive material layer with air or another oxygen-containing gas, such that the first intermediate layer material becomes an oxide of the first electroactive material.

[0221] 49. The method of any one of disclosures 31 to 47, wherein step (c) comprises passivating the surface of the first electroactive material layer with (i) ammonia, (ii) a gas containing ammonia and oxygen, or (iii) phosphine, so that the first interlayer material comprises a nitride, oxynitride, or phosphide of the first electroactive material.

[0222] 50. Step (c) comprises using a passivator selected from one or more compounds of the following formula: (i)R 1 -CH=CH-R 1 , (ii)R 1 -C≡CR 1 , (iii) O=CR 1 R 1 , (iv) HX-R 2 , (v) HX-C(O)-R1, where X is O, S, or NR 1 or PR 1 represents Each R 1 represent, independently of one another, H or an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 carbon atoms, or two R 1 The group forms an unsubstituted or substituted ring structure containing 3 to 8 carbon atoms in the ring; R 2 represents an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 carbon atoms, or R 1 and R 2 together form an unsubstituted or substituted ring structure containing 3 to 8 carbon atoms in the ring; passivating the surface of the first electroactive material layer by 48. The method of any of claims 31 to 47, wherein the first interlayer material comprises a carbon-containing organic moiety covalently bonded to the surface of the first electroactive material layer.

[0223] 51. The method of any of disclosures 31-50, wherein step (c) comprises depositing a layer of electrically conductive pyrolytic carbon material on the surface of the optionally passivated first electroactive material layer.

[0224] 52. Step (c) comprises depositing a layer of conductive metal on the optionally passivated surface of the first electroactive material layer; 51. The method of any one of claims 31 to 50, wherein the conductive metal is silver, if desired.

[0225] 53. The method of any of disclosures 31 to 50, wherein step (c) comprises depositing a layer of lithium-ion permeable solid electrolyte on the surface of the optionally passivated first electroactive material layer.

[0226] 54. Steps (c) and (d) are repeated one or more times to form a particulate material; the particulate material having n electroactive material layers and (n-1) interlayer materials disposed between each of the electroactive material layers; 54. The method of any one of Disclosures 31 to 53, wherein n is an integer from 3 to 20, from 3 to 15, from 3 to 12, from 3 to 10, from 4 to 10, or from 5 to 8.

[0227] 55. The method of Disclosure 54, wherein each iteration of step (d) is independently defined as in any of Disclosures 42 to 47, and where necessary, each of the n electroactive materials is the same electroactive material, and where necessary, each of the n electroactive materials is silicon.

[0228] 56. The method of Disclosure 54 or 55, wherein each iteration of step (c) is independently defined as in Disclosures 48 to 53, and, if necessary, each of the (n-1) interlayer materials is the same interlayer material.

[0229] 57. Furthermore, (e) forming a coating layer on the surface of the last deposited electroactive material layer; 57. The method of any of Disclosures 31 to 56, wherein step (e) optionally comprises any feature of step (c) of Disclosures 48 to 53.

[0230] 58. A composition comprising the particulate material of any one of Disclosures 1 to 30 and at least one other ingredient.

[0231] 59. The composition of Disclosure 58, comprising 1 to 95 wt %, 2 to 90 wt %, 5 to 85 wt %, or 10 to 80 wt %, based on the total dry weight of the composition, of the particulate material of Disclosures 1-27.

[0232] 60. The composition of Disclosure 58 or 59, wherein the at least one other component is selected from (i) a binder, (ii) a conductive additive, and (iii) an additional particulate electroactive material.

[0233] 61. The composition of disclosure 60, comprising at least one additional particulate electroactive material, where necessary, said at least one additional particulate electroactive material is selected from graphite, hard carbon, silicon, tin, germanium, aluminum, and lead.

[0234] 62. An electrode comprising the particulate material of any of disclosures 1 to 30 in electrical contact with a current collector, Optionally, the particulate material is in the form of a composition as described in any one of Disclosures 58-61.

[0235] 63. A rechargeable metal-ion battery comprising: (i) an anode, the anode comprising the electrode of Disclosure 62; (ii) a cathode comprising a cathode active material capable of releasing and resorbing metal ions; (iii) an electrolyte between the anode and the cathode; A metal ion battery comprising:

[0236] 64. Use of a particulate material according to any one of disclosures 1 to 30 as an anode active material.

[0237] 65. The use described in Disclosure 64, wherein the particulate material is in the form of a composition described in Disclosures 58 to 61.

[0238] Example - Preparation of Composite Particles in a Fluidized Bed Reactor 70 g of the particulate porous carbon skeleton was placed in a stainless steel fluidized-bed reactor equipped with a gas inlet consisting of five nozzles, each with 8 x 0.8 mm holes, to allow for dispersive gas mixing. The cross-sectional area of ​​the fluidized bed was 0.058 m, allowing for calculation of superficial velocities. The reactor was suspended from a frame, and a vertically oriented tube furnace was positioned so that the high-temperature zone was 3 / 4 the length from the conical section to the cylindrical section (approximately 380 mm long). The minimum fluidization velocity was determined by cold-flow pressure drop tests using nitrogen as the inert gas. The ramping gas flow rate was between 1 and 5 L / min. Once the minimum fluidization velocity was determined, the inert gas flow rate was held constant above the minimum fluidization velocity. The furnace was heated to the desired reaction temperature under a constant inert gas flow rate. After the target temperature stabilized between 435 and 500 °C, the fluidization gas was switched from pure nitrogen to a gas containing 4 vol% monosilane in nitrogen. The progress of the reaction was monitored by measuring the pressure drop between the top and bottom and the temperature difference of the furnace. To maintain a pressure drop consistent with continuous fluidization, the gas flow rate was adjusted throughout the run to maintain a minimum temperature difference of less than 100°C between the top and bottom of the fluidized bed. The monosilane feed was conducted for 6 hours, or depending on the layer thickness, after which the reactor was purged with nitrogen for 30 minutes to remove excess monosilane. Next, a pyrolytic carbon interlayer was formed by flowing a 30% ethylene / nitrogen gas mixture at temperatures between 300°C and 500°C for 30 minutes, after which the reactor was purged with nitrogen for 30 minutes to remove any ethylene. This process of introducing the monosilane and ethylene reactants was repeated depending on the number of layers required. At the end of the layering technique, the fluidization gas was switched to pure nitrogen while maintaining fluidization, and this purge was continued for 30 minutes. The furnace was then allowed to cool to ambient temperature over several hours. After reaching ambient temperature, the furnace atmosphere was gradually switched to air over several hours.

Claims

1. A particulate material composed of a plurality of composite particles, The composite particles are (a) an electrically conductive porous carbon particulate scaffold having at least 80% carbon, wherein the total pore volume of pores having pore diameters in the range of 3.5 to 100 nm as determined by nitrogen gas adsorption is P per gram of said porous particulate scaffold; 1 cm 3 where P 1 represents a number ranging from 0.3 to 2.4; and (b) a multilayer coating disposed on the interior pore surfaces of the porous particulate scaffold, the multilayer coating comprising at least (i) a first electroactive material layer consisting of or including silicon; (ii) a second electroactive material layer consisting of or including silicon; and (iii) a first interlayer material disposed between the first and second electroactive material layers; a multi-layer coating having and the first interlayer material comprises a conductive pyrolytic carbon material, a conductive metal layer, and a passivation layer formed on a surface of a lithium ion permeable solid electrolyte or the first electroactive material layer; The intermediate layer material is a particulate material having a thickness of less than 5 nm.

2. 10. The particulate material of claim 1, wherein the electrically conductive porous carbon particle skeleton comprises at least 85% by weight carbon, or at least 90% by weight carbon, or at least 95% by weight carbon.

3. 3. A particulate material according to claim 1 or 2, wherein the conductive porous carbon particle skeleton comprises amorphous carbon or a mixture of amorphous and crystalline carbon.

4. The conductive porous carbon particle skeleton has 50% to 98% sp 2 4. A particulate material according to any one of claims 1 to 3, comprising hybridized carbon.

5. The above P 1 5. The particulate material of claim 1 , wherein R is in the range of 0.6 to 2.4, 0.7 to 2.4, 0.8 to 2.3, 0.9 to 2.2, 0.95 to 2.1, 1 to 2, 1.05 to 1.95, 1.1 to 1.9, 1.15 to 1.85, or 1.2 to 1.

8.

6. 6. A particulate material according to any one of claims 1 to 5, wherein the volume fraction of pores having a pore diameter in the range of 5 to 60 nm is at least 50 vol%, at least 55 vol%, at least 60 vol%, at least 65 vol%, at least 70 vol%, at least 75 vol%, at least 80 vol%, at least 85 vol%, or at least 90 vol%, based on the total pore volume of pores having a pore diameter in the range of 3.5 to 100 nm in the porous particle skeleton.

7. The total volume of pores with diameters less than 3.5 nm in the porous particle skeleton as determined by nitrogen gas adsorption is P 2 cm 3 / g, The P 2 is [1×P 1 ] and below, [0.8×P 1 ] and below, [0.6×P 1 ] and below, [0.5×P 1 ] and below, [0.4×P 1 ] and below, [0.3×P 1 ] and below, [0.2×P 1 ] or less, or [0.1×P 1 7. A particulate material according to any one of claims 1 to 6, wherein:

8. The porous particle skeleton is 250 mm 2 / g to 2,500m 2 / g, 500m 2 / g to 2,500m 2 / g, 750m 2 / g to 2,000m 2 / g, 750m 2 / g to 1,750m 2 / g, 750m 2 / g to 1,500m 2 / g, 1,000 to 2,000m 2 / g, 1,000m 2 / g to 1,750m 2 / g, 1,000m 2 / g to 1,500m 2 / g, 1,250m 2 / g to 2,000m 2 / g, 1,250m 2 / g to 1,750m 2 / g, 250m 2 / g to 2,000m 2 / g, 250m 2 / g to 1,750m 2 / g, or 500m 2 / g to 1,500m 2 8. The particulate material of claim 1, having a BET surface area in the range of 0.1 wt. / g.

9. the first interlayer material has or consists of a passivation layer formed on a surface of the first electroactive material layer; 9. The particulate material of claim 1, wherein the passivation layer comprises a carbon-containing organic moiety covalently bonded to a surface of the first electroactive material layer.

10. 10. The particulate material of claim 1, wherein the first intermediate layer material comprises a lithium ion permeable solid electrolyte.

11. 11. The particulate material of claim 1, wherein the multilayer coating comprises n electroactive material layers and (n-1) intermediate layer materials disposed between each of the electroactive material layers, where n is an integer from 3 to 20, 3 to 15, 4 to 12, 4 to 10, 5 to 10, or 5 to 8.

12. moreover, (iv) a coating layer disposed on the outermost surface of the electroactive material layer; 12. The particulate material according to claim 1, having

13. The coating layer is a passivation layer, and the passivation layer comprises: (i) an oxide, nitride, oxynitride, or carbide of the first electroactive material, preferably the first interlayer material is SiO x (where 0 < x ≦ 2), or SiN x (where 0<x≦4 / 3), or SiC x (where 0<x≦1), and (ii) a carbon-containing organic moiety covalently bonded to the surface of the first electroactive material layer; 13. The particulate material of claim 12, selected from:

14. 13. The particulate material of claim 12, wherein the coating layer is selected from a conductive pyrolytic carbon material, a conductive metal layer, or a lithium ion permeable solid electrolyte.

15. 15. A particulate material according to any one of claims 1 to 14, wherein the amount of the electroactive material in the composite particles is selected so that at least 25% and up to 80% of the internal pore volume of the porous particle skeleton is occupied by the electroactive material and the intermediate layer material.

16. 16. A particulate material according to any one of claims 1 to 15, wherein the composite particles comprise 35% to 75% by weight silicon, 40% to 70% by weight silicon, or 45% to 65% by weight silicon.

17. 17. A particulate material according to any one of claims 1 to 16, wherein the composite particles comprise from 80 to 98% by weight of silicon and carbon combined.

18. 18. A particulate material according to any one of claims 1 to 17, wherein at least 85% by weight of the electroactive material within the composite particles is located within the internal pore volume of the porous particle framework.

19. The composite particles have a D in the range of 0.5 to 200 μm, 0.5 to 150 μm, 0.5 to 100 μm, 0.5 to 50 μm, 0.5 to 30 μm, 1 to 25 μm, 1 to 20 μm, 2 to 25 μm, 2 to 20 μm, 2 to 18 μm, 3 to 20 μm, 3 to 18 μm, 3 to 15 μm, 4 to 18 μm, 4 to 15 μm, 4 to 12 μm, 5 to 15 μm, 5 to 12 μm, or 5 to 10 μm. 50 19. A particulate material according to any one of claims 1 to 18, having a particle diameter of 1000 mm.

20. The particulate material contains 10% or less unoxidized silicon at 800°C as determined by thermogravimetric analysis in air at a heating rate of 10°C / min, the percentage of unoxidized silicon at 800°C being expressed as a percentage of the total amount of silicon according to the following formula: Z=1.875×[(M f -M 800 ) / M f ]×100% where Z is the percentage of unoxidized silicon at 800°C, and M f is the mass of the sample at the end of oxidation, and M 800 20. A particulate material according to any one of claims 1 to 19, wherein m is the mass of the sample at 800°C.

21. 21. A particulate material according to any one of claims 1 to 20, wherein the total oxygen content of the composite particles is less than 5% by weight, less than 2% by weight, less than 1% by weight, or less than 0.5% by weight.

22. 1. A method for preparing composite particles, comprising: (a) providing a plurality of porous particles, the total pore volume of pores having pore diameters in the range of 3.5 to 100 nm as determined by nitrogen gas adsorption is P per gram of said porous particles; 1 cm 3 where P 1 represents a number ranging from 0.3 to 2.4, and (b) depositing a first silicon layer on the interior pore surfaces of the porous particles; (c) forming a first interlayer material on the surface of the first electroactive material layer, the first interlayer material comprising a conductive pyrolytic carbon material, a conductive metal layer, a lithium ion permeable solid electrolyte, or a passivation layer formed on the surface of the first electroactive material layer, the first interlayer material having a thickness of less than 5 nm; (d) depositing a second silicon layer on the surface of the first interlayer material; A method comprising:

23. 23. The method of claim 22, wherein the porous particles have any of the features defined for the porous particle scaffolds of claims 2 to 8.

24. 24. The method of claim 22 or 23, wherein at least one of the first and second silicon layers in steps (b) and / or (d) is deposited by a chemical vapor infiltration (CVI) process using a gaseous silicon precursor.

25. The gaseous silicon precursors of the first and second silicon layers can be, independently of one another, silane (SiH 4 ), disilane (Si 2 H 6 ), trisilane (Si 3 H 8 ), tetrasilane (Si 4 H 10 ), trichlorosilane (HSiCl 3 ), methyltrichlorosilane (CH 3 SiCl 3 ), or dimethyldichlorosilane ((CH 3 ) 2 SiCl 2 25. The method of claim 24, wherein the hydroxyl group is selected from the group consisting of:

26. 26. The method of claim 24 or 25, wherein steps (b) and (d) independently comprise contacting the plurality of porous particles with a gas comprising 1 to 100 vol%, 1 to 50 vol%, 2 to 40 vol%, 5 to 30 vol%, or 5 to 25 vol% of the respective gaseous precursor.

27. 27. The method of any one of claims 22 to 26, wherein steps (b) and (d) are carried out, independently of one another, at a temperature in the range of 300 to 700°C, 350 to 700°C, 400 to 700°C, 400 to 650°C, 400 to 600°C, 400 to 550°C, 400 to 500°C, 400 to 450°C, or 450 to 500°C.

28. The step (c) (a) air or other oxygen-containing gas such that the first interlayer material comprises an oxide of the first electroactive material; (b) ammonia, or a gas comprising ammonia and oxygen, such that the first interlayer material comprises a nitride or oxynitride of the first electroactive material; (c) a phosphine, such that the first interlayer material comprises a phosphide of the first electroactive material; or (d) a passivator selected from one or more compounds of the following formula: (i)R 1 -CH=CH-R 1 、 (ii) R 1 -C≡C-R 1 、 (iii)O=CR 1 R 1 、 (iv) HX-R 2 , and (v) HX-C(O)-R1, where X is O, S, or NR 1 or PR 1 represents Each R 1 represent, independently of one another, H or an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 carbon atoms, or two R 1 The group forms an unsubstituted or substituted ring structure containing 3 to 8 carbon atoms in the ring; R 2 represents an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 carbon atoms, or R 1 and R 2 together form an unsubstituted or substituted ring structure containing from 3 to 8 carbon atoms in the ring; passivating the surface of the first electroactive material layer by 28. The method of any one of claims 22 to 27, wherein the first interlayer material comprises a carbon-containing organic moiety covalently bonded to the surface of the first electroactive material layer.

29. 29. The method of any one of claims 22 to 28, wherein step (c) comprises depositing a layer of lithium-ion permeable solid electrolyte on a surface of the optionally passivated first electroactive material layer.

30. Steps (c) and (d) are repeated one or more times to form a particulate material; the particulate material having n silicon layers and (n-1) intermediate layer materials disposed between each of the silicon layers; 30. The method of any one of claims 22 to 29, wherein n is an integer from 3 to 20, from 3 to 15, from 3 to 12, from 3 to 10, from 4 to 10, or from 5 to 8.

31. (i) each repetition of step (d) is independently defined according to any one of claims 23 to 26; and / or (ii) The method of claim 30, wherein each iteration of step (c) is independently defined as in claim 27 or claim 28.

32. moreover, (e) forming a coating layer on the surface of the last deposited electroactive material layer; 32. The method of claim 22, wherein

33. 22. A composition comprising a particulate material according to any one of claims 1 to 21 and at least one other ingredient.

34. 21. An electrode comprising the particulate material of any one of claims 1 to 20 in electrical contact with a current collector.

35. 1. A rechargeable metal ion battery, comprising: (i) an anode, the anode comprising the electrode of claim 34; (ii) a cathode comprising a cathode active material capable of releasing and resorbing metal ions; (iii) an electrolyte between the anode and the cathode; A metal ion battery comprising:

36. 22. Use of the particulate material according to any one of claims 1 to 21 as an anode active material.

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