Electroactive materials for use in metal-ion batteries

Abstract

To provide: composite particles that provide improved performance when used as electroactive materials in rechargeable metal-ion batteries; electrodes; and method of preparing the composite particles.SOLUTION: This invention relates to particulate electroactive materials comprising a plurality of composite particles, where the composite particles comprise: (a) a porous conductive particle framework including micropores and / or mesopores having a total volume of at least 0.4 to 2.2 cm3 / g; (b) an electroactive material disposed within the porous conductive particle framework; and (c) a lithium ion permeable filler penetrating the pores of the porous conductive particle framework and disposed intermediate between the nanoscale silicon domains and the exterior of the composite particles.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a particulate material composed of a plurality of composite particles having an electroactive material and a lithium ion permeable filler material within a conductive porous particle framework. The composite particles provide improved performance when used as an electroactive material in a rechargeable metal ion battery.

Background Art

[0002] Rechargeable metal ion batteries are widely used in portable electronic devices such as mobile phones and laptop computers. Also, the rapid development of electric vehicle and hybrid vehicle technologies has created a large new market for high-performance secondary batteries. Typically, the anode of a metal ion battery has a metal current collector, to which a layer of electroactive material (herein defined as a material capable of inserting and releasing metal ions during charging and discharging of the battery) is provided. When the metal ion battery is charged, metal ions are transported from the metal ion-containing cathode layer through the electrolyte and inserted into the anode material.

[0003] Conventional lithium ion batteries use graphite as the electroactive material in the anode. When the graphite-containing anode is charged, lithium is intercalated between the graphite layers, forming a material having the empirical formula Li x C 6 (where x is greater than 0 and less than or equal to 1). This means that in a lithium ion battery, graphite has a maximum theoretical capacity of 372 mAh / g. The actual capacity is somewhat lower (about 340 to 360 mAh / g). The development of portable electronic devices and electric vehicles with high energy demands means that there is a need for electroactive materials that provide improved weight and volume capacities of graphite.

[0004] Materials such as silicon, tin, and germanium have a significantly higher capacity for inserting lithium atoms than graphite. In particular, silicon has been identified as a promising alternative to graphite in the manufacture of rechargeable metal-ion batteries due to its high capacity for lithium, having a high weight capacity and volume capacity (see, for example, Winter, M. et al., "Insertion Electrode Materials for Rechargeable Lithium Batteries" in Adv. Mater. 1998, 10, No. 10). At room temperature, silicon has a theoretical maximum specific capacity in lithium-ion batteries of about 3,600 mAh / g (Li 15 Si 4 -based).

Summary of the Invention

Problems to be Solved by the Invention

[0005] The high specific capacity of silicon is accompanied by large volume changes during charging and discharging. In the intercalation of lithium into bulk silicon, the volume of the silicon material increases up to 400% of its original volume. Therefore, repeated charge-discharge cycles cause large mechanical stresses in the silicon material, resulting in damage and delamination of the silicon anode material and deformation of other battery components. During the contraction of silicon particles during de-lithiation, a loss of electrical contact can occur between the anode material and the current collector. Another problem is that as a result of electrolyte deposition, a solid electrolyte interface (SEI) layer is formed on the fresh silicon surface during the initial charge cycle. This SEI layer does not have sufficient mechanical durability to accommodate the expansion and contraction of silicon and delaminates from the silicon surface. Subsequently, the newly exposed silicon surface leads to further electrolyte decomposition and an increase in the thickness of the SEI layer, resulting in irreversible consumption of lithium. As an overall result of these malfunction mechanisms, unacceptable losses in electrochemical capacity occur over continuous charge and discharge cycles.

[0006] To overcome problems associated with volume changes observed when charging a silicon-containing anode, many approaches have been proposed. One approach is to use a certain form of nanostructured silicon as the electroactive material. Fine silicon structures with a cross-section of less than about 150 nm, such as silicon films and silicon nanoparticles, are more resistant to volume changes during charge and discharge compared to micron-sized silicon particles. However, none of these are very suitable for commercial-scale applications in their unmodified form. Nanoscale particles are difficult to prepare and handle, and silicon films do not provide sufficient bulk capacity. Also, the relatively high surface area of nanostructured silicon results in unacceptable capacity loss in the first charge cycle due to excessive SEI formation.

[0007] To address the need for a high-capacity electroactive material, the applicant has proposed a composite material. Here, an electroactive material such as silicon is formed into a film within the pores of a porous conductive material (e.g., a carbon-containing porous material such as an activated carbon material). By carefully controlling the total pore volume, the pore size distribution of the porous conductive material, and the occupancy of the pore volume by the electroactive material, it has been found that a material with controlled expansion characteristics, limited SEI formation, and a high reversible capacity retention rate can be obtained. Thus, these composite materials provide significant charge and discharge characteristics of nanoscale silicon particles while avoiding the handling difficulties and capacity losses associated with nanoparticles.

[0008] This application relates to another development of the composite material described above. Using a lithium-ion permeable filler material, the vacant pore volume remaining after an electroactive material such as silicon is deposited within the pores of a porous framework material is filled.

Means for Solving the Problem

[0009] In a first aspect of the present invention, A particulate material composed of a plurality of composite particles, The composite particles are (a) A conductive porous particle framework having micropores and / or mesopores, wherein the micropores and / or mesopores have a total pore volume in the range of 0.4 to 2.2 cm 3 / g, and a conductive porous particle framework; (b) A plurality of nanoscale electroactive material domains disposed within the conductive porous particle framework; (c) A lithium-ion permeable filler material that passes through the pores of the conductive porous particle framework and is disposed intermediate the nanoscale electroactive material domains and the exterior of the composite particles, and a lithium-ion permeable filler; A particulate material is provided.

[0010] Accordingly, the present invention relates to a particulate material in which the structure of the composite particles is defined by a conductive porous particle framework, such as a porous carbon particle framework, an electroactive material is disposed within the pores of the conductive porous particle framework, and a lithium-ion permeable filler is disposed within the pore volume remaining between the nanoscale electroactive material domains and the exterior of the composite particles. Accordingly, typically, the electroactive material is disposed toward the center of the conductive porous particle framework, and the lithium-ion permeable filler is disposed toward the outer boundary of the particles.

Mode for Carrying Out the Invention

[0011] As used herein, the term "lithium-ion permeable" refers to an ion-conductive material that enables the transport of lithium ions from the outside of the composite particles to the nanoscale electroactive material domains. Preferably, the lithium-ion permeable filler material is impermeable to liquids such as the solvent of the liquid electrolyte.

[0012] By reducing the surface area of the composite particles and sealing the nanoscale electroactive material domains away from electrolyte access, the use of a lithium-ion permeable filler provides an improvement in the properties of the composite material particles when used as an electroactive material in a lithium-ion battery. In particular, the use of a lithium-ion filler suppresses SEI formation by reducing the surface area of the composite particles and by preventing contact between the electrolyte inside the particles and the nanoscale electroactive material domains. Also, the reduction in the surface area of the composite particles has the effect of reducing the amount of binder required for the formation of the electrode active layer containing the composite particles. Excessive binder is known to affect the degradation of rate performance. Another advantage of the present invention is that the filler contributes to the improved compressive strength of the composite particles by providing structural reinforcement to the conductive porous particle framework. Also, the particulate material of the present invention is also related to various manufacturing advantages that will be described in more detail hereinafter.

[0013] The conductive porous particle framework has a three-dimensionally interconnected open pore network, which includes micropores and / or mesopores, and, if necessary, a small amount of macropores. In the present application, in accordance with the conventional IUPAC terminology, the term "micropore" represents pores with a diameter of less than 2 nm, the term "mesopore" represents pores with a diameter of 2 to 50 nm, and the term "macropore" is used to represent pores with a diameter exceeding 50 nm.

[0014] In the present application, unless otherwise indicated, reference to the volume of micropores, mesopores and macropores within the conductive porous particle framework, and also reference to the pore volume distribution within the conductive porous particle framework, relates to the internal pore volume of the conductive porous particle framework measured in isolation, i.e., in the absence of any electroactive material or lithium-ion permeable filler occupying the pore volume.

[0015] The conductive porous particle framework is from 0.4 to 2.2 cm 3It is characterized by the total volume of micropores and mesopores in the range of / g (i.e., the total pore volume in the range of 0 to 50 nm). Usually, the conductive porous particle framework contains both micropores and mesopores. The conductive porous particle framework is not excluded from being used when it contains micropores but not mesopores, or when it contains mesopores but not macropores. However, it is preferable that the conductive porous particle framework contains at least some micropores.

[0016] More preferably, the total volume of micropores and mesopores in the conductive porous particle framework is at least 0.45 cm 3 / g, at least 0.5 cm 3 / g, at least 0.55 cm 3 / g, at least 0.6 cm 3 / g, at least 0.65 cm 3 / g, at least 0.7 cm 3 / g, at least 0.75 cm 3 / g, at least 0.8 cm 3 / g, at least 0.85 cm 3 / g, at least 0.9 cm 3 / g, at least 0.95 cm 3 / g, or at least 1 cm 3 / g. More preferably, the total volume of micropores and mesopores in the conductive porous particle framework is at least 0.7, at least 0.75, at least 0.8, or at least 0.85. The use of a highly porous carbon framework is significant because it can accommodate a large amount of silicon within the pore structure. Also, a highly porous carbon framework with a pore volume mainly in the form of micropores and smaller mesopores has been found to have sufficient strength to accommodate the volume expansion of silicon without breaking or deteriorating the porous carbon framework.

[0017] The internal pore volume of the conductive porous particle framework is preferably capped at a value where the increase in the fragility of the conductive porous particle framework outweighs the advantage of an increased pore volume for accommodating a larger amount of electroactive material. Preferably, the total volume of micropores and mesopores in the conductive porous particle framework is 2 cm 3 / g or less, 1.8 cm 3 / g or less, 1.6 cm 3 / g or less, 1.5 cm 3 / g or less, 1.45 cm 3 / g or less, 1.4 cm 3 / g or less, 1.35 cm 3 / g or less, 1.3 cm 3 / g or less, 1.25 cm 3 / g or less, 1.2 cm 3 / g or less, 1.1 cm 3 / g or less, 1.0 cm 3 / g or less, or 0.9 cm 3 / g or less. More preferably, the total volume of micropores and mesopores in the conductive porous particle framework is 1.2 cm 3 / g or less, 1.1 cm 3 / g or less, 1.0 cm 3 / g or less, or 0.9 cm 3 / g or less.

[0018] In some examples, the total volume of micropores and mesopores in the conductive porous particle framework is in the range of 0.6 to 1.4 cm 3 / g, in the range of 0.65 to 1.4 cm 3 / g, in the range of 0.7 to 1.4 cm 3 / g, in the range of 0.75 to 1.4 cm 3 / g, in the range of 0.6 to 1.3 cm 3 / g, in the range of 0.65 to 1.3 cm 3 / g, in the range of 0.7 to 1.3 cm 3 / g, in the range of 0.75 to 1.3 cm 3 / g, in the range of 0.6 to 1.2 cm 3 / g, in the range of 0.65 to 1.2 cm 3 / g, in the range of 0.7 to 1.2 cm 3 / g, in the range of 0.75 to 1.2 cm3 in the range of / g, from 0.6 to 1 cm 3 in the range of / g, from 0.65 to 1 cm 3 in the range of / g, from 0.7 to 1 cm 3 in the range of / g, from 0.75 to 1 cm 3 in the range of / g, from 0.6 to 0.9 cm 3 in the range of / g, from 0.65 to 0.9 cm 3 in the range of / g, from 0.7 to 0.9 cm 3 in the range of / g, or from 0.75 to 0.9 cm 3 may be in the range of / g.

[0019] The general term "PD" n "pore diameter", when used in this application, represents the pore diameter of the n - percent value based on the total volume of micropores and mesopores. For example, the term "PD" 90 "pore diameter" used in this application 1 represents the pore diameter at which the pore diameter of less than 90% of the total micropore and mesopore volume is found to be less than it, and the PD50 pore diameter is the median pore diameter at which 50% of the total micropore and mesopore volume is found to be less than it.

[0020] The PD 90 pore diameter of the porous carbon framework may be 20 nm or less, or 15 nm or less. Preferably, the PD 90 pore diameter is 12 nm or less, 10 nm or less, 8 nm or less, or 6 nm or less. Preferably, the PD 90 pore diameter of the porous carbon framework is at least 3 nm, at least 3.2 nm, at least 3.5 nm, at least 3.8 nm, or at least 4 nm.

[0021] The PD 30 pore diameter of the porous carbon framework is preferably 1.6 nm or less, 1.5 nm or less, 1.4 nm or less, 1.3 nm or less, 1.2 nm or less, 1.1 nm or less, or 1 nm or less. Preferably, the PD 30The pore diameter is preferably at least 0.45 nm, at least 0.5 nm, at least 0.6 nm, or at least 0.7 nm.

[0022] PD of the conductive porous particle framework 50 The pore diameter is preferably 10 nm or less, 8 nm or less, 6 nm or less, 5 nm or less, 4 nm or less, 3 nm or less, 2.5 nm or less, 2 nm or less, 1.5 nm or less. Preferably, PD of the porous carbon framework 50 The pore diameter is at least 1 nm, at least 1.1 nm, or at least 1.2 nm. Therefore, in the present invention, it is preferable that at least 50% of the total volume of micropores and mesopores in the conductive porous particle framework is in the form of pores having a diameter of less than 8 nm.

[0023] To avoid ambiguity, any macropore volume (pore diameter greater than 50 nm) is not considered for the purpose of determining the PD 50 value.

[0024] The volume ratio of micropores to mesopores in the conductive porous particle framework may, in principle, range from 100:0 to 0:100. Preferably, the volume ratio of micropores to mesopores is from 90:10 to 55:45, from 90:10 to 60:40, or from 85:15 to 65:35.

[0025] The pore size distribution of the conductive porous particles may be monomodal, bimodal or multimodal. The term "pore size distribution" as used in the present application relates to the distribution of pore sizes with respect to the cumulative total internal pore volume of the conductive porous particles. A bimodal or multimodal pore size distribution is preferred. This is because the close proximity between the micropores and the larger diameter pores provides the advantage of efficient ion transport to silicon through the porous network.

[0026] According to the standardized methods described in ISO 15901-2 and ISO 15901-3, using the quenched solid density functional theory (QSDFT), at 77 K and relative pressure p / p0 is reduced to 10 -6 Using nitrogen gas adsorption reduced to up to 10, the total volume of micropores and mesopores and the pore size distribution of micropores and mesopores were determined. The nitrogen gas adsorption method is a technique for characterizing the porosity and pore diameter distribution of a porous material by condensing a gas in the pores of a solid. As the pressure increases, the gas first condenses in the pores with the smallest diameter, and the pressure increases until the saturation point where all pores are filled with liquid is reached. Thereafter, the nitrogen gas pressure is gradually decreased and the liquid evaporates from the system. The pore volume and pore size distribution can be determined by analyzing the adsorption and desorption isotherms and the hysteresis between them. Apparatus suitable for measuring the pore volume and pore diameter distribution by the nitrogen gas adsorption method include the TriStarII and TriStarII Plus porosity analyzers available from Micromeritics, USA, and the Autosorb IQ porosity analyzer available from Quantachrome Instruments.

[0027] The nitrogen gas adsorption method is effective for measuring the pore volume and pore size distribution of pores with a diameter of up to 50 nm, but is less reliable for pores with a larger diameter. Therefore, for the purposes of the present invention, the nitrogen adsorption method is used to measure the pore volume and pore size distribution only in the case of pores having a diameter of up to 50 nm (i.e., only micropores and mesopores). Similarly, PD 50 is defined only with respect to the total volume of micropores and mesopores.

[0028] Considering the limitations of available analytical techniques, it is impossible to measure the pore volume and pore size distribution over the entire range of micropores, mesopores and macropores using a single technique. When the conductive porous particle framework contains macropores, the volume of pores in the range of more than 50 nm and up to 100 nm in diameter is measured by mercury porosimetry and is preferably 0.3 cm 3 / g or less, 0.20 cm 3 / g or less, 0.1 cm 3 / g or less, or 0.05 cm 3is below / g. More preferably, the volume of pores having a diameter exceeding 50 nm and up to 100 nm is preferably 20% or less, 10% or less, 5% or less, 2% or less, 1% or less, or 0.5% or less of the total volume of the micropores and mesopores.

[0029] The small ratio of macropores is useful for facilitating access of electrolytes to the pore network, but the advantages of the present invention are substantially obtained by accommodating silicon in the micropores and smaller mesopores.

[0030] Any pore volume measured by mercury porosimetry with a pore size of 50 nm or less is ignored (as described above, the nitrogen adsorption method is used to characterize mesopores and micropores). The pore volume exceeding 100 nm measured by a mercury porosimeter is assumed to be the interparticle porosity for the purposes of the present invention and is ignored.

[0031] Mercury porosimetry is a technique for characterizing the porosity and pore diameter distribution of a material by applying various levels of pressure to a sample of the material immersed in mercury. The pressure required to penetrate mercury into the pores of the sample is inversely proportional to the size of the pores. The values obtained by reported mercury porosimetry are obtained in accordance with ASTM UOP578 - 11, the surface tension γ is 480 mN / m, and the contact angle φ is 140° with respect to mercury at room temperature. The density of mercury is 13.5462 g / cm at room temperature 3 is taken. Many high - precision mercury porosimeters are commercially available, such as the AutoPoreIV series of automatic mercury porosimeters from Micromerics Instrument Corporation in the United States. For a complete review of mercury porosimetry, see P.A. Webb and C. Orr, “Analysis of Fine Particle Technology,” 1997, Micromeritics Instrument Corporation, ISBN 0 - 9656783 - 0.

[0032] It is understood that intrusion techniques such as gas adsorption method and mercury porosimetry are only effective when determining the pore volume of pores accessible to nitrogen or mercury from the outside of the conductive porous particle framework. The value of porosity defined in the present application is understood to represent the volume of open pores, that is, the porosity accessible to the fluid from the outside of the conductive porous particles. Completely enclosed pores that cannot be identified by nitrogen adsorption method or mercury porosimetry are not considered when determining the value of porosity. Similarly, any pore volume located in pores finer than the detection limit by nitrogen adsorption method is not considered.

[0033] The conductive porous particle framework is preferably a conductive porous carbon particle framework. The conductive porous carbon particle framework preferably contains at least 80% by mass of carbon, more preferably at least 85% by mass of carbon, more preferably at least 90% by mass of carbon, more preferably at least 95% by mass of carbon, and, if necessary, at least 98% by mass or at least 99% by mass of carbon. The carbon may be crystalline carbon, amorphous carbon, or a mixture of amorphous and crystalline carbon. The conductive porous carbon particle framework may be derived from hard carbon porous particles or soft carbon porous particles.

[0034] The term "hard carbon" used in the present application refers to an irregular carbon matrix in which carbon atoms are mainly found in a nano-scale polyaromatic domain in an sp 2 hybrid state (trigonal bond). The polyaromatic domains are crosslinked by chemical bonds, such as C-O-C bonds. Due to the chemical crosslinking between polyaromatic domains, hard carbon cannot be converted into graphite at high temperatures. Hard carbon has properties similar to graphite, as is evident from the large G band (~1600 cm -1 ) in the Raman spectrum. However, as is evident from the prominent D band (~1350 cm -1 ) in the Raman spectrum, the carbon is not completely graphitized.

[0035] In addition, the term "soft carbon" as used in the present application means that carbon atoms are mainly in an sp 2 hybridized state (trigonal crystal bond) in polyaromatic domains having dimensions in the range of 5 to 200 nm, representing an irregular carbon matrix. In contrast to hard carbon, the polyaromatic domains of soft carbon are bonded by intermolecular forces but are not cross-linked to have chemical bonds. This means that they are graphitized at high temperatures. The conductive porous carbon particles preferably contain at least 50% sp 2 hybrid carbon when measured by XPS. For example, the conductive porous carbon particles may have 50% to 98% sp 2 hybrid carbon, 55% to 95% sp 2 hybrid carbon, 60% to 90% sp 2 hybrid carbon, or preferably 70% to 85% sp 2 hybrid carbon.

[0036] For preparing a suitable conductive porous carbon framework by pyrolysis, various different materials may be used. Examples of organic materials that can be used include plant biomass containing lignocellulosic materials (such as coconut shells, nut shells, rice husks, wood, etc.), and fossil carbon sources such as coal. Examples of resin and polymer materials that form porous carbon particles during pyrolysis include phenolic resins, novolac resins, pitch, melamine, polyacrylates, polystyrenes, polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), and various copolymers containing monomer units of acrylates, styrenes, α-olefins, vinyl pyrrolidone, and other ethylenically unsaturated monomers. Depending on the starting materials and the conditions of the pyrolysis process, various different carbon materials may be obtained. Porous carbon particles of various different specifications are available from commercial suppliers.

[0037] The porous carbon particles may be subjected to a chemical or gaseous activation process to increase the volume of mesopores and micropores. Suitable activation processes are carried out at a temperature in the range of 600 to 1000 °C with oxygen, steam, CO, CO 2and contacting the pyrolytic carbon with one or more of KOH. Also, the mesopores can be obtained by known templating processes using extractable pore formers such as MgO and other colloidal or polymeric templates that can be removed by heat or chemical means after heat treatment or activation.

[0038] Alternatives to the carbon-based conductive particle framework include porous metal oxides such as titanium oxides having the general formula TiO x where x has a value greater than 1 and less than 2.

[0039] The conductive porous particle framework preferably has a BET surface area of at least 750 m 2 / g, at least 1,000 m 2 / g, at least 1,250 m 2 / g, or at least 1,500 m 2 / g. The term "BET surface area" as used in this application should be understood to represent the surface area per unit mass calculated from the measurement of the physical adsorption of gas molecules on the solid surface using the Brunauer-Emmett-Teller theory in accordance with ISO9277. Preferably, the BET surface area of the conductive porous particle framework is 4,000 m 2 / g or less, 3,500 m 2 / g or less, 3,250 m 2 / g or less, or 3,000 m 2 / g or less. For example, the conductive porous particle framework may have a BET surface area of from 750 m 2 / g to 4,000 m 2 / g, from 1,000 m 2 / g to 3,500 m 2 / g, from 1,250 m 2 / g to 3,250 m 2 / g, or from 1,500 m 2 / g to 3,000 m 2 / g.

[0040] The electroactive material in the composite particles is preferably selected from silicon, tin, germanium, aluminum, and mixtures thereof. A preferred electroactive material is silicon. The electroactive material may be doped, if necessary, with, for example, boron or phosphorus, as will be described in more detail below.

[0041] The composite particles may have different ranges of electroactive material fillings. For example, the amount of electroactive material in the composite particles may be selected such that at least 20% and at most 60% or more of the internal pore volume of the conductive porous particle framework is occupied by the electroactive material. For example, the electroactive material may occupy 25% to 55%, 25% to 50%, 30% to 45%, or 30% to 40% of the internal pore volume of the conductive porous particle framework. Within these preferred ranges, the pore volume of the conductive porous carbon particle framework is effective in accommodating the expansion of the electroactive material during charge and discharge, but an excessive pore volume that does not contribute to the volume capacity of the core-shell composite particles is avoided. However, the amount of electroactive material is not so high as to prevent effective lithiation due to insufficient metal ion diffusion rate or insufficient expansion volume, resulting in mechanical resistance to lithiation.

[0042] When the electroactive material is silicon, the mass ratio of silicon to the conductive porous particle framework is in the range of [0.5×P 1 to 1.3×P 1 :1, and the amount of silicon in the composite particles can be correlated with the available pore volume. Here, P 1 is a dimensionless quantity representing the total pore volume of micropores and mesopores in the conductive porous particles, expressed in cm 3 / g. (For example, if the porous conductive particle framework has a total volume of micropores and mesopores of 1.2 cm 3 / g, then P 1 = 1.2). In this relationship, the density of silicon and the pore volume of the conductive porous particle framework are considered, and the weight ratio of silicon with a pore volume occupancy of about 20% to 55% is determined.

[0043] When the electroactive material is silicon, the amount of silicon in the composite particles preferably comprises from 0.35 wt% to 0.65 wt%, from 0.4 wt% to 0.6 wt%, or from 0.45 wt% to 0.55 wt% of silicon.

[0044] Preferred composite particles comprise a conductive carbon porous particle framework, and the composite particles comprise at least 80 mass%, or from 80 mass% to 98 mass% in total of silicon and carbon.

[0045] The amount of silicon in the composite particles can be determined by elemental analysis. Preferably, elemental analysis is used to determine the weight percentages of carbon (and optionally hydrogen, nitrogen and oxygen) in the porous carbon particles alone and in the silicon-containing composite particles. Determining the weight percentage of carbon in the porous carbon particles alone takes into account the possibility that the porous carbon particles contain small amounts of heteroatoms. By performing both measurements together, the weight percentage of silicon relative to the porous carbon particles can be determined with high reliability.

[0046] The silicon content is preferably measured by ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometer). Many ICP-OES instruments are commercially available, such as the iCAP (trademark) 7000 series of ICP-OES analyzers available from ThermoFisher Scientific. The carbon content (and optionally further the hydrogen, nitrogen and oxygen contents) of the composite particles and of the porous carbon particle framework alone is preferably measured by IR absorption. A suitable apparatus for measuring the carbon, hydrogen, nitrogen, and oxygen contents is the TruSpec (trademark) Micro elemental analyzer available from Leco.

[0047] Preferably, at least 85% by mass, more preferably at least 90% by mass, still more preferably at least 95% by mass, and even more preferably at least 98% by mass of the electroactive material in the composite particles is disposed within the internal pore volume of the conductive porous particle framework. As a result, there is no electroactive material disposed on the outer surface of the composite particles, or it is extremely small.

[0048] The particulate materials of the present invention can be further characterized by their properties under thermogravimetric analysis (TGA) in air. The particulate materials preferably contain 10% or less of non-oxidized silicon as determined by TGA in air at 800 °C with a heating rate of 10 °C / min. More preferably, the particulate materials contain 5% or less or 2% or less of unoxidized silicon as determined by TGA in air at 800 °C with a heating rate of 10 °C / min.

[0049] The determination of the amount of unoxidized silicon is derived from the characteristic TGA traces of these materials. The mass increase at about 300 to 500 °C corresponds to the initial oxidation of Si to SiO 2 , and then a mass loss occurs at about 500 to 600 °C as carbon is oxidized to CO 2 gas. Above about 600 °C, a further mass increase occurs corresponding to the continued conversion of silicon to SiO 2 . This rises towards an asymptotic value above 1000 °C as the oxidation of silicon is completed.

[0050] In this analysis, any mass increase above 800 °C corresponds to the oxidation of Si to SiO 2 , and the total mass at the end of oxidation is assumed to be SiO 2 . Thus, the proportion of unoxidized silicon at 800 °C can be determined as the proportion of the total amount of silicon according to the following formula: Z = 1.875 × [(M f - M 800 ) / M f × 100% Here, Z is the proportion of unoxidized silicon at 800 °C, M f is the mass of the sample at the completion of oxidation at 1400 °C, M 800 is the mass of the sample at 800 °C. In this analysis, any mass increase above 800 °C corresponds to the oxidation of silicon to SiO 2 , and the total mass at the completion of oxidation is assumed to be SiO 2 . For completeness, 1.875 is the molar mass ratio of SiO 2 to O 2 (i.e., the mass ratio of the formed SiO 2 to the mass increase due to the addition of oxygen).

[0051] Although not bound by theory, it is understood that the temperature of silicon oxidized 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 the silicon nanostructures limit the length scale of the thickness of the oxide coating. Thus, it is understood that silicon deposited within the micropores and mesopores oxidizes at a lower temperature than the silicon deposits on the particle surface due to the necessarily thinner oxide coatings present on these structures. Thus, the preferred materials according to the present invention exhibit substantially complete oxidation of silicon at low temperatures consistent with the small length scales of the silicon nanostructures disposed within the micropores and smaller mesopores. For the purposes of the present invention, the oxidation of silicon at 800 °C is assumed to be the silicon on the outer surface of the conductive porous particle framework.

[0052] Preferably, the value of Z is 10 wt% or less, 8 wt% or less, 6 wt% or less, or 5 wt% or less.

[0053] The composite particles preferably have a low total oxygen content. Oxygen may be present in the composite particles, for example, as part of the conductive porous particle framework or as an oxide layer on any exposed silicon surface. Preferably, the surface of the electroactive material is passivated, and oxide formation is inhibited or prevented.

[0054] Preferably, the total oxygen content of the composite particles is less than 15% by weight, more preferably less than 10% by weight, even more preferably less than 5% by weight, for example less than 2% by weight, or less than 1% by weight, or less than 0.5% by weight. When the filler material is a solid electrolyte material containing oxygen, the total oxygen content of the composite particles is preferably less than 25% by weight, or less than 20% by weight, more preferably less than 15% by weight, for example less than 12% by weight, or less than 10% by weight.

[0055] The lithium ion permeable filler material may be selected from any material that can transport lithium ions and is preferably impermeable to solvent molecules such as the solvent of the liquid electrolyte. Preferably, the lithium ion permeable filler material is electrochemically stable with reference to a <0.1V, Li / Li + reference electrode.

[0056] If necessary, the lithium ion permeable filler material may be a conductive pyrolytic carbon material. As will be described in more detail hereinafter, the conductive pyrolytic carbon filler may be obtained by heating precursor composite particles (including conductive porous particle frameworks and electroactive materials) in the presence of a suitable pyrolytic carbon precursor vapor. The conductive pyrolytic carbon filler may be doped with, for example, boron or phosphorus, as will be described in more detail hereinafter if necessary. If necessary, both the conductive pyrolytic carbon filler and the electroactive material may be doped with, for example, boron, or both may be doped with phosphorus, or a mixture of boron and phosphorus dopants may be used.

[0057] If necessary, the conductive pyrolytic carbon material is an amorphous carbon material, and the carbon atoms are mainly in a sp 2 hybrid state (trigonal bond) and are preferentially found in polyaromatic domains having dimensions in the range of 5 to 200 nm. The conductive pyrolytic carbon material preferably has at least 50% sp 2 hybrid carbon when measured by XPS. For example, the porous carbon framework has 50% to 98% sp2 Hybrid carbon, 55% to 95% sp 2 Hybrid carbon, 60% to 90% sp 2 Hybrid carbon, or 70% to 85% sp 2 It may preferably have hybrid carbon.

[0058] Alternatively, the lithium ion permeable filler material may be a lithium ion permeable solid electrolyte. Examples of suitable lithium permeable solid electrolytes include garnet type solid electrolytes (Li 7 La 3 Zr 2 O 12 and Li 6.5 La 3 Ti 0.5 Zr 1.5 O 12 such as "LLZO" electrolytes), perovskite type solid electrolytes (Li 0.33 La 0.57 TiO 3 such as "LLTO" electrolytes), LISICON type solid electrolytes, NaSICON type solid electrolytes (Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 etc.), lithium phosphorous oxynitride (LiPON), Li 3 N type solid electrolytes, lithium phosphate (Li 3 PO 4 ) solid electrolytes, lithium titanate (Li 4 Ti 5 O 12 ) solid electrolytes, lithium tantalate (LiTaO 3 ) solid electrolytes, sulfide type solid electrolytes, argyrodite type solid electrolytes, and antiperovskite type solid electrolytes.

[0059] Also, the lithium ion permeable solid electrolyte may form a coating over at least a part of the outer surface of the porous carbon framework.

[0060] Alternatively, the lithium ion permeable filler material may be a metal-oligomer filler material. As used herein, the term "metal-oligomer filler" refers to a filler consisting of an extended network of metal and / or metalloid atoms interconnected by non-metal elements such as oxygen and / or nitrogen. This type of filler material is preferably formed by a wet chemical method using sol-gel chemistry, and then the resulting gel is crystallized to form a dense cross-linked network, such as an oxide, nitride or oxynitride network. For example, the metal-oligomer filler material may be a cross-linked metal-oligomer network having oxides, nitrides, or oxynitrides of titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, aluminum, silicon, gallium, germanium, or mixtures thereof.

[0061] The use of a conductive filler is particularly advantageous for improving the rate characteristics of the composite particles when it is used as an electroactive material in a lithium ion battery. The rate characteristics of the composite particles are determined, at least in part, by the rate of migration of lithium ions from the electrolyte into the bulk of the composite particles prior to insertion into the nanoscale electroactive material domains. The use of a lithium ion permeable solid electrolyte is significant because it can function as a rapid transport system into the bulk of the composite particles during charging of the lithium ion battery. Conductive pyrolytic carbon materials are likewise significant. This is to improve the electron transport into or out of the bulk of the composite particles. This again aids in improving the rate characteristics of the composite particles.

[0062] The composite particles preferably have a D 50 particle diameter in the range of 1 to 30 μm. If necessary, the D 50 particle diameter of the composite particles may be at least 1.5 μm, at least 2 μm, at least 2.5 μm, at least 3 μm, at least 4 μm, or at least 5 μm. Preferably, the D 50 particle diameter of the composite particles is at least 2.5 μm, or at least 3 μm. If necessary, the D50 The particle diameter may be 25 μm or less, 20 μm or less, 18 μm or less, 15 μm or less, 12 μm or less, 10 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, or 5 μm or less. Preferably, the D of the composite particles 50 The particle diameter is 10 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, or 5 μm or less.

[0063] For example, the composite particles may have a D in the range of 1 to 25 μm, 1 to 20 μm, 1 to 15 μm, 1 to 10 μm, 1 to 8 μm, 2 to 20 μm, 2 to 15 μm, 2 to 10 μm, 2 to 8 μm, 2 to 6 μm, 3 to 15 μm, 3 to 10 μm, 3 to 8 μm, 3 to 6 μm, 3 to 5 μm, 4 to 12 μm, 4 to 10 μm, 4 to 8 μm, or 4 to 6 μm 50 particle diameter.

[0064] Particles within these size ranges and having the porosity and pore diameter distribution described in the present application are ideally suitable for the preparation of composite particles used in the anode of a metal ion battery by a fluidized bed method. These particles provide good fluidization characteristics over the deposition process, and the formed composite particles have good dispersibility in the slurry, structural robustness, and a high capacity retention rate over repeated charge and discharge cycles, and are suitable for the formation of a dense electrode layer of uniform thickness in a conventional thickness range of 20 to 50 μm.

[0065] The D of the 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. D 10 By maintaining the particle diameter at 0.5 μm or more, the possibility of undesirable aggregation of submicron-sized particles is reduced, and as a result, the dispersibility of the composite particles in the slurry used for electrode manufacturing is improved.

[0066] The D of the composite particles 90The particle diameter is preferably 40 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less. Using larger conductive porous particles as starting materials complicates the separation of composite particles from particulate additives. As a result, the formation of a non-uniform packing of composite particles in the electrode active layer occurs, thus preventing the formation of a dense electrode layer, particularly an electrode layer having a thickness in the range of 20 to 50 μm.

[0067] More preferably, the D of the conductive porous particles 98 The particle diameter is 40 μm or less, 30 μm or less, 25 μm or less, or 20 μm or less.

[0068] The composite particles preferably have a narrow size distribution span. For example, the particle size distribution span ((D 90 - D 10 ) / D 50 as defined) 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.

[0069] To avoid ambiguity, the term "particle diameter" as used in this application refers to the equivalent spherical diameter (esd), i.e., the diameter of a sphere having the same volume as a given particle, where the particle volume is understood to include the volume of any internal pores in the particle. The terms "D 50 " and "D 50 particle diameter" as used in this application refer to the volume-based median particle diameter, i.e., the diameter at which less than 50 volume % of the particle population is found to have a diameter less than that. The terms "D 10 " and "D 10 particle diameter" as used in this application refer to the 10th percentile volume-based median particle diameter, i.e., the diameter at which less than 10 volume % of the particle population is found to have a diameter less than that. The terms "D 90 " and "D 90"Particle diameter" refers to the 90th percentile volume-based median particle diameter, i.e., the diameter at which less than 90% of the particle population is found to have a diameter less than that value.

[0070] The particle diameter and particle size distribution can be determined by standard laser diffraction techniques in accordance with ISO 13320:2009. The laser diffraction method is based on the principle that particles scatter light at angles that vary according to the size of the particles, and the particles and aggregates of particles form a pattern of scattered light defined by the intensity and angle that correlates with the particle size distribution. Many laser diffraction devices are commercially available for the rapid and reliable measurement of particle size distributions. Unless otherwise specified, the particle size distribution measurements defined or reported in this application are those measured with a conventional Malvern Mastersizer (trademark) 3000 particle size analyzer manufactured by Malvern Instruments. The Malvern Mastersizer (trademark) 3000 particle size analyzer operates by irradiating a transparent cell containing the target particles suspended in an aqueous solution with a helium-neon gas laser beam. The light beam irradiated onto the particles is scattered through an angle inversely proportional to the particle size, and an array of photodetectors measures the intensity of the light at several predetermined angles. The intensities measured at different angles are processed by a computer using standard theoretical principles to determine the particle size distribution. The reported laser diffraction values are obtained using a wet dispersion of the particles in distilled water. The particle refractive index is set to 3.50 and the dispersant index is set to 1.330. The particle size distribution is calculated using the Mie scattering model.

[0071] The composite particles are preferably 200 m 2 / g or less, 150 m 2 / g or less, 100 m 2 / g or less, 80 m 2 / g or less, 60 m 2 / g or less, 40 m 2 / g or less, 30 m 2 / g or less, 25 m 2 / g or less, 20 m 2 / g or less, 15 m 2 / g or less, or 10 m2 It has a BET surface area of less than / g. Generally, a low BET surface area is preferred. This is because during the first charge-discharge cycle of the anode, the formation of the solid electrolyte interphase (SEI) layer on the surface of the composite particles is minimized. However, with an overly low BET surface area, due to the inaccessibility of the bulk of the electroactive material to metal ions in the surrounding electrolyte, an unacceptable low charging rate and capacity are obtained. For example, the BET surface area of the composite particles is preferably at least 0.1 m 2 / g, at least 1 m 2 / g, at least 2 m 2 / g, or at least 5 m 2 / g. For example, the BET surface area may be in the range of 1 m 2 / g to 25 m 2 / g, and preferably in the range of 2 to 15 m 2 / g.

[0072] The measurable volume of the micropores and mesopores of the composite particles (i.e., in the presence of the electroactive material and the lithium-ion permeable filler) is significantly lower than the total pore volume of the conductive porous particle framework due to pore occupancy. Preferably, the total measurable volume of the micropores and mesopores of the composite particles measured by the nitrogen gas adsorption method is (0.15×P 1 ) cm 3 / g or less, (0.10×P 1 ) cm 3 / g or less, (0.05×P 1 ) cm 3 / g or less, (0.02×P 1 ) cm 3 / g or less, or (0.01×P 1 ) cm 3 / g or less, where P 1 is as described above.

[0073] The composite particles may, if necessary, include a conductive coating different from the lithium ion permeable filler material. For example, the conductive coating may be a conductive carbon coating. The conductive carbon coating may be used together with the composite particles including a lithium ion permeable solid electrolyte as a filler material. Alternatively, when the filler material is a conductive pyrolytic carbon filler material, the conductive carbon coating may be a different type of conductive pyrolytic carbon with respect to the filler material, for example, formed from different carbon-containing precursors.

[0074] Preferably, the conductive carbon coating may be obtained by a chemical vapor deposition (CVD) method. The thickness of the carbon coating may preferably be in the range of 2 to 30 nm. If necessary, the carbon coating may be porous and / or may cover only a part of the surface of the composite particles.

[0075] The carbon coating has the advantage that it further reduces the BET surface area of the particulate material by smoothing any surface defects and filling any remaining surface micropores, thereby further suppressing the loss in the first cycle. Also, the carbon coating improves the conductivity of the surface of the composite particles, reduces the need for a conductive additive in the electrode composition, and forms an optimal surface for the formation of a more stable SEI layer, resulting in an improved capacity retention rate during cycling. Further, by introducing a dopant (e.g., boron or phosphorus dopant) into the carbon coating, a further improvement in conductivity can be obtained. Suitable dopants are described in more detail below.

[0076] The particulate material of the present invention preferably has a specific charge capacity of 1200 to 2340 mAh / g during the first lithiation. The silicon-containing particulate material according to the present invention preferably has a specific charge capacity of at least 1400 mAh / g during the first lithiation.

[0077] In a second aspect of the present invention, a method for preparing a particulate material, (a) Providing a plurality of conductive porous particles comprising micropores and / or mesopores, wherein the micropores and / or mesopores have a total pore volume in the range of 0.4 to 2.2 cm 3 / g, the step; (b) Using chemical vapor infiltration to deposit an electroactive material selected from silicon, tin, aluminum, germanium, and alloys thereof into the micropores and / or mesopores of the porous carbon framework, wherein the deposited electroactive material partially occupies the pore volume of the conductive porous particles, the step; (c) Depositing a lithium ion permeable filler material into a part or all of the remaining pore volume of the conductive porous particles, the step; A method is provided that has.

[0078] Therefore, in the method of the present invention, composite particles as described above are provided, and the conductive porous particles form a framework of an electroactive material and a lithium ion permeable filler.

[0079] A particular advantage of the method of the present invention is that it enables the use of conductive porous particles having a porosity greater than that required for the final product. By filling the remaining pore volume with a lithium-ion permeable filler, the final effective occupancy of the pore volume by the electroactive material is equivalent to that obtained by using low-porosity porous particles without the filler. On the other hand, the surface area of the composite particles is also reduced. To obtain a relatively high occupancy of the low-porosity material, controlled CVI conditions suitable for the low deposition rate of the electroactive material are required, resulting in a low manufacturing throughput. In the method of the present invention, although the CVI process is stopped before a high occupancy of the pore volume is obtained, CVI conditions suitable for a high film formation rate are made possible. This enables high process control and high throughput. The use of an ion-conductive or electron-conductive material as the lithium-ion permeable filler provides another advantage. Therefore, in the present invention, it is possible to prepare these composite materials on a scale suitable for commercial production and to provide high-quality products having uniformity in composition and properties.

[0080] In a second aspect of the present invention, the conductive porous particles used in step (a) form a conductive porous particle framework within the particles of the first aspect of the present invention. Accordingly, the conductive porous particles in step (a) may have any of the aforementioned properties regarding the framework of the conductive porous particles in the first aspect of the present invention. Accordingly, the conductive porous particles in step (a) are considered to be equivalent to the conductive porous particle framework in the aforementioned composite particles, and any and all properties of the conductive porous particle framework described in the present application are considered to be applicable to the conductive porous particles in the second aspect of the present invention.

[0081] Accordingly, the conductive porous particles include micropores and / or mesopores and, if necessary, a small amount of macropores and have a three-dimensionally interconnected open pore network.

[0082] The total volume of micropores and mesopores in the conductive porous particles is preferably at least 0.45 cm 3 / g, at least 0.5 cm 3 / g, at least 0.55 cm 3 / g, at least 0.6 cm 3 / g, at least 0.65 cm 3 / g, at least 0.7 cm 3 / g, at least 0.75 cm 3 / g, at least 0.8 cm 3 / g, at least 0.85 cm 3 / g, at least 0.9 cm 3 / g, at least 0.95 cm 3 / g, or at least 1 cm 3 / g. More preferably, the total volume of micropores and mesopores in the conductive porous particle framework is at least 0.7 cm 3 / g, at least 0.75 cm 3 / g, at least 0.8 cm 3 / g, or at least 0.85 cm 3 / g.

[0083] Preferably, the total volume of crospores and mesopores in the conductive porous particles is 2 cm 3 / g or less, 1.8 cm 3 / g or less, 1.6 cm 3 / g or less, 1.5 cm 3 / g or less, 1.45 cm 3 / g or less, 1.4 cm 3 / g or less, 1.35 cm 3 / g or less, 1.3 cm 3 / g or less, 1.25 cm 3 / g or less, 1.2 cm 3 / g or less, 1.1 cm 3 / g or less, 1.0 cm 3 / g or less, or 0.9 cm 3 / g or less. More preferably, the total volume of micropores and mesopores in the conductive porous particles is 1.2 cm 3 / g or less, 1.1 cm 3 / g or less, 1.0 cm 30.9 cm or less 3 It is 0.9 cm or less per g.

[0084] In one example, the total volume of micropores and mesopores in the conductive porous particles may be in the range of 0.6 to 1.4, 0.65 to 1.4, 0.7 to 1.4, 0.75 to 1.4, 0.6 to 1.3, 0.65 to 1.3, 0.7 to 1.3, 0.75 to 1.3, 0.6 to 1.2, 0.65 to 1.2, 0.7 to 1.2, 0.75 to 1.2, 0.6 to 1, 0.65 to 1, 0.7 to 1, 0.75 to 1, 0.6 to 0.9, 0.65 to 0.9, 0.7 to 0.9, or 0.75 to 0.9 per g.

[0085] PD of conductive porous particles 50 The pore diameter is preferably 10 nm or less, 8 nm or less, 6 nm or less, 5 nm or less, 4 nm or less, 3 nm or less, 2.5 nm or less, 2 nm or less, or 1.5 nm or less.

[0086] The volume ratio of micropores to mesopores in the conductive porous particles may, in principle, be in the range of 100:0 to 0:100. Preferably, the volume ratio of micropores to mesopores is 90:10 to 55:45, 90:10 to 60:40, or 85:25 to 65:35.

[0087] The pore size distribution of the conductive porous particles may be unimodal, bimodal or multimodal.

[0088] When the conductive porous particles contain macropores, the volume of pores having a diameter in the range of more than 50 nm and 100 nm or less is measured by the mercury porosimetry method, and is preferably 0.3 cm 3 / g or less, 0.20 cm 3 / g or less, 0.1 cm 3 / g or less, or 0.05 cm 3It is below / g. More preferably, the volume of pores having a diameter in the range of more than 50 nm and 100 nm or less is preferably 20% or less, 10% or less, 5% or less, 2% or less, 1% or less, or 0.5% or less of the total volume of micropores and mesopores.

[0089] The conductive porous particles are preferably the aforementioned porous carbon particles related to the conductive porous particle framework of the first aspect of the present invention.

[0090] The conductive porous particles are at least 750 m 2 / g, at least 1,000 m 2 / g, at least 1,250 m 2 / g, or preferably have a BET surface area of at least 1,500 m 2 / g. The term "BET surface area" used in the present application shall be interpreted as representing the surface area per unit mass calculated from the measurement of physical adsorption of gas molecules on the solid surface in accordance with ISO9277 and using the Brunauer-Emmett-Teller theory. Preferably, the BET surface area of the conductive porous particles is 4,000 m 2 / g or less, 3,500 m 2 / g or less, 3,250 m 2 / g or less, or 3,000 m 2 / g or less.

[0091] The conductive porous material preferably has a D 50 particle diameter in the range of 1 to 30 μm. If necessary, the D 50 particle diameter of the composite particles may be at least 1.5 μm, at least 2 μm, at least 2.5 μm, at least 3 μm, at least 4 μm, or at least 5 μm. The D 50 particle diameter of the conductive porous particles is preferably at least 2.5 μm, or at least 3 μm. If necessary, the D 50 particle diameter of the conductive porous particles may be 25 μm or less, 20 μm or less, 18 μm or less, 15 μm or less, 12 μm or less, 10 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, 5 μm or less. The D 50The particle size is preferably 10 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, or 5 μm or less.

[0092] For example, the conductive porous particles have a D in the range of 1 to 25 μm, 1 to 20 μm, 1 to 15 μm, 1 to 10 μm, 1 to 8 μm, 2 to 20 μm, 2 to 15 μm, 2 to 10 μm, 2 to 8 μm, 2 to 6 μm, 3 to 15 μm, 3 to 10 μm, 3 to 8 μm, 3 to 6 μm, 3 to 5 μm, 4 to 12 μm, 4 to 10 μm, 4 to 8 μm, or 4 to 4 to 6 μm. 50 It may have a particle diameter.

[0093] The D of the conductive porous particles 10 The particle diameter of the conductive porous particles 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.

[0094] The D of the conductive porous particles 90 The particle size is preferably 40 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

[0095] The conductive porous particles have at least 750 m 2 / g, at least 1,000 m 2 / g, at least 1,250 m 2 / g, or at least 1,500 m 2 / g of BET specific surface area is preferable. The BET specific surface area of the conductive porous particles is 4,000 m 2 / g or less, 3,500 m 2 / g or less, 3,250 m 2 / g or less, or 3,000 m 2 / g or less is preferable.

[0096] In step (b) of the method of the present invention, a chemical vapor infiltration (CVI) method of a precursor of an electroactive material is used for the pore structure of the porous carbon framework.

[0097] The chemical vapor infiltration (CVI) method is generally a process of infiltrating an additional phase into a porous material by flowing a mixture of a carrier gas and a reactive gas precursor over a porous substrate at a high temperature. The decomposition / reaction of the reactive gas precursor on the pore surface causes the formation of a solid-phase film in the pore structure.

[0098] The electroactive material formed in step (b) is preferably selected from silicon, tin, germanium, aluminum, and mixtures thereof. A preferred electroactive material is silicon.

[0099] Suitable gas precursors for the deposition of silicon include silane (SiH 4 ) and trichlorosilane (SiHCl 3 ). CVI is particularly useful in preparing the electroactive materials described in this application because it causes extremely little damage to the geometry of the porous substrate.

[0100] Suitable silicon-containing precursors include silane (SiH 4 ), disilane (Si 2 H 6 ), trisilane (Si 3 H 8 ), tetrasilane (Si 4 H 10 ), or chlorosilanes such as trichlorosilane (HSiCl 3 ), methyltrichlorosilane (CH 3 SiCl 3 ), or methyldichlorosilane ((CH 3 ) 2 SiCl 2 ). Preferably, the silicon-containing precursor is silane.

[0101] Suitable tin-containing precursors include bis[bis(trimethylsilyl)amino]tin(II) ([[(CH 3 ) 3 Si] 2 N] 2 Sn), tetraallyltin ((H 2 C=CHCH 2 )4 Sn), tetrakis(diethylamide)tin(IV) ([(C 2 H 5 ) 2 N] 4 Sn), tetrakis(dimethylamide)tin(IV) ([(CH 3 ) 2 N] 4 Sn), tetramethyltin (Sn(CH 3 ) 4 ), tetravinyltin (Sn(CH=CH 2 ) 4 ), tin(II) acetylacetonate (C 10 H 14 O 4 Sn), trimethyl(phenylethynyl)tin (C 6 H 5 C≡CSn(CH 3 ) 3 ), trimethyl(phenyl)tin (C 6 H 5 Sn(CH 3 ) 3 ) are included. Preferably, the tin-containing precursor is tetramethyltin.

[0102] Suitable aluminum-containing precursors include aluminum tris(2,2,6,6-tetramethyl-3,5-heptanedionate) (Al(OCC(CH 3 ) 3 CHCOC(CH 3 ) 3 ) 3 ), trimethylaluminum ((CH 3 ) 3 Al), and tris(dimethylamide)aluminum(III) (Al(N(CH 3 ) 2 ) 3 ) are included. Preferably, the aluminum-containing precursor is trimethylaluminum.

[0103] Suitable germanium-containing precursors include germane (GeH 4 ), hexamethyldigermane ((CH 3 ) 3 Ge Ge(CH 3) 3 )、tetramethylgermane ((CH 3 ) 4 Ge), tributylgermane hydride ([CH 3 (CH 2 ) 3 3 GeH), triethylgermane hydride ((C 2 H 5 ) 3 GeH), and triphenylgermane hydride ((C 6 H 5 ) 3 GeH) are included. Preferably, the germanium-containing precursor is germane.

[0104] Also, in the CVI process, a gaseous precursor of the dopant material may be utilized and the doped electroactive material may be deposited in the micropores and / or mesopores of the porous carbon framework. When the dopant is boron, suitable precursors include borane (BH 3 ), diborane (B 2 H 6 ), triisopropylborane ([(CH 3 ) 2 CHO] 3 B), triphenylborane ((C 6 H 5 ) 3 B), and tris(pentafluorophenyl)borane (C 6 F 5 ) 3 B are included, preferably borane. When the dopant is phosphorus, a suitable precursor is phosphine (PH 3 ).

[0105] ​The precursor may be used in pure form or, more generally, as a mixed gas diluted with an inert carrier gas such as nitrogen or argon. For example, the precursor may be used in an amount in the range of 0.5 to 20 vol%, 1 to 10 vol%, or 1 to 5 vol% based on the total volume of the precursor and the inert carrier gas. The CVI process is preferably carried out at a total pressure of 101.3 kPa (i.e., atmospheric pressure, 1 atm) or a pressure close thereto, with a low partial pressure of the gaseous precursor, and the remaining partial pressure is made up to atmospheric pressure using an inert padding gas such as hydrogen, nitrogen or argon. In accordance with conventional procedures operating in an inert atmosphere, the presence of oxygen needs to be minimized to prevent unwanted oxidation of the deposited electroactive material. The oxygen content is preferably less than 0.01 vol%, more preferably less than 0.001 vol% based on the total volume of the gas used in step (b).

[0106] The temperature of the CVI process is preferably selected to thermally decompose the precursor into the electroactive material. The CVI process is preferably carried out at a temperature in the range of 200 to 800 °C, 400 to 700 °C, 400 to 600 °C, 400 to 550 °C, 450 to 550 °C, or 450 to 500 °C. Preferably, the CVI process is carried out at a temperature in the range of 400 to 500 °C, preferably 450 to 500 °C.

[0107] The lithium ion permeable filler material may be a conductive pyrolytic carbon material. The conductive pyrolytic carbon material may be deposited in step (c) by the same CVI process as that used in step (b). By CVI, once a sufficient amount of electroactive material is deposited in step (b), the precursor vapor of the electroactive material may be replaced by a suitable pyrolytic carbon precursor by increasing the reaction temperature if necessary. For example, the CVI of the pyrolytic carbon filler in step (c) may be carried out at a temperature of 700 °C or less, 690 °C or less, 680 °C or less, 670 °C or less, 650 °C or less, 650 °C or less, 640 °C or less, 620 °C or less, or 600 °C or less. The minimum temperature in step (c) depends on the type of carbon precursor used. The temperature in step (c) is preferably at least 300 °C, for example, at least 500 °C, at least 520 °C, at least 540 °C, at least 560 °C, or at least 580 °C.

[0108] Suitable hydrocarbons include polycyclic hydrocarbons containing from 10 to 25 carbon atoms and, if necessary, 1 to 3 heteroatoms. If necessary, the polycyclic hydrocarbons are selected from naphthalene, substituted naphthalenes such as di-hydroxynaphthalene, anthracene, tetracene, pentacene, fluorene, acenaphene, phenanthrene, fluoranthene, pyrene, chrysene, perylene, coronene, fluorenone, anthraquinone, anthrone, and their alkyl-substituted derivatives. Also, suitable pyrolytic carbon precursors include bicyclic monoterpenoids, which, if necessary, are selected from camphor, borneol, eucalyptol, camphene, careen, sabinene, thujene and pinene. Another suitable pyrolytic carbon precursor is C 2 to C 10contains hydrocarbons, and if necessary, the hydrocarbons are selected from alkanes, alkenes, alkynes, cycloalkanes, cycloalkenes, and arenes, for example, methane, ethylene, propylene, limonene, styrene, cyclohexane, cyclohexene, α - terpinene, and acetylene. 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.

[0109] The conductive pyrolytic carbon material is deposited in step (c) by using a pyrolytic carbon precursor together with a gaseous precursor of the dopant material, and a doped pyrolytic carbon filler may be deposited. Doping of the pyrolytic carbon coating further enhances the conductivity of the filler. When the dopant is boron, suitable precursors include borane (BH 3 ), diborane (B 2 H 6 ), triisopropyl borate ([(CH 3 ) 2 CHO] 3 B), triphenylborane ((C 6 H 5 ) 3 B), and tris(pentafluorophenyl)borane (C 6 F 5 ) 3 B, and preferably diborane. When the dopant is phosphorus, a suitable precursor is phosphine (PH 3 ). The gaseous dopant precursor is usually introduced in an amount of up to 5% by mass based on the total mass of the pyrolytic carbon precursor and the gaseous dopant precursor.

[0110] The lithium-ion permeable filler material may be a lithium-ion permeable solid electrolyte. 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, in step (c), a lithium phosphate solid electrolyte may be deposited using an atmosphere of tert-butyl lithium and trimethyl phosphate. The CVI of the lithium-ion permeable solid electrolyte in step (c) may be preferably carried out at a maximum temperature of 700 °C, at a temperature of 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 of step (c) is preferably at least 300 °C, at least 350 °C, at least 400 °C, or at least 450 °C. For example, the temperature of step (c) may be in the range of 400 to 500 °C.

[0111] Similar to step (b), the gaseous precursor used in step (c) may be used in pure form or in the form of a mixed gas diluted with an inert carrier gas such as nitrogen or argon. For example, the precursor may be used in an amount in the range of 0.5 to 20 vol%, 1 to 10 vol%, or 1 to 5 vol% based on the total volume of the precursor and the inert carrier gas. Step (c) is preferably carried out at a total pressure of 101.3 kPa (atmospheric pressure, 1 atm) or near it at a low partial pressure of the gaseous precursor. The remaining partial pressure is made up to atmospheric pressure using an inert gas. The presence of oxygen again needs to be minimized to suppress the undesirable oxidation of the deposited electroactive material. The oxygen content is preferably less than 0.01 vol% and more preferably less than 0.001 vol% based on the total volume of the gas used in step (c).

[0112] Using the sol-gel method, in step (c), a metal-oligomer filler material may be deposited. Suitable methods include hydrolyzing and / or ammoniating a metal salt (e.g., alkoxide, halide, or nitrate) in an aqueous solution or an ammonia solution to form a liquid sol. The material from step (b) is combined with the liquid sol, and the sol penetrates the pore volume not occupied by the porous carbon particles through initial wet impregnation or diffusion. As a result of the aging of the sol, polycondensation of the sol occurs and a gel is formed. Crystallization occurs by removal of the solvent and heat treatment, forming a dense, expanded network of cross-linked oxides, nitrides, or oxynitrides.

[0113] Examples of suitable metal salts include alkoxides, halides, and nitrates of titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, aluminum, silicon, gallium, germanium, or mixtures thereof. Crystallization is preferably carried out at less than 700 °C, more preferably less than 600 °C, for example less than 500 °C.

[0114] The surface of the electroactive material deposited by CVI is reactive to oxygen, and when exposed to oxygen in the atmosphere, a native oxide layer is formed. In the case of silicon, when the silicon surface is exposed to oxygen, an amorphous silicon dioxide film is rapidly formed. The formation of the native oxide layer is exothermic, and thus careful process control is required to prevent overheating or sometimes combustion of the particulate material during manufacture. The presence of the native oxide layer is associated with irreversible capacity loss and shortening of cycle life, and thus can be detrimental to the properties of the electroactive material in a lithium-ion battery. Therefore, it is preferable that the electroactive material is not exposed to oxygen prior to the deposition of the lithium-ion permeable filler material.

[0115] More preferably, step (b) of the method of the present invention further comprises a further step (b2) of contacting the surface of the deposited electroactive material with a passivating agent, the electroactive material not being exposed to oxygen prior to contacting with the passivating agent. A passivating agent is defined herein as a compound capable of modifying the surface of the electroactive material in such a way as to inhibit or prevent the formation of surface oxides.

[0116] Suitable passivating agents include compounds that contain an alkene, alkyne or carbonyl functionality, more preferably compounds that contain a terminal alkene, terminal alkyne, or aldehyde group.

[0117] Preferred passivators have the general formula: (i) R-CH=CH-R; (ii) RC ≡ CR; (iii) O=CH-R and having one or more compounds of wherein R represents H or an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having from 1 to 20 carbon atoms, preferably from 2 to 10 carbon atoms, or the two R groups in formula (i) form an unsubstituted or substituted hydrocarbyl ring structure containing from 3 to 8 carbon atoms. Particularly preferred passivators are of the general formula: (i)CH 2 =CH-R; (ii) HC ≡ CR; wherein R is as defined above. Preferably, R is unsubstituted.

[0118] Examples of suitable compounds include ethylene, propylene, 1-butene, butadiene, 1-pentene, 1,4-pentadiene, 1-hexene, 1-octene, styrene, divinylbenzene, acetylene, phenylacetylene, norbornene, norbornadiene, and bicyclo[2.2.2]oct-2-ene. Mixtures of different passivators may also be used.

[0119] For alkenes, alkynes, or carbonyl groups of the passivating agent, an insertion reaction with the M-H group (where M represents an atom of the electroactive material) occurs on the surface of the electroactive material, and it is understood that a covalently bonded passivated surface resistant to atmospheric oxidation is formed. When silicon is the electroactive material, the passivation reaction between the silicon surface and the passivating agent can be understood in the form of a hydrosilylation reaction, as schematically shown below.

[0120]

Chemical formula

[0121] Suitable passivating agents in this category include compounds of the general formula HX-R, where X represents O, S, NR, or PR, and each R is independently defined as described above. The two R groups in the general formula (iv) may form an unsubstituted or substituted hydrocarbyl ring structure containing 3 to 8 carbon atoms. Preferably, X represents O or NH, and R represents a substituted aliphatic or aromatic group having 2 to 10 carbon atoms, if necessary. Also, the amine group may be incorporated into a 4- to 10-membered aliphatic or aromatic ring structure such as pyrrolidine, pyrrole, imidazole, piperazine, indole, or purine.

[0122] The step of contacting the electroactive material with the passivating agent in step (b2) may be carried out at a temperature in the range of 25 to 700 °C. For example, step (b2) may preferably be carried out within the preferred temperature range of step (b) and / or step (c) described in the present application. Preferably, step (c) is carried out at the same temperature as step (b2) or at a temperature higher than step (b2). For example, step (b2) may be carried out at a temperature in the range of 25 °C to less than 500 °C, and step (c) may be carried out at a temperature in the range of 500 °C to 700 °C.

[0123] Following the passivation of the electroactive material surface, as described above, in step (c), a lithium ion permeable filler material may be deposited. The R group of the aforementioned passivating agent may be incorporated into the lithium ion permeable filler, and a covalent bond may be formed between the lithium ion permeable filler and the surface of the electroactive material via the passivating agent.

[0124] When the lithium ion permeable filler material is a conductive pyrolytic carbon material, the same compound may function as both the passivating agent and the pyrolytic carbon precursor. For example, when styrene is selected as the pyrolytic carbon precursor, styrene also functions as a passivating agent as long as the electroactive material is not exposed to oxygen before contacting with styrene. Accordingly, step (c) may have a step of forming a conductive pyrolytic carbon material by a CVI process, and the pyrolytic carbon precursor is the same as the passivating agent used in step (b2). In this case, the passivation in step (b2) and the formation of the conductive carbon material in step (c) may be carried out simultaneously, for example, in a temperature range of 500 to 700 °C. Alternatively, the passivation in step (b2) and the formation of the conductive carbon material in step (c) may be carried out continuously. The passivating agent and the pyrolytic carbon precursor are the same material, but step (c) is carried out at a temperature higher than step (b2). For example, step (b2) may be carried out at a temperature in the range of 25 °C to less than 500 °C, and step (c) may be carried out at a temperature in the range of 500 °C to 700 °C.

[0125] Alternatively, in step (b2), different compounds may be used as the passivating agent, and in step (c), different compounds may be used as the pyrolytic carbon precursor. For example, the electroactive material is first contacted with the passivating agent in step (b2), and then the conductive pyrolytic carbon material is deposited in step (c). The pyrolytic carbon precursor used in step (c) is different from the passivating agent used in step (b2). For example, the passivating agent in step (b2) is styrene, and the pyrolytic carbon precursor in step (c) may be a compound such as cyclohexane that can form a pyrolytic carbon material but cannot passivate the surface of the electroactive material. When the passivating agent and the pyrolytic carbon precursor are different materials, steps (b2) and (c) may be carried out at the same temperature, for example, in the range of 500 to 700 °C. Alternatively, step (c) may be carried out at a higher temperature than step (b2). For example, step (b2) may be carried out at a temperature in the range of 25 °C to less than 500 °C, and step (c) may be carried out at a temperature in the range of 500 °C to 700 °C.

[0126] Another suitable passivating agent is ammonia. Thus, step (b2) may include contacting the surface of the deposited electroactive material with ammonia at a temperature in the range of 200 to 800 °C, preferably 400 to 700 °C. For example, when the passivating agent is ammonia, step (b2) may be carried out at the same temperature as the temperature used for the deposition of the electroactive material in step (b). Subsequently, if necessary, the temperature is raised to the range of 500 to 1,000 °C, and a crystalline nitride surface (for example, a silicon nitride surface of the general formula SiN x (x ≦ 4 / 3)) is formed. Thus, passivation with ammonia provides an alternative means of suppressing oxidation of the electroactive material. Also, sub-stoichiometric silicon nitride is conductive, and in this step, the formation of a conductive network occurs, enabling faster charge and discharge of the electroactive material.

[0127] If necessary, the method of the present invention may have a step (d) of forming a conductive coating on the surface of the particles from step (c). The conductive coating is different from the lithium ion permeable filler material. For example, the conductive coating may be the aforementioned conductive carbon coating. Preferably, step (d) has, if necessary, a step of forming a conductive coating via a chemical vapor deposition (CVD) method using a pyrolytic carbon precursor together with a gaseous dopant precursor. Suitable pyrolytic carbon precursors and gaseous dopant precursors.

[0128] In a third aspect of the present invention, a composite material obtainable by the method of the second aspect of the present invention is provided. In particular, a composite material obtained by a method including passivation of the aforementioned electroactive material is provided. Further, the composite material of the third aspect of the present invention may have any feature described with respect to the first aspect of the present invention.

[0129] In a fourth aspect of the present invention, a composition is provided that includes the particulate material according to the first or third aspect of the present invention and at least one other component. In particular, the particulate material of the first or third aspect of the present invention may be used as a component of an electrode composition. The particulate material used to prepare the electrode composition of the fourth aspect of the present invention may have any feature preferably or optionally described with respect to the first or third aspect of the present invention.

[0130] The at least one other component may be selected from (i) a binder, (ii) a conductive additive, and (iii) an additional particulate electroactive material.

[0131] The composition of the present invention preferably has from 1 to 95 wt%, from 2 to 90 wt%, from 5 to 85 wt%, or from 10 to 80 wt% of the particulate material according to the first or third aspect of the present invention, based on the total dry weight of the composition.

[0132] For example, the composition may be a hybrid electrode composition having a particulate material according to the first or third aspect of the present invention and at least one additional particulate electroactive material. Examples of additional particulate electroactive materials include graphite, hard carbon, silicon, tin, germanium, gallium, aluminum, and lead. The at least one additional particulate electroactive material is preferably selected from graphite and hard carbon, and most preferably, the at least one additional particulate electroactive material is graphite.

[0133] Preferably, the at least one additional particulate electroactive material is D in the range of 10 to 50 μm 50 selected from graphite particles having a particle diameter.

[0134] The electrode composition may include a binder, if necessary. The binder has a function of adhering the electrode composition to the current collector and maintaining the integrity of the electrode composition. Examples of binders that can be used according to the present invention include polyacrylic acid (PAA), and its alkali metal salts, as well as modified polyacrylic acid (mPAA) and its alkali metal salts, SBR, and CMC. The binder may preferably be present in an amount of 0.5 to 20% by weight, preferably 1 to 15% by weight, and most preferably 2 to 10% by weight, based on the total dry weight of the electrode composition.

[0135] If necessary, the electrode composition may include one or more conductive additives. Preferred conductive additives are non-electroactive materials, which are included to improve the electrical conductivity between the electroactive components of the electrode composition and between the electroactive components of the electrode composition and the current collector. The conductive additive may preferably be selected from carbon black, carbon fiber, carbon nanotube, graphene, acetylene black, ketjen black, metal fiber, metal powder, and conductive metal oxide. Suitable conductive additives include carbon black and carbon nanotubes.

[0136] One or more conductive additives may suitably be present in a total amount of from 0.5 to 20% by weight, preferably from 1 to 15% by weight, and most preferably from 2 to 10% by weight, based on the total dry weight of the electrode composition.

[0137] In a fifth aspect, the present invention provides an electrode having a particulate material that is in electrical contact with a current collector, as defined with reference to the first or third aspect of the present invention. The particulate material used in the preparation of the electrode of the fifth aspect of the present invention may have any of the features preferably or optionally described with respect to the first or third aspect of the present invention.

[0138] As used herein, the term "current collector" refers to any conductive substrate capable of carrying current from and to the electroactive particles in the electrode composition. Examples of materials that can be used as current collectors include copper, aluminum, stainless steel, nickel, titanium, and sintered carbon. Copper is the preferred material. The current collector is typically in the form of a foil or mesh having a thickness of from 3 to 500 μm. The particulate material of the present invention can be applied to one or more surfaces of the current collector, preferably to a thickness in the range of from 10 μm to 1 mm, such as from 20 to 500 μm, or from 50 to 200 μm.

[0139] The electrode preferably has an electrode composition as defined with respect to the fourth aspect of the present invention that is in electrical contact with the current collector. The electrode composition may have any of the features preferably or optionally described with respect to the fourth aspect of the present invention.

[0140] The electrode according to the fifth aspect of the present invention may be preferably manufactured by forming a slurry in combination with the particulate material of the present invention (in the form of the electrode composition of the present invention if necessary), a solvent, and, if necessary, one or more viscosity-modifying additives. Next, the slurry is cast on the surface of the current collector, and the solvent is removed, thereby forming an electrode layer on the surface of the current collector. Optionally, further steps such as curing of any binder by heat treatment and / or calendaring of the electrode layer may be preferably carried out. The electrode layer preferably 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, preferably 20 μm to 50 μm.

[0141] The electrode according to the fifth aspect of the present invention may be used as the anode of a metal ion battery. Thus, in a sixth aspect, the present invention provides a rechargeable metal ion battery having an anode having the aforementioned electrode, a cathode including a cathode active material capable of releasing and reabsorbing metal ions, and an electrolyte between the anode and the cathode.

[0142] 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 can release lithium ions.

[0143] In a seventh aspect, the present invention provides the use of the particulate material as an anode active material as defined with reference to the first or third aspect of the present invention. Preferably, the particulate material is in the form of an electrode composition as defined with reference to the fourth aspect of the present invention.

[0144] (Example 1: Synthesis of Composite Particles in a Fluidized Bed Reactor) In a vertical bubble fluidized bed reactor containing a stainless steel cylindrical vessel with an inner diameter of 83 mm, composite particles having silicon as an electroactive material and a pyrolytic carbon material as a lithium ion permeable filler were prepared. 75 g of powder of porous carbon framework particles was placed in the reactor, and then the reactor was sealed and purged with nitrogen gas at a flow rate of 2 L / min for 30 minutes. The particle bed was agitated using an air vibrator.

[0145] Next, the reactor was heated from 430 °C to a reaction temperature between 460 °C at a ramp rate of 10 °C per minute, and 4 vol% monosilane gas diluted with nitrogen was supplied to the bottom of the reactor at a flow rate of 3 L / min. After 9 hours of continuous silicon film formation, the reactor was purged with nitrogen again for 15 minutes. Next, under a nitrogen flow, the reactor temperature was raised to a target temperature of 675 °C. An excessive amount of styrene was placed in a Drescher bottle and heated to 75 °C in a water bath. 10 minutes after the furnace temperature became stable, nitrogen was bubbled at 2 L / min in the Drescher bottle, and styrene was allowed to flow into the reaction tube for 30 to 90 minutes. Then, the reactor was purged with nitrogen and cooled to room temperature under nitrogen, and a carbon-coated material was obtained. Next, by gradually switching the gas flow from nitrogen to air from a compressed air supply, the environment was gradually switched to air over 2 hours.

Claims

1. A particulate material comprising a plurality of composite particles, The composite particles include (a) an electrically conductive porous carbon particle framework having micropores and / or mesopores, said micropores and / or mesopores having a size of 0.6 to 1.4 cm 3 / g range of total pore volume, PD 50 The pore diameter is 5 nm or less, and the PD 90 a conductive porous carbon particle framework having a pore diameter of 12 nm or less; (b) a plurality of silicon domains disposed within the conductive porous particulate framework; and (c) a lithium ion permeable filler disposed through the pores of the conductive porous particulate framework and intermediate the nanoscale electroactive material domains and the exterior of the composite particle; having The lithium ion permeable filler material is a lithium ion permeable solid electrolyte, in the form of a particulate material.

2. The total volume of micropores and mesopores within the conductive porous particle framework is less than 0.65 cm 3 / g to 1.3cm 3 / g.

3. The conductive porous particle framework has a P.D. of 3 nm or less. 50 3. The particulate material according to claim 1 or 2, having a pore diameter.

4. 4. A particulate material according to claim 1 , wherein the electrically conductive porous carbon particle framework comprises at least 90% by weight carbon.

5. The conductive porous carbon particle framework is 750 mm 2 / g to 3000m 2 5. The particulate material according to claim 1 , having a BET surface area of ​​0.1 g / g.

6. 6. A particulate material according to claim 1 , wherein the amount of silicon in the composite particles is selected such that at least 20% and at most 60% of the internal pore volume of the conductive porous particle framework is occupied by the silicon.

7. The weight ratio of silicon to the conductive porous particle framework in the composite particle is [0.5×P 1 From 1.3 x P 1 ]: 1, where P 1 is cm 3 6. The particulate material according to claim 1 , wherein the pore volume of the conductive porous particle framework is a dimensionless quantity expressed in g / g.

8. 8. A particulate material according to claim 1 , wherein the composite particles have a combined silicon and carbon content of at least 80% by weight.

9. 9. A particulate material according to claim 1 , wherein at least 90% by mass of the electroactive material in the composite particles is disposed within the interior pore volume of the electrically conductive porous particulate framework.

10. The lithium ion permeable solid electrolyte may be a garnet type solid electrolyte, a perovskite type solid electrolyte, a LISICON type solid electrolyte, a NaSICON type solid electrolyte, a lithium phosphate oxynitride (LiPON) solid electrolyte, or a Li 3 N-type solid electrolyte, lithium phosphate (Li 3 PO 4 ) solid electrolyte, lithium titanate (Li 4 Ti 5 O 12 ) solid electrolyte, lithium tantalate (LiTaO 3 10. The particulate material according to claim 1 , wherein the particulate material is selected from the group consisting of a sulphide type solid electrolyte, an argyrodite type solid electrolyte and an antiperovskite type solid electrolyte.

11. 11. The particulate material of claim 1, wherein the lithium-ion permeable solid electrolyte forms a coating over at least a portion of an outer surface of the porous carbon framework.

12. The composite particles have a D in the range of 1 to 30 μm. 50 12. A particulate material according to any one of claims 1 to 11, having a particle diameter of

13. The composite particles have a D in the range of 2 to 20 μm. 50 13. A particulate material according to any one of claims 1 to 12, having a particle diameter of

14. The composite particles have a D of at least 0.5 μm 10 14. A particulate material according to any one of claims 1 to 13, having a particle diameter of

15. The composite particles are 100 mm 2 15. The particulate material according to claim 1 , having a BET surface area of ​​less than or equal to 1.0 μm / g.

16. The composite particles are 2 / g to 25m 2 16. The particulate material according to claim 1 , having a BET surface area in the range of 0.1% by mass / g.

17. The volume of the micropores and mesopores of the composite particles measured by nitrogen gas adsorption is (0.10×P 1 )cm 3 / g or less, where P 1 is cm 3 17. A particulate material according to any one of claims 1 to 16, wherein ρ is a dimensionless quantity having a measure of the total pore volume of micropores and mesopores within the electrically conductive porous particle framework, expressed in g / g.

18. 18. A particulate material according to any one of claims 1 to 17, comprising less than 10% unoxidized silicon at 800°C as determined by TGA at a temperature ramp rate of 10°C / min in air.

19. 19. A particulate material according to any one of claims 1 to 18, wherein the total oxygen content of the composite particles is less than or equal to 15% by weight.

20. 20. A particulate material according to any one of the preceding claims, wherein the composite particles have a conductive carbon coating.

21. 21. The particulate material of claim 20, wherein the conductive carbon coating has a thickness in the range of 2 to 30 nm.

22. A composition comprising a particulate material according to any one of claims 1 to 21 and at least one other ingredient, The composition, wherein the at least one other component is selected from (i) a binder, (ii) a conductive additive, and (iii) an additional particulate electroactive material.

23. 23. A composition according to claim 22 comprising from 1 to 95% by weight of a particulate material according to any one of claims 1 to 25, based on the total dry weight of the composition.

24. at least one additional particulate electroactive material; 24. The composition of claim 22 or 23, wherein the at least one additional particulate electroactive material is selected from graphite, hard carbon, silicon, tin, germanium, gallium, aluminum, and lead.

25. 22. An electrode comprising a particulate material according to any one of claims 1 to 21 in electrical contact with a current collector.

26. 26. An electrode as claimed in claim 25, wherein the particulate material is in the form of a composition as claimed in any one of claims 22 to 24.

27. 1. A rechargeable metal ion battery comprising: (i) an anode comprising the electrode of claim 25 or 26; (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:

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

29. 29. The use according to claim 28, wherein the particulate material is in the form of a composition according to any one of claims 22 to 24.

30. 1. A method for preparing a composite material, comprising the steps of: (a) providing a plurality of electrically conductive porous carbon particle frameworks comprising micropores and / or mesopores, said micropores and / or mesopores having a size of 0.6 to 1.4 cm 3 / g range of total pore volume, PD 50 The pore diameter is 5 nm or less, and the PD 90 The pore diameter is 12 nm or less, and (b) depositing silicon into the micropores and / or mesopores of the conductive porous particulate framework by chemical vapor infiltration, the deposited silicon partially occupying the pore volume of the conductive porous particulate framework; (c) depositing a lithium-ion permeable filler material into some or all of the remaining pore volume of the conductive porous particulate framework; having The method of claim 1, wherein the lithium ion permeable filler material is a lithium ion permeable solid electrolyte.

31. 31. The method of claim 30, wherein the electrically conductive porous particulate framework is an electrically conductive porous particulate framework according to any one of claims 2 to 5.

Images