Electroactive material for metal ion batteries

Abstract

The present invention relates to a particulate material and a method for preparing the same. The particulate material comprises a plurality of composite particles. The composite particles comprise a porous particle framework comprising micropores and / or mesopores. The total pore volume of the micropores and mesopores measured by gas adsorption is less than 0.4 cm. 3 / g~2.2cm 3 / g. The composite particle includes a plurality of electroactive material domains and a plurality of modifier material domains disposed within the interior pore volume of the porous particle framework, at least a portion of the modifier material domains being located between adjacent electroactive material domains.

Description

Technical Field

[0001] The present invention generally relates to an electroactive material suitable for use in electrodes for rechargeable metal ion batteries, and more particularly to a particulate material having a high electrochemical capacity suitable for use as an anode active material in rechargeable metal ion batteries.

Background Art

[0002] Rechargeable metal ion batteries are widely used in portable electronic devices such as mobile phones and laptop computers, and their applications in electric vehicles or hybrid vehicles are increasing. Rechargeable metal ion batteries generally include, as used herein, an anode in the form of a metal current collector having a layer of an electroactive material defined as a material capable of inserting and releasing metal ions during charging and discharging of the battery. As used herein, the terms "cathode" and "anode" are used in the sense that when a load is applied to the battery, the anode becomes the negative electrode. When the metal ion battery is charged, metal ions are transported from the metal ion-containing cathode layer through the electrolyte to the anode and inserted into the anode material. As used herein, the term "battery" is used to refer to both a device containing a single anode and a single cathode, as well as a device containing a plurality of anodes and / or a plurality of cathodes.

[0003] There is interest in improving the weight capacity and / or volume capacity of rechargeable metal ion batteries. Heretofore, commercially available lithium ion batteries have been mainly limited to the use of graphite as the anode active material. When the graphite anode is charged, lithium is inserted into the graphite interlayer, and the experimental formula Li xA material of C6 (where x is greater than 0 and less than or equal to 1) is formed. As a result, graphite has a maximum theoretical capacity of 372 mAh / g in a lithium-ion battery, and the practical capacity is slightly lower than that (about 340 mAh / g to 360 mAh / g). Other materials such as silicon, tin, and germanium can insert lithium with a significantly higher capacity than graphite, but it is difficult to maintain sufficient capacity over a large number of charge-discharge cycles, so they are not yet widely used commercially.

[0004] In particular, silicon has been recognized as a promising alternative to graphite in the manufacture of rechargeable metal-ion batteries with high weight and volume capacities because of its very high capacity for lithium (see, for example, Non-Patent Document 1). Silicon has a theoretical maximum specific capacity of about 3600 mAh / g (based on Li 15 Si4) at room temperature in a lithium-ion battery. However, when lithium is inserted into bulk silicon, the volume of the silicon material increases significantly, and when silicon is lithiated to its maximum capacity, it increases to 400% of its original volume. When the charge-discharge cycle is repeated, large mechanical stress is generated in the silicon material, resulting in the destruction and delamination of the silicon anode material. The volume shrinkage of silicon particles during delithiation may result in the loss of electrical contact between the anode material and the current collector. What is more difficult is that the solid electrolyte interface (SEI) layer formed on the silicon surface does not have sufficient mechanical durability to adapt to the expansion and contraction of silicon. As a result, the electrolyte is further decomposed by the newly exposed silicon surface, the thickness of the SEI layer increases, and lithium is irreversibly consumed. These defect mechanisms collectively result in unacceptable loss of electrochemical capacity over successive charge-discharge cycles.

[0005] Numerous efforts have been proposed to overcome problems associated with volume changes observed when charging a silicon-containing anode. Fine silicon structures with a cross-section of less than about 150 nm, such as silicon films and silicon nanoparticles, have been reported to be more durable against volume changes during charging and discharging compared to silicon particles in the micron-size range. However, none of these are suitable for application on a commercial scale without changing their form. Nanoscale particles are difficult to manufacture and handle, and silicon films do not provide sufficient bulk capacity.

[0006] Patent Document 1 discloses that the capacity retention rate can be improved by using silicon particles having a high aspect ratio, that is, the ratio of the maximum dimension to the minimum dimension of the particles. Due to such particles having a small cross-section, the structural stress applied to the material due to volume changes during charging and discharging is reduced. However, such particles can be difficult to manufacture, costly, and fragile. Also, having a large surface area can lead to the formation of an excessive SEI, which can lead to excessive capacity loss in the first charge-discharge cycle.

[0007] It is also generally known that electroactive materials such as silicon can be deposited within the pores of a porous carrier material such as an activated carbon material. These composite materials provide some of the beneficial charge-discharge characteristics of nanoscale silicon particles while avoiding the difficulties of handling nanoparticles. Guo et al. (Non-Patent Document 2) disclose a silicon-carbon composite material in which a porous carbon substrate provides a conductive skeleton with silicon nanoparticles uniformly distributed and deposited within the pore structure of the substrate. Although the capacity retention rate over multiple charge cycles was improved with this composite material, it has been shown that the initial capacity in mAh / g of the composite material is significantly lower than the capacity for silicon nanoparticles.

[0008] The present inventors have previously reported the development of a type of electroactive material having a composite structure in which a nanoscale electroactive material, such as silicon, is deposited within the pore network of a highly porous conductive particulate material, such as a porous carbon material. For example, Patent Documents 2 and 3 report that the improvement in the electrochemical performance of these materials can be attributed to the manner in which the electroactive material is located in the form of small domains having dimensions on the order of or less than a few nanometers. These fine electroactive structures are considered to have lower resistance to elastic deformation and higher fracture resistance than larger electroactive structures, and thus can be lithiated and delithiated without excessive structural stress. As a result, the electroactive material exhibits excellent reversible capacity retention over a large number of charge-discharge cycles. Second, by controlling the filling of silicon within the porous carbon skeleton such that only a portion of the pore volume is occupied by non-charged silicon, the unoccupied pore volume of the porous carbon skeleton can accommodate a substantial amount of internal silicon expansion. Furthermore, as described above, by arranging nanoscale electroactive material domains within small mesopores and / or micropores, the area accessible to the electrolyte at the electroactive material surface is minimal, and thus SEI formation is limited. Further exposure during subsequent charge-discharge cycles is substantially prevented such that the role of SEI formation as a failure mechanism leading to capacity loss is significantly reduced. This is in stark contrast to excessive SEI formation, which characterizes the materials disclosed, for example, by Guo (see above).

[0009] The materials described in Patent Document 2 and Patent Document 3 are synthesized by chemical vapor infiltration (CVI) in different reactor systems (static, rotating, and FBR). The porous conductive particles are contacted with a flow of a silicon-containing precursor (CVI), typically silane gas, at atmospheric pressure and a temperature of 400°C to 700°C until the required amount of silicon is deposited within the micropores and small mesopores. The deposition of silicon is carried out in a single step (single-step deposition). Although it is convenient to perform the deposition of silicon in a single step, it is hardly possible to control the length scale of the deposited silicon. The deposition of coarser silicon domains is considered to cause a decrease in the reversible capacity retention rate due to excessive structural stress and uncontrolled SEI formation for subsequent charge-discharge cycles.

[0010] Therefore, in the art, there is a need for electroactive material-containing composite particles that overcome the drawbacks of composite particles obtained from conventional single-step and multi-step deposition processes.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Documents

[0012]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

[0013] In a first aspect, the present invention is a particulate material composed of a plurality of composite particles, wherein the composite particles are (a) a porous particle skeleton containing micropores and / or mesopores, wherein the total pore volume of the micropores and mesopores as measured by gas adsorption is in the range of 0.4 cm 3 / g to 2.2 cm 3 / g, a porous particle skeleton, and (b) a plurality of electroactive material domains and a plurality of modifier material domains disposed within the internal pore volume of the porous particle skeleton, wherein at least a portion of the modifier material domains are located between adjacent electroactive material domains, a plurality of electroactive material domains and a plurality of modifier material domains, and provides a particulate material.

[0014] The present invention thus generally relates to a composite particulate material comprising a plurality of electroactive material (e.g., silicon) domains within the pore network of a porous particle. The porous particle thus forms a backbone for the electroactive material domains. As used herein, the term “electroactive material domain” refers to a body of an electroactive material, such as elemental silicon, having a maximum dimension determined by the dimensions of the micropores and / or mesopores of the porous particle in which they are located. The electroactive domain can thus also be described as a nanoscale electroactive domain, where the term “nanoscale” is generally understood to refer to dimensions less than 100 nm. However, due to the dimensions of the micropores and mesopores, the electroactive material domain typically has a maximum dimension of less than 50 nm, usually significantly less than 50 nm, in any direction. The domain can take the form of, for example, regular particles or irregular particles or a bounded layer or a coating region. The electroactive material domain is present in combination with a modifier material domain, and at least a portion of the modifier material domain is located between adjacent electroactive material domains. The plurality of electroactive material domains can be separate electroactive material domains. The electroactive material domain can comprise (or consist of) an amorphous electroactive material or a crystalline electroactive material.

[0015] When compared to materials that contain a similar porous particle skeleton but no modifier material, several different factors contribute to the performance improvement of these materials. The modifier material can act as a barrier that effectively prevents, for example, an increase in the size of the individual domains of the electroactive material when more electroactive material is deposited within the porous particles in a further deposition process. The modifier material thus limits the length scale of the deposited electroactive material and allows the electroactive material to deposit further and form separate electroactive material domains. Thus, composite particles are obtained that have both a desirable filling of the electroactive material and a desirable length scale of the electroactive material domains. Furthermore, the modifier material can reduce the exposed surface area of the electroactive material domains and thus minimize SEI formation and oxidation on the electroactive material surface. Additionally, the modifier material effectively prevents the exposure of the electroactive material to the electrolyte and thus reduces SEI formation. During the long-term cycling of the composite material, the structure of the composite particles can be disrupted, voids and channels can be opened, and electroactive surfaces that were previously located within the closed pore space can be exposed. This problem worsens when the composite material is cycled at higher temperatures and the reaction energy is enhanced from repeated volume changes and chemical interactions between the electrolyte solvent and other cell components. The addition of the modifier material protects the electroactive material domain surfaces and thus reduces the amount of degradation that can occur in such scenarios. The modifier material can also act as a conductive component, for example, a conductive carbon layer (such as a hydrocarbon passivation layer or a nitride passivation layer) can be used as the modifier material and act as a conductivity enhancer located throughout the internal volume of the composite particles. This is thought to further improve the cycle efficiency and the rate performance of the composite.

[0016] The porous particle framework includes a three-dimensionally interconnected open pore network containing micropores and / or mesopores, and optionally a small amount of macropores. According to conventional IUPAC terminology, in this specification, the term "micropore" is used to refer to pores with a diameter of less than 2 nm, and in this specification, the term "mesopore" is used to refer to pores with a diameter of 2 nm to 50 nm, and the term "macropore" is used to refer to pores with a diameter greater than 50 nm.

[0017] In this specification, any reference to the volume of micropores, mesopores, and macropores in the porous particle framework, as well as any reference to the pore volume distribution within the porous particle framework, is to be understood as relating to the internal pore volume of the porous particle framework alone (i.e., in the form of the porous particles before the deposition of the electroactive material and the modifier material). In this specification, any reference to the BET surface area of the porous particle framework is also to be understood as relating to the BET surface area of the porous particle framework alone.

[0018] The porous particle framework has a total volume of micropores and mesopores in the range of 0.4 cm 3 / g to 2.2 cm 3 / g (i.e., the total pore volume in the range of 0 nm to 50 nm). Typically, the porous particle framework contains both micropores and mesopores. However, it is not excluded that a porous particle framework containing micropores but no mesopores, or containing mesopores but no micropores, may be used.

[0019] More preferably, the total volume of micropores and mesopores in the porous particle framework is at least 0.45 cm 3 / g, or at least 0.5 cm 3 / g, at least 0.55 cm 3 / g, or at least 0.6 cm 3 / g, or at least 0.65 cm 3 / g, or at least 0.7 cm 3 / g, or at least 0.75 cm 3 / g, or at least 0.8 cm 3 / g, at least 0.85 cm3 / g, or at least 0.9 cm 3 / g, or at least 0.95 cm 3 / g, or at least 1 cm 3 / g. The use of a highly porous framework may be preferred as it allows for a greater amount of silicon to be accommodated within the pore structure.

[0020] The internal pore volume of the porous particle framework is appropriately limited at a value where the increase in the fragility of the porous particle framework is outweighed by the advantage of the increase in the pore volume accommodating a greater amount of silicon. Preferably, the total volume of micropores and mesopores in the porous particle framework is 2 cm 3 / g or less, or 1.8 cm 3 / g or less, or 1.6 cm 3 / g or less, or 1.5 cm 3 / g or less, or 1.45 cm 3 / g or less, or 1.4 cm 3 / g or less, or 1.35 cm 3 / g or less, or 1.3 cm 3 / g or less, or 1.25 cm 3 / g or less, or 1.2 cm 3 / g or less, or 1.1 cm 3 / g or less, or 1 cm 3 / g or less, or 0.95 cm 3 / g or less.

[0021] Preferably, the total volume of micropores and mesopores in the porous particle framework is 0.45 cm 3 / g to 2.2 cm 3 / g, or 0.5 cm 3 / g to 2 cm 3 / g, or 0.55 cm 3 / g to 2 cm 3 / g, or 0.6 cm 3 / g to 1.8 cm 3 / g, or 0.65 cm 3 / g to 1.8 cm 3 / g, or 0.7 cm 3 / g to 1.6 cm 3 / g, or 0.7 cm 3 / g to 1.5 cm 3 / g, or 0.7 cm 3 / g to 1.4 cm 3 is in the range of / g.

[0022] The total volume of micropores and mesopores in the porous particle skeleton is also 0.55 cm 3 / g to 1.4 cm 3 / g, or 0.6 cm 3 / g to 1.4 cm 3 / g, or 0.6 cm 3 / g to 1.3 cm 3 / g, or 0.65 cm 3 / g to 1.3 cm 3 / g, or 0.65 cm 3 / g to 1.2 cm 3 / g, or 0.7 cm 3 / g to 1.2 cm 3 / g, or 0.7 cm 3 / g to 1.1 cm 3 / g, or 0.7 cm 3 / g to 1 cm 3 / g, or 0.75 cm 3 / g to 0.95 cm 3 may also be in the range of / g.

[0023] The total volume of micropores and mesopores in the porous particle skeleton is also 0.4 cm 3 / g to 0.75 cm 3 / g, or 0.4 cm 3 / g to 0.7 cm 3 / g, or 0.4 cm 3 / g to 0.65 cm 3 / g, or 0.45 cm 3 / g to 0.75 cm 3 / g, or 0.45 cm 3 / g to 0.7 cm 3 / g, or 0.45 cm 3 / g to 0.65 cm 3 / g, or 0.45 cm 3 / g to 0.6 cm 3 may also be in the range of / g.

[0024] The total volume of micropores and mesopores in the porous particle skeleton is also 0.6 cm 3 / g to 2 cm 3 / g, or 0.6 cm 3 / g to 1.8 cm 3 / g, or 0.7 cm 3 / g to 1.8 cm 3 / g, or 0.7 cm 3 / g to 1.6 cm 3 / g, or 0.8 cm 3 / g to 1.6 cm 3 / g, or 0.8 cm 3 / g to 1.5 cm 3 / g, or 0.8 cm 3 / g to 1.4 cm 3 / g, or 0.9 cm 3 / g to 1.5 cm 3 / g, or 0.9 cm 3 / g to 1.4 cm 3 / g, or 1 cm 3 / g to 1.4 cm 3 It may be in the range of / g.

[0025] "PD n The general term "pore diameter" refers to the volume-based n-percentile pore diameter with respect to the total volume of micropores and mesopores in this specification. For example, the term "PD 50 pore diameter" used in this specification refers to the pore diameter at which 50% of the total micropore and mesopore volume is found below this value.

[0026] The PD 50 pore diameter of the porous particle skeleton may be 30 nm or less, preferably 25 nm or less, or 20 nm or less, or 15 nm or less, or 12 nm or less, or 10 nm or less, or 8 nm or less, or 6 nm or less, or 5 nm or less, or 4 nm or less, or 3 nm or less, or 2.5 nm or less, or 2 nm or less, or 1.5 nm or less. The term "PD 50 pore diameter" used in this specification refers to the median pore diameter on a volume basis with respect to the total volume of micropores and mesopores. Therefore, at least 50% of the total volume of micropores and mesopores is preferably in the form of pores having a diameter of less than 30 nm.

[0027] PD of the porous particle skeleton 30 The pore diameter may be 25 nm or less, or 20 nm or less, or 15 nm or less, or 12 nm or less, or 10 nm or less, or 8 nm or less, or 6 nm or less, or 5 nm or less, or 4 nm or less, or 3 nm or less, or 2.5 nm or less, or 2 nm or less, or 1 nm or less.

[0028] PD of the porous particle skeleton 90 The pore diameter may be 35 nm or less, or 30 nm or less, or 25 nm or less, or 20 nm or less, or 15 nm or less, or 12 nm or less, or 10 nm or less, or 8 nm or less, or 6 nm or less, or 5 nm or less, or 4 nm or less, or 3 nm or less, or 2.5 nm or less, or 2 nm or less. Preferably, for the PD of the porous particle skeleton 90 The pore diameter is at least 2.5 nm, or at least 3 nm, or at least 3.5 nm, or at least 4 nm. For example, for the PD of the porous particle skeleton 90 The pore diameter is preferably in the range of 2.5 nm to 20 nm, or 3 nm to 15 nm, or 3.5 nm to 10 nm, or 4 nm to 8 nm.

[0029] PD of the porous particle skeleton 10 The pore diameter may be 10 nm or less, or 9 nm or less, or 8 nm or less, or 7 nm or less, or 6 nm or less, or 5 nm or less, or 4 nm or less, or 3 nm or less, or 2.5 nm or less, or 2 nm or less, or 1.5 nm or less, or 1 nm or less. Preferably, for the PD of the porous particle skeleton 10 The pore diameter is at least 0.3 nm, or at least 0.4 nm, or at least 0.5 nm. For example, for the PD of the porous particle skeleton 10 The pore diameter is preferably in the range of 0.3 nm to 10 nm, or 0.3 nm to 5 nm, or 0.3 nm to 1 nm, or 0.4 nm to 1 nm, or 0.5 nm to 1 nm.

[0030] To avoid misunderstanding, for the PD n For the purpose of determining the value, any macropore volume (pore diameter greater than 50 nm) is not considered.

[0031] Preferably, the volume of micropores in the porous particle skeleton is at least 0.25 cm 3 / g, or at least 0.3 cm 3 / g, at least 0.4 cm 3 / g, or at least 0.5 cm 3 / g or less. Preferably, the volume of micropores in the porous particle skeleton is 1.7 cm 3 / g or less, or 1.5 cm 3 / g or less, or 1.2 cm 3 / g. The volume of micropores in the porous particle skeleton is 0.3 cm 3 / g to 1.7 cm 3 / g, or 0.3 cm 3 / g to 1.5 cm 3 / g, or 0.3 cm 3 / g to 1.2 cm 3 / g may be in the range. The volume of micropores in the porous particle skeleton is 0.4 cm 3 / g to 1.7 cm 3 / g, or 0.5 cm 3 / g to 1.7 cm 3 / g may be in the range. The volume of micropores in the porous particle skeleton is 0.4 cm 3 / g to 1.5 cm 3 / g, or 0.5 cm 3 / g to 1.2 cm 3 / g may be in the range. The presence of a specific amount of voids in the micropore size in the porous particle skeleton assists in achieving the deposition of small-sized electroactive material domains within the pores, while if the micropore volume is too high, the penetration of the porous particle skeleton by the precursors of the electroactive domain and the modifier domain may be overly restricted.

[0032] In principle, the volume ratio of micropores to mesopores in the porous particle skeleton can be in the range of 100:0 to 0:100. Preferably, the volume ratio of micropores to mesopores is 90:10 to 30:70, or 85:15 to 40:60, or 80:20 to 50:50, or 70:30 to 55:45.

[0033] The total volume of micropores and mesopores, as well as the pore size distribution of micropores and mesopores, were determined using the quenched solid density functional theory (QSDFT) in accordance with the standard methodology specified in ISO 15901-2 and ISO 15901-3, with nitrogen gas adsorption up to a relative pressure p / p0 of 10 -6 at 77 K. Nitrogen gas adsorption is a technique for characterizing the porosity and pore size distribution of a material by condensing the gas inside the pores of the solid. As the pressure is increased, the gas first condenses in the pores with the smallest diameters, and the pressure is increased until a saturation point is reached where all pores are filled with liquid. The nitrogen gas pressure is then decreased stepwise to evaporate the liquid from the system. By analyzing the adsorption isotherm and desorption isotherm, as well as the hysteresis between them, the pore volume and pore size distribution can be determined. Suitable apparatuses for measuring the pore volume and pore size distribution by nitrogen gas adsorption include the TriStar II Porosimeter and TriStar II Plus Porosimeter available from Micromeritics Instrument Corporation in the United States, and the Autosorb IQ Porosimeter available from Quantachrome Instruments.

[0034] Nitrogen gas adsorption is effective for measuring the pore volume and pore size distribution of pores with diameters up to 50 nm, but becomes less reliable for pores with much larger diameters. Therefore, for the purposes of the present invention, nitrogen adsorption is used to determine the pore volume and pore size distribution of only the pores with diameters up to 50 nm or less (i.e., only micropores and mesopores). Similarly, the value of PD 50 is determined with respect to the total volume of only micropores and mesopores.

[0035] In view of the limitations of available analytical techniques, it is not possible to measure the pore volume and pore size distribution over the entire range of micropores, mesopores, and macropores using a single technique. If the porous particles or the porous particle framework contain macropores, the volume of pores with diameters greater than 50 nm and up to a maximum of 100 nm can be measured by mercury intrusion porosimetry, preferably at 0.3 cm3 less than / g, or 0.2 cm or less 3 less than / g, or 0.1 cm or less 3 less than / g, or 0.05 cm or less 3 It is less than / g. A small proportion of macropores can be useful for promoting the access of electrolytes into the pore network, but the advantages of the present invention are substantially obtained by accommodating silicon in micropores and smaller mesopores.

[0036] Ignore any pore volume measured by mercury intrusion porosimetry with a pore diameter of 50 nm or less (as described above, nitrogen adsorption is used to characterize mesopores and micropores). The pore volume measured by mercury intrusion porosimetry above 100 nm is assumed to be the interparticle porosity for the purposes of the present invention, and this pore volume is also ignored.

[0037] Mercury intrusion porosimetry is a technique for characterizing the porosity and pore size 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 pore diameter. The values obtained by mercury intrusion porosimetry reported in this specification were obtained in accordance with ASTM UOP578 - 11, assuming a surface tension γ of mercury at room temperature of 480 mN / m and a contact angle φ of 140°. The density of mercury at room temperature is 13.5462 g / cm 3 shall be used. Many high-precision mercury intrusion devices are commercially available, such as the AutoPore IV series of automatic mercury intrusion porosimeters available from Micromeritics Instrument Corporation in the United States. For a complete report on mercury intrusion porosimetry, reference can be made to "Analytical Methods in Fine Particle Technology, 1997, Micromeritics Instrument Corporation" by P.A. Webb and C. Orr (ISBN 0 - 9656783 - 0).

[0038] It will be understood that intrusion techniques such as gas adsorption and mercury porosimetry are only effective for determining the pore volume of pores accessible to nitrogen or mercury from the outside of the porous particles. The value of the porosity defined herein should be understood to refer to the open pores, i.e., the volume of pores accessible to fluid from the outside of the porous particles. Completely enclosed pores that cannot be specified by nitrogen adsorption or mercury porosimetry shall not be considered when determining the porosity value herein. Similarly, any pore volume located within pores smaller than the detection limit by nitrogen adsorption is not considered.

[0039] The pore size distribution of the porous particle skeleton may be unimodal, bimodal or multimodal. The term "pore size distribution" as used herein relates to the distribution of pore sizes with respect to the cumulative total internal pore volume of the porous particle skeleton. A bimodal or multimodal pore size distribution may be preferred because the proximity of micropores to larger diameter pores provides the advantage of efficient ion transport to silicon through the porous network.

[0040] The porous particle skeleton preferably has a BET surface area of at least 100 m 2 / g, or at least 500 m 2 / g, or at least 750 m 2 / g, or at least 1000 m 2 / g, or at least 1250 m 2 / g, or at least 1500 m 2 / g. The term "BET surface area" as used herein should be interpreted to refer to the surface area per unit mass calculated from the measurement of physical adsorption of gas molecules on the solid surface using the Brunauer-Emmett-Teller theory and in accordance with ISO 9277. Preferably, the BET surface area of the porous particle skeleton is 4000 m 2 / g or less, or 3500 m 2 / g or less, or 3250 m 2 / g or less, or 3000 m 2 / g or less, or 2500 m 2 / g or less, or 2000 m2 / g or less. For example, the porous particle skeleton is 100 m 2 / g to 4000 m 2 / g, or 500 m 2 / g to 4000 m 2 / g, or 750 m 2 / g to 3500 m 2 / g, or 1000 m 2 / g to 3250 m 2 / g, 1000 m 2 / g to 3000 m 2 / g, or 1000 m 2 / g to 2500 m 2 / g, or 1000 m 2 / g to 2000 m 2 / g and may have a BET surface area in the range of.

[0041] The porous particle skeleton is preferably conductive. The conductive porous particle skeleton contains or consists of a conductive carbon material. The conductive porous carbon particle skeleton preferably contains at least 80% by weight of carbon, more preferably at least 90% by weight of carbon, more preferably at least 95% by weight of carbon, optionally at least 98% by weight or at least 99% by weight of carbon. The carbon may be crystalline carbon or amorphous carbon, or a mixture of amorphous carbon and crystalline carbon. The carbon may be either carbon or soft carbon.

[0042] As used herein, the term "hard carbon" refers to a disordered carbon matrix in which carbon atoms are mainly in an sp 2 hybrid state (triple bond) in a nanoscale polycyclic aromatic domain. This polycyclic aromatic domain is cross-linked by chemical bonds, for example, C-O-C bonds. Since the polycyclic aromatic domains are chemically cross-linked, hard carbon cannot be converted into graphite at high temperatures. As revealed by the high G band (about 1600 cm -1 ) in the Raman spectrum, hard carbon has properties similar to those of graphite. However, as revealed by the high D band (about 1350 cm -1 ) in the Raman spectrum, the carbon is not completely like graphite.

[0043] As used herein, the term "soft carbon" also refers to a disordered carbon matrix in which carbon atoms are mainly in an sp 2 hybrid state (triple bond) in polycyclic aromatic domains having dimensions in the range of 5 nm to 200 nm. In contrast to hard carbon, the polycyclic aromatic domains in soft carbon are bonded by intermolecular forces without cross-linking by chemical bonds. That is, at high temperatures, soft carbon can be graphitized. The porous carbon skeleton preferably contains at least 50% sp 2 hybrid carbon when measured by XPS. For example, the porous carbon skeleton preferably contains 50% to 98% sp 2 hybrid carbon, 55% to 95% sp 2 hybrid carbon, 60% to 90% sp 2 hybrid carbon, or 70% to 85% sp 2 hybrid carbon.

[0044] Using a variety of different materials, porous particles suitable for forming a porous particle skeleton can be prepared through a pyrolysis method. Examples of organic materials that can be used include plant biomass containing lignocellulosic materials (such as coconut shells, rice husks, wood, etc.) and fossil carbon sources such as coal. Examples of resins and polymer materials that form porous carbon particles by pyrolysis include phenolic resins, novolak resins, pitch, melamine, polyacrylates, polystyrenes, polyvinyl alcohols (PVA), polyvinyl pyrrolidones (PVP), and various copolymers containing monomer units of acrylates, styrenes, α-olefins, vinyl pyrrolidones, and other ethylenically unsaturated monomers. Depending on the starting materials and the conditions of the pyrolysis process, a variety of different carbon materials are available in the art. Porous carbon particles of various different specifications are available from suppliers.

[0045] To increase the volume of mesopores and micropores, a chemical activation process or a gas activation process can be performed on the porous carbon particles. Suitable activation processes include contacting the pyrolyzed carbon with one or more of oxygen, steam, CO, CO2, and KOH at a temperature in the range of 600 °C to 1000 °C.

[0046] Mesopores can also be obtained by known templating processes that use extractable pore formers such as MgO and other colloidal or polymeric templates that can be removed by thermal or chemical means after pyrolysis or activation.

[0047] Alternatives to the carbon-based particle skeleton include porous particle skeletons containing titanium nitride (TiN), titanium carbide (TiC), silicon carbide (SiC), nickel oxide (NiO x ), titanium silicon nitride (TiSiN), nickel nitride (Ni3N), molybdenum nitride (MoN), titanium oxynitride (TiO x N 1-x ), silicon oxycarbide (SiOC), boron nitride (BN), or vanadium nitride (VN). Preferably, the porous particle skeleton contains titanium nitride (TiN), silicon oxycarbide (SiOC), or boron nitride (BN). Further alternatives to the carbon-based particle skeleton include porous particle skeletons containing metal oxides, such as oxides of titanium having the formula TiO x (wherein x has a value greater than 1 and less than 2).

[0048] The porous particle skeleton may have an irregular shape or an ellipsoidal shape.

[0049] The plurality of electroactive material domains may each contain the same electroactive material, or different electroactive material domains may contain different electroactive materials. Preferably, the electroactive material domains contain an electroactive material selected from elemental silicon, elemental tin, elemental germanium, elemental aluminum, and mixtures and alloys thereof. For example, some electroactive material domains can contain (or consist of) elemental silicon, while other electroactive material domains can contain (or consist of) elemental germanium. A preferred electroactive material is silicon. Preferably, at least a portion of the electroactive material domains contains or consists of elemental silicon. More preferably, all of the electroactive material domains contain or consist of elemental silicon.

[0050] As used herein, the "modifier material domain" refers to a material domain having a chemical composition distinct from that of the electroactive material domain. At least a portion of the modifier material domain is located between adjacent electroactive material domains. The requirement that "at least a portion of the modifier material domain is located between adjacent electroactive material domains" should be interpreted to mean that the pore space of the porous particle skeleton is continuously occupied by an electroactive material domain, then a modifier material domain, and then a further electroactive material domain. Thus, the electroactive material does not form a network extending throughout the pore space and is interrupted by the modifier material domain. Thus, within a single pore space, there is an assembly of material domains in the order: [Electroactive material domain(s)] ↓ [Modifier material domain(s)] ↓ [Electroactive material domain(s)] There is an assembly of material domains according to.

[0051] This order of materials is generally obtained by continuously depositing an electroactive material and a modifier material within the pores of a porous particle backbone, as discussed in more detail below. This order can be extended, as appropriate, by additional electroactive material domains and / or by additional modifier material domains.

[0052] A modifier material domain located between adjacent electroactive material domains can act as a barrier separating the electroactive material domains and limit the length scale of continuous electroactive material domains within the composite particles. A modifier material domain located between adjacent electroactive material domains can act as a barrier separating the electroactive material domains. A modifier material domain located between adjacent electroactive material domains can function to limit the length scale of continuous electroactive material domains within the composite particles.

[0053] The electroactive material domains and the modifier material domains are distinct domains and may have a distinct boundary between the two, or there may be a compositional gradient between the electroactive domain and the modifier material domain. The modifier material domain may be a coating (e.g., a film) on at least some or all of the surface of the electroactive material domain. The modifier material domain may be chemically bonded (e.g., covalently, ionically, or metallically) to the electroactive material domain. For example, the modifier material domain may include a passivation layer on the surface of the electroactive material domain, or may include an alloy of the electroactive material on the surface of the electroactive material domain, or may include a doped electroactive material on the surface of the electroactive material domain. Alternatively, the modifier material domain may not be chemically bonded to the electroactive material domain. For example, the modifier material can include or consist of a solid state electrolyte or an inert filler.

[0054] The modifier material domain can include one or more of carbon, nitrogen, and / or oxygen.

[0055] The modifier material domain can be a passivation layer.

[0056] The modifier material domain may be an oxide passivation layer. One type of modifier material is, for example, a native oxide passivation layer formed by exposing the surface of the electroactive material domain to air or another oxygen-containing gas. When the electroactive material domain contains silicon, the modifier material domain may contain silicon oxide of the formula SiO x (where 0 < x ≦ 2). The silicon oxide is preferably amorphous silicon oxide.

[0057] The modifier material domain may be a nitride passivation layer. Another type of modifier material is, for example, a nitride passivation layer formed by exposing the surface of the electroactive material domain to ammonia or another nitrogen-containing molecule. When the electroactive material domain contains silicon, the modifier material domain may contain silicon nitride of the formula SiN x (where 0 < x ≦ 4 / 3). The silicon nitride is preferably amorphous silicon nitride. The nitride modifier material is more preferred than the oxide modifier material. Stoichiometric nitrides (e.g., SiN x (where 0 < x ≦ 4 / 3)) are conductive, so the nitride modifier domain functions as a conductive network that enables faster charging and discharging of the electroactive material. The nitride modifier material domain is also thought to improve the capacity retention rate. Phosphine may also be used as a passivating agent as a phosphorus analog of ammonia.

[0058] The modifier material domain may be an oxynitride passivation layer. Another type of modifier material is, for example, an oxynitride passivation layer formed by exposing the surface of the electroactive material domain to ammonia (or another nitrogen-containing molecule) and oxygen gas. When the electroactive material domain contains silicon, the modifier material domain may contain silicon oxynitride of the formula SiO x N y (where 0 < x < 2, 0 < y < 4 / 3, and 0 < (2x + 3y) ≦ 4). The silicon nitride is preferably amorphous silicon oxynitride.

[0059] The modifier material domain may be a carbide passivation layer. Another type of modifier material is a carbide passivation layer. When the electroactive material domain contains silicon, the modifier material domain may contain silicon carbide of the formula SiC x (where 0 < x ≦ 1). The silicon carbide is preferably amorphous silicon carbide. The silicon carbide layer may be formed by contacting the electroactive material domain surface with a carbon-containing precursor, such as methane or ethylene, at an elevated temperature.

[0060] Another type of modifier material is a passivation layer that includes an organic moiety covalently bonded to at least a portion of the surface of the electroactive material domain. For example, the modifier material domain may include a carbon-containing organic moiety covalently bonded to the electroactive material domain surface. For example, the modifier material domain may include a hydrocarbyl covalently bonded to the electroactive material domain surface.

[0061] Passivating agents suitable for forming a passivation layer that includes an organic moiety include compounds that contain an alkene, alkyne or carbonyl functional group, more preferably a terminal alkene, terminal alkyne, aldehyde or ketone group.

[0062] The covalently bonded organic modifier material domain can be formed by inserting an organic compound into the M-H groups (where M represents an atom of the electroactive material) on the electroactive material surface to form a covalent passivation surface that is resistant to oxidation by air. When silicon is the electroactive material, the passivation reaction between the silicon surface and the passivating agent can be understood as one form of hydrosilylation as schematically shown below.

Chemical formula

[0063] The hydride terminus may decompose to produce hydrogen gas, which can be detrimental to the topography of the electrode. Therefore, it is advantageous to replace the hydride terminus on the surface of the electroactive material domain with a covalently bonded organic modifier material domain, such as a carbon-containing organic moiety. Furthermore, the Si-C bond is thought to improve conductivity.

[0064] Suitable organic compounds that can be used to form the modifier material domain through passivation of the surface of the electroactive material domain include alkenes, alkynes or carbonyl functional groups, more preferably compounds containing terminal alkenes, terminal alkynes or aldehyde groups. For example, the modifier material domain may be formed by passivation of the surface of the electroactive material domain with one or more compounds of the following formulae.

[0065] Preferred passivating agents include the following formulae: (i) R 1 -CH=CH-R 1 , (ii) R 1 -C≡C-R 1 , and, (iii) O=CR 1 R 1 (wherein each R 1 independently represents H, or an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 carbon atoms, or two R 1 groups form an unsubstituted or substituted ring structure containing 3 to 8 carbon atoms in the ring) includes one or more compounds of.

[0066] The modifier material may be a hydrocarbyl covalently bonded to at least a portion of the surface of the electroactive material domain. The modifier material may be a C 2~22 hydrocarbyl covalently bonded to at least a portion of the surface of the electroactive material domain. The modifier material may be a saturated or unsaturated C 2~22 hydrocarbyl covalently bonded to at least a portion of the surface of the electroactive material domain. The modifier material may be a linear or branched C covalently bonded to at least a portion of the surface of the electroactive material domain.2~22 It may be a hydrocarbyl. The modifier material is a monocyclic or polycyclic C covalently bonded to at least a part of the surface of the electroactive material domain 2~22 It may be a hydrocarbyl. The modifier material is a C covalently bonded to at least a part of the surface of the electroactive material domain 2~22 alkyl, C 2~22 alkenyl, C 2~22 alkynyl, C 3~22 cycloalkyl, C 3~22 cycloalkenyl, C 3~22 cycloalkynyl or C 6~22 It may be aralkyl. The modifier material is covalently bonded to at least a part of the surface of the electroactive material domain, [Chemical formula] It may be selected from the group consisting of. It will be understood that the bond crossed by the dotted line is directed towards the atom on the surface of the electroactive material domain. For example, when the electroactive material is silicon, the bond crossed by the dotted line is directed towards Si.

[0067] Particularly preferred passivators include the following formula: (i) CH2=CH-R 1 , and, (ii) HC≡C-R 1 (wherein R 1 is as defined above) one or more compounds are included. Preferably, R 1 is unsubstituted.

[0068] Specific examples of suitable organic compounds that can be used to form the modifier material domain through passivation of the surface of the electroactive material domain 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 can also be used.

[0069] As a further example of an organic compound that can be used to form a modifier material domain through passivation of the surface of an electroactive material domain, compounds containing an active hydrogen atom bonded to oxygen, nitrogen, sulfur, or phosphorus can be mentioned. For example, the passivating agent may be an alcohol, an amine, a thiol, or a phosphine. The reaction between the -XH group and the hydride group on the electroactive material surface is understood to result in the removal of H2 and the formation of a direct bond between X and the electroactive material surface.

[0070] Suitable passivating agents for this category include the following formula: (iv) HX-R 2 and (v) HX-C(O)-R 1 (wherein X represents O, S, NR 1 or PR 1 , each R 1 is independently as defined above, R 2 represents an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 carbon atoms, or R 1 and R 2 together form an unsubstituted or substituted ring structure containing 3 to 8 carbon atoms in the ring) are included.

[0071] Preferably, X represents O or NH. Particularly preferably, X represents NH.

[0072] Preferably, R 2 represents an optionally substituted aliphatic or aromatic group having 2 to 10 carbon atoms. An amine group may also be incorporated into a 4- to 10-membered aliphatic or aromatic ring structure, as in pyrrolidine, pyrrole, imidazole, piperazine, indole, or purine.

[0073] As a further alternative, the modifier material domain may include a pyrolytic carbon material. The pyrolytic carbon domain can be formed by CVI using a suitable carbon-containing precursor, as discussed in more detail below. The use of a pyrolytic carbon material is preferred in that it significantly reduces the surface area of the composite particles, which is thought to improve cycle life and maintain capacity.

[0074] As a further alternative, the modifier material domain may be a conductive metal or metal alloy. The conductive metal or metal alloy domain can be formed by CVI using a suitable metal-containing precursor, as discussed in more detail below. Examples of suitable conductive metals include silver, gold, copper, and titanium.

[0075] As a further alternative, the modifier material domain may include an electroactive material containing a dopant selected from the group consisting of boron, aluminum, gallium, indium, phosphorus, arsenic, antimony, and bismuth. The dopant is preferably boron or phosphorus. The electroactive material may be the same electroactive material in the electroactive material domain or may be different. The electroactive material may be selected from the group consisting of elemental silicon, elemental tin, elemental germanium, elemental aluminum, and mixtures and alloys thereof. A preferred electroactive material is silicon.

[0076] As a further alternative, the modifier material domain may include a solid-state electrolyte or may consist of such an electrolyte. The solid-state electrolyte may be an organic solid electrolyte or an inorganic solid electrolyte.

[0077] Examples of organic solid electrolytes include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate esters polymers, polyester sulfides, polyvinyl alcohol, polyvinylidene fluoride, and polymers containing ionic dissociation groups.

[0078] Examples of inorganic solid electrolytes include nitrides, halides, and sulfides of lithium salts, such as Li5NI2, Li3N, LiI, LiSiO4, Li2SiS3, Li4SiO4, LiOH, and Li3PO4.

[0079] As a further alternative, the modifier material domain may include an inert filler or may consist of such a filler.

[0080] Preferably, the modifier material does not contain oxygen. The use of an oxygen-free modifier material is believed to contribute to providing composite particles with a low total oxygen content, thereby reducing the losses in the first cycle, improving the electron conductivity, improving the cycle life, and maintaining the capacity. Examples of oxygen-free modifier materials include nitride passivation layers, carbide passivation layers, hydrocarbyls covalently bonded to the surface of the electroactive material domain, pyrolytic carbon materials, conductive metals or metal alloys, electroactive materials containing dopants, solid state electrolytes, and inert fillers.

[0081] In a preferred embodiment, the modifier material is a hydrocarbyl (e.g., C 2~22 hydrocarbyl) covalently bonded to at least a portion of the surface of the electroactive material domain or a nitride passivation layer as described herein. These modifier materials are believed to provide a lower total oxygen content, improve conductivity, and reduce the chemical reactivity of the electroactive material domain.

[0082] The composite particles may optionally further include an outer modifier material domain located between the outermost electroactive material domain and the exterior of the composite particles. These modifier material domains form a barrier between the electroactive material and the exterior of the composite particles, thereby inhibiting the contact between the outermost electroactive material domain, which would otherwise tend to cause SEI formation, and the electrolyte. The outer modifier material domain may be formed from any of the modifier materials described herein. Preferred modifier materials for the outer modifier material domain are pyrolytic carbon materials. Another preferred modifier material for the outer modifier material domain is the native oxide of the electroactive material.

[0083] In a preferred embodiment, the particulate material of the present invention includes a plurality of elemental silicon domains (as electroactive domains) disposed within the internal pore volume of a porous particle skeleton, and a plurality of modifier material domains, the modifier material domains including an organic moiety located between adjacent elemental silicon domains and including a passivation layer covalently bonded to at least a portion of the surface of the elemental silicon domains. The composite particles may further include an outer modifier material domain that is a silicon oxide domain.

[0084] In a more preferred embodiment, the particulate material of the present invention includes a plurality of elemental silicon domains (as electroactive domains) disposed within the internal pore volume of a porous particle skeleton, and a plurality of pyrolytic carbon domains, at least a portion of the pyrolytic carbon domains being located between adjacent elemental silicon domains. The composite particles may further include an outer modifier material domain that is a silicon oxide domain.

[0085] In a more preferred embodiment, the particulate material of the present invention includes a plurality of elemental silicon domains (as electroactive domains) disposed within the internal pore volume of a porous particle skeleton, and a plurality of metal or metal alloy domains, at least a portion of the metal or metal alloy domains being located between adjacent elemental silicon domains. The composite particles may further include an outer modifier material domain that is a silicon oxide domain.

[0086] In the present invention, the filling of different electroactive materials in a certain range in the composite particles may also be used. For example, the amount of the electroactive material in the composite particles may be in the range of 5% by weight to 85% by weight based on the total mass of the composite particles. Preferably, the amount of the electroactive material in the composite particles is 10% by weight to 85% by weight, or 15% by weight to 85% by weight, or 20% by weight to 80% by weight, or 25% by weight to 80% by weight, or 30% by weight to 75% by weight, or 35% by weight to 75% by weight, or 40% by weight to 70% by weight, or 45% by weight to 65% by weight based on the total mass of the composite particles.

[0087] The composite particles can contain 40% by weight to 70% by weight, or 45% by weight to 70% by weight, or 48% by weight to 70% by weight, or 50% by weight to 70% by weight, or 40% by weight to 65% by weight, or 45% by weight to 65% by weight, or 48% by weight to 65% by weight, or 50% by weight to 65% by weight, or 40% by weight to 60% by weight, or 45% by weight to 60% by weight, or 48% by weight to 60% by weight, or 50% by weight to 60% by weight of the electroactive material based on the total mass of the composite particles.

[0088] Preferably, the composite particles contain 10% by weight to 85% by weight, or 15% by weight to 85% by weight, or 20% by weight to 80% by weight, or 25% by weight to 80% by weight, or 30% by weight to 75% by weight, or 35% by weight to 75% by weight, or 40% by weight to 70% by weight, or 45% by weight to 65% by weight of silicon based on the total mass of the composite particles.

[0089] The composite particles can contain 40% by weight to 70% by weight, or 45% by weight to 70% by weight, or 48% by weight to 70% by weight, or 50% by weight to 70% by weight, or 40% by weight to 65% by weight, or 45% by weight to 65% by weight, or 48% by weight to 65% by weight, or 50% by weight to 65% by weight, or 40% by weight to 60% by weight, or 45% by weight to 60% by weight, or 48% by weight to 60% by weight, or 50% by weight to 60% by weight of silicon based on the total mass of the composite particles.

[0090] The amount of the electroactive material (e.g., silicon) in the composite particles can be selected such that at least 25% and up to a maximum of 90% or more of the internal pore volume of the porous particle skeleton is occupied by the electroactive material. For example, the electroactive material (e.g., silicon) may occupy 25% - 80%, or 25% - 60%, or 25% - 55%, or 30% - 50%, or 53% - 55%, or 40% - 60%, or 25% - 45%, or 25% - 40% of the internal pore volume of the porous particle skeleton. Within these preferred ranges, the pore volume of the porous particle skeleton is effective in accommodating the expansion of the electroactive material (e.g., silicon) during charging and discharging, but excessive pore volume that does not contribute to the volume capacity of the particulate particles is avoided. However, the amount of the electroactive material is also not so much as to prevent effective lithiation due to an inappropriate metal ion diffusion rate or an inappropriate expansion volume that causes mechanical resistance to lithiation.

[0091] When the electroactive material is silicon, the amount of silicon in the composite particles can be related to the available pore volume by the requirement that the mass ratio of silicon to the porous particle skeleton is in the range of [0.5×P 1 ~1.9×P 1 :1, where P 1 is a dimensionless quantity having the degree of the total pore volume of the micropores and mesopores of the porous particle skeleton as shown in cm 3 / g (for example, if the porous particle or the porous particle skeleton has a total volume of micropores and mesopores of 1.2 cm 3 / g, then P 1 =1.2). This relationship defines the weight ratio of silicon that occupies approximately 20% - 82% of the pore volume, taking into account the density of silicon and the pore volume of the porous particle skeleton.

[0092] The amount of electroactive material (e.g., silicon) in the composite particles can be determined by elemental analysis. Elemental analysis can be used to determine the composition of the porous particles that form only the porous particle skeleton and the composition of the electroactive material-containing composite particles. For example, determining the weight percentage of carbon in only the porous carbon particles takes into account the possibility that the porous carbon particles contain trace amounts of heteroatoms. Combining both measurements makes it possible to reliably determine the weight percentage of electroactive material (e.g., silicon) relative to the porous carbon particles.

[0093] The silicon content is preferably determined by ICP-OES (inductively coupled plasma optical emission spectrometry). Many ICP-OES devices are commercially available, such as the iCAP (trademark) 7000 series of ICP-OES analyzers available from ThermoFisher Scientific. The carbon content (and, if necessary, the hydrogen, nitrogen, and oxygen contents) in only the composite particles and the porous carbon particles is preferably determined by IR absorption. A suitable device for determining the carbon, hydrogen, nitrogen, and oxygen contents is the TruSpec (trademark) Micro elemental analyzer available from Leco Corporation.

[0094] At least 85 wt% of the electroactive material mass in the composite particles can be located within the internal pore volume of the porous particle skeleton. Preferably, at least 90 wt%, more preferably at least 95 wt%, even more preferably at least 98 wt% of the electroactive material (e.g., silicon) mass in the composite particles is located within the internal pore volume of the porous particle skeleton so that little or no electroactive material (e.g., silicon) is located on the external surface of the composite particles. The reaction kinetics of the CVI process ensure that preferential deposition of the electroactive material (e.g., silicon) occurs on the internal surface of the porous particles.

[0095] The composite particles preferably have a low total oxygen content. Oxygen can be present in the composite particles, for example, as part of the porous particle skeleton or as an oxide layer on any exposed silicon surface. 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, such as less than 4% by weight, or less than 3% by weight, or less than 2% by weight, or less than 1% by weight, or less than 0.5% by weight, based on the total mass of the composite particles. Preferably, the total oxygen content of the composite particles is less than 5% by weight, or less than 4% by weight, or less than 3% by weight, or less than 2% by weight, or less than 1% by weight, or less than 0.5% by weight, based on the total mass of the composite particles.

[0096] The composite particles can include a total oxygen content to silicon content ratio of 0.1:1 or less with respect to the total mass of the composite particles.

[0097] The composite particles preferably have a low total chlorine content. Chlorine can be present in the composite particles, for example, as part of a by-product of the electroactive material deposition. Preferably, the total chlorine content of the composite particles is less than 100 ppm, or less than 90 ppm, or less than 80 ppm, or less than 70 ppm, based on the total mass of the composite particles. Without being bound by theory, chlorine is considered to be an impurity in the composite particles that is harmful to cell performance.

[0098] The composite particles preferably have a low total content of transition metals and / or alkali metals. For example, the total content of transition metals and alkali metals in the composite particles may be less than 0.5% by weight based on the total weight of the composite particles.

[0099] Optionally, the composite particles contain zirconium in an amount of 0.0001% to 0.5% by weight, such as 0.001% to 0.1% by weight, based on the total mass of the composite particles.

[0100] The composite particles preferably have a D 50 particle size in the range of 0.5 μm to 30 μm. The D of the composite particles at the end of the CVI process 50If the particle size is greater than 30 μm, it is preferably milled, for example by milling, to a D of 30 μm or less prior to use in electrode manufacture. 50 Reduce the size of the composite particles to a particle size of 30 μm or less D 50 The composite particles with particle size have excellent dispersibility in slurries, structural robustness, and high capacity retention over repeated charge-discharge cycles, making them suitable for forming dense electrode layers of uniform thickness in the conventional thickness range of 20 μm to 50 μm.

[0101] Optionally, D for composite particles 50 The particle size may be at least 1 μm, or at least 2 μm, or at least 3 μm, or at least 4 μm, or at least 5 μm. 50 The particle size may be 20 μm or less, or 18 μm or less, or 16 μm or less, or 14 μm or less, or 12 μm or less, or 10 μm or less, or 8 μm or less.

[0102] For example, the composite particles may have a D in the range of 1 μm to 25 μm, or 1 μm to 20 μm, or 1 μm to 18 μm, or 1 μm to 16 μm, or 2 μm to 16 μm, or 2 μm to 14 μm, or 2 μm to 12 μm, or 2 μm to 10 μm, or 2 μm to 8 μm. 50 It can have a particle size.

[0103] Composite particle D 10 The particle size is preferably at least 0.5 μm, or at least 0.8 μm, or at least 1 μm. 10 Maintaining particle size at or above 0.5 μm reduces the potential for undesirable agglomeration of submicron sized particles, improving dispersibility of the particulate material and improving capacity retention.

[0104] Composite particle D 90The particle size is preferably 50 μm or less, or 40 μm or less, or 30 μm or less, or 25 μm or less, or 20 μm or less, or 15 μm or less. The presence of very large particles leads to non-uniform molding and filling of the particles in the electrode active layer, thus hindering the formation of a dense electrode layer, particularly an electrode layer having a thickness in the range of 20 μm to 50 μm. Therefore, D 90 The particle size is preferably at most 40 μm, and more preferably even smaller.

[0105] The composite particles preferably have a narrow particle 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 particle size distribution span, more efficient filling of the particles into a dense electrode layer can be more easily achieved.

[0106] To avoid misunderstanding, the term "particle size" as used in this specification refers to the equivalent spherical diameter (esd), i.e., the diameter of a sphere having the same volume as a certain particle, where the volume of the particle is understood to include the volume of pores within the particle. The terms "D 50 " and "D 50 particle size" as used in this specification refer to the volume-based median particle size, i.e., the diameter at which 50 volume % of the particle population is present below that particle size. The terms "D 10 " and "D 10 particle size" as used in this specification refer to the volume-based 10th percentile median particle size, i.e., the diameter at which 10 volume % of the particle population is present below that particle size. The terms "D 90 " and "D 90 particle size" as used in this specification refer to the volume-based 90th percentile median particle size, i.e., the diameter at which 90 volume % of the particle population is present below that particle size.

[0107] The particle size and particle size distribution can be determined by a standard laser diffraction method in accordance with ISO 13320:2009. Laser diffraction is based on the principle that particles scatter light at angles that vary according to the size of the particles, and an aggregate of particles produces a scattered light pattern defined by the intensity and angle that can be correlated to the particle size distribution. Many laser diffraction devices are commercially available to quickly and reliably determine the particle size distribution. Unless otherwise specified, the particle size distribution measurements defined or reported in this specification are those measured by a conventional Malvern Mastersizer (trademark) 3000 particle size analyzer manufactured by Malvern Instruments (trademark). This Malvern Mastersizer (trademark) 3000 particle size analyzer operates by projecting a helium-neon gas laser beam through a transparent cell containing the target particles suspended in an aqueous solution. The light beam hitting the particles is scattered at an angle inversely proportional to the particle size, and a photodetector array measures the intensity of the light at several predetermined angles. The intensities measured at various angles are processed by a computer using standard theoretical principles to determine the particle size distribution. The laser diffraction values as reported in this specification are obtained using a wet dispersion of the particles in 2-propanol with 5% by volume of the surfactant SPAN (trademark)-40 (sorbitan monopalmitate) added. For porous particles, a refractive index of 2.68 is taken, and for composite particles, a refractive index of 3.50 is taken, and a refractive index of 1.378 is taken for the dispersant. The Mie scattering model is used to calculate the particle size distribution.

[0108] The composite particles preferably have a size of 0.35 cm 3 / g or less, or 0.25 cm 3 / g or less, or 0.15 cm 3 / g or less, or 0.1 cm 3 / g or less, or 0.05 cm 3 / g or less, or 0.03 cm 3 / g or less, or 0.02 cm 3It has a total volume of micropores and / or mesopores measured by nitrogen gas adsorption as described in this specification, which is below / g. Preferably, the total volume of micropores and / or mesopores of the composite particles is 20% by volume or less, more preferably 15% by volume or less, or 10% by volume or less, or 5% by volume or less of the total volume of micropores and / or mesopores of the porous particle skeleton. When the total volume of micropores and / or mesopores in the composite particles is lower, the penetration of the electrolyte solvent into the composite particles, which causes SEI formation inside, decreases, the overall surface area decreases, and better control is provided for avoiding undesirable surface reactions during use.

[0109] The composite particles preferably have a BET surface area of 300 m 2 / g or less, or 250 m 2 / g or less, or 200 m 2 / g or less, or 150 m 2 / g or less. More preferably, it is 100 m 2 / g or less, or 80 m 2 / g or less, or 60 m 2 / g or less, or 50 m 2 / g or less, or 40 m 2 / g or less, or 30 m 2 / g or less, or 25 m 2 / g or less, or 20 m 2 / g or less, or 15 m 2 / g or less, or 10 m 2 / g or less, or 5 m 2 / g or less. Preferably, the composite particles have a BET surface area of 30 m 2 / g or less, or 25 m 2 / g or less, or 20 m 2 / g or less, or 15 m 2 / g or less, or 10 m 2 / g or less, or 5 m 2It has a BET surface area of less than or equal to 100 m² / g. Generally, in order to minimize the formation of the solid electrolyte interface (SEI) layer on the surface of the composite particles during the first charge-discharge cycle of the anode, it is preferable to have a low BET surface area. However, if the BET surface area is excessively low, a large amount of the electroactive material becomes inaccessible to metal ions in the surrounding electrolyte, resulting in unacceptably low charging rates and capacities. For example, the BET surface area may be in the range of 0.1 m² / g to 100 m² / g, or 0.1 m² / g to 80 m² / g, or 0.5 m² / g to 60 m² / g, or 0.5 m² / g to 40 m² / g, or 1 m² / g to 30 m² / g, or 1 m² / g to 25 m² / g, or 2 m² / g to 20 m² / g. 2 / g to 100 m² 2 / g, or 0.1 m² 2 / g to 80 m² 2 / g, or 0.5 m² 2 / g to 60 m² 2 / g, or 0.5 m² 2 / g to 40 m² 2 / g, or 1 m² 2 / g to 30 m² 2 / g, or 1 m² 2 / g to 25 m² 2 / g, or 2 m² 2 / g to 20 m² 2 / g.

[0110] The composite particles can have an irregular shape or a spheroidal shape. The spheroidal particles as defined herein can include both spherical particles and ellipsoidal particles, and the shape of the composite particles of the present invention can preferably be defined by referring to the sphericity and aspect ratio of the particles of the present invention. It has been found that spheroidal particles are particularly suitable for dispersion in a slurry without forming aggregates. Also, the use of porous spheroidal particles has surprisingly been found to provide a further improvement in strength when compared to porous particles of irregular shape and porous particle fragments.

[0111] The sphericity of an object has conventionally been defined as the ratio of the surface area of a sphere to the surface area of this object, where the object and the sphere have the same volume. However, in practice, it is difficult to measure the surface area and volume of individual particles on the micron scale. However, by means of scanning electron microscopy (SEM) and dynamic image analysis that records the shadow projected by the particles using a digital camera, a high-precision two-dimensional projection image of the micron-scale particles can be obtained. The term "sphericity" as used herein is understood to be the ratio of the area of the particle projection image to the area of a circle, where the particle projection image and the circle have the same circumference. Thus, for individual particles, the sphericity S can be defined as follows: [Number] (where A m is the area measured for the particle projection image and C m is the circumference measured for the particle projection image). The average sphericity S of the particle population used herein is defined as follows: av is defined as follows: [Number] (where n represents the number of particles in the population).

[0112] In this specification, the term "rotationally ellipsoidal" as applied to and used in the composite particles of the present invention is understood to refer to a material having an average sphericity of at least 0.70. The composite particles of the present invention preferably have an average sphericity of at least 0.85, more preferably at least 0.90, more preferably at least 0.92, more preferably at least 0.93, more preferably at least 0.94, more preferably at least 0.95. The composite particles can optionally have an average sphericity of at least 0.96, or at least 0.97, or at least 0.98, or at least 0.99.

[0113] The circumference and area of the two-dimensional particle projection image will be understood to depend on the orientation of the particle in the case of any particle that is not a perfect ellipsoid of revolution. However, the influence of particle orientation can be offset by reporting sphericity and aspect ratio as average values obtained from a plurality of particles with random orientations. Many SEM devices and dynamic image analysis devices are commercially available, and the sphericity and aspect ratio of particulate materials can be determined quickly and reliably. Unless otherwise specified, the sphericity values defined or reported herein are those measured by a CamSizer XT particle analyzer manufactured by Retsch Technology GmbH. This CamSizer XT is a dynamic image analysis device that can obtain a high-precision distribution of the size and shape of particulate materials with a sample volume of 100 mg to 100 g, and characteristics such as average sphericity and aspect ratio can be directly calculated by this device.

[0114] Composite particles can be further characterized by their performance under thermogravimetric analysis (TGA) in air. This analytical method is based on the principle that a weight increase is observed when the electroactive material is oxidized in air and at elevated temperatures.

[0115] As defined herein, "surface silicon" is calculated from the initial weight increase of the TGA trace from the minimum value between 150 °C and 500 °C to the maximum mass measured in the temperature range between 550 °C and 650 °C, and the TGA is performed at a heating rate of 10 °C / min in air. This weight increase is assumed to result from the oxidation of surface silicon, and thus the following equation: Y = 1.875 × [(M max - M min ) / M f × 100% (where Y is the percentage of surface silicon as the ratio of total silicon in the sample, M max is the maximum mass of the sample measured in the temperature range between 550 °C and 650 °C, M min is the minimum mass of the sample at a temperature higher than 150 °C and lower than 500 °C, M fAccording to (which is the mass of the sample at the completion of oxidation at 1400 °C), the percentage of surface silicon as a ratio of the total amount of silicon can be determined. For the sake of completeness, it will be understood that 1.875 is the molar mass ratio of SiO2 to O2 (i.e., the mass ratio of the formed SiO2 to the mass increase due to oxygen addition). Typically, the TGA analysis is performed using a sample size of 10 mg ± 2 mg.

[0116] When the surface silicon as determined by the above-described TGA method is at least 20% by weight of the total amount of silicon in the material, it has been found that the reversible capacity retention over a number of charge / discharge cycles is significantly improved. Preferably, at least 22% by weight of silicon, or at least 25% by weight, at least 30% by weight, or at least 35% by weight of silicon, or at least 40% by weight of silicon, or at least 45% by weight of silicon is surface silicon as determined by thermogravimetric analysis (TGA).

[0117] In addition to the high surface silicon content, the particulate material of the present invention preferably has a low content of coarse bulk silicon, as determined by TGA. Coarse bulk silicon is defined herein as silicon that undergoes oxidation above 800 °C as determined by TGA, where the TGA is performed at a heating rate of 10 °C / min in air. Thus, the coarse bulk silicon content is given by the following formula: Z = 1.875 × [(M f - M 800 ) / M f × 100% (where Z is the percentage of unoxidized silicon at 800 °C, M 800 is the mass of the sample at 800 °C, and M f is the mass of the ash at the completion of oxidation at 1400 °C) and is determined accordingly. For the purposes of this analysis, any mass increase above 800 °C corresponds to the oxidation of silicon to SiO2, and it is assumed that the total mass at the completion of oxidation is SiO2. Typically, the TGA analysis is performed using a sample size of 10 mg ± 2 mg.

[0118] Silicon that undergoes oxidation above 800 °C is not very desirable. Preferably, 10 wt% or less, or 8 wt% or less, or 6 wt% or less, or 5 wt% or less, or 4 wt% or less, or 3 wt% or less, or 2 wt% or less, or 1.5 wt% or less of silicon is the crude bulk silicon as determined by TGA.

[0119] Preferably, at least 20 wt% of the silicon is surface silicon, 10 wt% or less of the silicon is crude bulk silicon, and both are determined by TGA. More preferably, at least 30 wt% of the silicon is surface silicon, 10 wt% or less of the silicon is crude bulk silicon, and both are determined by TGA. More preferably, at least 35 wt% of the silicon is surface silicon, 8 wt% or less of the silicon is crude bulk silicon, and both are determined by TGA. More preferably, at least 40 wt% of the silicon is surface silicon, 5 wt% or less of the silicon is crude bulk silicon, and both are determined by TGA. More preferably, at least 45 wt% of the silicon is surface silicon, 2 wt% or less of the silicon is crude bulk silicon, and both are determined by TGA.

[0120] The composite particles preferably have a specific charge capacity of 1200 mAh / g to 2340 mAh / g during the first lithiation. Preferably, the composite particles have a specific charge capacity of at least 1400 mAh / g during the first lithiation.

[0121] The composite particles may include a coating of a lithium ion permeable material, such as a carbon coating. The lithium ion permeable material coating has the advantage of further reducing the BET surface area of the composite particles by smoothing any surface defects and filling any remaining surface micropore structure, thereby further reducing the loss in the first cycle. Further, the lithium ion permeable material coating improves the conductivity of the composite particle surface, reduces the need for a conductive additive in the electrode composition, and also produces an optimal surface for the formation of a stable SEI layer, resulting in improved capacity retention for the cycle.

[0122] The reduction in the surface area of the composite particles also has the effect of reducing the amount of binder required to form the electrode active layer containing the composite particles. An excessive binder is known to contribute to a decrease in rate performance. A further advantage of the present invention is that the filler contributes to the improvement of the compressive strength of the composite particles by providing structural reinforcement to the porous particle skeleton.

[0123] When a carbon coating is present, the composite particles preferably have a BET surface area of 2 150 m 2 / g or less, or 100 m 2 / g or less, or 80 m 2 / g or less, or 60 m 2 / g or less, or 40 m 2 / g or less, or 30 m 2 / g or less, or 25 m 2 / g or less, or 15 m 2 / g or less, or 10 m 2 / g or less, or 5 m 2 / g or less, or 3 m 2 / g or less.

[0124] In a second aspect, the present invention is a method for preparing composite particles, comprising: (a) The total pore volume of micropores and mesopores as measured by gas adsorption is 0.4 cm 3 / g to 2.2 cm 3Preparing a plurality of porous particles comprising micropores and / or mesopores in the range of / g; (b) contacting the porous particles with a precursor of the electroactive material at a temperature effective to cause deposition of a plurality of electroactive material domains in the pores of the porous particles; (c) forming a plurality of modifier material domains in the pores of the porous particles adjacent to the electroactive material domains deposited in step (b); (d) contacting the particles resulting from step (c) with a precursor of the electroactive material in the pores of the porous particles adjacent to the modifier material domains formed in step (c) at a temperature effective to cause deposition of additional electroactive material domains; A method is provided that includes.

[0125] Accordingly, the method of the present invention is a multi-step process that includes, in order, a first step of depositing an electroactive material, a step of forming a modifier material adjacent to the electroactive material, and a further step of depositing an electroactive material adjacent to the modifier material. As a result of this series of steps, at least a portion of the modifier material domains in the product resulting from step (d) is located between the electroactive material deposited in step (b) and the electroactive material deposited in step (d). Accordingly, the product of the method of the second aspect of the present invention is the particulate material according to the first aspect of the present invention.

[0126] As discussed above, the porous particles used in step (a) form a porous particle skeleton in the composite particles. The term "porous particle skeleton" is used in the context of the composite particle product, while the term "porous particle" is used to describe the starting material that ultimately forms the porous particle skeleton. Accordingly, the porous particles used in step (a) of the method of the second aspect of the present invention may have any of the characteristics of the porous particle skeletons described herein in the context of the first aspect of the present invention. The characteristics of the porous particle skeleton may optionally be combined with any of the further characteristics of the porous particles shown below.

[0127] Generally, the porous particles can have a D particle size in the range of 0.5 μm to 200 μm. 50 Optionally, the D particle size of the porous particles can be at least 1 μm, or at least 1.5 μm, or at least 2 μm, or at least 2.5 μm, or at least 3 μm, or at least 4 μm, or at least 5 μm. 50 Optionally, the D particle size of the porous particles can be 150 μm or less, or 100 μm or less, or 70 μm or less, or 50 μm or less, or 40 μm or less, or 30 μm or less, or 25 μm or less, or 20 μm or less, or 18 μm or less, or 15 μm or less, or 12 μm or less, or 10 μm or less, or 8 μm or less. 50 For example, the porous particles can have a D particle size in the range of 0.5 μm to 150 μm, or 0.5 μm to 100 μm, or 0.5 μm to 50 μm, or 0.5 μm to 30 μm, or 1 μm to 25 μm, or 1 μm to 20 μm, or 2 μm to 25 μm, or 2 μm to 20 μm, or 2 μm to 18 μm, or 2 μm to 15 μm, or 2 μm to 12 μm, or 2.5 μm to 15 μm, or 2.5 μm to 12 μm, or 2 μm to 10 μm, or 3 μm to 20 μm, or 3 μm to 18 μm, or 3 μm to 15 μm, or 4 μm to 18 μm, or 4 μm to 15 μm, or 4 μm to 12 μm, or 5 μm to 15 μm, or 5 μm to 12 μm, or 5 μm to 10 μm, or 5 μm to 8 μm.

[0128] Particles within these size ranges and having a porosity and pore size distribution as shown herein are ideally suitable for the preparation of composite particles for use in anodes for metal ion batteries by the CVI process. 50 The D particle size of the porous particles is preferably at least 0.2 μm, or at least 0.5 μm, or at least 0.8 μm, or at least 1 μm, or at least 1.5 μm, or at least 2 μm.

[0129] By maintaining the D particle size at 0.2 μm or more, the possibility of undesirable aggregation of submicron-sized particles is reduced, and the dispersibility of the composite particles is improved. 10 10 10 10

[0130] D of the porous particles 90 The particle size is preferably 300 μm or less, or 250 μm or less, or 200 μm or less, or 150 μm or less, or 100 μm or less, or 80 μm or less, or 60 μm or less, or 40 μm or less, or 30 μm or less, or 25 μm or less, or 20 μm or less.

[0131] The porous particles preferably have a narrow particle 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 particle size distribution span, efficient packing of the particles into a high-density powder bed can be more easily achieved.

[0132] The porous particles preferably have at least 100 m 2 / g, or at least 500 m 2 / g, or at least 750 m 2 / g, or at least 1000 m 2 / g of BET surface area. As used herein, the term "BET surface area" should be interpreted to refer to 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 and in accordance with ISO 9277. Preferably, the BET surface area of the porous particles is 4000 m 2 / g or less, or 3500 m 2 / g or less, or 3250 m 2 / g or less, or 3000 m 2 / g, or 2500 m 2 / g or less, or 2000 m 2 / g. For example, the porous particles are 100 m 2 / g to 4000 m 2 / g, or 500 m 2 / g to 4000 m 2 / g, or 750 m 2 / g to 3500 m2 / g, or 1000 m 2 / g to 3250 m 2 / g, 1000 m 2 / g to 3000 m 2 / g, or 1000 m 2 / g to 2500 m 2 / g, or 1000 m 2 / g to 2000 m 2 It may have a BET surface area in the range of / g.

[0133] The porous particles may have an average sphericity greater than 0.5 (as defined above). Preferably, the porous particles have an average sphericity of at least 0.55, or at least 0.6, or at least 0.65, or at least 0.7, or at least 0.75, or at least 0.8, or at least 0.85. Preferably, the porous particles have an average sphericity of at least 0.90, or at least 0.92, or at least 0.93, or at least 0.94, or at least 0.95.

[0134] Preferably, the porous particles (i) 0.4 cm 3 / g to 2.2 cm 3 The total pore volume of micropores and mesopores as measured by nitrogen gas adsorption in the range of / g, (ii) PD of 20 nm or less 50 Pore diameter, preferably PD of 30 nm or less 90 Pore diameter, preferably PD of 15 nm or less 30 Pore diameter, and (iii) D in the range of 0.5 μm to 30 μm 50 Particle diameter, and optionally, (iv) Particle size distribution span of 5 or less ((D 90 -D 10 ) / D 50 ), have.

[0135] More preferably, the porous particles (i) 0.6 cm 3 / g to 1.8 cm 3The total pore volume of micropores and mesopores as measured by nitrogen gas adsorption in the range of / g, (ii) PD of 10 nm or less 50 Pore diameter, preferably PD of 20 nm or less 90 Pore diameter, preferably PD of 8 nm or less 30 Pore diameter, and, (iii) D in the range of 1 μm to 25 μm 50 Particle diameter, and optionally, (iv) Particle size distribution span of 5 or less ((D 90 -D 10 ) / D 50 ), and has.

[0136] More preferably, the porous particles are, (i) 0.7 cm 3 / g to 1.6 cm 3 / g of the total pore volume of micropores and mesopores as measured by nitrogen gas adsorption in the range of, (ii) PD of 10 nm or less 50 Pore diameter, preferably PD of 20 nm or less 90 Pore diameter, preferably PD of 8 nm or less 30 Pore diameter, and, (iii) D in the range of 1 μm to 20 μm 50 Particle diameter, and optionally, (iv) Particle size distribution span of 5 or less ((D 90 -D 10 ) / D 50 ), and has.

[0137] More preferably, the porous particles are, (i) 0.7 cm 3 / g to 1.5 cm 3 / g of the total pore volume of micropores and mesopores as measured by nitrogen gas adsorption in the range of, (ii) PD of 5 nm or less 50 Pore diameter, preferably PD of 10 nm or less 90 Pore diameter, preferably PD of 3 nm or less 30 Pore diameter, and, (iii) D in the range of 2 μm to 20 μm50 Particle diameter, and optionally, (iv) A particle size distribution span of 5 or less ((D 90 -D 10 ) / D 50 ), and has.

[0138] More preferably, the porous particles are (i) The total pore volume of micropores and mesopores as measured by nitrogen gas adsorption in the range of 0.7 cm 3 / g to 1.4 cm 3 / g, (ii) A PD pore diameter of 5 nm or less, preferably a PD pore diameter of 10 nm or less 50 pore diameter, preferably a PD pore diameter of 3 nm or less 90 pore diameter, and, 30 and (iii) A D particle diameter in the range of 2 μm to 20 μm, and optionally, 50 particle diameter, and (iv) A particle size distribution span of 5 or less ((D 90 -D 10 ) / D 50 ), and has.

[0139] More preferably, the porous particles are (i) The total pore volume of micropores and mesopores as measured by nitrogen gas adsorption in the range of 0.7 cm 3 / g to 1.4 cm 3 / g, (ii) A PD pore diameter of 5 nm or less, preferably a PD pore diameter of 10 nm or less 50 pore diameter, preferably a PD pore diameter of 3 nm or less 90 pore diameter, and, 30 and (iii) A D particle diameter in the range of 2 μm to 18 μm, and optionally, 50 particle diameter, and (iv) A particle size distribution span of 5 or less ((D 90 -D 10 ) / D 50 ), and has.

[0140] More preferably, the porous particles are (i) 0.7 cm 3 / g to 1.4 cm 3 The total pore volume of micropores and mesopores as measured by nitrogen gas adsorption in the range of / g, (ii) PD of 2 nm or less 50 Pore diameter, preferably PD of 5 nm or less 90 Pore diameter, preferably PD of 1 nm or less 30 Pore diameter, and (iii) D in the range of 2 μm to 15 μm 50 Particle diameter, and optionally, (iv) Particle size distribution span of 5 or less ((D 90 -D 10 ) / D 50 ), have.

[0141] The composite particles (i) D of at least 0.5 μm 10 Particle diameter, (ii) D of 50 μm or less 90 Particle diameter, and (iii) Total volume of micropores and mesopores of 0.35 cm 3 / g or less, and optionally, (iv) Particle size distribution span of 5 or less ((D 90 -D 10 ) / D 50 ), may have.

[0142] The composite particles (i) D of at least 0.8 μm 10 Particle diameter, (ii) D of 40 μm or less 90 Particle diameter, and (iii) Total volume of micropores and mesopores of 0.35 cm 3 / g or less, and optionally, (iv) Particle size distribution span of 5 or less ((D 90 -D 10 ) / D 50 ), may have.

[0143] The composite particles (i) D of at least 0.8 μm 10 Particle size, (ii) D of 30 μm or less 90 Particle size, and, (iii) Total volume of micropores and mesopores of 0.35 cm 3 / g or less, and optionally, (iv) Particle size distribution span of 5 or less ((D 90 - D 10 ) / D 50 ), may be possessed.

[0144] The composite particles are, (i) D of at least 1 μm 10 Particle size, (ii) D of 25 μm or less 90 Particle size, and, (iii) Total volume of micropores and mesopores of 0.25 cm 3 / g or less, and optionally, (iv) Particle size distribution span of 5 or less ((D 90 - D 10 ) / D 50 ), may be possessed.

[0145] The composite particles are, (i) Total oxygen content of less than 5% by weight based on the total mass of the composite particles, (ii) 40% to 70% by weight of silicon based on the total mass of the composite particles, and, (iii) BET surface area of 30 m 2 / g or less, and optionally, (iv) Particle size distribution span of 5 or less ((D 90 - D 10 ) / D 50 ), may be possessed.

[0146] The composite particles are, (i) Total oxygen content of less than 5% by weight based on the total mass of the composite particles, (ii) 40% to 60% by weight of silicon based on the total mass of the composite particles, and, (iii) 20 m 2A BET surface area of less than / g, and optionally, (iv) A particle size distribution span of 5 or less ((D 90 -D 10 ) / D 50 ), may have.

[0147] The composite particles (i) A total oxygen content of less than 5 wt% based on the total mass of the composite particles, (ii) 40 wt% to 60 wt% of silicon based on the total mass of the composite particles, and (iii) A BET surface area of 15 m 2 / g or less, and optionally, (iv) A particle size distribution span of 5 or less ((D 90 -D 10 ) / D 50 ), may have.

[0148] Composite particles having these preferred total oxygen content, silicon content and BET surface area are considered to have improved cycle life and energy capacity.

[0149] The composite particles (i) A D 10 particle diameter of at least 0.5 μm, (ii) A D 90 particle diameter of 50 μm or less, (iii) A total volume of micropores and mesopores of 0.35 cm 3 / g or less, (iv) A total oxygen content of less than 5 wt% based on the total mass of the composite particles, (v) 40 wt% to 70 wt% of silicon based on the total mass of the composite particles, and (vi) A BET surface area of 30 m 2 / g or less, and optionally, (vii) A particle size distribution span of 5 or less ((D 90 -D 10 ) / D 50 ), may have.

[0150] The composite particles (i) D of at least 0.8 μm 10 Particle diameter (ii) D of 40 μm or less 90 Particle diameter (iii) Total volume of micropores and mesopores of 0.35 cm 3 / g or less, (iv) Total oxygen content of less than 5 wt% based on the total mass of the composite particles, (v) 40 wt% to 60 wt% of silicon based on the total mass of the composite particles, and, (vi) BET surface area of 20 m 2 / g or less, and optionally, (vii) Particle size distribution span of 5 or less ((D 90 -D 10 ) / D 50 ), may be possessed.

[0151] The composite particles (i) D of at least 0.8 μm 10 Particle diameter (ii) D of 30 μm or less 90 Particle diameter (iii) Total volume of micropores and mesopores of 0.35 cm 3 / g or less, (iv) Total oxygen content of less than 5 wt% based on the total mass of the composite particles, (v) 40 wt% to 60 wt% of silicon based on the total mass of the composite particles, and, (vi) BET surface area of 15 m 2 / g or less, and optionally, (vii) Particle size distribution span of 5 or less ((D 90 -D 10 ) / D 50 ), may be possessed.

[0152] The composite particles (i) D of at least 1 μm 10 Particle diameter (ii) D of 25 μm or less 90 Particle diameter (iii) 0.25 cm 3The total volume of micropores and mesopores below / g, (iv) a total oxygen content of less than 5% by weight based on the total mass of the composite particles, (v) 40% to 60% by weight of silicon, and, (vi) 15 m 2 / g or less BET surface area, and optionally, (vii) a particle size distribution span of 5 or less ((D 90 -D 10 ) / D 50 ), and may have.

[0153] The aforementioned preferred features of the porous particles also apply to the porous particle skeleton in the composite particles of the first aspect of the present invention.

[0154] The electroactive materials deposited in steps (b) and (d) may be the same or different, and optionally, independently, may be selected from silicon, tin, germanium, aluminum, and mixtures and alloys thereof. A preferred electroactive material is silicon. Preferably, the electroactive material deposited in at least one of steps (b) and (d) is silicon. More preferably, the electroactive materials deposited in each of steps (b) and (d) are both silicon.

[0155] Suitable precursors for silicon include silane (SiH4), disilane (Si2H6), trisilane (Si3H8), tetrasilane (Si4H 10 ), methylsilane (CH3SiH3), dimethylsilane ((CH3)2SiH2), or chlorosilanes such as trichlorosilane (HSiCl3) or methylchlorosilanes such as methyltrichlorosilane (CH3SiCl3) or dimethyldichlorosilane ((CH3)2SiCl2). A preferred precursor for silicon is silane.

[0156] Suitable precursors for tin include bis[bis(trimethylsilyl)amino]tin(II) ([[(CH3)3Si]2N]2Sn), tetraallyltin ((H2C=CHCH2)4Sn), tetrakis(diethylamide)tin(IV) ([(C2H5)2N]4Sn), tetrakis(dimethylamide)tin(IV) ([(CH3)2N]4Sn), tetramethyltin (Sn(CH3)4), tetravinyltin (Sn(CH=CH2)4), tin(II) acetylacetonate (C 10 H 14 O4Sn), trimethyl(phenylethynyl)tin (C6H5C≡CSn(CH3)3), and trimethyl(phenyl)tin (C6H5Sn(CH3)3). A preferred precursor for tin is tetramethyltin.

[0157] Suitable precursors for aluminum include aluminum tris(2,2,6,6-tetramethyl-3,5-heptanedionate) (Al(OCC(CH3)3CHCOC(CH3)3)3), trimethylaluminum ((CH3)3Al), and tris(dimethylamide)aluminum(III) (Al(N(CH3)2)3). A preferred precursor for aluminum is trimethylaluminum.

[0158] Suitable precursors for germanium include germane (GeH4), hexamethyldigermane ((CH3)3GeGe(CH3)3), tetramethylgermanium ((CH3)4Ge), tributylgermanium hydride ([CH3(CH2)3]3GeH), triethylgermanium hydride ((C2H5)3GeH), and triphenylgermanium hydride ((C6H5)3GeH). A preferred precursor for germanium is germane.

[0159] When the precursor is a chlorinated compound, e.g., a chlorosilane, the precursor is preferably used in admixture with hydrogen gas at an atomic ratio of hydrogen to chlorine of at least 1:1.

[0160] Optionally, the precursor does not contain chlorine. Not containing chlorine means that the precursor contains less than 1% by weight, preferably less than 0.1% by weight, preferably less than 0.01% by weight of chlorine-containing compounds.

[0161] In steps (b) and (d), the precursor may be used either in pure form (or substantially pure form) or as a diluted mixture with an inert carrier gas, such as nitrogen or argon. When in a diluted mixture with an inert carrier gas, the precursor may be used in an amount in the range of 1% to 95% by volume, or 1% to 85% by volume, or 1% to 70% by volume, or 1% to 50% by volume, or 2% to 40% by volume, or 5% to 30% by volume, or 5% to 25% by volume, based on the total gas volume of the precursor and the inert carrier gas. In accordance with conventional methods for working in an inert atmosphere, the presence of oxygen should be minimized to prevent undesirable oxidation of the deposited electroactive material. Preferably, the oxygen content is less than 0.01% by volume, more preferably less than 0.001% by volume, based on the total volume of the gas used in steps (b) and (d).

[0162] The temperature in steps (b) and (d) is any temperature effective to decompose the precursor to form the electroactive material. Preferably, the temperature in steps (b) and (d) is independently in the range of 300 °C to 800 °C, or 350 °C to 800 °C, or 380 °C to 700 °C, or 380 °C to 650 °C, or 380 °C to 600 °C, or 380 °C to 550 °C, or 380 °C to 500 °C, or 400 °C to 450 °C, or 450 °C to 500 °C. More preferably, the temperature in steps (b) and (d) is independently in the range of 380 °C to 500 °C, preferably 420 °C to 480 °C. Optionally, the temperature is substantially the same in steps (b) and (d).

[0163] The operating pressure in step (b) and step (d) may be less than atmospheric pressure, above atmospheric pressure, or atmospheric pressure. Optionally, the pressure in at least one of step (b) and step (d) is maintained at less than 200 kPa, or 150 kPa or less, or 120 kPa or less, or 110 kPa or less, or 100 kPa or less, or 90 kPa or less, or 80 kPa or less, or 70 kPa or less, or 60 kPa or less, or 50 kPa or less.

[0164] For example, the pressure in at least step (b) is maintained at less than 200 kPa, or 150 kPa or less, or 120 kPa or less, or 110 kPa or less, or 100 kPa or less, or 90 kPa or less, or 80 kPa or less, or 70 kPa or less, or 60 kPa or less, or 50 kPa or less.

[0165] Optionally, the pressure in both step (b) and step (d) may be maintained at less than 200 kPa, or 150 kPa or less, or 120 kPa or less, or 110 kPa or less, or 100 kPa or less, or 90 kPa or less, or 80 kPa or less, or 70 kPa or less, or 60 kPa or less, or 50 kPa or less.

[0166] Any reference to the pressure in any step of the claimed method refers to the absolute pressure in the reaction zone, which may include a reactor vessel of an appropriate type.

[0167] The deposition of the electroactive material by CVI results in the removal of by-products, particularly by-product gases such as hydrogen. Step (b) and / or step (d) preferably further includes separating the by-products. The separation of the by-products from the particles formed in step (b) and / or step (d) can be achieved by flushing the reactor with an inert gas and / or evacuating the reactor by reducing the pressure. For example, the separation of the by-products from the intermediate particles formed in step (b) can be achieved by evacuating the reactor to a pressure of less than 100 kPa, or less than 80 kPa, or less than 60 kPa, or less than 40 kPa, or less than 20 kPa, or less than 10 kPa, or less than 5 kPa, or less than 2 kPa, or less than 1 kPa. Evacuating the reactor to a low pressure can be effective not only to remove the gaseous by-products but also to desorb any by-products that may be adsorbed on the surface of the deposited electroactive material.

[0168] The modifier material formed in step (c) may optionally be a passivation layer formed on the surface of the electroactive material deposited in step (b). Thus, step (c) may further include contacting the intermediate particles from step (b) with a passivating agent. As described above, the passivating agent is a compound or mixture of compounds capable of reacting with the surface of the electroactive material deposited in step (b) to form a modified surface. Any of the passivating agents described in connection with the first aspect of the present invention can be used in step (c).

[0169] The contact between the electroactive material and the passivating agent in step (c) may be carried out at a temperature in the range of 25°C to 800°C, preferably in the range of 50°C to 500°C, more preferably in the range of 100°C to 300°C.

[0170] The formation of the native oxide layer is exothermic and thus requires careful process control to prevent overheating or even combustion of the particulate material. If the modifier material formed in step (c) is a native oxide layer, step (c) may include cooling the material formed in step (b) to less than 300 °C, preferably less than 200 °C, optionally less than 100 °C, before contacting the surface of the electroactive material domain with an oxygen-containing gas.

[0171] The modifier material formed in step (c) may be a nitride of the electroactive material domain. Step (c) may include contacting ammonia with the surface of the electroactive material domain. The nitride layer can be formed by contacting the surface of the electroactive material domain with ammonia at a temperature in the range of 200 °C to 700 °C, preferably 400 °C to 700 °C, more preferably 400 °C to 600 °C. Then, if necessary, the temperature can be raised to the range of 500 °C to 1000 °C to form a nitride surface (e.g., a silicon nitride surface of the formula SiN x (where x ≤ 4 / 3)). For example, when using ammonia, step (c) may be carried out at the same or a similar temperature as that used for depositing the electroactive material domain in step (b). Since stoichiometric silicon nitride is conductive, this step will also result in the formation of a conductive network that allows for more rapid charging and discharging of the electroactive material.

[0172] Another type of modifier material is an oxynitride layer. Step (c) may include exposing the surface of the electroactive material domain to ammonia (or another nitrogen-containing molecule) and oxygen gas. If the electroactive material domain contains silicon, the modifier material domain may include silicon oxynitride of the formula SiO x N y (where 0 < x < 2, 0 < y < 4 / 3, and 0 < (2x + 3y) ≤ 4). The silicon nitride is preferably amorphous silicon oxynitride.

[0173] As a further option, an amorphous or nanocrystalline carbide layer may be formed. Step (c) may include contacting the electroactive material domain surface with a carbon-containing precursor, such as methane or ethylene, at a temperature in the range of 250 °C to 700 °C. At lower temperatures, covalent bonds are formed between the electroactive material surface and the carbon-containing precursor, which is converted to a single layer of crystalline silicon carbide as the temperature increases. When the electroactive material domain contains silicon, the modifier material domain may contain silicon carbide of the formula SiC x (where 0 < x ≦ 1). The silicon carbide is preferably amorphous silicon carbide.

[0174] Other suitable passivating agents include compounds containing alkene, alkyne or carbonyl functional groups, more preferably terminal alkenes, terminal alkynes, aldehyde or ketone groups. Suitable passivating agents of these types are described above.

[0175] Other suitable passivating agents include compounds containing active hydrogen atoms bonded to oxygen, nitrogen, sulfur or phosphorus. For example, the passivating agent may be an alcohol, an amine, a thiol or a phosphine. The reaction of the -XH group with the hydride group on the electroactive material surface is understood to result in the removal of H2 and the formation of a direct bond between X and the electroactive material surface. Suitable passivating agents of these types are described above.

[0176] The modifier material formed in step (c) may optionally include a pyrolytic carbon material deposited on the electroactive material surface by thermal decomposition of the carbon-containing precursor, i.e., by chemical vapor infiltration (CVI). The deposition of the pyrolytic carbon material in step (c) may be suitable for forming a conductive network between electroactive material domains that can facilitate electron transfer within the composite particles. Step (c) may thus include contacting the intermediate particles resulting from step (b) with a carbon-containing precursor, preferably a hydrocarbon, at a temperature effective to cause deposition of the pyrolytic carbon material in the pores of the intermediate particles.

[0177] Suitable hydrocarbons include polycyclic hydrocarbons containing 10 to 25 carbon atoms and optionally 1 to 3 heteroatoms. Optionally, the polycyclic aromatic hydrocarbons are selected from naphthalene, substituted naphthalenes such as dihydroxynaphthalene, anthracene, tetracene, pentacene, fluorene, acenaphthene, phenanthrene, fluoranthene, pyrene, chrysene, perylene, coronene, fluorenone, anthraquinone, anthrone and their alkyl-substituted derivatives. Suitable pyrolytic carbon precursors also include bicyclic monoterpenoids. Optionally, the bicyclic monoterpenoids are selected from camphor, borneol, eucalyptol, camphene, careen, sabinene, thujene and pinene. Further suitable pyrolytic carbon precursors include C2 - C 10 hydrocarbons. Optionally, the hydrocarbons are selected from alkanes, alkenes, alkynes, cycloalkanes, cycloalkenes, and arenes such as 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.

[0178] The temperature suitable for the deposition of the pyrolytic carbon material in step (c) ranges from 300°C to 800°C, or from 400°C to 800°C. For example, the temperature may be 750°C or lower, or 700°C or lower, or 680°C or lower, or 660°C or lower, or 640°C or lower, or 620°C or lower, or 600°C or lower, or 580°C or lower, or 560°C or lower, or 540°C or lower, or 520°C or lower, or 500°C or lower. The minimum temperature varies depending on the type of carbon precursor used. Preferably, the temperature is at least 300°C, or at least 350°C, or at least 400°C, or at least 450°C, or at least 500°C.

[0179] The carbon-containing precursor used in step (c) may be used in pure form or in a mixture diluted with an inert carrier gas such as nitrogen or argon. For example, the carbon-containing precursor may be used in an amount in the range of 0.1% to 100% by volume, or 0.5% to 20% by volume, or 1% to 10% by volume, or 1% to 5% by volume, based on the total volume of the precursor and the inert carrier gas. To prevent unwanted oxidation of the deposited electroactive material, the presence of oxygen must be minimized. Preferably, the oxygen content is less than 0.01% by volume, more preferably less than 0.001% by volume, based on the total volume of the gas.

[0180] When a pyrolytic carbon material is deposited in step (c), the same compound can function as both a passivating agent and a pyrolytic carbon precursor. For example, if styrene is selected as the pyrolytic carbon precursor, it will also function as a passivating agent if the intermediate particles from step (b) are not exposed to oxygen prior to contact with styrene. In this case, the passivation and deposition of the conductive carbon material during the process can be carried out simultaneously, for example, at a temperature in the range of 300°C to 700°C. Alternatively, the passivation and deposition of the conductive carbon material can be carried out sequentially if the passivating agent and the pyrolytic carbon precursor are the same material, but the deposition of the pyrolytic carbon precursor is carried out at a higher temperature than the passivation. For example, the passivation can be carried out at a temperature in the range of 25°C to less than 300°C, and the deposition of the pyrolytic carbon can be carried out at a temperature in the range of 300°C to 700°C. These two steps can be carried out appropriately sequentially by increasing the temperature while maintaining contact with the compound that functions as both a passivating agent and a pyrolytic carbon precursor. At a lower temperature (for example, in the range of 25°C to less than 300°C), passivation will be the main process. As the temperature rises (for example, to 300°C to 700°C), the deposition of the pyrolytic carbon is thought to subsequently occur.

[0181] As a further option, step (c) may include depositing a layer of a conductive metal or metal alloy as a modifier material on the surface of the electroactive material domain. The conductive metal layer or metal alloy may be obtained by chemical vapor infiltration (CVI). Examples of suitable conductive metals include silver, gold, copper, and titanium.

[0182] The formation of the conductive metal or metal alloy modifier material in step (c) may optionally be carried out following passivation of the surface of the electroactive material domain by one of the processes as described above. Thus, the modifier material formed in step (c) may include both a passivation layer and a conductive metal or metal alloy layer on the surface of the electroactive material domain.

[0183] As a further alternative, step (c) may include forming a modifier material domain that includes an electroactive material containing a dopant selected from the group consisting of boron, aluminum, gallium, indium, phosphorus, arsenic, antimony, and bismuth. The doped electroactive material may be formed by a CVI process in which porous particles are contacted simultaneously with both a precursor of the electroactive material and the dopant. Alternatively, the doped electroactive material may be formed by contacting a deposited electroactive material with the dopant.

[0184] As a further alternative, step (c) may include forming a solid state electrolyte as the modifier material.

[0185] As a further alternative, step (c) may include forming an inert filler as the modifier material.

[0186] Depending on the amount of electroactive material deposited in each step, the method of the present invention may be operated as a multi-pass process in which steps (c) and (d) are repeated as many times as necessary to deposit the target amount of electroactive material. For example, steps (c) and (d) may be performed 2 to 15 times, and a total of 3 to 16 electroactive material deposition steps may occur, including the repetitions of steps (b) and (d).

[0187] When repeating steps (c) and (d), each process of steps (c) and (d) is independently as described above. For example, each repetition of step (c) may include the formation of the same or different modifier materials. Similarly, the electroactive materials deposited during each repetition of step (d) may be the same or different, and may also be the same as or different from the electroactive materials deposited in step (b). Preferably, the electroactive material deposited in at least one of step (b) and the repeating step (d) is silicon. More preferably, the electroactive material deposited in each of step (b) and the repeating step (d) is silicon.

[0188]

[0189] The method of the present invention optionally (e) forming a plurality of modifier material domains in the pores and / or on the outer surface of the composite particles derived from step (d); further includes.

[0190] After the final deposition step of the electroactive material (i.e., step (d), or the last repetition of step (d) when repeating steps (c) and (d)), step (e) is immediately performed. The formation of the modifier material domains in step (e) is a process similar to the above-described step (c) except that step (e) is performed after the final deposition step of the electroactive material (the last step (d)), while step (c) is performed during consecutive deposition steps of the electroactive material. All of the modifier materials and deposition conditions shown above in connection with step (c) also apply to step (e).

[0191] ​The modifier material domain formed in step (e) may contain the same or a different modifier material as the modifier material domain formed in step (c).

[0192] Optionally, step (e) includes contacting the composite particles from step (d) with a passivating agent. The preferred passivating agents and passivation conditions shown above in connection with step (c) also apply to passivation in step (e).

[0193] The modifier material domain formed in step (e) may be a natural oxide of the electroactive material. In this case, it is preferred that the modifier material domain formed in step (c) (and any repetition of step (c)) is not a natural oxide of the electroactive material.

[0194] Optionally, step (e) includes depositing a lithium ion permeable material within and / or on the outer surface of the pores of the composite particles from step (d). This results in a further improvement in the performance of the composite particles when used as an electroactive material for a lithium ion battery by reducing the surface area of the composite particles and blocking the electroactive material domain from access to the electrolyte.

[0195] The lithium ion permeable material may be deposited immediately after the final electroactive material deposition step (i.e., step (d), or if steps (c) and (d) are repeated one or more times, after the last step (d)). Alternatively, as discussed above, the lithium ion permeable material may be deposited after first performing the passivation step during step (e).

[0196] A suitable lithium ion permeable material is a pyrolytic carbon material. The pyrolytic carbon material can be obtained by chemical vapor infiltration (CVI), i.e., by pyrolysis of a volatile carbon-containing gas (such as ethylene) on the surface of the silicon-containing composite particles.

[0197] A process suitable for depositing a pyrolytic carbon material involves combining the composite particles from step (d) with a pyrolytic carbon precursor and heating the pyrolytic carbon precursor to a temperature effective to cause deposition of the pyrolytic conductive carbon material within and / or on the outer surface of the pores of the composite particles.

[0198] The preferred pyrolytic carbon precursors and pyrolysis conditions shown above in connection with step (c) also apply to the formation of the pyrolytic carbon material in step (e).

[0199] When the lithium ion permeable material is a pyrolytic carbon material, the same compound can function as both a passivating agent and a pyrolytic carbon precursor in step (e). Conditions suitable for using the same compound as both a passivating agent and a pyrolytic carbon precursor to passivate and form the pyrolytic carbon material in step (e) are the same as those shown above in connection with step (c).

[0200] Alternatively, different compounds may be used as the passivating agent and as the pyrolytic carbon precursor. For example, the passivating agent may be styrene, and the pyrolytic carbon precursor may be a compound such as cyclohexane that can form a pyrolytic carbon material but cannot passivate the surface of the electroactive material.

[0201] In a preferred embodiment, the electroactive material deposited in steps (b) and (d) is elemental silicon, and the modifier material domain formed in step (c) is a passivation layer that includes an organic moiety covalently bonded to at least a portion of the surface of the elemental silicon domain formed in step (b). Optionally, the method includes step (e), and the modifier material domain formed in step (e) is a silicon oxide domain formed by passivation using an oxygen-containing gas.

[0202] In a more preferred embodiment, the electroactive material deposited in steps (b) and (d) is elemental silicon, and the modifier material domain formed in step (c) is a pyrolytic carbon domain. Optionally, the method includes step (e), and the modifier material domain formed in step (e) is a silicon oxide domain formed by passivation using an oxygen-containing gas.

[0203] In a more preferred embodiment, the electroactive material deposited in steps (b) and (d) is elemental silicon, and the modifier material domain formed in step (c) is a metal or metal alloy domain. Optionally, the method includes step (e), and the modifier material domain formed in step (e) is a silicon oxide domain formed by passivation using an oxygen-containing gas.

[0204] In a more preferred embodiment, the electroactive material deposited in steps (b) and (d) is elemental silicon, and the modifier material domain formed in step (c) is a silicon oxide domain formed by passivation using an oxygen-containing gas.

[0205] The method of the present invention may be carried out in any reactor capable of bringing a solid and a gas into contact at an elevated temperature. The porous particles and the composite particles to be formed may be present in the reactor in the form of a fixed bed of particles, or in the form of a moving bed or a stirred bed of particles.

[0206] The product obtained from the method of the present invention can have any of the features described herein with respect to the particulate material of the first aspect of the present invention.

[0207] In a third aspect of the present invention, there is provided a composition comprising the composite particles according to the second aspect of the present invention and at least one other component. In particular, there is provided a composition comprising the composite particles according to the second aspect of the present invention and at least one other component selected from (i) a binder, (ii) a conductive additive, and (iii) an additional particulate electroactive material. The composition according to the present invention is useful as an electrode composition and can thus be used to form the active layer of an electrode.

[0208] The composition can be a hybrid electrode composition comprising the composite particles and at least one additional particulate electroactive material. Examples of additional particulate electroactive materials include graphite, hard carbon, silicon, tin, germanium, aluminum, and lead. The at least one additional particulate electroactive material is preferably selected from graphite and hard carbon. The at least one additional particulate electroactive material is most preferably graphite.

[0209] In the case of a hybrid electrode composition, the composition can contain 1 wt% to 95 wt%, or 2 wt% to 90 wt%, or 5 wt% to 85 wt%, or 10 wt% to 80 wt% particulate material, based on the total dry weight of the composition. The composition preferably contains 3 wt% to 60 wt%, or 3 wt% to 50 wt%, or 5 wt% to 50 wt%, or 10 wt% to 50 wt%, or 15 wt% to 50 wt% composite particles, based on the total dry weight of the composition.

[0210] The at least one additional particulate electroactive material is preferably present in an amount of 20 wt% to 95 wt%, or 25 wt% to 90 wt%, or 30 wt% to 75 wt% of the at least one additional particulate electroactive material.

[0211] The at least one additional particulate electroactive material preferably has a D 50 particle size in the range of 10 μm to 50 μm, preferably 10 μm to 40 μm, more preferably 10 μm to 30 μm, most preferably 10 μm to 25 μm, for example 15 μm to 25 μm.

[0212] D of at least one additional particulate electroactive material 10 The particle size is preferably at least 5 μm, more preferably at least 6 μm, more preferably at least 7 μm, more preferably at least 8 μm, more preferably at least 9 μm, still more preferably at least 10 μm.

[0213] D of at least one additional particulate electroactive material 90 The particle size is preferably at most 100 μm, more preferably at most 80 μm, more preferably at most 60 μm, more preferably at most 50 μm, most preferably at most 40 μm.

[0214] At least one additional particulate electroactive material is preferably selected from carbon-containing particles, graphite particles, and / or hard carbon particles, wherein the graphite particles and the hard carbon particles have a D in the range of 10 μm to 50 μm. 50 The particle size. More preferably, at least one additional particulate electroactive material is selected from graphite particles, wherein the graphite particles have a D in the range of 10 μm to 50 μm. 50 The particle size.

[0215] The composition may be a non-hybrid (i.e., "high loading") electrode composition that substantially does not contain an additional particulate electroactive material. In this context, the term "substantially does not contain an additional particulate electroactive material" means that the composition contains, based on the total dry weight of the composition, any additional electroactive material (i.e., an additional material capable of inserting and releasing metal ions during charging and discharging of the battery) in an amount of less than 15 wt%, preferably less than 10 wt%, preferably less than 5 wt%, preferably less than 2 wt%, more preferably less than 1 wt%, still more preferably less than 0.5 wt%.

[0216] This type of "high loading" electrode composition preferably contains, based on the total dry weight of the composition, the composite particles according to the present invention in an amount of at least 50 wt%, or at least 60 wt%, or at least 70 wt%, or at least 80 wt%, or at least 90 wt%.

[0217] The composition can optionally contain a binder. The binder functions to adhere the composition to the current collector and to maintain the integrity of the composition. Examples of binders that can be used according to the present invention include polyvinylidene fluoride (PVDF), polyacrylic acid (PAA) and its alkali metal salts, modified polyacrylic acid (mPAA) and its alkali metal salts, carboxymethyl cellulose (CMC), modified carboxymethyl cellulose (mCMC), sodium carboxymethyl cellulose (Na-CMC), polyvinyl alcohol (PVA), alginates and their alkali metal salts, styrene-butadiene rubber (SBR), and polyimide. The composition can contain a mixture of binders. Preferably, the binder contains polymers selected from polyacrylic acid (PAA) and its alkali metal salts, modified polyacrylic acid (mPAA) and its alkali metal salts, SBR, and CMC.

[0218] The binder can preferably be present in an amount of 0.5 wt% to 20 wt%, preferably 1 wt% to 15 wt%, preferably 2 wt% to 10 wt%, and most preferably 5 wt% to 10 wt% based on the total dry weight of the composition.

[0219] The binder can optionally be present in combination with one or more additives that modify the properties of the binder, such as a crosslinking accelerator, a coupling agent, and / or an adhesion promoter.

[0220] The composition can optionally contain one or more conductive additives. Preferred conductive additives are non-electrically active materials included to improve the conductivity between the electroactive components of the composition and between the electroactive components of the composition and the current collector. The conductive additive can be selected from carbon black, carbon fiber, carbon nanotube, graphene, acetylene black, ketjen black, metal fiber, metal powder, and conductive metal oxide. Preferred conductive additives include carbon black and carbon nanotubes.

[0221] One or more conductive additives can preferably be present in a total amount of 0.5% to 20% by weight, preferably 1% to 15% by weight, preferably 2% to 10% by weight, and most preferably 5% to 10% by weight based on the total dry weight of the composition.

[0222] The present invention provides an electrode comprising the particulate material according to the present invention that is in electrical contact with a current collector. The particulate material used to manufacture the electrode can be in the form of the composition of the present invention.

[0223] As used herein, the term current collector refers to any conductive substrate that can conduct current to and from the electroactive particles in the composition. Examples of materials that can be used as the current collector include copper, aluminum, stainless steel, nickel, titanium, and sintered carbon. Copper is a preferred material. The current collector typically has the form of a foil or mesh having a thickness of 3 μm to 500 μm. The particulate material of the present invention can be applied to one or both surfaces of the current collector to a thickness preferably in the range of 10 μm to 1 mm, such as 20 μm to 500 μm, or 50 μm to 200 μm.

[0224] The electrode of the present invention can be produced by forming a slurry of the particulate material of the present invention in combination with a solvent and optionally one or more viscosity-adjusting additives. The slurry is then cast onto the surface of the current collector, and the solvent is removed to form an electrode layer on the surface of the current collector. Further steps such as heat treatment to cure any binder and / or calendaring treatment of the electrode layer can be carried out as appropriate. The electrode layer preferably has a thickness in the range 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.

[0225] Alternatively, for example, the slurry can be cast into a suitable casting template, the solvent removed, and then the casting template removed to form the slurry into a self-standing film or mat containing the particulate material of the present invention. The resulting film or mat has the form of a self-standing agglomerate and can then be adhered to the current collector by known methods.

[0226] The electrodes of the present invention can be used as anodes of metal ion batteries. Thus, the present invention provides a rechargeable metal ion battery comprising an anode including an electrode according to the present invention as described above, a cathode including a cathode active material capable of releasing and reabsorbing metal ions, and an electrolyte between the anode and the cathode.

[0227] 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 and receive lithium ions.

[0228] The cathode active material is preferably a metal oxide-based composite material. Examples of suitable cathode active materials include LiCoO2, LiCo 0.99 Al 0.01 O2, LiNiO2, LiMnO2, LiCo 0.5 Ni 0.5 O2, LiCo 0.7 Ni 0.3 O2, LiCo 0.8 Ni 0.2 O2, LiCo 0.82 Ni 0.18 O2, LiCo 0.8 Ni 0.15 Al 0.05 O2, LiNi 0.4 Co 0.3 Mn 0.3 O2, and LiNi 0.33 Co 0.33 Mn 0.34O2 is included. The cathode current collector usually has a thickness of 3 μm to 500 μm. Examples of materials that can be used as the cathode current collector include aluminum, stainless steel, nickel, titanium, and sintered carbon.

[0229] The electrolyte is preferably a non-aqueous electrolyte containing a metal salt, such as a lithium salt, and can include, but is not limited to, non-aqueous electrolytic solutions, solid electrolytes, and inorganic solid electrolytes. Examples of non-aqueous electrolytic solutions that can be used include aprotic organic solvents such as propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, acetonitrile, nitromethane, methyl formate, methyl acetate, triphosphate ester, trimethoxymethane, sulfolane, methyl sulfolane, and 1,3-dimethyl-2-imidazolidinone.

[0230] Examples of organic solid electrolytes include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate ester polymers, polyester sulfides, polyvinyl alcohol, polyvinylidene fluoride, and polymers containing ionic dissociation groups.

[0231] Examples of inorganic solid electrolytes include nitrides, halides, and sulfides of lithium salts such as Li5NI2, Li3N, LiI, LiSiO4, Li2SiS3, Li4SiO4, LiOH, and Li3PO4.

[0232] The lithium salt is preferably soluble in the selected solvent or a mixture of solvents. Examples of suitable lithium salts include LiCl, LiBr, LiI, LiClO4, LiBF4, LiBC4O8, LiPF6, LiCF3SO3, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, and CF3SO3Li.

[0233] When the electrolyte is a non-aqueous organic solution, the metal ion battery preferably includes a separator inserted between the anode and the cathode. The separator is typically formed of an insulating material having high ion permeability and high mechanical strength. The separator typically has a pore diameter of 0.01 μm to 100 μm and a thickness of 5 μm to 300 μm. An example of a suitable electrode separator is a microporous polyethylene film.

[0234] The separator can be replaced with a polymer electrolyte material, in which case the polymer electrolyte material is present in both the composite anode layer and the composite cathode layer. The polymer electrolyte material can be a solid polymer electrolyte or a gel-type polymer electrolyte.

Claims

1. A particulate material composed of a plurality of composite particles, wherein the composite particles are (a) a porous particle skeleton containing micropores and / or mesopores, and the total pore volume of the micropores and mesopores measured by gas adsorption is 0.4 cm ３ / g to 2.2 cm ３ / g, and a porous particle skeleton, (b) a plurality of electroactive material domains and a plurality of modifier material domains disposed within the internal pore volume of the porous particle skeleton, wherein at least a part of the modifier material domains is located between adjacent electroactive material domains, and a plurality of electroactive material domains and a plurality of modifier material domains, A particulate material comprising.

2. The total pore volume of the micropores and mesopores in the porous particle skeleton is 0.45 cm ３ / g to 2.2 cm ３ / g, or 0.5 cm ３ / g to 2 cm ３ / g, or 0.55 cm ３ / g to 2 cm ３ / g, or 0.6 cm ３ / g to 1.8 cm ３ / g, or 0.65 cm ３ / g to 1.8 cm ３ / g, or 0.7 cm ３ / g to 1.6 cm ３ / g, or 0.7 cm ３ / g to 1.5 cm ３ / g, or 0.7 cm ３ / g to 1.4 cm ３ / g, and the particulate material according to claim 1.

3. The PD of the porous particle skeleton ５０ The pore diameter is 30 nm or less, or 25 nm or less, or 20 nm or less, or 15 nm or less, or 12 nm or less, or 10 nm or less, or 8 nm or less, or 6 nm or less, or 5 nm or less, or 4 nm or less, or 3 nm or less, or 2.5 nm or less, or 2 nm or less, or 1.5 nm or less, and the particulate material according to claim 1.

4. The PD of the porous particle skeleton ３０ The particle material according to claim 1, wherein the pore diameter is 25 nm or less, or 20 nm or less, or 15 nm or less, or 12 nm or less, or 10 nm or less, or 8 nm or less, or 6 nm or less, or 5 nm or less, or 4 nm or less, or 3 nm or less, or 2.5 nm or less, or 2 nm or less, or 1 nm or less.

5. The porous particle skeleton is 100 m ２ / g to 4000 m ２ / g, or 500 m ２ / g to 4000 m ２ / g, or 750 m ２ / g to 3500 m ２ / g, or 1000 m ２ / g to 3250 m ２ / g, or 1000 m ２ / g to 3000 m ２ / g, or 1000 m ２ / g to 2500 m ２ / g, or 1000 m ２ / g to 2000 m ２ The particle material according to claim 1, having a BET surface area in the range of / g.

6. The particle material according to claim 1, wherein the porous particle skeleton is a conductive porous particle skeleton.

7. The particle material according to claim 6, wherein the conductive porous particle skeleton is a conductive porous carbon particle skeleton.

8. The particle material according to claim 7, wherein the conductive porous carbon particle skeleton contains at least 80% by weight of carbon, or at least 85% by weight of carbon, or at least 90% by weight of carbon, or at least 95% by weight of carbon.

9. The particle material according to claim 1, wherein the porous particle skeleton has a volume ratio of micropores to mesopores of 90:10 to 30:70, or 85:15 to 40:60, or 80:20 to 50:50, or 70:30 to 55:

45.

10. PD of the porous particle skeleton １０ The particulate material according to claim 1, wherein the pore diameter is 10 nm or less, or 9 nm or less, or 8 nm or less, or 7 nm or less, or 6 nm or less, or 5 nm or less, or 4 nm or less, or 3 nm or less, or 2.5 nm or less, or 2 nm or less, or 1.5 nm or less, or 1 nm or less.

11. PD of the porous particle skeleton ９０ The particulate material according to claim 1, wherein the pore diameter is 35 nm or less, or 30 nm or less, or 25 nm or less, or 20 nm or less, or 15 nm or less, or 12 nm or less, or 10 nm or less, or 8 nm or less, or 6 nm or less, or 5 nm or less, or 4 nm or less, or 3 nm or less, or 2.5 nm or less, or 2 nm or less.

12. The particulate material according to claim 1, wherein each of the electroactive material domains contains an electroactive material independently selected from silicon, tin, germanium, aluminum, and mixtures and alloys thereof.

13. The particulate material according to claim 1, wherein at least a part of the electroactive material domain contains or consists of silicon, or all of the electroactive material domain contains or consists of silicon.

14. The particulate material according to claim 1, wherein the modifier material contains one or more of carbon, nitrogen, and oxygen.

15. The modifier material is an oxide, nitride, oxynitride, or carbide passivation layer formed on at least a part of the surface of the electroactive material domain, or the modifier material is SiO ｘ (where 0 < x ≦ 2) selected oxides, or SiN ｘ (where 0 < x ≦ 4 / 3) selected nitrides, or SiC ｘ (where 0 < x ≦ 1) selected carbides, or the modifier material is of the formula SiN ｘThe particulate material according to claim 1, which is a nitride passivation layer formed on at least a part of the surface of the electroactive material domain and has (where 0 < x ≤ 4 / 3).

16. The particulate material according to claim 1, wherein the modifier material is a passivation layer containing a carbon-containing organic moiety covalently bonded to at least a part of the surface of the electroactive material domain.

17. The particulate material according to claim 1, wherein the modifier material contains C ２～２２ hydrocarbyl covalently bonded to at least a part of the surface of the electroactive material domain.

18. The particulate material according to claim 1, wherein the modifier material contains C ２～２２ alkyl, C ２～２２ alkenyl, C ２～２２ alkynyl, C ３～２２ cycloalkyl, C ３～２２ cycloalkenyl, C ３～２２ cycloalkynyl or C ６～２２ aralkyl covalently bonded to at least a part of the surface of the electroactive material domain.

19. The particulate material according to claim 1, wherein the modifier material is covalently bonded to at least a part of the surface of the electroactive material domain, 【Chemical Formula 1】 and is selected from the group consisting of.

20. The particulate material according to claim 1, wherein the modifier material contains a pyrolytic carbon material.

21. The particulate material according to claim 1, wherein the modifier material contains a conductive metal or metal alloy.

22. The particulate material according to claim 1, wherein the modifier material contains an electroactive material containing a dopant selected from boron and phosphorus.

23. Further comprising an outer modifier material domain located between the outermost electroactive material domain and the outside of the composite particles, wherein the modifier material comprises one or more of carbon, nitrogen, and oxygen, the particulate material according to claim 1.

24. The composite particles contain 5 wt% to 85 wt%, or 10 wt% to 85 wt%, or 15 wt% to 85 wt%, or 20 wt% to 80 wt%, or 25 wt% to 80 wt%, or 30 wt% to 75 wt%, or 35 wt% to 75 wt%, or 40 wt% to 70 wt%, or 45 wt% to 65 wt% of the electroactive material based on the total mass of the composite particles, the particulate material according to claim 1.

25. The composite particles contain 40 wt% to 70 wt%, or 45 wt% to 70 wt%, or 48 wt% to 70 wt%, or 50 wt% to 70 wt%, or 40 wt% to 65 wt%, or 45 wt% to 65 wt%, or 48 wt% to 65 wt%, or 50 wt% to 65 wt%, or 40 wt% to 60 wt%, or 45 wt% to 60 wt%, or 48 wt% to 60 wt%, or 50 wt% to 60 wt% of the electroactive material based on the total mass of the composite particles, the particulate material according to claim 1.

26. The composite particles contain 10 wt% to 85 wt%, or 15 wt% to 85 wt%, or 20 wt% to 80 wt%, or 25 wt% to 80 wt%, or 30 wt% to 75 wt%, or 35 wt% to 75 wt%, or 40 wt% to 70 wt%, or 45 wt% to 65 wt% of silicon based on the total mass of the composite particles, the particulate material according to claim 1.

27. The composite particles contain 40 wt% to 70 wt%, or 45 wt% to 70 wt%, or 48 wt% to 70 wt%, or 50 wt% to 70 wt%, or 40 wt% to 65 wt%, or 45 wt% to 65 wt%, or 48 wt% to 65 wt%, or 50 wt% to 65 wt%, or 40 wt% to 60 wt%, or 45 wt% to 60 wt%, or 48 wt% to 60 wt%, or 50 wt% to 60 wt% of silicon based on the total mass of the composite particles, the particulate material according to claim 1.

28. The particulate material according to claim 1, wherein the amount of the electroactive material occupies at least 25% and at most 90% of the internal pore volume of the porous particle skeleton.

29. The particulate material according to claim 1, wherein at least 85 wt%, or at least 90 wt%, or at least 95 wt%, or at least 98 wt% of the mass of the electroactive material in the composite particles is located within the internal pore volume of the porous particle skeleton.

30. The composite particles have a D ５０ particle diameter in the range of 0.5 μm to 30 μm, or 1 μm to 25 μm, or 1 μm to 20 μm, or 1 μm to 18 μm, or 1 μm to 16 μm, or 2 μm to 16 μm, or 2 μm to 14 μm, or 2 μm to 12 μm, or 2 μm to 10 μm, or 2 μm to 8 μm, and the particulate material according to claim 1.

31. The composite particles have a BET surface area in the range of 0.1 m ２ / g to 100 m ２ / g, or 0.1 m ２ / g to 80 m ２ / g, or 0.5 m ２ / g to 60 m ２ / g, or 0.5 m ２ / g to 40 m ２ / g, or 1 m ２ / g to 30 m ２ / g, or 1 m ２ / g to 25 m ２ / g, or 2 m ２ / g to 20 m ２ / g, and the particulate material according to claim 1.

32. The composite particles contain an oxygen total content of less than 15 wt%, or less than 10 wt%, or less than 5 wt%, or less than 4 wt%, or less than 3 wt%, or less than 2 wt%, or less than 1 wt%, or less than 0.5 wt% based on the total mass of the composite particles, and the particulate material according to claim 1.

33. The particulate material according to claim 1, wherein the composite particles contain a total chlorine content of less than 100 ppm, or less than 90 ppm, or less than 80 ppm, or less than 70 ppm with respect to the total mass of the composite particles.

34. The particulate material according to claim 1, wherein the composite particles contain a total content of transition metals and alkali metals of less than 0.5% by weight with respect to the total weight of the composite particles.

35. The particulate material according to claim 1, wherein the composite particles contain zirconium in an amount of 0.0001% to 0.5% by weight with respect to the total weight of the composite particles.

36. The particulate material according to claim 1, wherein the composite particles have a D １０ particle diameter of at least 0.5 μm, or at least 0.8 μm, or at least 1 μm.

37. The particulate material according to claim 1, wherein the composite particles have a D ９０ particle diameter of 50 μm or less, or 40 μm or less, or 30 μm or less, or 25 μm or less, or 20 μm or less, or 15 μm or less.

38. The particulate material according to claim 1, wherein the composite particles have a particle size distribution span ((D ９０ -D １０ ) / D ５０ ) of 5 or less, or 4 or less, or 3 or less, or 2 or less, or 1.5 or less.

39. The particulate material according to claim 1, wherein the composite particles have a total volume of micropores and mesopores of 0.35 cm ３ / g or less, or 0.25 cm ３ / g or less, or 0.15 cm ３ / g or less, or 0.1 cm ３ / g or less, or 0.05 cm ３ / g or less, or 0.03 cm ３ / g or less, or 0.02 cm ３ / g or less. **Claim 40**: The particulate material according to claim 1, wherein the electroactive material is silicon, and 10 wt% or less, or 8 wt% or less, or 6 wt% or less, or 5 wt% or less, or 4 wt% or less, or 3 wt% or less, or 2 wt% or less, or 1.5 wt% or less of the silicon is the crude bulk silicon determined by TGA. **Claim 41**: The particulate material according to claim 1, wherein the electroactive material is silicon, and at least 20 wt%, or at least 22 wt%, or at least 25 wt%, or at least 30 wt%, or at least 35 wt%, or at least 40 wt%, or at least 45 wt% of the silicon is the surface silicon determined by TGA. **Claim 42** A method for preparing composite particles, (a) preparing a plurality of porous particles containing micropores and / or mesopores, wherein the total pore volume of the micropores and mesopores measured by gas adsorption is in the range of 0.4 cm ３ / g to 2.2 cm ３ / g; (b) contacting the porous particles with a precursor of the electroactive material at a temperature effective to cause deposition of a plurality of electroactive material domains in the pores of the porous particles; (c) forming a plurality of modifier material domains in the pores of the porous particles adjacent to the electroactive material domains deposited in step (b); (d) contacting the particles derived from step (c) with a precursor of the electroactive material at a temperature effective to cause further deposition of electroactive material domains in the pores of the porous particles adjacent to the modifier material domains formed in step (c). A method comprising the above steps. **Claim 43** The method according to claim 42, wherein the porous particles have any of the features described with respect to the porous particle skeleton according to claims 2 to 11. **Claim 44** The porous particles have a D in the range of 0.5 μm to 30 μm, or 1 μm to 25 μm, or 1 μm to 20 μm, or 2 μm to 25 μm, or 2 μm to 20 μm, or 2 μm to 18 μm, or 2 μm to 15 μm, or 2 μm to 12 μm, or 2.5 μm to 15 μm, or 2.5 μm to 12 μm, or 2 μm to 10 μm. ５０ The method according to claim 42, having a particle diameter.

45. The electroactive material deposited in step (b) and step (d) is independently selected from silicon, tin, germanium, aluminum, and mixtures and alloys thereof, or the electroactive material deposited in at least one of step (b) and step (d) is silicon. The method according to claim 42.

46. The electroactive material deposited in each of step (b) and step (d) is the same electroactive material, or the electroactive material deposited in each of step (b) and step (d) is silicon. The method according to claim 42.

47. The precursors of the electroactive material in each of step (b) and step (d) are independently selected from silane (SiH ４ ), disilane (Si ２ H ６ ), trisilane (Si ３ H ８ ), tetrasilane (Si ４ H １０ ), methylsilane, dimethylsilane, and chlorosilane. The method according to claim 42.

48. Step (b) and step (d) are independently carried out at a temperature in the range of 300 °C to 800 °C, or 350 °C to 800 °C, or 380 °C to 700 °C, or 380 °C to 650 °C, or 380 °C to 600 °C, or 380 °C to 550 °C, or 380 °C to 500 °C, or 400 °C to 450 °C, or 450 °C to 500 °C. The method according to claim 42.

49. Step (b) and / or step (d) further includes separating by-products from the particles. The method according to claim 42.

50. The method according to claim 42, wherein step (c) further comprises contacting the intermediate particles derived from step (b) with a passivating agent.

51. The method according to claim 50, wherein the passivating agent is selected from (i) an oxygen-containing gas, (ii) ammonia, (iii) a gas containing ammonia and oxygen, and (iv) phosphine, or the passivating agent is ammonia.

52. The passivating agent is (i) R １ -CH=CH-R １ , (ii) R １ -C≡C-R １ , (iii) O=CR １ R １ , (iv) HX-R ２ , and (v) HX-C(O)-R １ (wherein X represents O, S, NR １ or PR １ , each R １ independently represents H, or an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 carbon atoms, or two R １ groups form an unsubstituted or substituted ring structure containing 3 to 8 carbon atoms in the ring, R ２ represents an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 carbon atoms, or R １ and R ２ together form an unsubstituted or substituted ring structure containing 3 to 8 carbon atoms in the ring), and is selected from The method according to claim 50.

53. The method according to claim 50, wherein the passivating agent is selected from the group consisting of 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.

54. The method according to claim 42, wherein step (c) comprises contacting the intermediate particles derived from step (b) with a carbon-containing precursor at a temperature effective to cause deposition of a pyrolytic carbon material in the pores of the intermediate particles.

55. The method according to claim 42, wherein steps (c) and (d) are repeated one or more times.

56. (e) forming a plurality of modifier material domains in the pores of the composite particles derived from step (d) and / or on the outer surface thereof; The method according to claim 42, further comprising the above.

57. The method according to claim 56, wherein step (e) comprises contacting the surface of the composite particles derived from the last step (d) with a passivating agent, or the passivating agent is as defined in any one of claims 51 to 53.

58. The method according to claim 56, wherein step (e) comprises combining the composite particles derived from step (d) with a pyrolytic carbon precursor and heating the pyrolytic carbon precursor to a temperature effective to cause deposition of a pyrolytic conductive carbon material in the pores of the composite particles and / or on the outer surface thereof.

59. The porous particles have a particle size distribution span ((D ９０ - D １０ ) / D ５０ ) of 5 or less, or 4 or less, or 3 or less, or 2 or less, or 1.5 or less. The method according to claim 42.

60. A composition comprising the particulate material according to any one of claims 1 to 41 and at least one other component. Claim 61 An electrode comprising the particulate material according to any one of claims 1 to 41. Claim 62 A rechargeable metal ion battery comprising the electrode according to claim 61.

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