Electroactive materials for metal-ion batteries

Abstract

To provide a silicon-containing electroactive material that combines sufficient capacity retention and structural stability. [Solution] A particulate material containing multiple composite particles, wherein the composite particles (a) are at least 0.6 cm 3 A porous carbon skeleton having a total pore volume of / g including micropores and mesopores, wherein the volume fraction of micropores is in the range of 0.1 to 0.9, and the volume fraction of pores having a pore diameter of 20 nm or less is at least 0.75, and D is less than 20 μm 50 A particulate material is provided, comprising (b) a porous carbon skeleton having a particle size, and (b) silicon located within the micropores and / or mesopores in an amount specified relative to the volume of the micropores and / or mesopores of the porous carbon skeleton.

Description

[Technical Field]

[0001] The present invention relates, in general, to electroactive materials suitable for use in electrodes for rechargeable metal-ion batteries, and more particularly to particulate materials having high electrochemical capacity suitable for use as anode active materials in rechargeable metal-ion batteries. The particulate electroactive materials of the present invention are particularly useful in hybrid anodes comprising two or more different electroactive materials. [Background technology]

[0002] Rechargeable metal-ion batteries are widely used in portable electronic devices such as mobile phones and laptop computers, and their application in electric or hybrid vehicles is increasing. A rechargeable metal-ion battery generally includes an anode layer, a cathode layer, an electrolyte for transporting metal ions between the anode and cathode layers, and an electrically insulating porous separator positioned between the anode and cathode. The cathode typically includes a metal current collector comprising a layer of metal ions containing a metal oxide composite material, and the anode typically includes a metal current collector comprising a layer of electroactive material defined herein as a material capable of inserting and releasing metal ions during charging and discharging of the battery. To avoid misunderstanding, the terms “cathode” and “anode” are used herein in the sense that the battery is loaded such that the cathode becomes the positive electrode and the anode becomes the negative electrode. When a 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. In this specification, the term “battery” is used to refer to both a device containing a single anode and a single cathode, and a device containing multiple anodes and / or multiple cathodes.

[0003] We are interested in improving the gravimetric and / or volumetric capacity of rechargeable metal-ion batteries. While the use of lithium-ion batteries has already brought about considerable improvements compared to other battery technologies, there is still room for further development. To date, commercially available lithium-ion batteries have been primarily limited to the use of graphite as the anode active material. When a graphite anode is charged, lithium is inserted between the graphite layers, and empirically, Li... x This forms a C6 material (where x is greater than 0 and less than or equal to 1). As a result, graphite has a maximum theoretical capacity of 372 mAh / g in lithium-ion batteries, with practical capacities being slightly lower (approximately 340 mAh / g to 360 mAh / g). Other materials such as silicon, tin, and germanium can insert lithium at significantly higher capacities than graphite, but they are not yet widely used commercially because it is difficult to maintain sufficient capacity over many charge-discharge cycles.

[0004] In particular, silicon has been recognized as a promising substitute for graphite in the manufacture of rechargeable metal-ion batteries with high gravimetric and volumetric capacities due to its very high capacity relative to lithium (see, for example, Non-Patent Document 1). At room temperature, silicon has a theoretical maximum specific capacity of approximately 3600 mAh / g in lithium-ion batteries. 15 (Based on Si4). However, the use of silicon as an anode material is complicated due to the large volume changes during charging and discharging.

[0005] When lithium is inserted into bulk silicon, the volume of the silicon material increases significantly, and when the silicon is lithified to its maximum capacity, it increases to 400% of its original volume. Then, as charge-discharge cycles are repeated, large mechanical stresses are generated in the silicon material, leading to fracture and delamination of the silicon anode material. The volume contraction of silicon particles during delithiation can lead to a loss of electrical contact between the anode material and the current collector. Further complicating matters 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 exposed silicon surface leads to further decomposition of the electrolyte, increasing the thickness of the SEI layer and irreversibly consuming lithium. Collectively, these defect mechanisms result in unacceptable electrochemical capacity loss over consecutive charge-discharge cycles.

[0006] Numerous approaches have been proposed to overcome the volume changes and related problems observed when charging silicon-containing anodes. The most widespread approach to address irreversible capacity loss in silicon-containing anodes is to use silicon microstructured in some form as an electroactive material. Micro-silicon structures with cross-sections of less than approximately 150 nm, such as silicon films and silicon nanoparticles, have been reported to be more tolerant of volume changes during charging and discharging compared to silicon particles in the micron size range. However, none of these are particularly suitable for commercial-scale application without modification of their form. Nanoscale particles are difficult to manufacture and handle, and silicon films do not provide sufficient bulk capacity. For example, nanoscale particles tend to form aggregates, making it difficult to effectively disperse them within the anode material matrix. Furthermore, the formation of nanoscale particle aggregates results in unacceptable capacity loss during repeated charge-discharge cycles.

[0007] Ohara et al. (Non-Patent Document 2) describes depositing silicon as a thin film onto a nickel foil current collector. This document describes the use of this structure as an anode in a lithium-ion battery. While this approach yields good capacity retention, the thin-film structure does not have a useful amount of capacity per unit area, and any improvements are eliminated as the film thickness increases.

[0008] Patent Document 1 discloses that the volume retention rate can be improved by using silicon particles with a high aspect ratio, that is, the ratio of the maximum dimension to the minimum dimension of the particle.

[0009] It is also generally known that electroactive materials such as silicon can be deposited within the pores of porous carrier materials such as activated carbon. These composite materials offer some of the beneficial charge-discharge properties of nanoscale silicon particles while avoiding the difficulties in handling nanoparticles. For example, Guo et al. (Non-Patent Literature 3) have shown that a porous carbon substrate can be uniformly distributed and deposited within the pore structure of the substrate. We disclose a silicon-carbon composite material that provides a conductive framework with deposited silicon nanoparticles. The formation of SEI during the initial charge cycle is limited to the remaining pore volume so that the remaining silicon is not exposed to the electrolyte in subsequent charge cycles. This composite material shows improved capacity retention over multiple charge cycles, although the initial capacity in mAh / g of the composite material has been shown to be significantly lower than that of silicon nanoparticles alone.

[0010] Patent Document 2 discloses an active material comprising a carbon-based scaffold having smaller pores branching from a number of larger pores. The electroactive material (e.g., silicon) is randomly located on the walls of both the large and small pores, as well as on the outer surface of the carbon-based scaffold.

[0011] Despite previous efforts, there remains a continuing need to improve the electrochemical storage capacity of lithium-ion batteries. One long-term goal is to develop electrodes containing a high proportion of silicon as the electroactive material, while another objective for battery manufacturers is to find ways to supplement the capacity of graphite anodes using small amounts of silicon. Therefore, the current focus is not on a large-scale shift from graphite anodes to silicon anodes, but rather on gradually improving existing metal-ion battery technology using "hybrid" electrodes, including combinations of graphite and Si-based electroactive materials.

[0012] The use of hybrid electrodes itself presents challenges. Any additional electroactive material is metallic. The material must be provided in a form compatible with the particulate shape of graphite conventionally used in on-cells. For example, it must be possible to disperse the additional electroactive material throughout the matrix of graphite particles, and the particles of the additional electroactive material must have sufficient structural integrity to withstand compounding with the graphite particles and subsequent electrode layer formation through processes such as compression, drying, and calendering.

[0013] Furthermore, when developing hybrid anodes, it is necessary to consider the differences in metallization properties between graphite and other electroactive materials. For example, in the lithiumization of a silicon-graphite hybrid anode where graphite constitutes at least 50% by weight of the electroactive material, silicon must be lithiumized to its maximum capacity in order to obtain capacity advantages from all electroactive materials. On the other hand, in non-hybrid silicon electrodes, it is common to limit the silicon material to about 25% to 60% of the maximum weight capacity during charge and discharge to avoid excessive mechanical stress on the silicon material, which would result in a decrease in the overall volumetric capacity of the cell, but this option is not available in hybrid electrodes. Consequently, the silicon material must be able to withstand very high levels of mechanical stress over repeated charge and discharge cycles. [Prior art documents] [Patent Documents]

[0014] [Patent Document 1] International Publication No. 2007 / 083155 [Patent Document 2] Japanese Patent Publication No. 2003-100284 [Non-patent literature]

[0015] [Non-Patent Document 1] Insertion Electrode Materials for Rechargeable Lithium Batteries, Winter, M. et al. in Adv. Mater. 1998, 10, No. 10 [Non-Patent Document 2] Journal of Power Sources 136 (2004) 303-306 [Non-Patent Document 3] Journal of Materials Chemistry A, 2013, pp. 14075-14079 [Overview of the Initiative] [Problems that the invention aims to solve]

[0016] Therefore, in this field, there is a need for silicon-containing electroactive materials that combine high lithium capacity with sufficient capacity retention and structural stability over multiple charge-discharge cycles. In particular, materials used to supplement conventional electroactive materials such as graphite need to maintain capacity and structural stability when repeatedly lithium-ionized to their maximum capacity. The present invention addresses this problem by providing a particulate material comprising a porous carbon skeleton and nanoscale domains of multiple elements of silicon located within the pores of the porous carbon skeleton. In particular, the pore structure of the porous carbon skeleton and the ratio of silicon to the effective pore volume of the porous carbon skeleton are carefully controlled to obtain optimal performance under the stringent standards required for hybrid electrodes. [Means for solving the problem]

[0017] In a first embodiment, the present invention relates to a particulate material comprising a plurality of composite particles, wherein the composite particles are (a) A porous carbon skeleton including micropores and mesopores, (i) The total pore volume of the micropores and mesopores measured by gas adsorption is P1cm 3 / g, where P1 has a value of at least 0.6, (ii) Volume ratio of micropores to the total volume of micropores and mesopores (φ a ) is in the range of 0.1 to 0.9, (iii) Volume ratio of pores with a diameter of 20 nm or less relative to the total volume of micropores and mesopores (φ20 ) is at least 0.75, and (iv) the porous carbon framework has a D 50 particle size of less than 20 μm, a porous carbon framework, and (b) a plurality of nano-scale domains of elemental silicon located within the micropores and / or mesopores of the porous carbon framework, and includes a particulate material, wherein the weight ratio of silicon to the porous carbon framework in the composite particles is in the range of [1×P1~2.2×P1]:1.

[0018] Therefore, the present invention relates to a particulate material in which the porous carbon framework includes both micropores and mesopores and the minimum total volume is at least 0.6 cm 3 / g. In the present specification, the total volume of the micropores and mesopores is represented as P1 cm 3 / g. P1 itself is a dimensionless quantity having a value of at least 0.6 and is also used to correlate the effective pore volume with the weight ratio of silicon in the particulate material.

[0019] According to the conventional IUPAC terminology, in the present specification, the term "micropore" is used to refer to pores having a diameter of less than 2 nm, the term "mesopore" is used to refer to pores having a diameter of 2 nm to 50 nm, and the term "macropore" is used to refer to pores having a diameter of more than 50 nm.

[0020] The pore volume is distributed between the micropores and mesopores such that the volume fraction of the micropores with respect to the total volume of the micropores and mesopores is in the range of 0.1 to 0.9. In the present specification, the volume fraction of the micropores (with respect to the total volume of the micropores and mesopores) is represented by the symbol φ a and the volume fraction of the mesopores (with respect to the total volume of the micropores and mesopores) is represented by the symbol φ b , so it will be understood that φ a +φ b = 1.

[0021] The porous carbon skeleton is also defined by a pore volume that is substantially strained toward smaller pores, such that at least 75% of the total micropore and mesopore volume has pores with a diameter of 20 nm or less. In this specification, the volume fraction of pores with a diameter of 20 nm or less (relative to the total volume of micropores and mesopores) is denoted by φ. 20 It is represented by the sign φ 10 The symbols φ5 and φ5 are used to define the volume fractions corresponding to pores with diameters of 10 nm or less and 5 nm or less, respectively.

[0022] Furthermore, the porous carbon skeleton has a diameter of less than 20 μm. 50 It is determined by the particle size.

[0023] To avoid misunderstanding, as used herein, P1 refers to the pore volume of the porous carbon skeleton measured alone, i.e., in the absence of silicon or other materials occupying the pores of the porous carbon skeleton. Similarly, any reference herein to the volumes of micropores, mesopores, and macropores in the porous carbon skeleton, as well as any reference to the distribution of pore volumes within the porous carbon skeleton, refers to the internal pore volume of the porous carbon skeleton alone (i.e., in the absence of silicon or other materials occupying the pore volume).

[0024] In composite particles, the weight ratio of silicon to the porous carbon skeleton is in the range of [1×P1 to 2.2×P1]:1. Therefore, since the weight ratio of silicon to the porous carbon skeleton is proportional to the effective pore volume in the porous carbon skeleton, a weight ratio of [1×P1]:1 corresponds to a silicon density of approximately 2.3 g / cm³. 3 This corresponds to a pore occupancy rate of approximately 43 v / v% in a porous carbon skeleton made of silicon. The upper limit of the above weight ratio [2.2 × P1]:1 corresponds to a pore occupancy rate of approximately 95 v / v% in a porous carbon skeleton made of silicon. These ratios are typically calculated based on pure carbon and pure silicon.

[0025] Elemental silicon exists in the form of multiple nanoscale silicon domains, micropores and / or It is located in mesopores. As used herein, the term “nanoscale silicon domain” refers to nanoscale silicon located within the pores of a porous carbon skeleton. The maximum dimension of a nanoscale silicon domain is defined by the pore diameter of the pore in which the silicon is located.

[0026] Therefore, the present invention generally relates to a particulate material in which a porous carbon skeleton has pore volume distributed in both small mesopores (diameter 20 nm or less) and micropores, and in which a significant portion of the pore volume is occupied by nanoscale silicon domains. It has been found that this particle structure provides an electroactive material with very high gravimetric and volumetric capacity when lithium-ionized and with a high reversible capacity retention rate over multiple charge-discharge cycles.

[0027] While not bound by theory, it is believed that the location of nanoscale silicon domains within small mesopores and / or micropores provides, firstly, a fine silicon structure that can be lithitated and delithiated without excessive structural stress. These extremely fine silicon domains are thought to have lower resistance to elastic deformation and higher fracture resistance than larger silicon structures. By ensuring that the pore volume is occupied by silicon at a relatively high rate, the particulate material of the present invention has high capacity. Furthermore, as described above, the location of nanoscale silicon domains within small mesopores and / or micropores limits the formation of SEI because only a small area of ​​the silicon surface can access the electrolyte.

[0028] The inventors found that achieving two objectives—high capacity and high reversible capacity retention—depends on carefully controlling the pore size distribution. While extremely fine silicon structures within micropores are expected to lithiate reversibly most effectively, porous carbon skeletons with excessive microporosity may accommodate less silicon than optimal, resulting in a lower volumetric capacity for the material. Although not bound by theory, it is thought that depositing silicon on an ultra-high microporous carbon skeleton leads to the formation of silicon structures (lids or walls, etc.) that obstruct access to unoccupied pore volumes, thereby limiting the amount of silicon that can be filled.

[0029] However, depositing silicon onto a carbon skeleton with a very high degree of mesoporosity results in unnecessarily large silicon nanostructures and increased carbon wall thickness. While this allows for the achievement of higher volumetric capacity, lithiumization, particularly to maximum capacity, as in the case of hybrid anodes containing graphite as an electroactive material, leads to excessive structural strain in both the silicon nanostructures and the porous carbon skeleton. This excessive structural strain can lead to the failure of both the silicon nanostructures and the porous carbon skeleton. In subsequent charge-discharge cycles, additional silicon exposure from the damaged surface in the electrolyte can lead to SEI formation, a significant defect mechanism resulting in capacity loss. By controlling the relative volume fraction of micropores and mesopores, and limiting the mesopore volume primarily to pores smaller than 20 nm, the particulate material of the present invention avoids these defect mechanisms while accommodating a relatively high proportion of silicon within the pore volume of the porous carbon skeleton, and maintains high reversible capacity over multiple charge-discharge cycles. This is similar to, for example, the material disclosed by Guo. This is in stark contrast to the formation of excessive and unconstrained SEI, which is a characteristic of this species (see above).

[0030] While the lithiumization of silicon can cause some degree of external expansion of the composite material, by carefully controlling the volume fractions of micropores and mesopores, and by carefully controlling the pore size distribution of the mesopore volume fraction toward smaller pore sizes, the particulate material can be reversibly deformed without damage over multiple charge-discharge cycles. Therefore, the stress on the carbon framework and silicon material is controlled to an acceptable level over many charge-discharge cycles without substantial capacity loss.

[0031] As a result of the unique particle structure of the composite material of the present invention, the silicon in the particulate material of the present invention has electrochemical performance comparable to that of fine silicon nanoparticles, but without the disadvantages of excessive SEI formation and low dispersibility that make loose silicon nanoparticles unsuitable for commercial use as electrode materials. Due to the relatively high volume content of silicon in the particulate material, it is particularly suitable for use as a component in hybrid anodes.

[0032] The porous carbon skeleton preferably comprises a three-dimensionally interconnected pore network including a combination of micropores and / or mesopores, and optionally a small amount of macropores. The porous carbon skeleton is characterized by a high pore volume in the form of micropores and / or mesopores. In this specification, the total volume of micropores and mesopores (i.e., the total pore volume in the range of 0 nm to 50 nm) is P1 cm 3 This is expressed as / g, where P1 represents a dimensionless natural number with a value of at least 0.6. The value of P1 is also used to correlate the effective pore volume in the porous carbon skeleton with the weight ratio of silicon to the porous carbon skeleton, as described above.

[0033] Preferably, the value of P1 is at least 0.65, or at least 0.7, or at least 0.75, or at least 0.8, or at least 0.85, or at least 0.9, or at least 0.95, or at least 1. More preferably, the value of P1 is at least 0.7, or at least 0.75, or at least 0.8, or at least 0.85. Optionally, the total volume of micropores and mesopores is 1 cm³. 3 It can be greater than / g, for example, P1 can be at least 1.05, or at least 1.1, or at least 1.15, or at least 1.2.

[0034] The use of a high-porosity carbon skeleton is advantageous because it allows for the accommodating of larger amounts of silicon within the pore structure. It has been found that high-porosity carbon skeletons, whose pore volume is mainly in the form of micropores and even smaller mesopores, possess sufficient strength to adapt to the volume expansion of silicon without the porous carbon skeleton fracturing or otherwise degrading.

[0035] The internal pore volume of the porous carbon skeleton is limited to a value such that the increased fragility of the porous carbon skeleton outweighs the benefit of increased pore volume that can accommodate more silicon. Typically, the value of P1 can be 2.2 or less. However, preferably, the value of P1 can be 2 or less, or 1.8 or less, or 1.6 or less, or 1.5 or less, or 1.4 or less, or 1.3 or less, or 1.2 or less, or 1.1 or less, or 1.0 or less, or 0.9 or less. More preferably, the value of P1 is 1.2 or less, or 1.1 or less, or 1.0 or less, or 0.9 or less.

[0036] According to the present invention, the value of P1 is, for example, in the range of 0.6 to 2 (i.e., the total volume of micropores and mesopores is 0.6 cm³). 3 / g~2cm 3It can be set to / g). For example, P1 is in the range of 0.6~1.8, or 0.65~1.8, or 0.7~1.8, or 0.75~1.8, or 0.8~1.8, or 0.85~1.8, or 0.9~1.8, or 0.65~1.7, or 0.7~1.7, or 0.75~1.7, or 0.8~1.7, or 0.85~1.7, or 0.9~1.7, or 0.95~1.7, or 0.7~1.6, or within the range of 0.75~1.6 It can be a range of 0.8 to 1.6, or 0.85 to 1.6, or 0.9 to 1.6, or 0.95 to 1.6, or 1 to 1.6, or 0.75 to 1.5, or 0.8 to 1.5, or 0.85 to 1.5, or 0.9 to 1.5, or 0.95 to 1.5, or 1 to 1.5, or 0.8 to 1.4, or 0.85 to 1.4, or 0.9 to 1.4, or 0.95 to 1.4, or 1 to 1.4.

[0037] Preferably, the value of P1 can be, for example, in the range of 0.6 to 1.4, or 0.65 to 1.4, or 0.7 to 1.4, or 0.75 to 1.4, or 0.6 to 1.3, or 0.65 to 1.3, or 0.7 to 1.3, or 0.75 to 1.3, or 0.6 to 1.2, or 0.65 to 1.2, or 0.7 to 1.2, or 0.75 to 1.2, or 0.6 to 1, or 0.65 to 1, or 0.7 to 1, or 0.75 to 1, or 0.6 to 0.9, or 0.65 to 0.9, or 0.7 to 0.9, or 0.75 to 0.9.

[0038] Volume fraction of micropores (φ a The value is preferably in the range of 0.15 to 0.85, and more preferably in the range of 0.2 to 0.8.

[0039] In particular, to take advantage of the high capacity retention rate provided by the extremely fine silicon nanostructures located within the micropores, φ aThe range is preferably 0.45 to 0.85, more preferably 0.5 to 0.8, more preferably 0.5 to 0.75, and more preferably 0.5 to 0.7. For example, φ a This can be in the range of 0.55 to 0.8, or 0.6 to 0.8, or 0.6 to 0.75.

[0040] Alternatively, in order to take advantage of the opportunity for high silicon filling, φ a This can be in the range of 0.2 to 0.5, more preferably in the range of 0.3 to 0.5.

[0041] As described above, the pore volume is substantially distorted toward smaller pores such that at least 75% of the total micropore and mesopore volume of the porous carbon skeleton has a pore morphology with a diameter of 20 nm or less. More preferably, φ 20 This is at least 0.8, more preferably at least 0.85, and more preferably at least 0.9.

[0042] Preferably, φ relative to the total volume of micropores and mesopores. 10 φ5 is at least 0.70, or at least 0.75, or at least 0.8, or at least 0.85. More preferably, φ5 relative to the total volume of micropores and mesopores is at least 0.75, or at least 0.8, or at least 0.85. Thus, in a preferred embodiment, at least 75% of the total volume of micropores and mesopores in the porous carbon skeleton has a pore morphology with a diameter of 10 nm or less, more preferably 5 nm or less.

[0043] Pore ​​fractions with diameters in the larger mesopore range can be advantageous because they facilitate electrolyte access to silicon domains. Therefore, pores with diameters in the range of 10 nm to 50 nm (i.e., larger mesopores) can optionally constitute 1% or less, 2% or less, 5% or less, or 10% or less of the total micropore and mesopore volume of the porous carbon skeleton.

[0044] In principle, the volume ratio of micropores to mesopores in a porous carbon skeleton can be in the range of 100:0 to 0:100. Preferably, the volume ratio of micropores to mesopores is 90:10 to 55:45, or 90:10 to 60:40, or 85:15 to 65:35.

[0045] The pore size distribution of a porous carbon skeleton can be unimodal, bimodal, or multimodal. As used herein, the term “pore size distribution” refers to the distribution of pore sizes relative to the cumulative total internal pore volume of the porous carbon skeleton. Bimodal or multimodal pore size distributions may be preferred because the proximity of the smallest pores to the larger diameter pores provides the advantage of efficient ion transport through the porous network to silicon. Therefore, the particulate material exhibits high ion diffusivity, resulting in improved rate performance.

[0046] Preferably, the bimodal or multimodal pore size distribution includes peak pore sizes in the micropore range and peak pore sizes in the mesopore range, which differ from each other by 5 to 20 times, more preferably by about 10 times. For example, a porous carbon skeleton can have a bimodal pore size distribution with a peak at a pore size of 1.5 nm and another peak at a pore size of 15 nm.

[0047] The total volume of micropores and mesopores, as well as the pore size distribution of micropores and mesopores, were determined using the rapid solid density functional theory (QSDFT) according to the standard methodology specified in ISO 15901-2 and ISO 15901-3, at 77K for 10 -6This is determined using nitrogen gas adsorption up to a relative pressure p / p0. Nitrogen gas adsorption is a technique for characterizing the porosity and pore size distribution of a material by condensing a gas within the pores of a solid. As the pressure is increased, the gas initially condenses in the pores with the smallest diameter, and the pressure is increased until a saturation point is reached where all pores are filled with liquid. Then, the nitrogen gas pressure is gradually decreased to evaporate the liquid from the system. Pore volume and pore size distribution can be determined by analyzing the adsorption isotherms and desorption isotherms, as well as the hysteresis between them. Suitable instruments for measuring pore volume and pore size distribution by nitrogen gas adsorption include the TriStar II porosity analyzer and TriStar II, available from Micromeritics Instrument Corporation in the United States. Examples include the Plus porosity analyzer and the Autosorb IQ porosity analyzer available from Quantachrome Instruments.

[0048] Nitrogen gas adsorption is effective for measuring pore volume and pore size distribution of pores with a maximum diameter of 50 nm, but becomes unreliable for pores with much larger diameters. Therefore, for the purposes of this invention, nitrogen adsorption is used to determine pore volume and pore size distribution only for pores with a maximum diameter of 50 nm or less. As described above, the value of P1 is determined considering only pores with a maximum diameter of 50 nm or less (i.e., only micropores and mesopores), and similarly, φ a , φ b , φ 20 , φ 10 The values ​​of φ5 and φ5 are determined for the total volume of micropores and mesopores only.

[0049] Given the limitations of available analytical techniques, it is impossible to measure pore volume and pore size distribution across the entire range of micropores, mesopores, and macropores using a single method. When a porous carbon skeleton contains macropores, the volume of pores greater than 50 nm and up to 100 nm is P2 cm² as specified herein. 3It is specified by a value of / g and measured by the mercury intrusion method. As described above, the value of P2 relates to the pore volume of the porous carbon skeleton when measured alone, i.e., in the absence of silicon or other materials occupying the pores of the porous carbon skeleton.

[0050] To avoid misunderstanding, the P2 value considers only pores with diameters greater than 50 nm and a maximum of 100 nm. That is, the P2 value includes only the volume of macropores with a maximum diameter of 100 nm. Any pore volume measured by mercury intrusion at pore diameters of 50 nm or less is ignored for the purpose of determining the P2 value (as described above, nitrogen adsorption is used to characterize mesopores and micropores). Pore volumes measured by mercury intrusion at pore diameters greater than 100 nm are assumed to be interparticle porosity for the purposes of this invention, and these pore volumes are also not considered when determining the P2 value.

[0051] The mercury intrusion method is a technique for characterizing the porosity and pore size distribution of a material by applying various levels of pressure to a sample of material immersed in mercury. The pressure required to penetrate the pores of the sample with mercury is inversely proportional to the pore size. The values ​​obtained by the mercury intrusion method reported herein were obtained according to ASTM UOP578-11, with 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 / cm³. 3 Many high-precision mercury intrusion devices are available, such as the AutoPore IV series automatic mercury intrusion gauges from Micromeritics Instrument Corporation in the United States. It is commercially available. For a complete report on the mercury intrusion method, see "Analytical Methods in Fine Particle Technology, 1997, Micromeritics Instrument Corporation" by PA Webb and C. Orr (ISBN 0-9656783-0).

[0052] The volume of macropores (i.e., the value of P2) is preferably smaller than the volumes of micropores and mesopores (i.e., the value of P1). While some macropores may be useful for facilitating electrolyte access to the pore network, the advantages of the present invention are substantially obtained by accommodating silicon in micropores and even smaller mesopores.

[0053] Therefore, according to the present invention, the total volume of macropores in a porous carbon skeleton is measured by the mercury intrusion method, P2cm 3 / g, where P2 preferably has a value of 0.2 × P1 or less, or 0.1 × P1 or less, or 0.05 × P1 or less, or 0.02 × P1 or less, or 0.01 × P1 or less, or 0.005 × P1 or less.

[0054] In preferred embodiments, P2 has a value of 0.3 or less, or 0.25 or less, or 0.20 or less, or 0.15 or less, or 0.1 or less, or 0.05 or less. As discussed above in relation to larger mesopores, small pore volume fractions in the macropore range may be advantageous for facilitating electrolyte access to silicon.

[0055] The pore network optionally includes a hierarchical pore structure, i.e., a pore structure in which smaller pores branch off from larger pores and the pore diameters have a certain order.

[0056] It will be understood that intrusion methods such as gas adsorption and mercury intrusion are effective only for determining the pore volume of pores in which nitrogen or mercury can access from outside the porous carbon framework. The porosity values ​​(P1 and P2) specified herein should be understood to refer to the volume of openings, i.e., pores in which fluid can access from outside the porous carbon framework. Completely enclosed pores that cannot be identified by nitrogen adsorption or mercury intrusion are not considered herein when specifying the porosity values. Similarly, any pore volume located in pores small enough to be below the detection limit by nitrogen adsorption is not considered in determining the value of P1.

[0057] The porous carbon skeleton may include crystalline carbon, amorphous carbon, or a mixture of amorphous and crystalline carbon. The porous carbon skeleton may be either a rigid carbon skeleton or a flexible carbon skeleton, and can preferably be obtained by known procedures including the thermal decomposition of a polymer or organic material.

[0058] The porous carbon skeleton is preferably at least 750m 2 / g, or at least 1000m 2 / g, or at least 1250m 2 / g, or at least 1500m 2 It has a BET surface area of ​​4000 m² / g. The term "BET surface area" as used herein should be interpreted as referring to the surface area per unit mass calculated from measurements of physicoadsorption of gas molecules onto a solid surface using the Brunauer-Emmett-Teller theory in accordance with ISO 9277. Preferably, the BET surface area of ​​the conductive porous particle framework is 4000 m² / g. 2 / g or less, or 3500m 2 / g or less, or 3250m 2 / g or less, or 3000m 2 It is less than / g.

[0059] As used herein, the term “hard carbon” refers to carbon atoms that are primarily composed of nanoscale polycyclic aromatic domains sp. 2 This refers to a disordered carbon matrix that takes on a hybrid state (three-way bonding). These polycyclic aromatic domains are cross-linked by chemical bonds, such as COC bonds. Because the polycyclic aromatic domains are chemically cross-linked with each other, hard carbon cannot be converted to graphite at high temperatures. The high G band (approximately 1600 cm⁻¹) in the Raman spectrum... - 1 As is evident from the results, hard carbon has graphite-like properties. However, in the Raman spectrum, the high D band (approximately 1350 cm⁻¹) -1 As is evident from the above, carbon is not entirely like graphite.

[0060] The term "soft carbon" as used herein also refers to carbon atoms that are primarily polycyclic aromatic domains with dimensions in the range of 5 nm to 200 nm. 2 This refers to a disordered carbon matrix that takes on a hybrid state (three-way bonding). In contrast to hard carbon, the polycyclic aromatic domains in soft carbon are bonded by intermolecular forces rather than by chemical bonds. That is, soft carbon can graphitize at high temperatures. The porous carbon skeleton preferably has at least 50% sp when measured by XPS. 2 It contains hybrid carbon. For example, the porous carbon skeleton preferably contains 50% to 98% sp 2 Hybrid carbon, 55%~95% sp 2 Hybrid carbon, 60%~90% sp 2 Mixed carbon, or 70%-85% sp 2 It can contain hybrid carbon.

[0061] Various different materials can be used to produce a suitable porous carbon skeleton. Examples of usable organic materials include plant biomass, including lignocellulosic materials (such as coconut shells, rice husks, and wood), and fossil carbon sources such as coal. Examples of polymer materials that form a porous carbon skeleton by thermal decomposition include phenolic resins, novolac resins, pitch, melamine, polyacrylate, polystyrene, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and various copolymers containing monomer units of acrylate, styrene, α-olefin, vinylpyrrolidone, and other ethylenically unsaturated monomers. Depending on the starting materials and the conditions of the thermal decomposition process, various different rigid carbon materials are available in the art.

[0062] To increase the volume of mesopores and micropores, a chemical or gas activation process can be performed on the porous carbon skeleton. A preferred activation process involves contacting the thermally decomposed carbon with one or more of oxygen, steam, CO, CO2, and KOH at a temperature in the range of 600°C to 1000°C.

[0063] Mesopores can also be obtained by known templating processes using extractable pore-forming agents such as MgO and other colloidal or polymer templates, which can be removed by thermal or chemical means after thermal decomposition or activation.

[0064] The porous carbon skeleton is D in the range of 0.5 μm to 20 μm. 50 It can have a particle size. Preferably, D 50 The particle size is at least 1 μm, more preferably at least 2 μm, for example, at least 3 μm, or at least 4 μm, or at least 5 μm. Preferably, particulate material D 50 The particle size is 18 μm or less, more preferably 16 μm or less, more preferably 14 μm or less, more preferably 12 μm or less, more preferably 10 μm or less, for example, 9 μm or less, or 8 μm or less. More preferably D 50 The particle size is 10 μm or less, or 9 μm or less, or 8 μm or less, or 7 μm or less, or 6 μm or less, or 5 μm or less.

[0065] For example, the porous carbon skeleton is D in the range of 1 μm to 12 μm, or 1 μm to 10 μm, or 2 μm to 10 μm, or 2 μm to 8 μm, or 2 μm to 6 μm, or 3 μm to 10 μm, or 3 μm to 8 μm, or 3 μm to 7 μm, or 3 μm to 6 μm, or 3 μm to 5 μm. 50 It can have a particle size.

[0066] The amount of silicon in a porous carbon skeleton correlates with the effective pore volume, provided that the weight ratio of silicon to the porous carbon skeleton in the composite particles is in the range of [1×P1 to 2.2×P1]:1. This relationship takes into account the silicon density and the pore volume of the porous carbon skeleton. The internal pore volume (P1cm) of the porous carbon skeleton. 3 This defines the weight ratio of silicon where approximately 43V / v% to 95V / v% of the weight (in an uncharged state) is occupied by silicon.

[0067] Preferably, the weight ratio of silicon to porous carbon skeleton is at least 1.1 × P1, more preferably at least 1.15 × P1, more preferably at least 1.2 × P1, more preferably at least 1.25 × P1, more preferably at least 1.3 × P1, more preferably at least 1.35 × P1, and more preferably at least 1.4 × P1.

[0068] When the porous carbon skeleton has a relatively high ratio of mesopores to micropores (for example, φ a If the ratio is in the range of 0.2 to 0.5 or 0.3 to 0.5, the weight ratio of silicon to porous carbon skeleton can be further increased, for example, to at least 1.45 × P1, more preferably at least 1.5 × P1, more preferably at least 1.55 × P1, more preferably at least 1.6 × P1, more preferably at least 1.65 × P1, and more preferably at least 1.7 × P1.

[0069] The minimum weight ratio of silicon to porous carbon skeleton is determined by the requirement that the weight ratio of silicon to porous carbon skeleton in the composite particle is at least 1 × P1, which determines the mesoporosity (φ b It correlates with both the pore size and the total pore volume. More preferably, the weight ratio of silicon to the porous carbon skeleton is at least [φ b The value given by +0.75] × P1, more preferably at least [φ b The value given by +0.8] × P1, more preferably at least [φ b The value given by [+0.9] × P1, more preferably at least [φ b The value given by [φ +1] × P1, more preferably at least [φ b It has a value given by +1.1] × P1 (where this value is at least 1 × P1). Therefore, the mesoporality (φ bWhen the value of ) is higher, the minimum amount of silicon in the composite particles also increases. This correlation between the mesoporosity and the minimum weight ratio of silicon to the porous carbon framework means that porous carbon frameworks with higher mesoporosity are occupied to a greater extent by silicon, thereby optimizing the volumetric capacity of the particulate material. In porous carbon frameworks with higher mesoporosity, the larger minimum amount of silicon reduces the possibility of larger micropores being partially occupied by silicon, thereby reducing the silicon surface area exposed to the electrolyte and limiting the formation of undesirable SEIs.

[0070] The maximum weight ratio of silicon to porous carbon skeleton is also determined by the requirement that the weight ratio of silicon to porous carbon skeleton in the composite particle is less than or equal to the value given by 1.9 × P1, which determines the mesoporosity (φ b It correlates with both the pore size and the total pore volume. More preferably, the weight ratio of silicon to the porous carbon skeleton is [φ b [φ] is less than or equal to the value given by +1.6 × P1, more preferably less than or equal to [φ b The value is less than or equal to the value given by [+1.5] × P1 (however, this value is less than or equal to 1.9 × P1). The correlation between this mesoporosity and the maximum weight ratio of the porous carbon skeleton prevents the porous carbon skeleton with higher microporosity from being overfilled with silicon. As mentioned above, when the porous carbon skeleton is more microporous, it may be more difficult to achieve a very high ratio of silicon because a wall or lid may form surrounding the occupied pore volume. Also, when the porous carbon skeleton is more microporous, the diffusion of lithium through the very fine silicon structure becomes rate-limited, reducing the rate capacity of the particulate material. Therefore, by controlling the upper limit of the silicon ratio, the degree of electrolyte access to the internal pore volume of the porous carbon skeleton is ensured, and the transport of lithium ions to the silicon domains is facilitated.

[0071] Preferably, the silicon mass in the composite particles is substantially or completely present within the pores of the porous carbon skeleton in the form of nanoscale silicon domains as described above. For example, the silicon in the composite particles is such that there is little to no silicon located on the outer surface of the composite particles. Preferably, at least 90% by weight, more preferably at least 95% by weight, more preferably at least 98% by weight, and more preferably at least 99% by weight of the carbon mass is located within the internal pore volume of the porous carbon skeleton.

[0072] The particulate material of the present invention can be further characterized by its performance as determined by thermogravimetric analysis (TGA) in air. When the particulate material is measured by TGA in air at a temperature rise rate of 10°C / min, it is preferable that 10% or less of the silicon contained in the particulate material remains unoxidized at 800°C. When the particulate material is measured by TGA in air at a temperature rise rate of 10°C / min, it is more preferable that 5% or less, or 2% or less, of the silicon contained in the particulate material remains unoxidized at 800°C.

[0073] The amount of unoxide silicon is determined by derivation from the TGA trace specific to these materials. The mass increase at approximately 300°C–500°C corresponds to the initial oxidation of silicon to SiO2, followed by a decrease in mass at approximately 500°C–600°C as carbon is oxidized to CO2 gas. Above approximately 600°C, there is a further mass increase corresponding to the continued conversion of silicon to SiO2, and as the oxidation of silicon is completed, it increases asymptotically above 1000°C.

[0074] For the purposes of this analysis, any mass increase above 800°C is assumed to correspond to the oxidation of silicon to SiO2, and the total mass upon completion of oxidation is assumed to be SiO2. Therefore, the proportion of unoxidized silicon at 800°C can be determined as a percentage of the total amount of silicon according to the following formula: Z = 1.875 × [(M f -M 800 ) / M f ] × 100% (In the formula, Z is the percentage of unoxide silicon at 800°C, and M f This is the mass of the sample when oxidation is complete, and M 800 (This is the mass of the sample at 800°C).

[0075] While not bound by theory, it is understood that the temperature at which silicon is oxidized under TGA generally corresponds to the length scale of the oxide film on the silicon, since the diffusion of oxygen atoms through the oxide layer is thermally activated. The length scale of the oxide film thickness is limited by the size and location of the silicon nanostructures. Therefore, it is understood that silicon deposited in micropores and mesopores oxidizes at a lower temperature than silicon deposits on particle surfaces, because the oxide film present on these structures is necessarily thinner. Thus, preferred materials according to the present invention exhibit substantially complete oxidation of silicon at low temperatures, consistent with the fact that silicon nanostructures located in micropores and even smaller mesopores have a small length scale. For the purposes of the present invention, the oxidation of silicon at 800°C is assumed to be silicon on the outer surface of a porous carbon skeleton. In this specification, this is also referred to as "crude silicon".

[0076] The silicon is preferably amorphous silicon. Amorphous silicon is considered to have better performance as an electroactive material. The morphology of the silicon can be determined by known procedures using X-ray diffraction (XRD).

[0077] The volumes of micropores and mesopores in the composite particles (i.e., in the presence of silicon), as measured by nitrogen gas adsorption, are preferably 0.15 × P1 or less, or 0.10 × P1 or less, or 0.05 × P1 or less, or 0.02 × P1 or less.

[0078] The weight ratio of silicon to porous carbon framework can be determined by elemental analysis. Elemental analysis is used to determine the weight ratio of both silicon and carbon in the composite particles. Optionally, the amounts of hydrogen, nitrogen, and oxygen can also be determined by elemental analysis. Preferably, elemental analysis is performed only on the carbon in the porous carbon framework (and optionally on the amounts of hydrogen and nitrogen). It is also used to determine the weight percentage of (and oxygen). By determining the weight percentage of carbon in the porous carbon skeleton alone, it is possible to account for the possibility that this porous carbon skeleton contains small amounts of heteroatoms within its molecular framework. By performing both measurements together, the weight percentage of silicon relative to the entire porous carbon skeleton can be reliably determined.

[0079] The silicon content is preferably determined by ICP-OES (inductively coupled plasma emission spectroscopy). ICP-OES analyzers are available from ThermoFisher Scientific. Many ICP-OES instruments are commercially available, such as the iCAP® 7000 series. The carbon content (and, if necessary, the hydrogen, nitrogen, and oxygen content) in composite particles and porous carbon skeletons is preferably determined by IR absorption. A suitable instrument for determining the carbon, hydrogen, nitrogen, and oxygen content is the TruSpec® Micro elemental analyzer, available from Leco Corporation.

[0080] The composite particles preferably have a low total oxygen content. Oxygen may be present in the composite particles, for example, as part of the porous carbon skeleton or as an oxide layer on any exposed silicon surface. The total oxygen content of the composite particles is preferably less than 15% by weight, more preferably less than 10% by weight, more preferably less than 5% by weight, for example less than 2% by weight, or less than 1% by weight, or less than 0.5% by weight.

[0081] The silicon may optionally contain small amounts of one or more dopants. Suitable dopants include boron and phosphorus, other n-type or p-type dopants, nitrogen, or germanium. Preferably, the dopants are present in a total amount of 2% by weight or less relative to the total amount of silicon and dopants (there may be more than one).

[0082] To avoid misunderstanding, the term “particle size” as used herein refers to the equivalent diameter (ESD), i.e., the diameter of a sphere having the same volume as a given particle, where the particle volume is understood to include the volume of pores within the particle. 50 " and "D 50 The term "particle diameter" refers to the median particle diameter on a volume basis, i.e., the diameter below which 50% of the particle population is located. 10 " and "D 10 The term "particle diameter" refers to the median particle diameter of the 10th percentile on a volume basis, i.e., the diameter at which 10% of the particle population is below that diameter. 90 " and "D 90 The term "particle diameter" refers to the median particle diameter of the 90th percentile on a volume basis, i.e., the diameter below which 90% of the particle population is located.

[0083] Particle size and particle size distribution can be determined by conventional laser diffraction techniques in accordance with ISO 13320:2009. Laser diffraction is based on the principle that particles scatter light at angles that vary depending on the particle size, and that the aggregate of particles generates a scattered light pattern defined by intensity and angle that can correlate with the particle size distribution. Many laser diffraction devices are commercially available for the rapid and reliable determination of particle size distribution. Unless otherwise specified, the particle size distribution measurements specified or reported herein are those of conventional Malvern Instruments lasers. The particle size distribution was measured using a Malvern Mastersizer™ 3000 particle size analyzer. This analyzer operates by projecting a helium-neon gas laser beam through a transparent cell containing target particles suspended in an aqueous solution. The light beam striking the particles is scattered at an angle inversely proportional to the particle diameter. A photodetector array measures the intensity of the light at several predetermined angles, and 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 ​​reported herein are obtained using a wet dispersion of particles in distilled water. The refractive index of the particles is assumed to be 3.50, and the refractive index of the dispersant is assumed to be 1.330. The particle size distribution is calculated using the Mie scattering model.

[0084] The composite particles are in the range of 0.5 μm to 20 μm. 50 It can have a particle size. Preferably, D 50 The particle size is at least 1 μm, more preferably at least 2 μm, for example, at least 3 μm, or at least 4 μm, or at least 5 μm. Preferably, particulate material D 50 The particle size is 18 μm or less, more preferably 16 μm or less, more preferably 14 μm or less, more preferably 12 μm or less, more preferably 10 μm or less, for example, 9 μm or less, or 8 μm or less.

[0085] For example, composite particles are in the range of 1 μm to 12 μm, or 1 μm to 10 μm, or 2 μm to 10 μm, or 3 μm to 10 μm, or 3 μm to 8 μm. 50 The particles may have a particle size. Particles within these size ranges and having the porosity and pore size distribution described herein are ideally suited for use in hybrid anodes for metal-ion batteries because they are dispersible in slurries, structurally robust, maintain capacity over repeated charge-discharge cycles, and have the ability to occupy the interparticle voids between conventional graphite particles used in electrodes for metal-ion batteries.

[0086] D of composite particles 10The particle size 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. D 10 By maintaining the particle size at 0.2 μm or more, the possibility of undesirable aggregation of submicron-sized particles is reduced, the dispersibility of the particulate material is improved, and the capacity retention rate is improved.

[0087] D of the composite particles 90 The particle size is preferably 40 μm or less, or 30 μm or less, or 20 μm or less, or 15 μm or less, or 12 μm or less, or 10 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 conventional thickness in the range of 20 μm to 50 μm. Therefore, D 90 The particle size is preferably 20 μm or less, and more preferably even smaller.

[0088] 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.

[0089] The composite particles can have a spheroidal shape. The spheroidal particles 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 irregularly shaped porous particles and porous particle fragments.

[0090] The sphericity of an object has traditionally been defined as the ratio of the surface area of ​​a sphere to the surface area of ​​the 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 a micron scale. Nevertheless, high-precision two-dimensional projection images of micron-scale particles can be obtained using scanning electron microscopy (SEM) and dynamic image analysis, which records the shadows projected by the particles using a digital camera. As used herein, the term "sphericity" is understood as 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. Therefore, for individual particles, the sphericity S is defined as follows:

number

number

[0091] In this specification, the term “rotational elliptic” as used in application to the composite particles of the present invention shall be understood to refer to a material having an average sphericity of at least 0.70. The porous rotational elliptic 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, and more preferably at least 0.95. The porous rotational elliptic particles may 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.

[0092] 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 having a random orientation. 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 capable of obtaining 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.

[0093] The composite particles preferably have a BET surface area of 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 20 m 2 / g or less, or 15 m 2 / g or less, or 10 m 2 / g or less. Usually, during the first charge-discharge cycle of the anode containing the particulate material of the present invention, in order to minimize the formation of the solid electrolyte interface (SEI) layer on the surface of the composite particles, it is preferable that the BET surface area is small. However, if the BET surface area is excessively small, metal ions in the surrounding electrolyte cannot access most of the electroactive material, leading to an unacceptable low charge rate and capacity. For example, the BET surface area is preferably at least 0.1 m 2 / g, or at least 1 m 2 / g, or at least 2 m 2 / g, or at least 5 m 2 / g. For example, the BET surface area is 1 m2 / g~25m 2 Range of / g, more preferably 2m 2 / g~15m 2 It can be in the range of / g.

[0094] The particulate material of the present invention typically has a specific charge capacity of 1200 mAh / g to 2340 mAh / g upon initial lithiumization. Preferably, the particulate material of the present invention has a specific charge capacity of at least 1400 mAh / g upon initial lithiumization.

[0095] The composite particles of the present invention preferably contain a silicon-containing precursor in the pore structure of a porous carbon skeleton. It is prepared by chemical vapor permeation (CVI). As used herein, CVI refers to a process in which a gaseous silicon-containing precursor is thermally decomposed on a surface, forming elemental silicon and gaseous by-products on the surface.

[0096] Suitable gaseous silicon-containing precursors include silane (SiH4), silane derivatives (e.g., disilane, trisilane, and tetrasilane), and trichlorosilane (SiHCl3). The silicon-containing precursor can be used in pure form or, more generally, as a diluted mixture with an inert carrier gas such as nitrogen or argon. For example, the silicon-containing precursor can be used in amounts ranging from 0.5% to 20% by volume, 1% to 10% by volume, or 1% to 5% by volume relative to the total volume of the silicon-containing precursor and the inert carrier gas. The CVI process is preferably carried out at a total pressure of 101.3 kPa (i.e., 1 atm) with a low partial pressure of the silicon precursor, and the remaining partial pressure is controlled by an inert padding gas such as hydrogen, nitrogen, or argon in the atmosphere. Pressure is applied. A deposition temperature in the range of 400°C to 700°C is used, for example, 400°C to 550°C, or 400°C to 500°C, or 400°C to 450°C, or 450°C to 500°C. The CVI process can preferably be carried out in a fixed-bed reactor, a fluidized-bed reactor (including a jet-bed reactor), or a rotary kiln.

[0097] A particularly advantageous aspect of the present invention is that the porous carbon skeleton has a very small pore diameter, resulting in a very high ratio of internal surface area to external surface area. As a result, the deposition of silicon on the internal surface of the porous carbon skeleton is kinematically advantageous. Therefore, a very high proportion of silicon in the composite particles of the present invention (for example, as described above, at least 90% by weight, more preferably at least 95% by weight, more preferably at least 98% by weight, more preferably at least 99% by weight of the silicon mass in the composite particles) is in the form of nanoscale elemental silicon domains located within the micropores and / or mesopores of the porous carbon skeleton.

[0098] In contrast, the formation of silicon deposits on the outer surface of the porous carbon framework occurs at a significantly slower rate, resulting in composite particles typically containing very small amounts of external silicon on the outer surface of the porous carbon framework. While not bound by theory, a larger dimension of silicon on the outer surface of the porous carbon framework suggests that this external silicon (referred to herein as "crude silicon") has a lower ability to cycle reversibly, and proportionally, a greater amount of silicon oxide and SEI formation. Consequently, composite particles with a higher amount of external silicon are thought to have lower capacity retention over multiple charge-discharge cycles.

[0099] The particulate material of the present invention may optionally include a conductive carbon coating. Preferably, the conductive carbon coating can be obtained by chemical vapor deposition (CVD). CVD is a known methodology in the art and involves the thermal decomposition of a volatile carbon-containing gas (e.g., ethylene) on the surface of the particulate material. Alternatively, the carbon coating can be formed by depositing a solution of a carbon-containing compound onto the surface of the particulate material, followed by thermal decomposition. The conductive carbon coating has sufficient permeability to allow lithium to access the interior of the composite particles without excessive resistance, so as not to degrade the rate performance of the composite particles. For example, the thickness of the carbon coating can preferably be in the range of 2 nm to 30 nm. The carbon coating may optionally be porous and / or only partially cover the surface of the composite particles.

[0100] The carbon coating smooths out any surface defects and the remaining microstructure (microporosity) of the surface. By filling the gaps, the BET surface area of ​​the particulate material is further reduced, which has the advantage of further reducing the initial cycle loss. In addition, the carbon coating improves the conductivity of the composite particle surface, reducing the need for conductive additives in the electrode composition, and also forms an optimal surface for the formation of a stable SEI layer, improving the capacity retention rate during cycling.

[0101] According to a first aspect of the present invention, particulate materials according to the following aspects 1-1 to 1-41 are further provided.

[0102] Appearance 1-1: (i) P1 is in the range of 0.7 to 1.4, (ii)φ a The range is 0.5 to 0.8. (iii)φ 20 It is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 1 μm to 18 μm. A particulate material according to a first aspect of the present invention.

[0103] Appearance 1-2: (i) P1 is in the range of 0.7 to 1.4, (ii)φ a The range is 0.5 to 0.8. (iii)φ 10 It is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 1 μm to 12 μm. A particulate material according to a first aspect of the present invention.

[0104] Appearances 1-3: (i) P1 is in the range of 0.7 to 1.4, (ii)φ a The range is 0.5 to 0.8. (iii)φ10 It is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 2 μm to 8 μm. A particulate material according to a first aspect of the present invention.

[0105] Appearances 1-4: (i) P1 is in the range of 0.7 to 1.4, (ii)φ a The range is 0.5 to 0.8. (iii) φ5 is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 2 μm to 8 μm. A particulate material according to a first aspect of the present invention.

[0106] Appearances 1-5: (i) P1 is in the range of 0.7 to 1.4, (ii)φ a The range is 0.5 to 0.8. (iii) φ5 is at least 0.75, (iv) D of porous carbon skeleton 50 The particle size is in the range of 2 μm to 8 μm. A particulate material according to a first aspect of the present invention.

[0107] Appearances 1-6: (i) P1 is in the range of 0.8 to 1.2, (ii)φ a The range is 0.6 to 0.8. (iii)φ 20 It is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 1 μm to 18 μm. A particulate material according to a first aspect of the present invention.

[0108] Appearances 1-7: (i) P1 is in the range of 0.8 to 1.2, (ii)φ a The range is 0.6 to 0.8. (iii)φ 10 It is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 1 μm to 12 μm. A particulate material according to a first aspect of the present invention.

[0109] Appearances 1-8: (i) P1 is in the range of 0.8 to 1.2, (ii)φ a The range is 0.6 to 0.8. (iii)φ 10 It is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 2 μm to 8 μm. A particulate material according to a first aspect of the present invention.

[0110] Appearances 1-9: (i) P1 is in the range of 0.8 to 1.2, (ii)φ a The range is 0.6 to 0.8. (iii) φ5 is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 2 μm to 8 μm. A particulate material according to a first aspect of the present invention.

[0111] Appearance 1-10: (i) P1 is in the range of 0.8 to 1.2, (ii)φ a The range is 0.6 to 0.8. (iii) φ5 is at least 0.75, (iv) D of porous carbon skeleton 50 The particle size is in the range of 2 μm to 8 μm. A particulate material according to a first aspect of the present invention.

[0112] Appearance 1-11: (i) P1 is in the range of 0.7 to 0.9, (ii)φ a The range is 0.6 to 0.8. (iii) φ5 is at least 0.75, (iv) D of porous carbon skeleton 50 The particle size is in the range of 3 μm to 6 μm. A particulate material according to a first aspect of the present invention.

[0113] Appearance 1-12: (i) P1 is in the range of 0.7 to 1.4, (ii)φ a The range is 0.5 to 0.8. (iii)φ 20 It is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 1 μm to 18 μm. (v) The weight ratio of silicon to porous carbon skeleton is at least [φ b The value is given by [φ + 0.8] × P1, preferably [φ b It is less than or equal to the value given by +1.6 × P1. A particulate material according to a first aspect of the present invention.

[0114] Appearance 1-13: (i) P1 is in the range of 0.7 to 1.4, (ii)φ a The range is 0.5 to 0.8. (iii)φ 10 It is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 1 μm to 12 μm. (v) The weight ratio of silicon to porous carbon skeleton is at least [φ b The value is given by [φ + 0.8] × P1, preferably [φ b It is less than or equal to the value given by +1.6 × P1. A particulate material according to a first aspect of the present invention.

[0115] Appearance 1-14: (i) P1 is in the range of 0.7 to 1.4, (ii)φ a The range is 0.5 to 0.8. (iii)φ 10 It is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 2 μm to 8 μm. (v) The weight ratio of silicon to porous carbon skeleton is at least [φ b The value is given by [φ + 0.8] × P1, preferably [φ b It is less than or equal to the value given by +1.6 × P1. A particulate material according to a first aspect of the present invention.

[0116] Appearance 1-15: (i) P1 is in the range of 0.7 to 1.4, (ii)φ a The range is 0.5 to 0.8. (iii) φ5 is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 2 μm to 8 μm. (v) The weight ratio of silicon to porous carbon skeleton is at least [φ b The value is given by [φ + 0.8] × P1, preferably [φ b It is less than or equal to the value given by +1.6 × P1. A particulate material according to a first aspect of the present invention.

[0117] Appearance 1-16: (i) P1 is in the range of 0.7 to 1.4, (ii)φ a The range is 0.5 to 0.8. (iii) φ5 is at least 0.75, (iv) D of porous carbon skeleton 50 The particle size is in the range of 2 μm to 8 μm. (v) The weight ratio of silicon to porous carbon skeleton is at least [φ b The value is given by [φ + 0.8] × P1, preferably [φ b It is less than or equal to the value given by +1.6 × P1. A particulate material according to a first aspect of the present invention.

[0118] Appearance 1-17: (i) P1 is in the range of 0.7 to 0.9, (ii)φ a The range is 0.6 to 0.8. (iii) φ5 is at least 0.75, (iv) D of porous carbon skeleton 50 The particle size is in the range of 3 μm to 6 μm. (v) The weight ratio of silicon to porous carbon skeleton is at least [φ b The value is given by [φ + 0.8] × P1, preferably [φ b It is less than or equal to the value given by +1.6 × P1. A particulate material according to a first aspect of the present invention.

[0119] Appearance 1-18: (i) P1 is in the range of 0.8 to 1.2, (ii)φ a The range is 0.6 to 0.8. (iii)φ 20 It is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 1 μm to 18 μm. (v) The weight ratio of silicon to porous carbon skeleton is at least [φ b The value is given by [φ +0.9] × P1, preferably [φ b It is less than or equal to the value given by +1.5 × P1. A particulate material according to a first aspect of the present invention.

[0120] Appearance 1-19: (i) P1 is in the range of 0.8 to 1.2, (ii)φ a The range is 0.6 to 0.8. (iii)φ 10 It is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 1 μm to 12 μm. (v) The weight ratio of silicon to porous carbon skeleton is at least [φ bThe value is given by [φ +0.9] × P1, preferably [φ b It is less than or equal to the value given by +1.5 × P1. A particulate material according to a first aspect of the present invention.

[0121] Appearance 1-20: (i) P1 is in the range of 0.8 to 1.2, (ii)φ a The range is 0.6 to 0.8. (iii)φ 10 It is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 2 μm to 8 μm. (v) The weight ratio of silicon to porous carbon skeleton is at least [φ b The value is given by [φ +0.9] × P1, preferably [φ b It is less than or equal to the value given by +1.5 × P1. A particulate material according to a first aspect of the present invention.

[0122] Appearance 1-21: (i) P1 is in the range of 0.8 to 1.2, (ii)φ a The range is 0.6 to 0.8. (iii) φ5 is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 2 μm to 8 μm. (v) The weight ratio of silicon to porous carbon skeleton is at least [φ b The value is given by [φ +0.9] × P1, preferably [φ b It is less than or equal to the value given by +1.5 × P1. A particulate material according to a first aspect of the present invention.

[0123] Appearance 1-22: (i) P1 is in the range of 0.8 to 1.2, (ii)φ a The range is 0.6 to 0.8. (iii) φ5 is at least 0.75, (iv) D of porous carbon skeleton 50 The particle size is in the range of 2 μm to 8 μm. (v) The weight ratio of silicon to porous carbon skeleton is at least [φ b The value is given by [φ +0.9] × P1, preferably [φ b It is less than or equal to the value given by +1.5 × P1. A particulate material according to a first aspect of the present invention.

[0124] Appearance 1-23: (i) P1 is in the range of 0.7 to 0.9, (ii)φ a The range is 0.6 to 0.8. (iii) φ5 is at least 0.75, (iv) D of porous carbon skeleton 50 The particle size is in the range of 3 μm to 6 μm. (v) The weight ratio of silicon to porous carbon skeleton is at least [φ b The value is given by [φ +0.9] × P1, preferably [φ b It is less than or equal to the value given by +1.5 × P1. A particulate material according to a first aspect of the present invention.

[0125] Appearance 1-24: (i) P1 is in the range of 0.8 to 1.2, (ii)φ a The range is 0.6 to 0.8. (iii)φ 20 It is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 1 μm to 18 μm. (v) The weight ratio of silicon to porous carbon skeleton is at least [φ b The value is given by [φ +1] × P1, preferably [φ b It is less than or equal to the value given by +1.5 × P1. A particulate material according to a first aspect of the present invention.

[0126] Appearance 1-25: (i) P1 is in the range of 0.8 to 1.2, (ii)φ a The range is 0.6 to 0.8. (iii)φ 10 It is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 1 μm to 12 μm. (v) The weight ratio of silicon to porous carbon skeleton is at least [φ b The value is given by [φ +1] × P1, preferably [φ b It is less than or equal to the value given by +1.5 × P1. A particulate material according to a first aspect of the present invention.

[0127] Appearance 1-26: (i) P1 is in the range of 0.8 to 1.2, (ii)φ a The range is 0.6 to 0.8. (iii)φ 10 It is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 2 μm to 8 μm. (v) The weight ratio of silicon to porous carbon skeleton is at least [φ b The value is given by [φ +1] × P1, preferably [φ b It is less than or equal to the value given by +1.5 × P1. A particulate material according to a first aspect of the present invention.

[0128] Appearance 1-27: (i) P1 is in the range of 0.8 to 1.2, (ii)φ a The range is 0.6 to 0.8. (iii) φ5 is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 2 μm to 8 μm. (v) The weight ratio of silicon to porous carbon skeleton is at least [φ b The value is given by [φ +1] × P1, preferably [φ bIt is less than or equal to the value given by +1.5 × P1. A particulate material according to a first aspect of the present invention.

[0129] Appearance 1-28: (i) P1 is in the range of 0.8 to 1.2, (ii)φ a The range is 0.6 to 0.8. (iii) φ5 is at least 0.75, (iv) D of porous carbon skeleton 50 The particle size is in the range of 2 μm to 8 μm. (v) The weight ratio of silicon to porous carbon skeleton is at least [φ b The value is given by [φ +1] × P1, preferably [φ b It is less than or equal to the value given by +1.5 × P1. A particulate material according to a first aspect of the present invention.

[0130] Appearance 1-29: (i) P1 is in the range of 0.7 to 0.9, (ii)φ a The range is 0.6 to 0.8. (iii) φ5 is at least 0.75, (iv) D of porous carbon skeleton 50 The particle size is in the range of 3 μm to 6 μm. (v) The weight ratio of silicon to porous carbon skeleton is at least [φ b The value is given by [φ +1] × P1, preferably [φ b It is less than or equal to the value given by +1.5 × P1. A particulate material according to a first aspect of the present invention.

[0131] Appearance 1-30: (i) P1 is in the range of 0.7 to 1.4, (ii)φ a The range is 0.5 to 0.8. (iii)φ 20 It is at least 0.8, (iv) D of porous carbon skeleton 50The particle size is in the range of 1 μm to 18 μm, (v) The weight ratio of silicon to the porous carbon framework is in the range of [1.2 × P1 to 1.8 × P1]:1, The particulate material according to the first aspect of the present invention.

[0132] Aspect 1-31: (i) P1 is in the range of 0.7 to 1.4, (ii) φ a is in the range of 0.5 to 0.8, (iii) φ 10 is at least 0.8, (iv) The D 50 particle size of the porous carbon framework is in the range of 1 μm to 12 μm, (v) The weight ratio of silicon to the porous carbon framework is in the range of [1.2 × P1 to 1.8 × P1]:1, The particulate material according to the first aspect of the present invention.

[0133] Aspect 1-32: (i) P1 is in the range of 0.7 to 1.4, (ii) φ a is in the range of 0.5 to 0.8, (iii) φ 10 is at least 0.8, (iv) The D 50 particle size of the porous carbon framework is in the range of 2 μm to 8 μm, (v) The weight ratio of silicon to the porous carbon framework is in the range of [1.2 × P1 to 1.8 × P1]:1, The particulate material according to the first aspect of the present invention.

[0134] Aspect 1-33: (i) P1 is in the range of 0.7 to 1.4, (ii) φ a is in the range of 0.5 to 0.8, (iii) φ5 is at least 0.8, (iv) The D 50 particle size of the porous carbon framework is in the range of 2 μm to 8 μm, (v) The weight ratio of silicon to porous carbon skeleton is in the range of [1.2×P1~1.8×P1]:1. A particulate material according to a first aspect of the present invention.

[0135] Appearance 1-34: (i) P1 is in the range of 0.7 to 1.4, (ii)φ a The range is 0.5 to 0.8. (iii) φ5 is at least 0.75, (iv) D of porous carbon skeleton 50 The particle size is in the range of 2 μm to 8 μm. (v) The weight ratio of silicon to porous carbon skeleton is in the range of [1.2×P1~1.8×P1]:1. A particulate material according to a first aspect of the present invention.

[0136] Appearance 1-35: (i) P1 is in the range of 0.7 to 0.9, (ii)φ a The range is 0.6 to 0.8. (iii) φ5 is at least 0.75, (iv) D of porous carbon skeleton 50 The particle size is in the range of 3 μm to 6 μm. (v) The weight ratio of silicon to porous carbon skeleton is in the range of [1.2×P1~1.8×P1]:1. A particulate material according to a first aspect of the present invention.

[0137] Appearance 1-36: (i) P1 is in the range of 0.8 to 1.2, (ii)φ a The range is 0.6 to 0.8. (iii)φ 20 It is at least 0.8, (iv) D of porous carbon skeleton 50 The particle size is in the range of 1 μm to 18 μm. (v) The weight ratio of silicon to porous carbon skeleton is in the range of [1.2×P1~1.6×P1]:1. Particulate material according to the first aspect of the present invention.

[0138] Aspect 1-37: (i) P1 is in the range of 0.8 to 1.2, (ii) φ a is in the range of 0.6 to 0.8, (iii) φ 10 is at least 0.8, (iv) The D 50 particle diameter of the porous carbon skeleton is in the range of 1 μm to 12 μm, (v) The weight ratio of silicon to the porous carbon skeleton is in the range of [1.2 × P1 to 1.6 × P1]:1. Particulate material according to the first aspect of the present invention.

[0139] Aspect 1-38: (i) P1 is in the range of 0.8 to 1.2, (ii) φ a is in the range of 0.6 to 0.8, (iii) φ 10 is at least 0.8, (iv) The D 50 particle diameter of the porous carbon skeleton is in the range of 2 μm to 8 μm, (v) The weight ratio of silicon to the porous carbon skeleton is in the range of [1.2 × P1 to 1.6 × P1]:1. Particulate material according to the first aspect of the present invention.

[0140] Aspect 1-39: (i) P1 is in the range of 0.8 to 1.2, (ii) φ a is in the range of 0.6 to 0.8, (iii) φ5 is at least 0.8, (iv) The D 50 particle diameter of the porous carbon skeleton is in the range of 2 μm to 8 μm, (v) The weight ratio of silicon to the porous carbon skeleton is in the range of [1.2 × P1 to 1.6 × P1]:1. Particulate material according to the first aspect of the present invention.

[0141] Appearance 1-40: (i) P1 is in the range of 0.8 to 1.2, (ii)φ a The range is 0.6 to 0.8. (iii) φ5 is at least 0.75, (iv) D of porous carbon skeleton 50 The particle size is in the range of 2 μm to 8 μm. (v) The weight ratio of silicon to porous carbon skeleton is [1.2×P1~1.6×P1] : is within the range of 1 A particulate material according to a first aspect of the present invention.

[0142] Appearance 1-41: (i) P1 is in the range of 0.7 to 0.9, (ii)φ a The range is 0.6 to 0.8. (iii) φ5 is at least 0.75, (iv) D of porous carbon skeleton 50 The particle size is in the range of 3 μm to 6 μm. (v) The weight ratio of silicon to porous carbon skeleton is in the range of [1.2×P1~1.6×P1]:1. A particulate material according to a first aspect of the present invention.

[0143] According to the present invention, it should be understood that any preferred / optional features disclosed herein with respect to a first aspect of the present invention, which fall within the scope of aspects 1-1 to 1-41 described above, should also be considered as preferred / optional features of aspects 1-1 to 1-41. Similarly, any features of dependent claims that fall within the scope of aspects 1-1 to 1-41 described above should be interpreted as those claims being dependent on aspects 1-1 to 1-41.

[0144] A second aspect of the present invention provides a composition comprising a particulate material according to the first aspect of the present invention and at least one other component. Preferably, the composition according to the second aspect of the present invention can be used to form an active layer of an electrode. In this specification, such a composition may be referred to as an “electrode composition”. The particulate material used to prepare the composition according to the second aspect of the present invention may have any of the features described as preferred or optional with respect to the first aspect of the present invention, and may be a particulate material according to any aspect 1-1 to 1-41.

[0145] Therefore, a composition is provided comprising a particulate material according to a first 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.

[0146] The above composition is preferably a hybrid electrode composition comprising a particulate material according to a first aspect of the present invention and at least one additional particulate electroactive material.

[0147] The at least one additional particulate electroactive material preferably has a specific capacity in the range of 100 mAh / g to 600 mAh / g or 200 mAh / g to 500 mAh / g when lithium-ionized. Examples of additional particulate electroactive materials include graphite, hard carbon, silicon, tin, germanium, gallium, aluminum, and lead. The at least one additional particulate electroactive material is preferably selected from graphite and hard carbon. The at least one additional particulate electroactive material is most preferably graphite.

[0148] At least one additional particulate electroactive material is preferably 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, in the range of 15 μm to 25 μm. 50 It has a particle size.

[0149] D of at least one additional particulate electroactive material 10The 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, and even more preferably at least 10 μm.

[0150] D of at least one additional particulate electroactive material 90 The particle size is preferably 100 μm. The more preferably, the thickness is 80 μm or less, more preferably 60 μm or less, more preferably 50 μm or less, and most preferably 40 μm or less.

[0151] In a preferred embodiment, at least one additional particulate electroactive material is a D in the range of 10 μm to 50 μm. 50 The material is selected from graphite particles and hard carbon particles having particle sizes. More preferably, at least one additional particulate electroactive material is selected from graphite particles, where the graphite particles are in the range of 10 μm to 50 μm. 50 It has a particle size.

[0152] The at least one additional particulate electroactive material preferably has the form of rotational elliptical particles having an average sphericity of at least 0.70, preferably 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, and most preferably at least 0.95.

[0153] The at least one additional particulate electroactive material preferably has an average aspect ratio of less than 3:1, preferably 2.5:1 or less, more preferably 2:1 or less, more preferably 1.8:1 or less, more preferably 1.6:1 or less, more preferably 1.4:1 or less, and most preferably 1.2:1 or less.

[0154] The particulate material of the present invention can constitute 0.5% to 80% by weight of the total dry weight of the electroactive material in the composition. For example, the particulate material of the present invention can constitute 2% to 70% by weight, or 4% to 60% by weight, or 5% to 50% by weight of the total dry weight of the electroactive material in the composition.

[0155] As described above, if the above composition is a hybrid electrode composition comprising at least one additional particulate electroactive material, the electrode composition preferably contains the particulate material of the present invention in an amount of 1% to 20% by weight, or 2% to 15% by weight, or 2% to 10% by weight, or 2% to 5% by weight, relative to the total dry weight of the composition.

[0156] Furthermore, if the above composition is a hybrid electrode composition, the electrode composition contains at least one additional particulate electroactive material, preferably in an amount of 10% to 98% by weight, or 15% to 97% by weight, or 20% to 97% by weight, or 25% to 97% by weight, relative to the total dry weight of the composition.

[0157] The ratio of at least one additional particulate electroactive material to the particulate material of the present invention is preferably in the range of 50:50 to 99:1 by weight, more preferably 60:40 to 98:2 by weight, more preferably 70:30 to 97:3 by weight, more preferably 80:20 to 96:4 by weight, and most preferably 85:15 to 95:5 by weight.

[0158] It is preferable that at least one additional particulate electroactive material and the particulate material of the present invention together constitute at least 50% by weight, more preferably at least 60% by weight, more preferably at least 70% by weight, and most preferably at least 80% by weight, for example, at least 85% by weight, at least 90% by weight, or at least 95% by weight of the total weight of the composition.

[0159] The above composition may 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, carboxymethylcellulose (CMC), and modified carboxymethyl Examples include cellulose (mCMC), sodium carboxymethylcellulose (Na-CMC), polyvinyl alcohol (PVA), alginates and their alkali metal salts, styrene-butadiene rubber (SBR), and polyimides. The above compositions may include a mixture of binders. Preferably, the binder comprises polymers selected from polyacrylic acid (PAA) and its alkali metal salts, as well as modified polyacrylic acid (mPAA) and its alkali metal salts, SBR, and CMC.

[0160] The binder can preferably be present in an amount of 0.5% to 20% by weight, more preferably 1% to 15% by weight, and most preferably 2% to 10% by weight, relative to the total dry weight of the above composition.

[0161] The binder may optionally be present in combination with one or more additives that modify the properties of the binder, such as crosslinking accelerators, coupling agents, and / or adhesion accelerators.

[0162] The above composition may optionally contain one or more conductive additives. Preferred conductive additives are non-electroactive materials included to improve conductivity between the electroactive components of the electrode composition and between the electroactive components of the electrode composition and the current collector. Conductive additives can preferably be selected from carbon black, carbon fibers, carbon nanotubes, graphene, acetylene black, Ketjenblack, metal fibers, metal powders, and conductive metal oxides. Preferred conductive additives include carbon black and carbon nanotubes.

[0163] One or more conductive additives may preferably be present in a total amount of 0.5% to 20% by weight, more preferably 1% to 15% by weight, and most preferably 2% to 10% by weight, relative to the total dry weight of the electrode composition.

[0164] In a third aspect, the present invention provides an electrode comprising a particulate material defined with reference to a first aspect of the present invention, which is electrically in contact with a current collector. The particulate material used to manufacture the electrode of the third aspect of the present invention may have any of the features described as preferred or optional with reference to a first aspect of the present invention, and may be a particulate material according to any aspect 1-1 to 1-41.

[0165] As used herein, the term "current collector" refers to any conductive substrate that can conduct electric current to or from electroactive particles in an electrode composition. Examples of materials that can be used as current collectors include copper, aluminum, stainless steel, nickel, titanium, and sintered carbon. Copper is a preferred material. Current collectors typically have the form of foil or mesh with a thickness of 3 μm to 500 μm. The particulate material of the present invention can be applied to one or both sides of a current collector, preferably with a thickness ranging from 10 μm to 1 mm, for example, 20 μm to 500 μm, or 50 μm to 200 μm.

[0166] Preferably, the electrode comprises an electrode composition defined with reference to a second aspect of the present invention, which is electrically in contact with the current collector. The electrode composition may have any of the features described as preferred or optional with reference to a second aspect of the present invention.

[0167] An electrode according to a third aspect of the present invention can preferably be prepared by combining the particulate material of the present invention (optionally having the form of the electrode composition of the present invention) with a solvent and optionally one or more viscosity-modifying additives to form a slurry. The slurry is then cast onto the surface of a current collector, and the solvent is removed to form an electrode layer on the surface of the current collector. Further steps such as heat treatment to cure an optional binder and / or calendering of the electrode layer can be performed as appropriate. The electrode layer is preferably 20 μm to 2 mm thick, preferably 20 μm thick. It has a thickness in the range of m to 1 mm, preferably 20 μm to 500 μm, preferably 20 μm to 200 μm, preferably 20 μm to 100 μm, and preferably 20 μm to 50 μm.

[0168] Alternatively, the slurry can be formed into a self-supporting film or mat containing the particulate material of the present invention by, for example, casting the slurry onto a suitable cast template, removing the solvent, and then removing the cast template. The resulting film or mat has the form of self-supporting aggregates and can then be adhered to a current collector by known methods.

[0169] The electrode of the third aspect of the present invention can be used as an anode in a metal-ion battery. Thus, in the fourth aspect, the present invention provides a rechargeable metal-ion battery comprising an anode including the electrode 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. The particulate material used to manufacture the battery of the fourth aspect of the present invention may have any of the features described as preferred or optional with respect to the first aspect of the present invention, and may be a particulate material according to any aspect 1-1 to 1-41.

[0170] The metal ions are preferably lithium ions. More preferably, the rechargeable metal ion battery of the present invention is a lithium ion battery, and the cathode active material is capable of releasing lithium ions.

[0171] The cathode active material is preferably a metal oxide 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, LiLiLi 0.4 Co 0.3 Mn 0.3 O2 and LiNi 0.33 Co 0.33 Mn 0.34 O2 is one example. The cathode current collector typically has a thickness of 3 μm to 500 μm. Examples of materials that can be used as cathode current collectors include aluminum, stainless steel, nickel, titanium, and sintered carbon.

[0172] The electrolyte is preferably a non-aqueous electrolyte containing a metal salt, such as a lithium salt, and may include, but is not limited to, non-aqueous electrolytes, solid electrolytes, and inorganic solid electrolytes. Examples of non-aqueous electrolytes that can be used include 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, triester phosphate, trimethoxymethane, sulfolane, methylsulfolane, and aprotic organic solvents such as 1,3-dimethyl-2-imidazolidinone.

[0173] 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.

[0174] Examples of inorganic solid electrolytes include nitrides, halides, and sulfides of lithium salts such as Li5NI2, Li3N, LiI, LiSiO4, Li2SiS3, Li4SiO4, LiOH, and Li3PO4.

[0175] Lithium salts are preferably soluble in a selected solvent or mixture of solvents. Examples of um salts include LiCl, LiBr, LiI, LiClO4, LiBF4, LiBC4O8, LiPF6, LiCF3SO3, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, and CF3SO3Li.

[0176] 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 made of an insulating material having high ion permeability and high mechanical strength. The separator typically has a pore size of 0.01 μm to 100 μm and a thickness of 5 μm to 300 μm. A suitable example of an electrode separator is a microporous polyethylene film.

[0177] 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.

[0178] In a fifth aspect, the present invention provides the use of a particulate material as an anode active material, as defined with reference to a first aspect of the present invention. Preferably, the particulate material has the form of an electrode composition as defined with reference to a second aspect of the present invention, most preferably the electrode composition comprises one or more additional particulate electroactive materials as defined above. The particulate material used according to a fifth aspect of the present invention may have any of the features described as preferred or optional with reference to a first aspect of the present invention, and may be a particulate material according to any of aspects 1-1 to 1-41. [Brief explanation of the drawing]

[0179] [Figure 1] This graph shows the capacity retention rate over multiple cycles in the example. [Modes for carrying out the invention] [Examples]

[0180] The porous carbon skeletons C1 to C3 used in the following examples have the properties shown in Table 1.

[0181] [Table 1]

[0182] Example 1 - Preparation of composite particles in a fixed-bed reactor Silicon-carbon composite particles were prepared by arranging 1.8 g of particulate porous skeleton having the properties shown in Table 1 on a stainless steel plate at a constant thickness of 1 mm along its length. The plate was then placed inside a stainless steel tube with an outer diameter of 60 mm, and the gas inlet and outlet lines were positioned in the hot zone of a retort furnace. After purging the furnace tube with nitrogen gas at room temperature for 30 minutes, the sample temperature was raised to 450°C to 500°C. The nitrogen gas flow rate was adjusted to ensure a gas residence time of at least 90 seconds in the furnace tube and maintained at that rate for 30 minutes. Next, the gas supply was switched from nitrogen to a mixture of monosilane in nitrogen at a concentration of 1.25 vol%. Monosilane was added over 5 hours while maintaining the reactor pressure at 101.3 kPa (1 atm). After the addition was complete, the silane was removed from the furnace using nitrogen. Maintain a constant gas flow rate during purging. After purging the furnace under nitrogen for 30 minutes, allow it to cool to room temperature over several hours. Then, gradually switch the atmosphere to air over 2 hours by switching the gas flow from nitrogen to air from a compressed air supply.

[0183] The composite prepared according to Example 1 has the properties shown in Table 2 below.

[0184] Example 2 - Preparation of composite particles in a fluidized bed reactor Silicon-carbon composite particles were prepared in a vertical fluidized bed reactor equipped with a stainless steel cylindrical vessel with an inner diameter of 83 mm. 250 g of carbon skeleton particle powder having the properties shown in Table 1 was placed in the reactor. Inert gas (nitrogen) was injected into the reactor at a low flow rate to remove oxygen. The reactor was then heated to a reaction temperature of 400°C to 500°C, and 4 v / v% monosilane gas diluted with nitrogen was supplied to the bottom of the reactor at a flow rate sufficient to fluidize the carbon skeleton particles for a duration sufficient to deposit the target mass of silicon. The reactor was purged under nitrogen for 30 minutes and then cooled to room temperature over several hours. The atmosphere was then gradually switched to air over 2 hours by switching the gas flow from nitrogen to air from a compressed air supply.

[0185] The composite prepared according to Example 2 has the properties shown in Table 2 below.

[0186] Example 3 - Preparation of composite particles in a rotary tube reactor Silicon-carbon composite particles were prepared by placing 5 g of particulate porous skeleton having the properties shown in Table 1 into a quartz tube (11.4 cm in length) equipped with a spherical section. The quartz tube was then placed inside a rotary tube furnace reactor with a heating zone of approximately 15 cm × 20 cm (L × D), with the gas inlet and outlet lines positioned approximately 29 cm away from the furnace's hot zone. The quartz tube inside the furnace was rotated approximately 315° clockwise, then counterclockwise, thereby continuously moving / rotating the porous carbon. After purging the furnace tube with nitrogen gas at room temperature for 30 minutes, the sample temperature was raised to 450°C to 500°C. The nitrogen gas flow rate was adjusted to ensure a gas residence time of at least 90 seconds in the furnace tube and maintained at that rate for 30 minutes. The gas supply was then switched from nitrogen to a mixture of monosilane in nitrogen at a concentration of 1.25 vol%. The monosilane is added over 5 hours while maintaining the reactor pressure at 101.3 kPa (1 atm). After the addition is complete, the gas flow rate is kept constant while purging the silane from the furnace using nitrogen. After purging the furnace under nitrogen for 30 minutes, it is cooled to room temperature over several hours. The atmosphere is then gradually switched to air over 2 hours by switching the gas flow from nitrogen to air from the compressed air supply.

[0187] The composite prepared according to Example 3 has the properties shown in Table 2 below.

[0188] [Table 2]

[0189] Example 4 - Electrode Fabrication The negative electrode coating (anode) was prepared from the materials of the sample and comparative sample shown in Table 1 using the following method.

[0190] A test coin cell was fabricated using a negative electrode containing the silicon-based composite material prepared as described above. A CMC binder dispersion of carbon black Super P (trademark) (conductive carbon) was mixed in a Thinky (trademark) mixer. Si-C composite material was added to this mixture and mixed in a Thinky (trademark) mixer for 30 minutes. Next, SBR binder was added to make the CMC:SBR ratio 1:1, and a slurry was obtained in which the weight ratio of Si-C composite material:CMC / SBR:carbon black was 70%:16%:14%. The slurry was mixed in a Thinky (trademark) mixer for another 30 minutes, and then coated onto a 10 μm thick copper substrate (current collector). The negative electrode was formed by drying at 50°C for 10 minutes and then further drying at 110°C for 12 hours.

[0191] Example 5 - Manufacturing of a full cell A full coin cell was fabricated using a porous polyethylene separator and a nickel-manganese-cobalt (NMC532) positive electrode, along with a circular negative electrode with a radius of 0.8 cm cut from the electrode of Example 4. The positive and negative electrodes were designed to form a well-balanced pair such that the capacity ratio of the positive electrode to the negative electrode was 0.9. Then, an electrolyte containing 1 M LiPF6 was added to the cell in a 7:3 EMC / FEC (ethylene methyl carbonate / fluoroethylene carbonate) solution containing 3 wt% vinylene carbonate before sealing.

[0192] A full coin cell was cycled as follows: The anode was lithiumized by applying a constant current at a rate of C / 25 with a cutoff voltage of 4.3V. Once the cutoff voltage was reached, a constant voltage of 4.3V was applied until the cutoff current of C / 100 was reached. The cell was then left to rest for 10 minutes in the lithiumized state. The anode was then delithiated with a constant current of C / 25 at a cutoff voltage of 2.75V. The cell was then left to rest for 10 minutes. After this initial cycle, the anode was lithiumized by applying a constant current of C / 2 at a cutoff voltage of 4.3V, followed by applying a constant voltage of 4.3V with a cutoff current of C / 40, and a rest period of 5 minutes. The anode was then delithiated with a constant current of C / 2 at a cutoff voltage of 2.75V. This was then repeated for the desired number of cycles. For each sample, the charge and discharge capacity was tracked up to the 1000th cycle, and the capacity retention rates (CR100 and CR300) at the 100th and 300th cycles were determined. For S1, S2, and S3, CR500 and CR1000 were also determined. This data, along with the initial lithium capacity, initial delithiation capacity, and initial cycle loss (FCL) for each sample, is shown in Table 3. The capacity retention rates over multiple cycles are also shown graphically in Figure 1.

[0193] The charging (lithiumization) and discharging (delithiumization) capacities for each cycle were calculated per unit mass of the silicon-carbon composite material, and the capacity retention value was calculated for each discharge capacity as a percentage of the discharge capacity of the second cycle. The first cycle loss (FCL) is (1 - (initial delithiumization capacity / initial lithiumization capacity)) × 100%. Table 3 shows the average values ​​for each sample across three coin cells.

[0194] [Table 3]

Claims

1. A particulate material containing multiple composite particles, wherein the composite particles are (a) A porous carbon skeleton including micropores and mesopores, (i) The total pore volume of the micropores and mesopores, as measured by gas adsorption, is P １ cm ３ / g, where P １ This represents a natural number that has a value of at least 0.6, (ii) Volume ratio of micropores to the total volume of micropores and mesopores (φ ａ ) is in the range of 0.1 to 0.9, (iii) Volume ratio of pores with a diameter of 20 nm or less relative to the total volume of micropores and mesopores (φ ２０ ) is at least 0.75, and, (iv) The porous carbon skeleton is less than 20 μm ５０ A porous carbon skeleton having particle size, (b) A plurality of nanoscale elemental silicon domains located within the micropores and / or mesopores of the porous carbon skeleton, Includes, In the composite particles, the weight ratio of silicon to the porous carbon skeleton is [1 × P １ ~2.2 x P １ ]: A particulate material in the range of 1.

2. P １ The particulate material according to claim 1, wherein P has a value of at least 0.65, or at least 0.7, or at least 0.75, or at least 0.8, or at least 0.85, or at least 0.9, or at least 0.95, or at least 1.

3. P １ The particulate material according to claim 1 or 2, wherein the value is 2 or less, or 1.8 or less, or 1.6 or less, or 1.5 or less, or 1.4 or less, or 1.3 or less, or 1.2 or less, or 1.1 or less, or 1.0 or less, or 0.9 or less.

4. The volume ratio of micropores to the total volume of micropores and mesopores (φ ａ The particulate material according to any one of claims 1 to 3, wherein the range of ) is in the range of 0.15 to 0.85, or in the range of 0.2 to 0.8, or in the range of 0.45 to 0.85, or in the range of 0.5 to 0.8, or in the range of 0.55 to 0.8, or in the range of 0.6 to 0.8, or in the range of 0.6 to 0.

75.

5. The volume ratio of micropores to the total volume of micropores and mesopores (φ ａ The particulate material according to claim 4, wherein the coefficient of the ions is in the range of 0.45 to 0.85, or 0.5 to 0.8, or 0.5 to 0.75, or 0.5 to 0.

7.

6. The volume ratio of micropores to the total volume of micropores and mesopores (φ ａ The particulate material according to claim 4, wherein the coefficient of the ions is in the range of 0.2 to 0.5 or 0.3 to 0.

5.

7. In the composite particles, the weight ratio of silicon to the porous carbon skeleton is at least [φ ｂ +0.75] × P １ The value is given by, where φ ｂ The particulate material according to any one of claims 1 to 6, wherein is the volume ratio of mesopores to the total volume of micropores and mesopores.

8. In the composite particles, the weight ratio of silicon to the porous carbon skeleton is at least [φ ｂ +1] × P １ The particulate material according to claim 7, which is a value given by .

9. In the composite particles, the weight ratio of silicon to the porous carbon skeleton is at least [φ ｂ +1.1] × P １ The particulate material according to claim 8, which is a value given by .

10. In the composite particles, the weight ratio of silicon to the porous carbon skeleton is [φ ｂ +1 6] × P １ A particulate material according to any one of claims 1 to 9, wherein the value is less than or equal to the value given by .

11. In the composite particles, the weight ratio of silicon to the porous carbon skeleton is [φ ｂ +1.5] × P １ A particulate material according to any one of claims 1 to 10, wherein the value is less than or equal to the value given by .

12. In the composite particles, the weight ratio of silicon to the porous carbon skeleton is at least 1.1 × P １ , or at least 1.15 × P １ , or at least 1.2 × P １ , or at least 1.25 × P １ , or at least 1.3 × P １ , or at least 1.35 × P １ , or at least 1.4 × P １ The particulate material according to any one of claims 4 to 6.

13. In the composite particles, the weight ratio of silicon to the porous carbon skeleton is at least 1.45 × P １ , or at least 1.5 × P １ , or at least 1.55 × P １ , or at least 1.6 × P １ , or at least 1.65 × P １ , or at least 1.7 × P １ The particulate material according to claim 6.

14. The volume ratio of pores with a diameter of 20 nm or less relative to the total volume of micropores and mesopores (φ ２０ The particulate material according to any one of claims 1 to 13, wherein the ratio is at least 0.8, or at least 0.85, or at least 0.

9.

15. The volume ratio of pores with a diameter of 10 nm or less relative to the total volume of micropores and mesopores (φ １０ The particulate material according to any one of claims 1 to 14, wherein the ratio is at least 0.70, or at least 0.75, or at least 0.8, or at least 0.

85.

16. The volume ratio of pores with a diameter of 5 nm or less relative to the total volume of micropores and mesopores (φ ５ The particulate material according to any one of claims 1 to 15, wherein the ratio is at least 0.7, or at least 0.75, or at least 0.8, or at least 0.

85.

17. The particulate material according to any one of claims 1 to 16, wherein the porous carbon skeleton has a unimodal pore size distribution.

18. The particulate material according to any one of claims 1 to 16, wherein the porous carbon skeleton has a bimodal or multimodal pore size distribution.

19. The porous carbon skeleton has a diameter in the range of more than 50 nm to 100 nm, and the total volume measured by the mercury intrusion method is P ２ cm ３ It includes macropores where P is / g. ２ is 0.2 × P １ The following, or 0.1 × P １ The following, or 0.05 × P １ The following, or 0.02 × P １ The following, or 0.01 × P １ Below, or 0.005 or less × P １ The particulate material according to any one of claims 1 to 18.

20. The composite particles have a diameter of at least 0.5 μm, or 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 A particulate material according to any one of claims 1 to 19, having a particle size.

21. The composite particles are 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 9 μm or less, or 8 μm or less, or 7 μm or less, or 6 μm or less, or 5 μm or less. ５０ A particulate material according to any one of claims 1 to 20, having a particle size.

22. The composite particles are 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 of D １０ A particulate material according to any one of claims 1 to 21, having a particle size.

23. The composite particles are 40 μm or less, or 30 μm or less, or 20 μm or less, or 15 μm or less, or 12 μm or less, or 10 μm or less D ９０ A particulate material according to any one of claims 1 to 22, having a particle size.

24. The particulate material according to any one of claims 1 to 23, wherein the composite particles have a particle size distribution span of 5 or less, or 4 or less, or 3 or less, or 2 or less, or 1.5 or less.

25. The composite particles are 150 m ２ / g or less, or 100m ２ / g or less, or 80m ２ / g or less, or 60m ２ / g or less, or 40m ２ / g or less, or 30m ２ / g or less, or 25m ２ / g or less, or 20m ２ / g or less, or 15m ２ A particulate material according to any one of claims 1 to 24, having a BET surface area of ​​less than or equal to / g.

26. The composite particles are at least 0.1 m ２ / g, or at least 1m ２ / g, or at least 2m ２ / g, or at least 5m ２ A particulate material according to any one of claims 1 to 25, having a BET surface area of ​​1 / g.

27. The particulate material according to any one of claims 1 to 26, wherein the specific capacity when lithium-ionized is 1200 mAh / g to 2340 mAh / g.

28. The particulate material according to any one of claims 1 to 27, wherein at least 90% by weight, preferably at least 95% by weight, preferably at least 98% by weight, and more preferably at least 99% by weight of the silicon mass in the composite particles is located in the internal pore volume of the porous carbon skeleton.

29. The particulate material according to any one of claims 1 to 28, wherein when the particulate material is analyzed by TGA in air at a temperature rise rate of 10°C / min, 10% or less, preferably 5% or less, more preferably 2% or less of the silicon content of the particulate material is unoxidized at 800°C.

30. A composition comprising the particulate material according to any one of claims 1 to 29 and at least one other component.

31. The composition according to claim 30, comprising (i) a particulate material according to any one of claims 1 to 29, and at least one other component selected from (i) a binder, (ii) a conductive additive, and (iii) an additional particulate electroactive material.

32. The composition according to claim 31, comprising at least one additional particulate electroactive material.

33. The composition according to claim 32, comprising 1% to 20% by weight, or 2% to 15% by weight, or 2% to 10% by weight, or 2% to 5% by weight of the particulate material according to any one of claims 1 to 29, based on the total dry weight of the composition.

34. The composition according to claim 32 or 33, comprising 10% to 98% by weight, or 15% to 97% by weight, or 20% to 97% by weight, or 25% to 97% by weight, of the total dry weight of the composition.

35. The composition according to any one of claims 32 to 34, wherein the specific capacity of the at least one additional particulate electroactive material when lithified is in the range of 100 mAh / g to 600 mAh / g, or 200 mAh / g to 500 mAh / g.

36. The composition according to claim 35, wherein the at least one additional particulate electroactive material is selected from graphite and hard carbon.

37. The composition according to any one of claims 31 to 36, wherein the binder is optionally contained in an amount of 0.5% to 20% by weight, 1% to 15% by weight, or 2% to 10% by weight, based on the total dry weight of the composition.

38. The composition according to any one of claims 31 to 37, wherein one or more conductive additives are optionally included in a total amount of 0.5% to 20% by weight, or 1% to 15% by weight, or 2% to 10% by weight, based on the total dry weight of the composition.

39. An electrode comprising the particulate material according to any one of claims 1 to 29, which is in electrical contact with a current collector.

40. The electrode according to claim 39, wherein the particulate material has the form of the composition described in any one of claims 30 to 38.

41. (i) an anode including the electrode described in claim 39 or 40, (ii) A cathode comprising a cathode active material capable of releasing and reabsorbing metal ions, (iii) The electrolyte between the anode and the cathode, Rechargeable metal-ion batteries, including [specific component].

42. Use of the particulate material described in any one of claims 1 to 29 as the anode active material.

43. The use according to claim 42, wherein the particulate material has the form of the composition described in any one of claims 30 to 38.

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