Silicon-containing composite particles

Abstract

This invention relates to a process for preparing composite particles suitable as anode active materials in metal-ion batteries. Multiple nanoscale silicon domains are deposited within a pore network of porous particles, including micropores and mesopores, using the thermal decomposition of a silicon-containing precursor material. The composite particles are subsequently subjected to a stabilization treatment using liquid water or steam at an elevated temperature, which has been found to reduce the problem of hydrogen generation that occurs during the processing of the composite particles for electrode formation.

Description

[Technical Field]

[0001] This invention relates to a method for producing composite particles containing silicon deposited in the pores of a porous particle framework. In particular, this method relates to an improved method for reducing the susceptibility of the composite particles to oxidation upon exposure to water. The invention also relates to novel composite particles with reduced susceptibility to oxidation upon exposure to water, as indicated by the generation of hydrogen gas over time. [Background technology]

[0002] A lithium-ion battery (LIB) generally comprises an anode, a cathode, and a lithium-containing electrolyte. The anode generally comprises a metal current collector coated with a layer of electroactive material, as defined herein, a material capable of inserting and releasing lithium ions during charging and discharging of the battery. When an LIB is charged, lithium ions are transported from the cathode through the electrolyte to the anode and inserted into the electroactive material of the anode as inserted lithium atoms. Thus, in this specification, the terms “cathode” and “anode” are used in the sense that the battery is loaded such that the anode becomes the negative electrode. In this specification, the term “battery” is used to refer to both a device containing a single lithium-ion cell and a device containing multiple connected lithium-ion cells.

[0003] Conventional lithium-ion batteries (LIBs) use graphite as the anode electroactive material. A graphite anode can accommodate up to one lithium atom for every six carbon atoms, resulting in a maximum theoretical specific capacity of 372 mAh / g in lithium-ion batteries, although the practical capacity is slightly lower (approximately 340 mAh / g to 360 mAh / g). However, due to its very high capacity relative to lithium, there is growing interest in using silicon as a substitute for graphite. Silicon has a theoretical maximum specific capacity of approximately 3600 mAh / g in lithium-ion batteries. 15This is based on Si4. However, the implementation of silicon in lithium-ion batteries is hindered by the significant expansion of silicon during lithium insertion. This results in significant mechanical stress, leading to fracture and structural failure. Furthermore, the expansion and contraction of the silicon anode leads to the fracture and delamination of the SEI layer, as well as the exposure of new silicon surfaces, making the solid electrolyte interface (SEI) layer formed on the exposed silicon surface during the initial charge unstable. Further SEI formation on the exposed surface leads to further electrolyte decomposition and irreversible lithium consumption. Collectively, these defect mechanisms result in unacceptable losses of electrochemical capacity over successive charge-discharge cycles.

[0004] The inventors have previously reported the development of a type of electroactive material having a composite structure in which electroactive materials, such as silicon, are deposited within a pore network of highly porous particles, such as porous carbon material, having a carefully controlled pore size distribution. Patent documents 1 and 2 disclose a type of composite particle with improved electrochemical properties, which may be attributed to the microstructure of the particles. The electroactive material forms small domains of several nanometers or less in size within the pore network of the porous particles, which function as the backbone of the composite particle. The fine electroactive structure is thought to have lower resistance to elastic deformation and higher fracture resistance than larger electroactive structures, and therefore can be lithium-ionized and delithiated without excessive structural stress. As a result, the electroactive material exhibits excellent reversible capacity retention over many charge-discharge cycles. Secondly, by controlling the filling of silicon within the porous carbon backbone so that only a portion of the pore volume is occupied by uncharged silicon, the unoccupied pore volume of the porous carbon backbone can accommodate a considerable amount of silicon expansion inside. Excessive expansion is suppressed by the particle backbone. Furthermore, since only a small portion of the electroactive material surface is accessible to the electrolyte, SEI formation is substantially hindered.

[0005] Exposed silicon surfaces are highly reactive and rapidly form a native oxide layer when exposed to air or moisture. When silicon is deposited in the pore structure of highly porous particles by the thermal decomposition of silicon-containing precursor compounds (silane, SiH4, etc.), the silicon surface is terminated with Si-H bonds, which rapidly react with oxygen and / or moisture in the atmosphere to form silicon oxide, generating hydrogen gas (H2 gas) as a byproduct. Uncontrolled reactions on the silicon surface result in composite particles with excessive oxidation and impaired electrochemical properties.

[0006] Therefore, the applicant has developed various techniques for passivating silicon-containing composite particles that reduce surface activity while maintaining favorable electrochemical properties, including initial capacity and capacity retention over multiple charge-discharge cycles. For example, Patent Document 3 describes passivation of silicon surfaces using controlled air oxidation and / or passivation with a series of chemical agents that can react with the silicon surface to prevent further oxidation. First-cycle efficiency is a critical parameter for lithium-ion batteries. If silicon is extensively oxidized, silicon oxide reacts with lithium during the first charge cycle to form lithium silicate, which hinders the release of lithium during subsequent discharges. Since this irreversible consumption of lithium reduces the battery capacity in subsequent discharge cycles, controlling silicon oxidation is extremely important.

[0007] Currently, even these passivated particles retain a low level of surface reactivity, and it is known that hydrogen gas is generated during storage through reaction with moisture in the atmosphere. Hydrogen gas can also be generated during electrode manufacturing when composite particles are combined with binders and conductive additives in an aqueous slurry before being coated onto the current collector. Although not bound by theory, it is thought that hydrogen generation is caused by water diffusing into the composite particles, diffusing through the passivation layer on the silicon surface, where it reacts with the internal silicon to form silicon oxide, generating hydrogen gas as a byproduct. This problem is even more serious in the case of electroactive materials as described above, because the silicon domain size is extremely small, allowing more silicon surface potential access through the diffusion of water into the composite particles.

[0008] While hydrogen gas generation can pose a significant risk when electrodes are manufactured on a production scale, much of the research on silicon-based electrodes to date has been conducted on a laboratory scale. As silicon-based electroactive materials move towards full commercialization, the problem of hydrogen generation must be addressed to meet the safety standards required in full-scale manufacturing. Furthermore, excessive hydrogen gas generation can have detrimental effects on the manufacture of electrode coatings, particularly when aqueous binders are used. Hydrogen gas generated during the formation of electrode slurries can cause foaming and viscosity increases in the slurry, potentially leading to the formation of poor-quality coatings when the slurry is cast onto current collectors. References to hydrogen gas generation in this specification are understood to mean the generation of H2 gas. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] International Publication No. 2020 / 095067 [Patent Document 2] International Publication No. 2020 / 128495 [Patent Document 3] International Publication No. 2022 / 029422 [Overview of the project]

[0010] In a first embodiment, the present invention relates to a method for producing composite particles, (a) A step of preparing a plurality of porous particles including micropores and / or mesopores, wherein the total pore volume of the micropores and mesopores, as measured by nitrogen gas adsorption, is 0.4 cm³. 3 / g~2.2cm 3 Processes within the range of / g (b) A step of bringing porous particles into contact with a silicon-containing precursor at a temperature and pressure effective for depositing silicon in the pores of the porous particles to form silicon-containing composite particles, (c) Optionally, a step of bringing silicon-containing composite particles derived from step (b) into contact with a passivation agent, (d) A step of contacting silicon-containing composite particles derived from step (b) or step (c) with liquid water or a gas containing water vapor, wherein the contact is carried out at a temperature of at least 30°C. The present invention provides a manufacturing method that includes the following:

[0011] Accordingly, the present invention generally relates to a method for producing composite particles, wherein a plurality of nanoscale silicon domains are deposited in a pore network of porous particles, including micropores and mesopores, by thermal decomposition of a silicon-containing precursor material. This type of deposition method is referred to as chemical vapor infiltration (CVI). Accordingly, the composite particles produced according to the production method of the present invention comprise a first component in the form of a porous particle skeleton derived from porous particles prepared in step (a), and a second component in the form of a plurality of nanoscale silicon domains deposited in the pore structure of the porous particle skeleton in step (b). As used herein, the term “nanoscale silicon domain” refers to a nanoscale body of silicon having a maximum size determined by the position of silicon in the micropores and / or mesopores of the porous particles.

[0012] The manufacturing method of the present invention is based on the prior disclosure by the applicant, by using step (d) in which composite particles formed by a CVI process are subjected to a stabilization treatment using liquid water or steam at an increased temperature. Here, the manufacturing method of the present invention has been confirmed to provide an effective solution to the problem of hydrogen generation from composite particles containing nanoscale silicon domains within the conductive particle framework. Although not bound by theory, it is thought that water molecules from the liquid water or steam used in step (d) diffuse into the composite particle structure and react with residual reactive sites on the silicon surface to form silicon oxides, generating hydrogen gas as a byproduct. These active sites are thought to be mainly in the form of hydride-terminated silicon on the surface of the silicon nanostructure. Therefore, the manufacturing method of the present invention essentially ensures that the reactions of these residual reactive sites occur under controlled conditions during particle manufacturing, rather than under uncontrolled conditions during downstream processing of the composite particles for electrode formation.

[0013] Furthermore, it is understood that the passivated silicon surface of composite particles prepared according to the manufacturing method of the present invention is more effectively attenuated than known passivated materials in preventing subsequent access of water (e.g., moisture in the atmosphere or water used to form the slurry during electrode manufacturing) to the underlying silicon. Therefore, hydrogen generation over time from composite particles formed according to the manufacturing method of the present invention is significantly reduced compared to known composite particles.

[0014] A further advantage is that the manufacturing method of the present invention achieves a reduction in hydrogen generation (i.e., H2 gas generation) without a significant increase in the silicon oxide content of the composite particles. As described above, a low oxygen content of the composite particles is required to maintain high first-cycle efficiency.

[0015] This manufacturing method also allows for the subsequent application of any functional coating or shell to the outer surface of the composite particles, completely or partially covering the passivated silicon surface. As a result, the diffusion of water through the functional coating or shell during handling, storage, and / or use is prevented from further inward diffusion by the passivated silicon surface of the present invention, thereby maintaining the chemical stability of the composite particles. The functional coating or shell is a coating or shell that improves the functionality of the composite particles, for example, by improving electronic conductivity and / or ionic conductivity, improving the structural strength or robustness of the particles, or by enhancing the chemical compatibility of the composite particle surface with electrodes, electrode compositions, or other components in electrode slurries.

[0016] In a second embodiment, the present invention provides composite particles that can be obtained by the manufacturing method of the first embodiment.

[0017] In a third aspect, the present invention relates to a composite particle comprising a porous particle skeleton and silicon, (a) The porous particle framework contains micropores and / or mesopores, and the total pore volume of micropores and mesopores, as measured by nitrogen gas adsorption, is 0.4 cm³. 3 / g~2.2cm 3 It is within the range of / g. (b) Silicon is located within the micropores and / or mesopores of the porous particle framework, The present invention provides composite particles having a hydrogen activity of less than 40 μmol per gram of silicon for 7 days in water.

[0018] As used herein, the 7-day hydrogen activity of composite particles represents the cumulative amount of hydrogen generated (as H2 gas) observed when 0.5 g of composite particles are stored in 10 g of deionized water at 25°C for 7 days (168 hours), and is quantified according to the measurement method defined below. The present invention provides, in particular, a composition consisting solely of composite particles of a third embodiment.

[0019] In a fourth embodiment, the present invention relates to a method for manufacturing an electrode, (a) A step of combining composite particles of the second or third embodiment with an aqueous liquid and at least one binder, (b) A step of casting the slurry onto the current collector, (c) A step of drying the cast slurry to form a coating layer on the current collector, The present invention provides a manufacturing method that includes the following: [Modes for carrying out the invention]

[0020] A manufacturing method according to the first aspect of the present invention is: (a) A step of preparing a plurality of porous particles including micropores and / or mesopores, wherein the total pore volume of the micropores and mesopores, as measured by nitrogen gas adsorption, is 0.4 cm³. 3 / g~2.2cm 3 Processes within the range of / g (b) A step of bringing porous particles into contact with a silicon-containing precursor at a temperature and pressure effective for depositing silicon in the pores of the porous particles to form silicon-containing composite particles, (c) Optionally, a step of bringing silicon-containing composite particles derived from step (b) into contact with a passivation agent, (d) A step of contacting silicon-containing composite particles derived from step (b) or step (c) with liquid water or a gas containing water vapor, wherein the contact is carried out at a temperature of at least 30°C. Includes.

[0021] Porous particles serve as a framework for deposited silicon in the form of multiple silicon domains extending throughout the entire pore volume of the porous particles. Due to the dimensions of the micropores and mesopores, silicon domains generally have a maximum dimension of less than 50 nm in any direction, and usually significantly smaller than 50 nm. Domains can take the form of, for example, regular or irregular particles, bounded layers, or coating regions.

[0022] The manufacturing method of the present invention differs from known CVI processes in that it uses a water contact step (step (d)) to react with residual active sites on the silicon surface when the composite particles are exposed to moisture during storage or downstream processing, and to minimize hydrogen generation.

[0023] Step (d) is carried out at a temperature of at least 30°C. More preferably, the temperature in step (d) is at least 40°C, more preferably at least 50°C, more preferably at least 60°C, more preferably at least 80°C, more preferably at least 100°C, more preferably at least 120°C, more preferably at least 140°C, more preferably at least 160°C, more preferably at least 180°C, more preferably at least 200°C, more preferably at least 220°C, and more preferably at least 240°C. When the temperature rises above 50°C, the diffusion rate of water into the composite particles increases, and as a result, a complete reaction can be achieved in a shorter time.

[0024] If the conditions in step (d) are too harsh, excessive oxidation of silicon may occur, which leads to a loss of electrochemical capacity. Therefore, in order to maintain the oxide content of the composite particles within the desirable range of less than 4% by weight, the temperature in step (d) is preferably 400°C or lower, more preferably 380°C or lower, more preferably 360°C or lower, more preferably 350°C or lower, more preferably 340°C or lower, more preferably 320°C or lower, more preferably 300°C or lower, and more preferably 280°C or lower.

[0025] For example, the temperature in step (d) is preferably in the range of 40°C to 400°C, more preferably 100°C to 350°C, more preferably 120°C to 300°C, and more preferably 140°C to 280°C.

[0026] Preferably, the manufacturing method of the present invention is controlled so that the silicon nanoscale domains of the composite particles contain amorphous silicon, which is substantially non-crystalline.

[0027] Preferably, the composite particles obtained from step (d) have a total oxygen content of less than 6% by weight, or less than 5% by weight, or less than 4.5% by weight, or less than 4% by weight, or less than 3.5% by weight, or less than 3.2% by weight, or less than 3% by weight, or less than 2% by weight, or less than 1% by weight, or less than 0.5% by weight, relative to the total mass of the composite particles.

[0028] The water used in process (d) may be in the form of liquid water or water vapor. Below the boiling point of water, water may be liquid or water vapor in the form of a humidified gas. Above the boiling point of water, water takes the form of water vapor. The use of water vapor may be preferred in terms of faster diffusion and the possibility of using higher temperatures.

[0029] If water vapor is used in step (d), it is preferably used in a mixture with a carrier gas, so that the carrier gas contains 1 mol% to 60 mol% water vapor, or 2 mol% to 55 mol% water vapor, or 3 mol% to 50 mol% water vapor, or 4 mol% to 45 mol% water vapor, or 5 mol% to 40 mol% water vapor, or 8 mol% to 35 mol% water vapor, or 10 mol% to 30 mol% water vapor, or 12 mol% to 25 mol% water vapor, or 15 mol% to 20 mol% water vapor. A suitable carrier gas is air. The average molar mass of air (approximately 78% nitrogen, N2; 21% oxygen, O2; 1% other gas) is said to be 28.57 g / mol.

[0030] If steam is used in process (d), the pressure in process (d) is preferably in the range of 5 kPa to 5000 kPa, or 10 kPa to 2000 kPa, or 20 kPa to 1000 kPa, or 50 kPa to 500 kPa, or 80 kPa to 200 kPa, or 90 kPa to 150 kPa, or 95 kPa to 120 kPa, or about 100 kPa.

[0031] If steam is used in step (d), the total duration of contact in step (d) may be in the range of 1 minute to 600 minutes, for example, 2 minutes to 300 minutes, or 5 minutes to 240 minutes, or 10 minutes to 180 minutes, or 15 minutes to 120 minutes, or 20 minutes to 100 minutes, or 25 minutes to 80 minutes, or 30 minutes to 60 minutes.

[0032] Optionally, if water vapor is used in step (d), step (d) may be carried out in steps, for example, by first contacting the composite particles with a gas with a low water vapor content in the initial contact step, and then increasing the water vapor content in subsequent contact steps. This ensures control of the reaction rate in the initial step, where the composite particles contain more densely packed reactive sites. As the density of reactive sites decreases, the water vapor content may be increased to expedite the completion of the reaction. For example, step (d) may include an initial step in which the gas contains 1 mol% to less than 10 mol% water vapor, and at least one subsequent step in which the water vapor content of the gas is increased to 10 mol% to 60 mol%. Each step can independently have a duration of 1 minute to 60 minutes. Optionally, there may be up to 10 steps in which the water vapor content of the gas in each step increases compared to the previous step.

[0033] If the carrier gas contains oxygen, the oxidative passivation of the silicon surface by oxygen can be carried out simultaneously with the reaction with water in step (d).

[0034] If liquid water is used in step (d), the temperature in step (d) is preferably in the range of 30°C to 150°C, more preferably in the range of 30°C to 99.5°C, more preferably in the range of 40°C to 99°C, more preferably in the range of 50°C to 98°C, more preferably in the range of 60°C to 97°C, more preferably in the range of 70°C to 96°C, and more preferably in the range of 80°C to 95°C. It will be understood that temperatures above 100°C may be used, provided that the reaction vessel is pressurized to a pressure sufficient to prevent the water from boiling. In some embodiments, temperatures up to 350°C, or up to 300°C, and pressures up to 10,000 kPa may be used.

[0035] If liquid water is used in step (d), the pressure in step (d) is preferably in the range of 1 kPa to 1000 kPa, or 1 kPa to 500 kPa, or 50 kPa to 200 kPa, or 80 kPa to 150 kPa, or 90 kPa to 120 kPa, or about 100 kPa.

[0036] If liquid water is used in step (d), the silicon-containing composite particles and water may be in the form of an aqueous suspension (slurry) containing more than 60% by weight of water or more than 80% by weight of water. Alternatively, the silicon-containing composite particles and water may be in the form of a moist cake containing 2% to 60% by weight of water (e.g., 10% to 60% by weight of water or 20% to 50% by weight of water) relative to the total amount of water and silicon-containing composite particles. Preferably, the moist cake can be obtained by forming a slurry using excess water and then removing the excess water by filtration.

[0037] If liquid water is used in step (d), the total duration of contact in step (d) may be in the range of 5 minutes to 24 hours, or 10 minutes to 12 hours, or 15 minutes to 6 hours, or 20 minutes to 5 hours, or 25 minutes to 3 hours, or 30 minutes to 2 hours.

[0038] Preferably, step (d) includes contacting silicon-containing composite particles derived from step (b) or step (c) with liquid water at a temperature in the range of 60°C to 120°C, where the composite particles and liquid water are in the form of a slurry containing more than 60% by weight of water. Preferably, the duration of contact is 30 minutes to 6 hours. Optionally, the composite particles and liquid water are stirred during step (d).

[0039] The contact between the silicon-containing composite particles and liquid water in step (d) is preferably carried out in a sealed container. The sealed container prevents water loss to the atmosphere so that a specific weight ratio of composite particles to water is maintained throughout step (d).

[0040] In step (d), when silicon-containing composite particles are brought into contact with liquid water, the liquid water may contain one or more additives.

[0041] Suitable additives include polymers such as polyacrylic acid (PAA), polyvinyl acetate (PVA), polyvinylpyrrolidone (PVP), polystyrene sulfonic acid (PSS), polyethylene glycol (PEG), poly(3,4-ethylenedioxythiophene) (PEDOT), or combinations thereof. Preferred polymer additives include mixtures of PAA and PVA.

[0042] Furthermore, suitable additives may include anionic and cationic dyes, xanthene dyes, indigo dyes, phthalocyanine dyes, anthraquinone dyes, azo dyes, nitro dyes, arylmethane dyes, nitroso dyes, reactive dyes, vat dyes, direct dyes, disperse dyes, and sulfur dyes.

[0043] These polymers or dyes are thought to adsorb onto the surface of the composite particles, thereby providing a barrier against the subsequent oxidation of the silicon.

[0044] Other suitable additives include organic acids such as gallic acid, oxalic acid, acetic acid, lactic acid, tartaric acid, citric acid, and ascorbic acid.

[0045] Other additives may include sugars such as glucose, dextrose, sucrose, or fructose.

[0046] The liquid water may contain one or more of the additives listed above, and such additives may be added at different points in step (d).

[0047] The pH value can be controlled during contact with liquid water. Preferably, the pH is neutral or acidic. The pH value can be controlled during step (d) to be less than 7, less than 5, or less than 3.

[0048] If step (d) involves contacting silicon-containing composite particles with liquid water, it is preferable to dry the composite particles after step (d). Any method that removes liquid water in a broad sense may be used. However, generally, water is removed by a combination of filtration and evaporation. Filtration is effective in substantially removing any free water. However, composite particles generally still contain a considerable amount of water adsorbed on the surface and permeating into the pores. This water is preferably removed by evaporation using heating (e.g., above 50°C), optionally combined with reduced pressure (e.g., below 80kPa).

[0049] Drying is preferably carried out using a combination of heating and depressurization, preferably at a temperature of at least 50°C and a pressure of 50kPa or less, more preferably 10kPa or less.

[0050] Drying is preferably carried out under conditions in which the drying temperature increases as the residual moisture content of the composite particles decreases. For example, the drying temperature may initially be in the range of 50°C to 80°C and can be increased to a temperature in the range of over 80°C to 150°C. The temperature may be increased continuously throughout the drying period. Alternatively, the temperature profile may include one or more fixed drying temperatures that hold the composite particles for a certain period, for example, at least 20 minutes. For example, the composite particles may be held at a first drying temperature in the range of 50°C to 80°C for at least 20 minutes, then heated to a second drying temperature in the range of over 80°C to 150°C, and held at the second drying temperature for at least 20 minutes.

[0051] In a preferred drying method, the composite particles are heated to a first drying temperature in the range of 50°C to 80°C and held at that temperature until the moisture content of the composite particles is less than 3% w / w, and then heated to a second drying temperature in the range of 120°C to 150°C and held at that temperature until the moisture content of the composite particles is less than 0.5% w / w.

[0052] The dried composite particles preferably contain less than 1% by weight of water, more preferably less than 0.5% by weight of water, or less than 0.3% by weight of water.

[0053] Optionally, drying may be carried out using spray drying. Alternatively, kiln, ring dryer, mill drying, or microwave heating may be used.

[0054] In other embodiments, the contact of the silicon-containing composite particles in step (d) may be carried out in an open container. In particular, if the silicon-containing composite particles and water are in the form of a moist cake, the contact in step (d) may be carried out in an open container such that a dry powder is obtained at the end of step (d) by evaporation of the water.

[0055] As defined herein, an open container refers to any container that enables the separation of water from composite particles to obtain a dry powder, such as a container directly open to the atmosphere or a container operated under a gas flow such that water vapor can be removed in the effluent gas stream.

[0056] As defined herein, the dry powder preferably contains less than 1% by weight of water, more preferably less than 0.5% by weight of water.

[0057] The porous particles used in step (a) generally include a three-dimensionally interconnected open pore network containing micropores and / or mesopores, and optionally a small amount of macropores. According to the conventional IUPAC terminology, in this specification, the term "micropore" is used to refer to pores with a diameter less than 2 nm, the term "mesopore" is used to refer to pores with a diameter of 2 nm to 50 nm, and the term "macropore" is used to refer to pores with a diameter greater than 50 nm.

[0058] References herein to the volume of micropores, mesopores, and macropores in the porous particles, and also references to the pore volume distribution within the porous particles, relate to the internal pore volume of the porous particles used as starting materials in step (a) of the production method of the present invention, i.e., before the deposition of silicon into the pore volume in step (b).

[0059] The porous particles used in step (a) can be characterized by the total volume of micropores and mesopores (i.e., the total pore volume in the pore diameter range of 0 nm to 50 nm). Typically, the porous particles contain both micropores and mesopores. However, it is not excluded that porous particles containing only micropores and no mesopores, or containing only mesopores and no micropores, can be used.

[0060] The total volume of micropores and mesopores in the porous particles is at least 0.45 cm 3 / g, or at least 0.5 cm 3 / g, or at least 0.55 cm 3 / g, or at least 0.6cm 3 / g, or at least 0.65cm 3 / g, or at least 0.7cm 3 / g, or at least 0.75cm 3 It is preferable that the value is / g. The use of highly porous particles may be preferable because it allows for a larger amount of silicon to be contained within the pore volume.

[0061] The internal pore volume of the porous particles used in process (a) is appropriately limited such that the increased fragility of the particle structure outweighs the benefits of increased pore volume that can accommodate a larger amount of silicon.

[0062] Preferably, the total volume of micropores and mesopores in the porous particles is 2.0 cm³. 3 Less than / g, or 1.8cm 3 Less than / g, or 1.7cm 3 Less than / g, or 1.6cm 3 Less than / g, or 1.55cm 3 Less than / g, or 1.5cm 3 Less than / g, or 1.45cm 3 Less than / g, or 1.4cm 3 Less than / g, or 1.35cm 3 Less than / g, or 1.3cm 3 Less than / g, or 1.25cm 3 Less than / g, or 1.2cm 3 Less than / g, or 1.15cm 3 Less than / g, or 1.1cm 3 It is less than / g.

[0063] For example, the total volume of micropores and mesopores in the porous particles used in process (a) is 0.45 cm³. 3 / g~2cm 3 / g, or 0.5cm 3 / g~1.8cm 3 / g, or 0.55cm 3 / g~1.6cm 3 / g, or 0.6cm 3 / g~1.5cm 3 / g, or 0.65cm 3 / g~1.4cm 3 / g, or 0.7cm 3 / g~1.3cm 3 / g, or 0.75cm 3 / g~1.2cm 3 The range of / g is also acceptable.

[0064] "PD n In this specification, the general term "pore diameter" refers to the pore diameter of the nth percentile on a volume basis with respect to the total volume of micropores and mesopores in porous particles. For example, as used herein, "PD 50 The term "pore diameter" refers to the pore diameter below which 50% of the total micropore and mesopore volume is observed. To avoid misunderstanding, any macropore volume (pore diameter greater than 50 nm) is not included in the PD. n This is not considered for the purpose of calculating the value.

[0065] PD of porous particles used in process (a) 50 The pore size is preferably 10 nm or less, or 8 nm or less, or 6 nm or less, or 5 nm or less, or 4 nm or less, or 3 nm or less, or 2.5 nm or less, or 2 nm or less, or 1.9 nm or less, or 1.8 nm or less, or 1.7 nm or less, or 1.6 nm or less.

[0066] PD of porous particles used in process (a) 90 The pore size is preferably 20 nm or less, or 15 nm or less, or 12 nm or less, or 10 nm or less, or 8 nm or less, or 6 nm or less, or 5 nm or less. PD of porous particles 90 The pore size is preferably at least 3.2 nm, or at least 3.5 nm, or at least 3.8 nm, or at least 4 nm. For example, PD of porous particles 90 The pore size is preferably in the range of 3.2 nm to 20 nm, 3.5 nm to 15 nm, 3.8 nm to 10 nm, or 4 nm to 8 nm.

[0067] The micropore volume fraction of the porous particles used in step (a) is preferably at least 0.4, at least 0.45, at least 0.5, at least 0.55, or at least 0.6 relative to the total volume of micropores and mesopores in the porous particles.

[0068] The micropore volume fraction of the porous particles used in step (a) is preferably 0.85 or less, or 0.8 or less, or 0.75 or less, or 0.7 or less, relative to the total volume of micropores and mesopores in the porous particles.

[0069] For example, the micropore volume fraction may be in the range of 0.4 to 0.85, 0.45 to 0.85, 0.5 to 0.8, 0.55 to 0.75, or 0.6 to 0.7 relative to the total volume of micropores and mesopores in the porous particle.

[0070] The pore size distribution of the porous particles used in step (a) may be unimodal, bimodal, or multimodal. As used herein, the term “pore size distribution” refers to the distribution of pore sizes with respect to the cumulative total internal pore volume of the porous particles. Bimodal or multimodal pore size distributions may be preferred because the proximity of micropores to larger diameter pores provides the advantage of efficient ion transport through the porous network to silicon.

[0071] 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, with a result of 0.8 × 10⁻⁶. -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 in 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 ASAP 2020 Plus porosity analyzer available from Micromeritics Instrument Corporation in the United States, and the Autosorb IQ porosity analyzer available from Quantachrome Instruments.

[0072] Nitrogen gas adsorption is effective for measuring pore volume and pore size distribution of pores with a diameter of up to 50 nm, but its reliability is low for pores with very large 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 diameter of up to 50 nm, including 50 nm (i.e., only micropores and mesopores). Similarly, PD n The value is determined for the total volume of micropores and mesopores only.

[0073] Given the limitations of available analytical techniques, it is impossible to measure the pore volume and pore size distribution across the entire range of micropores, mesopores, and macropores using a single method. When porous particles contain macropores, the volume of pores with diameters greater than 50 nm and up to 100 nm can be measured by mercury intrusion, preferably at 0.3 cm³. 3 Less than / g, or 0.2cm 3 Less than / g, or 0.1cm 3 Less than / g, or 0.05cm 3The value is less than / g. While a small proportion of macropores may be useful for facilitating electrolyte access within the pore network, the advantages of the present invention are substantially obtained by accommodating silicon in micropores and even smaller mesopores.

[0074] Any pore volume measured by mercury intrusion at pore diameters of 50 nm or less is ignored (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 ignored.

[0075] 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 commercially available, such as the AutoPore IV series automatic mercury intrusion gauges from Micromeritics Instrument Corporation in the United States. For a complete report on mercury intrusion methods, refer to "Analytical Methods in Fine Particle Technology" by PA Webb and C. Orr, 1997, Micromeritics Instrument Corporation (ISBN 0-9656783-0).

[0076] 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 particle. The porosity values ​​specified herein should be understood to refer to the volume of openings, i.e., pores in which fluid can access from outside the porous particle. Completely enclosed pores that cannot be identified by nitrogen adsorption or mercury intrusion shall not be considered when determining the porosity values ​​herein. Similarly, any pore volume located in pores so small that they fall below the detection limit by nitrogen adsorption shall not be considered.

[0077] Porous particles have a minimum size of 500 m 2 / g, or at least 750m 2 / g, or at least 1000m 2 / g, or at least 1250m 2 / g, or at least 1500m 2 It is preferable to have 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 the measurement of the physical adsorption of gas molecules on a solid surface using the Brunauer-Emmett-Teller theory and in accordance with ISO 9277:2022. The BET surface area of ​​porous particles is 4000 m² / g. 2 / g or less, or 3500m 2 / g or less, or 3250m 2 / g or less, or 3000m 2 / g or less, or 2500m 2 / g or less, or 2000m 2 It is preferable that the amount is less than or equal to / g. For example, porous particles are 500m 2 / g~4000m 2 / g, or 750m 2 / g~3500m 2 / g, or 1000m 2 / g~3250m 2 / g, or 1000m 2 / g~3000m 2 / g, or 1000m 2 / g~2500m 2 / g, or 1000m2 / g to 2000 m 2 It may have a BET surface area within the range of / g.

[0078] The porous particles preferably have a particle density of at least 0.35 g / cm 3 and preferably less than 3 g / cm 3 and more preferably less than 2 g / cm 3 and more preferably less than 1.5 g / cm 3 and most preferably less than 0.35 g / cm 3 to 1.2 g / cm 3 As used herein, the term "particle density" refers to the "apparent particle density" measured by mercury intrusion porosimetry (i.e., the particle mass divided by the particle volume, where the particle volume is interpreted as the sum of the volumes of the solid material and any closed pores or blocked pores (a "blocked pore" is a pore too small to be measured by mercury intrusion porosimetry)). The porous particles have a particle density of at least 0.4 g / cm 3 or at least 0.45 g / cm 3 or at least 0.5 g / cm 3 or at least 0.55 g / cm 3 or at least 0.6 g / cm 3 or at least 0.65 g / cm 3 or at least 0.7 g / cm 3 It is preferred to have a particle density of. The porous particles have a particle density of 1.15 g / cm 3 or less, or 1.1 g / cm 3 or less, or 1.05 g / cm 3 or less, or 1 g / cm 3 or less, or 0.95 g / cm 3 or less, or 0.9 g / cm 3 It is preferred to have a particle density of less than.

[0079] The porous particles preferably have a tap density of at least 0.3 g / cm 3 or at least 0.35 g / cm 3 or at least 0.4 g / cm 3 or at least 0.5 g / cm 3 It is preferred to have a tap density of.

[0080] Preferably, porous particles D 10 The particle size is at least 0.8 μm, or at least 1.0 μm, or at least 1.2 μm, or at least 1.4 μm, or at least 1.5 μm, or at least 1.6 μm, or at least 1.8 μm, or at least 2.0 μm, or at least 2.2 μm, or at least 2.4 μm, or at least 2.5 μm, or at least 2.6 μm, or at least 2.8 μm, or at least 3.0 μm.

[0081] Preferably, the porous particles are in the range of 1 μm to 20 μm. 50 It has a particle size. Preferably, porous particles D 50 The particle size is at least 1.5 μm, or at least 2 μm, or at least 2.5 μm, or at least 3 μm. Preferably, porous particles D 50 The particle size is 18 μm or less, or 15 μm or less, or 12 μm or less, or 10 μm or less, or 8 μm or less. For example, porous particles D 50 The particle size may be in the range of 1.5 μm to 18 μm, or 1.5 μm to 15 μm, or 2 μm to 12 μm, or 2 μm to 10 μm, or 2.5 μm to 8 μm, or 3 μm to 8 μm.

[0082] D of porous particles 90 The particle size is preferably 30 μm or less, or 25 μm or less, or 20 μm or less, or 18 μm or less, or 15 μm or less.

[0083] Preferably, the D1 particle diameter of the porous particles is at least 0.1 μm, or at least 0.25 μm, or at least 0.5 μm. Preferably, the D 99 The particle size is 50 μm or less, or 40 μm or less, or 30 μm or less.

[0084] Depositing silicon into excessively large porous particles can be inefficient because precursor molecules must diffuse a longer distance through the pore structure to reach the innermost pores. Depositing silicon into pores close to the particle surface can hinder the access of precursor molecules to the innermost pores, resulting in underfilled particles and thus heterogeneous deposition of silicon between particles of different sizes. Oversized particles also have low packing efficiency and therefore hinder the formation of electrode layers with homogeneous structure and composition.

[0085] Porous particles preferably have a narrow particle size distribution span. For example, a particle size distribution span ((D 90 -D 10 ) / D 50 The (defined as) is preferably 3 or less, more preferably 2 or less, and most preferably 1.5 or less. By maintaining a narrow particle size distribution span, efficient filling of particles into a high-density powder bed can be more easily achieved.

[0086] The particle size distribution of porous particles may be unimodal, bimodal, or multimodal.

[0087] As used herein, the term “particle size” refers to the equivalent diameter (ESD), i.e., the diameter of a sphere having the same volume as a given particle, where the volume of the particle is understood to include the volume of any pores within the particle. n " and "D n The term "particle diameter" refers to the median particle diameter of the nth percentile based on volume, i.e., the diameter at which n% of the volume of the particle population is less than that particle diameter. For example, as used herein, "D 50 " and "D 50 The term "particle diameter" refers to the volume-based median particle diameter, i.e., the diameter below which 50% of the particle population is located.

[0088] Particle size and particle size distribution can be determined by standard 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 a collection of particles generates a scattered light pattern defined by intensity and angle that can correlate with the particle size distribution. Many laser diffraction instruments 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 were measured using a conventional Malvern Mastersizer™ 3000 particle size analyzer manufactured by Malvern Instruments™. This Malvern Mastersizer™ 3000 particle size analyzer operates by projecting a helium-neon gas laser beam through a transparent cell containing the target particles suspended in an aqueous solution. Light rays striking the particles are scattered at angles inversely proportional to the particle size. 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 2-propanol with 5 volume% of the surfactant SPAN(trademark)-40 (sorbitan monopalmitate) added. The particle refractive index is 2.68 for porous particles and 3.50 for composite particles, while the refractive index of the dispersant is 1.378. The particle size distribution is calculated using the Mie scattering model.

[0089] Porous particles are (i) 0.4cm 3 / g~1.8cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, (ii) PD of 10 nm or less 50 PD with a pore size of preferably 20 nm or less 90 Pore ​​diameter, and (iii) D in the range of 1 μm to 20 μm 50 Particle size, It is preferable that it has

[0090] Porous particles are (i) 0.5cm 3 / g~1.6cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, (ii) PD of 8nm or less 50 PD with a pore size of preferably 15 nm or less 90 Pore ​​diameter, and (iii) D in the range of 1 μm to 18 μm 50 Particle size, It is more preferable to have it.

[0091] Porous particles are (i) 0.6 cm 3 / g~1.5cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, (ii) PD of 6nm or less 50 PD with a pore size of preferably 12 nm or less 90 Pore ​​diameter, and (iii) D in the range of 1.5 μm to 15 μm 50 Particle size, It is more preferable to have it.

[0092] Porous particles are (i) 0.65 cm 3 / g~1.4cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, (ii) PD of 2.5 nm or less 50 PD with a pore size of preferably 10 nm or less 90 Pore ​​diameter, and (iii) D in the range of 1.5 μm to 12 μm 50 Particle size, It is more preferable to have it.

[0093] Porous particles are (i) 0.7cm 3 / g~1.3cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, (ii) PD of 4nm or less 50 PD with a pore size of preferably 8 nm or less 90 Pore ​​diameter, and (iii) D in the range of 2 μm to 10 μm 50 Particle size, It is more preferable to have it.

[0094] Porous particles are (i) 0.75 cm 3 / g~1.2cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, (ii) PD of 3nm or less 50 PD with a pore size of preferably 6 nm or less 90 pore diameter, (iii) D in the range of 2 μm to 10 μm 50 Particle size, It is more preferable to have it.

[0095] Porous particles are (i) 0.8cm 3 / g~1.2cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, (ii) PD of 2nm or less 50 PD with a pore size of preferably 5 nm or less 90 pore diameter, (iii) D in the range of 2.5 μm to 8 μm 50 Particle size, It is more preferable to have it.

[0096] The porous particles preferably contain a conductive material. The use of conductive porous particles is preferable because the porous particles form a conductive framework within the composite particles, which facilitates the flow of electrons between the lithium atoms / ions inserted into the silicon and the current collector.

[0097] A preferred type of conductive porous particle is a particle containing or consisting solely of a conductive carbon-based material, which is referred to herein as conductive porous carbon particle.

[0098] The conductive porous carbon particles preferably contain at least 80% by weight of carbon, more preferably at least 85% by weight of carbon, more preferably at least 90% by weight of carbon, more preferably at least 95% by weight of carbon, and optionally at least 98% by weight or at least 99% by weight of carbon. The ash content of the conductive porous carbon particles is preferably 0.5% by weight or less, more preferably 0.4% by weight or less, or 0.3% by weight or less, or 0.2% by weight or less, or 0.15% by weight or less. The carbon may be crystalline carbon, amorphous carbon, or a mixture of amorphous and crystalline carbon. The porous carbon particles may be either hard carbon particles or soft carbon particles.

[0099] As used herein, the term “hard carbon” means 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.

[0100] As used herein, the term "soft carbon" also refers to carbon atoms that are primarily polycyclic aromatic domains having dimensions in the range of 5 nm to 200 nm. 2 This refers to a disordered carbon matrix that exhibits 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, at high temperatures, soft carbon can graphitize. Porous carbon particles preferably have at least 50% sp when measured by XPS. 2It contains mixed carbon. For example, porous carbon particles preferably contain 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.

[0101] If the particulate porous framework is a particulate porous carbon framework, the particulate porous carbon framework is defined by the ratio of the relative intensities of the D peak and G peak (I) of 2.0 or less or 1.8 or less, as measured by Raman spectroscopy. D / I G ) may have. Alternatively or additionally, particulate porous carbon skeleton I D / I G I may be 0.6 or higher, or 0.8 or higher, or 1 or higher, or 1.05 or higher. For example, I of a particulate porous carbon skeleton D / I G This may be in the range of 0.6 to 1.8, or 1.0 to 1.6.

[0102] Various different materials can be used to produce suitable porous carbon particles by pyrolysis. Examples of usable organic materials include plant biomass, including lignocellulosic materials (such as coconut shells, rice husks, hardwoods and softwoods, and products made from them, including bark and sawdust), and fossil carbon sources such as coal. Examples of resins and polymer materials that form porous carbon particles by pyrolysis 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 pyrolysis process, various different carbon materials are available in the art. A wide variety of porous carbon particles with different specifications are available from suppliers.

[0103] To increase the volume of mesopores and micropores, porous carbon particles can be subjected to a chemical or gas activation process. A preferred activation process involves contacting the thermally decomposed carbon with one or more of the following at a temperature in the range of 600°C to 1000°C: oxygen, steam, CO, CO2, boric acid, phosphoric acid, and KOH.

[0104] 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.

[0105] Alternatives to carbon-based conductive particles include titanium nitride (TiN), titanium carbide (TiC), silicon carbide (SiC), and nickel oxide (NiO x ), titanium silicon nitride (TiSiN), nickel nitride (Ni3N), molybdenum nitride (MoN), titanium oxynitride (TiO2) x N 1-x The porous particles include silicon oxide, silicon oxycarbide (SiOC), boron nitride (BN), or vanadium nitride (VN). Preferably, the porous particles include titanium nitride (TiN), silicon oxycarbide (SiOC), or boron nitride (BN).

[0106] Silicon is deposited via a chemical vapor impregnation (CVI) process. As used herein, CVI refers to the process by which a gaseous silicon-containing precursor is thermally decomposed on a surface, forming silicon on the surface and gaseous byproducts. The term “gaseous silicon-containing precursor” is interpreted herein to mean a molecule that is thermally decomposable to form silicon and is in the gas phase under the conditions of step (b).

[0107] The gaseous silicon-containing precursor used in step (b) may be used in pure form (or substantially pure form) or as a diluted mixture with an inert carrier gas, such as nitrogen or argon. Step (b) preferably involves contacting porous particles with a gas containing at least 30 vol%, or at least 40 vol%, or at least 50 vol%, or at least 60 vol%, or at least 70 vol%, or at least 80 vol%, or at least 90 vol%, or at least 95 vol%, or at least 97 vol%, or at least 99 vol% of the silicon-containing precursor relative to the total volume of the gas.

[0108] Suitable gaseous silicon-containing precursors include silane (SiH4), disilane (Si2H6), trisilane (Si3H8), and tetrasilane (Si4H 10 Silicon-containing precursors include silane (SiH4), disilane (Si2H6), trisilane (Si3H8), tetrasilane (Si4H 10 It is preferable to select from the group consisting of ). A particularly preferred silicon precursor is silane.

[0109] When the precursor is a chlorinated compound, such as chlorosilane, the precursor is used in a mixture with hydrogen gas, preferably in an atomic ratio of at least 1:1 between hydrogen and chlorine.

[0110] Optionally, the precursor is chlorine-free. Chlorine-free means that the precursor contains less than 1% by weight, preferably less than 0.1% by weight, and preferably less than 0.01% by weight of a chlorine-containing compound.

[0111] In accordance with conventional methods for operations in an inert atmosphere, the presence of oxygen in step (b) should be avoided to prevent undesirable oxidation of the deposited silicon. Preferably, the oxygen content is less than 0.01% by volume, more preferably less than 0.001% by volume, relative to the total volume of gas used in step (b).

[0112] The temperature in step (b) is preferably in the range of 340°C to 500°C, or 350°C to 480°C, or 350°C to 450°C, or 350°C to 420°C, or 350°C to less than 400°C, or 355°C to 395°C, or 360°C to 390°C, or 365°C to 385°C, or 370°C to 380°C.

[0113] The pressure in process (b) is preferably in the range of 10kPa to 10000kPa, or 20kPa to 5000kPa, or 50kPa to 2000kPa, or 60kPa to 1500kPa, or 70kPa to 1000kPa, or 80kPa to 800kPa, or 90kPa to 600kPa.

[0114] Any reference to pressure in any step of the manufacturing method of the present invention refers to the absolute pressure in the reaction zone, which may include any suitable type of reactor vessel.

[0115] The deposition of silicon by CVI results in the removal of by-products, particularly by-product gases such as hydrogen. Step (b) preferably further includes the separation of by-products from the particles formed in step (b). The separation of by-products can be achieved by flushing the reactor with an inert gas and / or by evacuating the reactor by reducing the pressure. For example, the separation of by-products from the particles formed in step (b) can be achieved by evacuating the reactor to a pressure of less than 100 kPa, or less than 80 kPa, or less than 60 kPa, or less than 40 kPa, or less than 20 kPa, or less than 10 kPa, or less than 5 kPa, or less than 2 kPa, or less than 1 kPa. Evacuating the reactor to a low pressure can be effective not only to remove gaseous by-products but also to desorb any by-products that may be adsorbed on the deposited silicon surface.

[0116] The composite particles obtained in step (b) preferably contain at least 26 wt% silicon, or at least 28 wt% silicon, or at least 30 wt% silicon, or at least 32 wt% silicon, or at least 34 wt% silicon, or at least 36 wt% silicon, or at least 38 wt% silicon, or at least 40 wt% silicon, or at least 42 wt% silicon, or at least 44 wt% silicon, based on the total mass of the particles.

[0117] The amount of silicon in the composite particles is preferably selected such that at least 20% and up to 90% of the internal pore volume of the porous particles is occupied by silicon after step (b). For example, silicon may occupy 20% to 80%, or 25% to 75%, or 30% to 70%, or 35% to 65%, or 40% to 60%, or 45% to 55% of the internal pore volume of the porous particles. Within these preferred ranges, the remaining pore volume of the porous particles is effective in accommodating the expansion of silicon during charging and discharging without having an excessively large pore volume that does not contribute to the volumetric capacity of the particulate particles. However, the amount of silicon is also not high enough to hinder effective lithiation due to an inadequate metal ion diffusion rate or an inadequate expansion volume that results in mechanical resistance to lithiation.

[0118] The amount of silicon in the composite particles is determined by the mass ratio of silicon to porous particles [0.5 × P 1 ~1.9×P 1 The requirement that ]:1 can be related to the available pore volume in porous particles, where P 1 is, cm 3 This is a dimensionless number representing the size of the total pore volume of micropores and mesopores in porous particles, as shown in / g (for example, if the porous particle is 1.2 cm²). 3 If the total volume of micropores and mesopores is 1 / g, then P 1 (=1.2). This relationship defines the weight ratio of silicon that occupies approximately 20% to 82% of the pore volume, taking into account the density of silicon and the pore volume of the porous particles. The weight ratio of silicon deposited in process (b) to porous particles is [0.6 × P 1 ~1.8×P 1 ]:1, or [0.7 × P 1 ~1.7×P 1 ]:1, or [0.8 × P 1 ~1.6×P 1 It is preferable that the range is 1.

[0119] The amount of silicon in the composite particles can be determined by elemental analysis. Preferably, elemental analysis is used to determine the elemental composition of only the porous particles and the composition of the composite particles.

[0120] The silicon content is preferably determined by ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry). Many ICP-OES devices are commercially available, such as the iCAP (trademark) 7000 series of ICP-OES analyzers available from ThermoFisher Scientific. The carbon content (and, if necessary, the hydrogen, nitrogen, and oxygen contents) in the composite particles and the porous carbon particles is preferably determined by IR absorption. A suitable device for determining the carbon, hydrogen, nitrogen, and oxygen contents is the TruSpec (trademark) Micro elemental analyzer available from Leco Corporation.

[0121] On the outer surface of the composite particles, preferably at least 90 wt%, more preferably at least 95 wt%, even more preferably at least 98 wt% of the silicon in the composite particles is located within the internal pore volume of the porous particles so that hardly any or almost no silicon is located on the outer surface. As discussed above, the deposition of silicon during the CVI process occurs on the surface of the porous particles. Considering the very high internal surface area of the porous particles, the reaction kinetics of the CVI process ensures that the deposition of silicon occurs almost entirely within the pores of the porous particles. The internal deposition of silicon is further improved by the requirement that the pressure in step (b) is maintained below 200 kPa or within the more preferred pressure range discussed above.

[0122] The production method of the present invention (c) a step of contacting the surface of the particles derived from step (b) with a passivating agent is preferably further included.

[0123] Therefore, it is preferable that the manufacturing method of the present invention includes a two-step passivation procedure in which step (d) is performed as a post-passivation treatment following passivation in step (c). It will be understood that the passivating agent used in step (c) is different from the water used in step (d).

[0124] As defined herein, a passivating agent is a compound or mixture of compounds capable of reacting with the silicon surface deposited in step (b) to form a modified surface. In particular, the passivating agent defined herein is a material that can react with the surface of silicon and further reduce its surface energy.

[0125] One type of passivation layer is a native oxide layer. For example, a native oxide layer may be formed by exposing the silicon surface to a passivating agent selected from air or another oxygen-containing gas. The passivation layer may contain an oxide of the formula SiO x (where 0 < x ≦ 2). The oxide is preferably amorphous. The formation of the native oxide layer is exothermic and therefore requires careful process control to prevent overheating or even combustion of the particulate material. When the passivating agent is an oxygen-containing gas, step (c) may include cooling the material formed in step (b) to a temperature below 400°C, preferably below 300°C, optionally below 200°C, before contacting the silicon surface with the oxygen-containing gas.

[0126] Another type of passivation layer is a nitride layer formed, for example, by exposing the silicon surface to a passivating agent selected from ammonia or another nitrogen-containing molecule. The passivation layer has the formula SiN x(where 0 < x ≦ 4 / 3) may contain a nitride. The nitride is preferably amorphous. The nitride layer can be formed by contacting the silicon surface with ammonia at a temperature in the range of 200°C to 700°C, preferably 400°C to 700°C, more preferably 400°C to 600°C. Then, if necessary, the temperature can be raised to the range of 500°C to 1000°C to form a nitride surface. Nitride passivation may be preferred over oxide passivation. Stoichiometric nitrides (e.g., SiN x (where 0 < x ≦ 4 / 3)) are conductive, so the nitride passivation layer can function as a conductive network that enables faster charging and discharging. Phosphine may also be used as a passivating agent as a phosphorus analog of ammonia.

[0127] Another type of passivation layer is, for example, an oxynitride layer formed by exposing the silicon surface to a passivating agent containing ammonia (or another nitrogen-containing molecule) and oxygen gas. The passivation layer may contain silicon oxynitride of the formula SiO x N y (where 0 < x < 2, 0 < y < 4 / 3, and 0 < (2x + 3y) ≦ 4). The oxynitride is preferably amorphous.

[0128] Another type of passivation layer is a carbide layer. The passivation layer may contain silicon carbide of the formula SiC x (where 0 < x ≦ 1). The carbide is preferably amorphous. The carbide layer may be formed by contacting the silicon surface with a passivating agent selected from carbon-containing precursors such as methane or ethylene at an elevated temperature, for example, in the range of 250°C to 700°C. At lower temperatures, covalent bonds are formed between the silicon surface and the carbon-containing precursor, which is converted to a single layer of crystalline carbide as the temperature rises.

[0129] Other suitable passivating agents include compounds containing alkene, alkyne or carbonyl functional groups, more preferably terminal alkene, terminal alkyne, aldehyde or ketone groups.

[0130] A preferred passivating agent is one with the formula: (i)R 1 -CH=CH-R 1 , (ii)R 1 -C≡CR 1 , and, (iii) O=CR 1 R 1 , (In the formula, each R 1 This independently represents H, or an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 carbon atoms, or two R 1 Examples include one or more compounds in which the group forms an unsubstituted or substituted ring structure containing 3 to 8 carbon atoms in the ring.

[0131] A particularly preferred passivator is one of the following formulas: (i) CH2 = CH-R 1 , and, (ii) HC≡CR 1 , (In the formula, R 1 Examples include one or more compounds of (as defined above). Preferably, R 1 This is a non-substitution.

[0132] Suitable passivators include ethylene, propylene, 1-butene, butadiene, 1-pentene, 1,4-pentadiene, 1-hexene, 1-octene, styrene, divinylbenzene, acetylene, phenylacetylene, norbornene, norbornadiene, and bicyclo[2.2.2]octa-2-ene. Optionally, mixtures of different passivators may also be used.

[0133] Passivating agents containing alkenes, alkynes, or carbonyl groups are thought to form a covalently passivated surface resistant to oxidation by air through insertion reactions with MH groups (e.g., Si-H groups) on the silicon surface. For example, the passivation reaction between the silicon surface and the passivating agent can be understood as one form of hydrosilylation, as schematically shown below. [Chemical]

[0134] Other suitable passivating agents include compounds containing active hydrogen atoms bonded to oxygen, nitrogen, sulfur or phosphorus. For example, the passivating agent may be an alcohol, an amine, a thiol or a phosphine. The reaction of the -XH group with the hydride group on the silicon surface is understood to result in the removal of H2 and the formation of a direct bond between X and the silicon surface.

[0135] Suitable passivating agents in this category include the formula: (iv) HX-R 2 and (v) HX-C(O)-R 1 where X represents O, S, NR 1 or PR 1 each R 1 is independently as defined above, and R 2 represents an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 carbon atoms, or R 1 and R 2 together form an unsubstituted or substituted ring structure containing 3 to 8 carbon atoms in the ring).

[0136] Preferably, X represents O or NH.

[0137] Preferably, R 2 represents an optionally substituted aliphatic or aromatic group having 2 to 10 carbon atoms. An amine group may be incorporated into a 4- to 10-member aliphatic or aromatic ring structure, as in pyrrolidine, pyrrole, imidazole, piperazine, indole, or purine.

[0138] The contact of silicon with the passivating agent in step (d) can be carried out at a temperature in the range of 25°C to 500°C, preferably 50°C to 450°C, more preferably 100°C to 400°C. <00

[0139] The manufacturing method of the present invention optionally further includes, before the subsequent steps, a step of heat-treating the particles derived from step (b) at a temperature of at least 400°C in the presence of an inert gas.

[0140] This heat treatment is thought to promote hydrogen desorption and solid-phase rearrangement of silicon atoms, thereby reducing the density of unstable and reactive Si-H bonds and promoting the formation of more thermodynamically stable Si-Si bonds. This is expected to contribute to improved silicon stability during charging and discharging, and consequently to improved cycle life of metal-ion batteries containing composite particles.

[0141] The temperature during the heat treatment process is generally higher than the temperature in process (b). Preferably, the temperature during the heat treatment process is at least 20°C, or at least 40°C, or at least 60°C, or at least 80°C, or at least 100°C, or at least 120°C, or at least 140°C, or at least 150°C higher than the temperature in process (b).

[0142] The heat treatment process is carried out in the presence of an inert gas. In this specification, an inert gas refers to any gas that does not react under general reaction conditions. Preferably, the inert gas is selected from nitrogen and noble gases, particularly argon. Optionally, the inert gas may include hydrogen. The inert gas can be selected from the group consisting of nitrogen, argon, helium, and combinations thereof.

[0143] The heat treatment process is performed before processes (c) and (d). One effect of the heat treatment process is to reopen the pore spaces that were previously blocked or capped by the silicon nanostructure, thereby allowing the pore spaces to access the passivation gas, and thus enabling more extensive passivation of the silicon surface and reduction or elimination of hydrogen-terminated silicon surfaces.

[0144] The characteristics of the porous particles used in the manufacturing method of the present invention, and the CVI conditions described above, are carefully controlled to obtain composite particles containing fine silicon nanostructures having dimensions of a few nanometers or less. The morphology of these silicon nanostructures can be analyzed by thermogravimetric analysis (TGA) in air. This analytical method is based on the principle that a weight increase is observed when silicon is oxidized in air and at increasing temperatures. Atoms on or near the surface of electroactive nanostructures are oxidized at lower temperatures than atoms in the bulk (Reference: Bardet et al., Phys. Chem. Chem. Phys. (2016), 18, 18201). By plotting the weight increase against temperature, it is possible to distinguish and quantify the environment of silicon atoms in the sample.

[0145] As described above, Patent Document 3 uses the term "surface silicon" to refer to silicon atoms in the surface region of silicon nanostructures, and the term "crude bulk silicon" to refer to silicon atoms located inside bulky / crude silicon structures. It has been found that optimal performance is achieved when the ratio of "surface silicon" to "crude bulk silicon" is high.

[0146] As defined herein, “surface silicon” is calculated from the initial mass increase of the TGA trace from a minimum value between 150°C and 500°C to a maximum mass measured in the temperature range between 550°C and 650°C, with the TGA performed at a heating rate of 10°C / min in air. This mass increase is due to the oxidation of silicon atoms adjacent to the surface of the silicon nanostructures, and is therefore referred to herein as “surface silicon”. A high surface silicon content indicates that the silicon content of the composite particles is primarily in the form of very fine nanostructures.

[0147] The percentage of surface silicon relative to the total amount of silicon is given by the following formula: Y = 1.875 × [(M max -M min ) / M f ] × 100% (In the formula, Y is the percentage of surface silicon as a ratio to the total silicon in the sample, and M max This is the maximum mass of a sample measured in the temperature range between 550°C and 650°C, and M min This is the minimum mass of the sample at temperatures above 150°C and below 500°C, M f The ratio is determined according to the mass of the sample at 1400°C (where is the mass of the sample when oxidation is complete). For completeness, it will be understood that 1.875 is the molar mass ratio of SiO2 to O2 (i.e., the mass ratio of formed SiO2 to the mass increase due to the addition of oxygen). Typically, TGA analysis is performed using a sample size of 10 mg ± 2 mg.

[0148] It has been found that when the surface silicon determined by the above TGA method is at least 20% by weight of the total silicon in the material, the reversible capacity retention rate over many charge-discharge cycles is significantly improved. Preferably, the surface silicon determined by thermogravimetric analysis (TGA) is at least 22% by weight, or at least 25% by weight, at least 30% by weight, or at least 35% by weight, or at least 40% by weight, or at least 45% by weight of silicon.

[0149] In addition to the surface silicon content, silicon-containing composite particles obtained by the manufacturing method of the present invention preferably have a low content of coarse bulk silicon, as determined by TGA. Coarse bulk silicon is defined herein as silicon that undergoes oxidation above 800°C, as determined by TGA, where TGA is performed in air at a heating rate of 10°C / min. A high coarse bulk silicon content indicates that the silicon content of the composite particles is mainly in the form of bulky, coarse silicon domains, which may include undesirable silicon deposits on the outer surface of the composite particles.

[0150] The crude bulk silicon content is given by the following formula: Z = 1.875 × [(M f -M 800 ) / Mf ] × 100% (In the formula, Z is the percentage of unoxidized silicon at 800°C, and M 800 This is the mass of the sample at 800°C, M f The TGA is determined according to the mass of ash at 1400°C (where is the mass of ash when oxidation is complete). For the purposes of this analysis, any mass increase above 800°C is assumed to correspond to oxidation from silicon to SiO2, and the total mass at the completion of oxidation is assumed to be SiO2. Typically, TGA analysis is performed using a sample size of 10 mg ± 2 mg.

[0151] Silicon that undergoes oxidation above 800°C is undesirable. As determined by TGA, the crude bulk silicon is preferably 10% by weight or less, or 8% by weight or less, or 6% by weight or less, or 5% by weight or less, or 4% by weight or less, or 3% by weight or less, or 2% by weight or less, or 1.5% by weight or less of the total silicon.

[0152] Preferably, at least 25% by weight of the silicon is surface silicon and 10% by weight or less of the silicon is crude bulk silicon, both determined by TGA. More preferably, at least 30% by weight of the silicon is surface silicon and 10% by weight or less of the silicon is crude bulk silicon, both determined by TGA. More preferably, at least 30% by weight of the silicon is surface silicon and 8% by weight or less of the silicon is crude bulk silicon, both determined by TGA. More preferably, at least 35% by weight of the silicon is surface silicon and 8% by weight or less of the silicon is crude bulk silicon, both determined by TGA. More preferably, at least 30% by weight of the silicon is surface silicon and 6% by weight or less of the silicon is crude bulk silicon, both determined by TGA. More preferably, at least 35% by weight of the silicon is surface silicon and 4% by weight or less of the silicon is crude bulk silicon, both determined by TGA. More preferably, at least 40% by weight of the silicon is surface silicon and 5% by weight or less of the silicon is crude bulk silicon, both determined by TGA. More preferably, at least 45% by weight of the silicon is surface silicon and 2% by weight or less of the silicon is crude bulk silicon, both of which are determined by TGA.

[0153] For further disclosures regarding the production of composite particles containing high-content "surface silicon" and low-content "crude bulk silicon," and their measurement by TGA, see Patent Document 3.

[0154] The aforementioned disclosure of preferred embodiments provides an optimized pore structure for the porous particle framework and a set of conditions for the deposition of silicon within the porous particle framework. This also ensures that a large amount of silicon is incorporated into the composite particles as a whole to satisfy the overall volumetric energy density requirements, while allowing for an increased proportion of "surface silicon" and a low content of "crude bulk silicon".

[0155] The composite particles obtained according to the manufacturing method of the present invention are preferably 100 m 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 / g or less, or 10m 2 / g or less, or 5m 2 The BET surface area is less than or equal to 0.1 m² / g. Generally, a low BET surface area is preferred to minimize the formation of a solid electrolyte interface (SEI) layer on the composite particle surface during the first charge-discharge cycle of the anode. However, if the BET surface area is excessively low, the charging speed and capacity will be unacceptably low because a large amount of silicon in the surrounding electrolyte cannot access the metal ions. The BET surface area is preferably at least 0.1 m². 2 / g, or at least 1m 2 / g, or at least 2m 2 / g, or at least 5m 2 The value is / g. For example, the BET surface area of ​​a composite particle is 0.1m². 2 / g~100m 2 / g, or 0.1m 2 / g~80m 2 / g, or 0.5m 2 / g~60m 2 / g, or 0.5m 2 / g~40m 2 / g, or 1m 2 / g~30m 2 / g, or 1m 2 / g~25m 2 / g, or 2m 2 / g~20m 2 The range of / g is also acceptable.

[0156] The composite particles obtained according to the manufacturing method of the present invention generally have a 7-day hydrogen activity in water of less than 40 μmol per gram of silicon, or less than 35 μmol per gram of silicon, or less than 30 μmol per gram of silicon, or less than 25 μmol per gram of silicon, or less than 20 μmol per gram of silicon, or less than 15 μmol per gram of silicon, or less than 12 μmol per gram of silicon, or less than 10 μmol per gram of silicon.

[0157] Preferably, the composite particles obtained according to the manufacturing method of the present invention have a hydrogen activity in water for 7 days of less than 8 μmol per gram of silicon, or less than 7 μmol per gram of silicon.

[0158] More preferably, the composite particles obtained according to the manufacturing method of the present invention have a 7-day hydrogen activity in water of less than 6 μmol per gram of silicon, or less than 5.5 μmol per gram of silicon, or less than 5 μmol per gram of silicon, or less than 4.5 μmol per gram of silicon, or less than 3.5 μmol per gram of silicon, or less than 3 μmol per gram of silicon, or less than 2.5 μmol per gram of silicon, or less than 2 μmol per gram of silicon.

[0159] The composite particles obtained according to the manufacturing method of the present invention optionally have a 7-day hydrogen activity in water of at least 0.1 μmol per gram of silicon, or at least 0.2 μmol per gram of silicon, or at least 0.3 μmol per gram of silicon, or at least 0.4 μmol per gram of silicon, or at least 0.5 μmol per gram of silicon, or at least 0.6 μmol per gram of silicon, or at least 0.8 μmol per gram of silicon, or at least 1 μmol per gram of silicon.

[0160] Preferably, the composite particles obtained according to the manufacturing method of the present invention have a 3-day hydrogen activity in water of less than 30 μmol per gram of silicon, or less than 20 μmol per gram of silicon, or less than 15 μmol per gram of silicon, or less than 12 μmol per gram of silicon, or less than 10 μmol per gram of silicon, or less than 8 μmol per gram of silicon, or less than 7 μmol per gram of silicon, or less than 6 μmol per gram of silicon, or less than 5 μmol per gram of silicon.

[0161] More preferably, the composite particles obtained according to the manufacturing method of the present invention have a 3-day hydrogen activity in water of less than 4.5 μmol per gram of silicon, or less than 4 μmol per gram of silicon, or less than 3.5 μmol per gram of silicon, or less than 3 μmol per gram of silicon, or less than 2.5 μmol per gram of silicon, or less than 2 μmol per gram of silicon, or less than 1.5 μmol per gram of silicon, or less than 1.2 μmol per gram of silicon.

[0162] Preferably, the composite particles obtained according to the manufacturing method of the present invention have a hydrogen activity in water for 2 days of less than 20 μmol per gram of silicon, or less than 15 μmol per gram of silicon, or less than 12 μmol per gram of silicon, or less than 10 μmol per gram of silicon, or less than 8 μmol per gram of silicon, or less than 7 μmol per gram of silicon, or less than 6 μmol per gram of silicon, or less than 5 μmol per gram of silicon, or less than 4.5 μmol per gram of silicon.

[0163] More preferably, the composite particles obtained according to the manufacturing method of the present invention have a hydrogen activity in water for 2 days of less than 4 μmol per gram of silicon, or less than 3.5 μmol per gram of silicon, or less than 3 μmol per gram of silicon, or less than 2.5 μmol per gram of silicon, or less than 2 μmol per gram of silicon, or less than 1.5 μmol per gram of silicon, or less than 1.2 μmol per gram of silicon, or less than 1 μmol per gram of silicon.

[0164] Preferably, the composite particles obtained according to the manufacturing method of the present invention have a daily hydrogen activity in water of less than 7 μmol per gram of silicon, or less than 6 μmol per gram of silicon, or less than 5 μmol per gram of silicon, or less than 4.5 μmol per gram of silicon, or less than 4 μmol per gram of silicon, or less than 3.5 μmol per gram of silicon, or less than 3 μmol per gram of silicon, or less than 2.5 μmol per gram of silicon, or less than 2 μmol per gram of silicon, or less than 1.5 μmol per gram of silicon, or less than 1.2 μmol per gram of silicon, or less than 1 μmol per gram of silicon, or less than 0.8 μmol per gram of silicon, or less than 0.6 μmol per gram of silicon, or less than 0.5 μmol per gram of silicon.

[0165] Preferably, the composite particles obtained according to the manufacturing method of the present invention have a hydrogen activity in water per hour of less than 1 μmol per gram of silicon, or less than 0.8 μmol per gram of silicon, or less than 0.6 μmol per gram of silicon, or less than 0.5 μmol per gram of silicon, or less than 0.4 μmol per gram of silicon, or less than 0.3 μmol per gram of silicon, or less than 0.2 μmol per gram of silicon, or less than 0.1 μmol per gram of silicon, or less than 0.05 μmol per gram of silicon, or less than 0.01 μmol per gram of silicon.

[0166] The reaction process may be carried out using any reactor capable of bringing solids and gases into contact by raising the temperature. The porous particles and the composite particles to be formed may be present in the reactor in the form of a fixed bed of particles, or in the form of a moving bed or agitated bed of particles.

[0167] The composite particles obtained according to the first aspect of the present invention are novel materials in terms of their exceptional stability against oxidation and hydrogen generation when in contact with water (e.g., moisture in the air or water used to generate an aqueous particle slurry during electrode manufacturing). Accordingly, the second aspect of the present invention provides composite particles that can be obtained by the manufacturing method of the first aspect.

[0168] In a third aspect, the present invention relates to a composite particle comprising a porous particle skeleton and silicon, (a) The porous particle framework contains micropores and / or mesopores, and the total pore volume of micropores and mesopores, as measured by nitrogen gas adsorption, is 0.4 cm³. 3 / g~2.2cm 3 It is within the range of / g. (b) Silicon is located within the micropores and / or mesopores of the porous particle framework, The present invention provides composite particles having a hydrogen activity of less than 40 μmol per gram of silicon for 7 days in water.

[0169] The composite particles of the third embodiment are characterized by very low levels of hydrogen generation upon contact with water. This property of the composite particles is referred to herein as the "hydrogen activity" of the composite particles and is defined as the cumulative amount of hydrogen generated over 7 days in μmoles per gram of silicon. The hydrogen activity is measured by storing 0.5 g of composite particles in 10 g of deionized water in a 20 mL vial with an injectable vial cap at 25°C for 7 days (168 hours). The cumulative amount of hydrogen generated is measured by gas chromatography. The results are then normalized to 1 g of silicon.

[0170] Preferably, the composite particles of the present invention have a 7-day hydrogen activity in water of less than 35 μmol per gram of silicon, or less than 30 μmol per gram of silicon, or less than 25 μmol per gram of silicon, or less than 20 μmol per gram of silicon, or less than 15 μmol per gram of silicon, or less than 12 μmol per gram of silicon, or less than 10 μmol per gram of silicon.

[0171] More preferably, the composite particles of the present invention have a hydrogen activity in water for 7 days of less than 8 μmol per gram of silicon, or less than 7 μmol per gram of silicon.

[0172] More preferably, the composite particles of the present invention have a 7-day hydrogen activity in water of less than 6 μmol per gram of silicon, or less than 5.5 μmol per gram of silicon, or less than 5 μmol per gram of silicon, or less than 4.5 μmol per gram of silicon, or less than 3.5 μmol per gram of silicon, or less than 3 μmol per gram of silicon, or less than 2.5 μmol per gram of silicon, or less than 2 μmol per gram of silicon.

[0173] Optionally, the composite particles of the present invention have a 7-day hydrogen activity in water of at least 0.1 μmol per gram of silicon, or at least 0.2 μmol per gram of silicon, or at least 0.3 μmol per gram of silicon, or at least 0.4 μmol per gram of silicon, or at least 0.5 μmol per gram of silicon, or at least 0.6 μmol per gram of silicon, or at least 0.8 μmol per gram of silicon, or at least 1 μmol per gram of silicon.

[0174] Preferably, the composite particles of the present invention have a hydrogen activity in water for 3 days of less than 30 μmol per gram of silicon, or less than 20 μmol per gram of silicon, or less than 15 μmol per gram of silicon, or less than 12 μmol per gram of silicon, or less than 10 μmol per gram of silicon, or less than 8 μmol per gram of silicon, or less than 7 μmol per gram of silicon, or less than 6 μmol per gram of silicon, or less than 5 μmol per gram of silicon.

[0175] More preferably, the composite particles of the present invention have a 3-day hydrogen activity in water of less than 4.5 μmol per gram of silicon, or less than 4 μmol per gram of silicon, or less than 3.5 μmol per gram of silicon, or less than 3 μmol per gram of silicon, or less than 2.5 μmol per gram of silicon, or less than 2 μmol per gram of silicon, or less than 1.5 μmol per gram of silicon, or less than 1.2 μmol per gram of silicon.

[0176] Preferably, the composite particles of the present invention have a hydrogen activity in water for 2 days of less than 20 μmol per gram of silicon, or less than 15 μmol per gram of silicon, or less than 12 μmol per gram of silicon, or less than 10 μmol per gram of silicon, or less than 8 μmol per gram of silicon, or less than 7 μmol per gram of silicon, or less than 6 μmol per gram of silicon, or less than 5 μmol per gram of silicon, or less than 4.5 μmol per gram of silicon.

[0177] More preferably, the composite particles of the present invention have a hydrogen activity in water for 2 days of less than 4 μmol per gram of silicon, or less than 3.5 μmol per gram of silicon, or less than 3 μmol per gram of silicon, or less than 2.5 μmol per gram of silicon, or less than 2 μmol per gram of silicon, or less than 1.5 μmol per gram of silicon, or less than 1.2 μmol per gram of silicon, or less than 1 μmol per gram of silicon.

[0178] Preferably, the composite particles of the present invention have a daily hydrogen activity in water of less than 7 μmol per gram of silicon, or less than 6 μmol per gram of silicon, or less than 5 μmol per gram of silicon, or less than 4.5 μmol per gram of silicon, or 4 μmol per gram of silicon, or less than 3.5 μmol per gram of silicon, or less than 3 μmol per gram of silicon, or less than 2.5 μmol per gram of silicon, or less than 2 μmol per gram of silicon, or less than 1.5 μmol per gram of silicon, or less than 1.2 μmol per gram of silicon, or less than 1 μmol per gram of silicon, or less than 0.8 μmol per gram of silicon, or less than 0.6 μmol per gram of silicon, or less than 0.5 μmol per gram of silicon.

[0179] Preferably, the composite particles of the present invention have a hydrogen activity in water per hour of less than 1 μmol per gram of silicon, or less than 0.8 μmol per gram of silicon, or less than 0.6 μmol per gram of silicon, or less than 0.5 μmol per gram of silicon, or less than 0.4 μmol per gram of silicon, or less than 0.3 μmol per gram of silicon, or less than 0.2 μmol per gram of silicon, or less than 0.1 μmol per gram of silicon, or less than 0.05 μmol per gram of silicon, or less than 0.01 μmol per gram of silicon.

[0180] Preferably, the composite particles of the present invention have a total oxygen content of less than 5% by weight, or less than 4.5% by weight, or less than 4% by weight, or less than 3.5% by weight, or less than 3.2% by weight, or less than 3% by weight, or less than 2% by weight, or less than 1% by weight, or less than 0.5% by weight, relative to the total mass of the composite particles.

[0181] The porous particle skeleton corresponds to the porous particles used in the first aspect of the present invention after they have been incorporated into the composite particles. Therefore, the porous particle skeleton may have any of the properties described herein for the porous particles used in the first aspect.

[0182] Porous carbon skeletons generally contain a three-dimensionally interconnected network of pores, including micropores and / or mesopores. The total pore volume of micropores and mesopores, as measured by nitrogen gas adsorption, is 0.4 cm³. 3 / g~2.2cm 3 It is in the range of / g. The porous carbon skeleton may optionally contain a small amount of additional macropores. To avoid misunderstanding, references herein to the pore volume of a porous carbon skeleton refer to the pore volume of an isolated porous carbon skeleton, i.e., the pore volume measured in the absence of silicon (or any other material) occupying the pores of the porous carbon skeleton (unless otherwise indicated).

[0183] The total volume of micropores and mesopores in the porous particle skeleton, as measured by nitrogen gas adsorption, is preferably at least 0.45 cm³. 3 / g, or at least 0.5cm 3 / g, or at least 0.55cm 3 / g, or at least 0.6cm 3 / g, or at least 0.65cm 3 / g, or at least 0.7cm 3 / g, or at least 0.75cm 3 It is / g.

[0184] Preferably, the total volume of micropores and mesopores in the porous particle skeleton, as measured by nitrogen gas adsorption, is 2.0 cm³. 3 Less than / g, or 1.8cm 3 Less than / g, or 1.7cm 3 Less than / g, or 1.6cm 3 Less than / g, or 1.55cm 3 Less than / g, or 1.5cm 3 Less than / g, or 1.45cm 3 Less than / g, or 1.4cm 3 Less than / g, or 1.35cm 3 Less than / g, or 1.3cm 3 Less than / g, or 1.25cm 3 Less than / g, or 1.2cm 3Less than / g, or 1.15cm 3 Less than / g, or 1.1cm 3 It is less than / g.

[0185] For example, the total volume of micropores and mesopores in a porous particle framework is 0.45 cm³. 3 / g~2cm 3 / g, or 0.5cm 3 / g~1.8cm 3 / g, or 0.55cm 3 / g~1.6cm 3 / g, or 0.6cm 3 / g~1.5cm 3 / g, or 0.65cm 3 / g~1.4cm 3 / g, or 0.7cm 3 / g~1.3cm 3 / g, or 0.75cm 3 / g~1.2cm 3 The range of / g is also acceptable.

[0186] Porous particle skeleton PD 50 The pore size is preferably 10 nm or less, or 8 nm or less, or 6 nm or less, or 5 nm or less, or 4 nm or less, or 3 nm or less, or 2.5 nm or less, or 2 nm or less, or 1.9 nm or less, or 1.8 nm or less, or 1.7 nm or less, or 1.6 nm or less.

[0187] Porous particle skeleton PD 90 The pore size is preferably 20 nm or less, or 15 nm or less, or 12 nm or less, or 10 nm or less, or 8 nm or less, or 6 nm or less, or 5 nm or less. PD of porous particle skeleton 90 The pore size is preferably at least 3.2 nm, or at least 3.5 nm, or at least 3.8 nm, or at least 4 nm. For example, the PD of the porous particle skeleton. 90 The pore size is preferably in the range of 3.2 nm to 20 nm, 3.5 nm to 15 nm, 3.8 nm to 10 nm, or 4 nm to 8 nm.

[0188] The micropore volume fraction of the porous particle skeleton is preferably at least 0.4, at least 0.45, at least 0.5, at least 0.55, or at least 0.6 relative to the total volume of micropores and mesopores in the porous particle skeleton.

[0189] The micropore volume fraction of the porous particle skeleton is preferably 0.95 or less, or 0.85 or less, or 0.8 or less, or 0.7 or less, or 0.7 or less, relative to the total volume of micropores and mesopores in the porous particle skeleton.

[0190] For example, the micropore volume fraction may be in the range of 0.4 to 0.95, 0.4 to 0.85, 0.45 to 0.85, 0.5 to 0.8, 0.55 to 0.75, or 0.6 to 0.7 relative to the total volume of micropores and mesopores in the porous particle framework.

[0191] Preferably, the BET surface area of ​​the porous particle skeleton is 4000 m². 2 / g or less, or 3500m 2 / g or less, or 3250m 2 / g or less, or 3000m 2 / g or less, or 2500m 2 / g or less, or 2000m 2 It is less than / g. For example, the porous particle skeleton is 100m 2 / g~4000m 2 / g, or 500m 2 / g~4000m 2 / g, or 750m 2 / g~3500m 2 / g, or 1000m 2 / g~3250m 2 / g, or 1000m 2 / g~3000m 2 / g, or 1000m 2 / g~2500m 2 / g, or 1000m 2 / g~2000m 2 It may have a BET surface area in the range of / g.

[0192] The porous particle skeleton is preferably a conductive porous particle skeleton, more preferably a conductive porous carbon particle skeleton, more preferably a conductive porous carbon particle skeleton containing at least 80% by weight of carbon, or at least 85% by weight of carbon, or at least 90% by weight of carbon, or at least 95% by weight of carbon. Suitable materials for the porous carbon skeleton are described in relation to the first aspect of the present invention.

[0193] The composite particles of the third embodiment preferably contain at least 26% by weight, or at least 28% by weight, or at least 30% by weight, or at least 32% by weight, or at least 34% by weight, or at least 36% by weight, or at least 38% by weight, or at least 40% by weight, or at least 42% by weight, or at least 44% by weight of silicon. Preferably, the composite particles of the third embodiment contain 64% by weight or less of silicon, or 62% by weight or less of silicon, or 60% by weight or less, or 58% by weight or less, or 56% by weight or less, or 54% by weight or less, or 52% by weight or less, or 50% by weight or less of silicon.

[0194] For example, the composite particles of the third embodiment may contain silicon in an amount of 26% to 65% by weight, or 28% to 65% by weight, or 30% to 65% by weight, or 32% to 60% by weight, or 34% to 60% by weight, or 36% to 60% by weight, or 38% to 58% by weight, or 40% to 58% by weight, or 42% to 56% by weight, or 44% to 54% by weight.

[0195] The composite particles of the third embodiment can be characterized by their performance under thermogravimetric analysis (TGA) in air, as described above.

[0196] Preferably, at least 22% by weight of silicon, or at least 25% by weight, at least 30% by weight, or at least 35% by weight of silicon, or at least 40% by weight of silicon, or at least 45% by weight of silicon is surface silicon determined by thermogravimetric analysis (TGA).

[0197] Preferably, 10% by weight or less, or 8% by weight or less, or 6% by weight or less, or 5% by weight or less, or 4% by weight or less, or 3% by weight or less, or 2% by weight or less, or 1.5% by weight or less of the silicon is crude bulk silicon determined by TGA.

[0198] Preferably, at least 30% by weight of the silicon (e.g., 30% to 75% by weight, 30% to 70% by weight, or 30% to 65% by weight) is surface silicon, and 10% or less of the silicon is crude bulk silicon, both of which are determined by TGA. More preferably, at least 35% by weight of the silicon (e.g., 35% to 70% by weight, 35% to 65% by weight, or 35% to 60% by weight) is surface silicon, and 8% or less of the silicon is crude bulk silicon, both of which are determined by TGA. More preferably, at least 40% by weight of the silicon (e.g., 40% to 65% by weight, 40% to 60% by weight, or 40% to 55% by weight) is surface silicon, and 5% or less of the silicon is crude bulk silicon, both of which are determined by TGA. More preferably, at least 45% by weight of the silicon is surface silicon, and 2% or less of the silicon is crude bulk silicon, both of which are determined by TGA.

[0199] Generally, the composite particles of the third embodiment are in the range of 1 μm to 25 μm. 50 It has a particle size. Preferably, composite particles D 50 The particle size is at least 1.5 μm, or at least 2 μm, or at least 2.5 μm, or at least 3 μm. Preferably, the composite particle D 50 The particle size is 20 μm or less, or 18 μm or less, or 15 μm or less, or 12 μm or less, or 10 μm or less, or 8 μm or less. For example, the D of composite particles 50 The particle size may be in the range of 1.5 μm to 18 μm, or 1.5 μm to 15 μm, or 2 μm to 12 μm, or 2 μm to 10 μm, or 2.5 μm to 8 μm, or 3 μm to 8 μm.

[0200] D of composite particles 90 The particle size is preferably 30 μm or less, or 25 μm or less, or 20 μm or less, or 18 μm or less, or 15 μm or less.

[0201] The D1 particle diameter of the composite particles is preferably at least 0.1 μm, or at least 0.25 μm, or at least 0.5 μm. Preferably, the D of the composite particles 99 The particle size is 50 μm or less, or 40 μm or less, or 30 μm or less.

[0202] The composite particles preferably have a narrow particle size distribution span. For example, a particle size distribution span ((D 90 -D 10 ) / D 50 The (defined as) is preferably 3 or less, more preferably 2 or less, and most preferably 1.5 or less. By maintaining a narrow particle size distribution span, efficient filling of particles into a high-density powder bed can be more easily achieved.

[0203] The composite particles preferably have a positive skew in their volume-based particle size distribution. Preferably, D 50 The diameter is smaller than the average particle diameter on a volume basis. Preferably, the skew of the composite particle size distribution (measured by Malvern's Mastersizer® 3000 analyzer) is 4 or less, or 3 or less, or 2 or less, or 1.5 or less. Preferably, the skew is at least 0.2, or at least 0.3, or at least 0.4. The particle size distribution of the composite particles may be unimodal, bimodal, or multimodal.

[0204] The composite particles of the third embodiment are 100 m 2 / g or less, or 80m 2 / g or less, or 60m 2 / g or less, or 50m 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 / g or less, or 10m 2 It is preferable that the BET surface area be less than or equal to / g.

[0205] Generally, a low BET surface area is preferred to minimize the formation of a solid electrolyte interface (SEI) layer on the composite particle surface during the first charge-discharge cycle of the anode. However, if the BET surface area is excessively low, the charging speed and capacity will be unacceptably low because a large amount of silicon in the surrounding electrolyte cannot access metal ions. The BET surface area is preferably at least 0.1 m². 2 / g, or at least 1m 2 / g, or at least 2m 2 / g, or at least 5m 2 The value is / g. For example, the BET surface area of ​​a composite particle is 0.1m². 2 / g~100m 2 / g, or 0.1m 2 / g~80m 2 / g, or 0.5m 2 / g~60m 2 / g, or 0.5m 2 / g~40m 2 / g, or 1m 2 / g~30m 2 / g, or 1m 2 / g~25m 2 / g, or 2m 2 / g~20m 2 The range of / g is also acceptable.

[0206] The composite particles of the third embodiment are preferably 0.1 cm 3 Less than / g, or 0.05cm 3 Less than / g, or 0.02cm 3 Less than / g, or 0.01cm 3 Less than / g, or 0.008cm 3 It has a total pore volume of gas-accessible micropores and mesopores of less than / g.

[0207] The composite particles of the third embodiment may also have a functional coating or shell that completely or partially covers the outer surface of the composite particles. The functional coating or shell is a coating or shell that improves the functional performance of the composite particles when used as an electroactive material in the negative electrode of a lithium-ion cell or battery. For example, the functional coating or shell may increase the electronic conductivity and / or ionic conductivity, improve the structural strength or mechanical robustness of the particles during handling or lithiation / delithiation in the cell, or improve the chemical compatibility of the composite particle surface with electrodes, electrode compositions, or other components in electrode slurries.

[0208] Preferably, in the composite particles of the present invention, (i) The porous particle framework is 0.6 cm 3 / g~1.5cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 3 nm or less. 50 Pore ​​diameter, and preferably PD of 10 nm or less. 90 Having a pore size, (ii) Z is 10% or less, preferably Y is at least 20%, (iii) The oxygen content is less than 4% by weight, (iv)D 50 The particle size is in the range of 1 μm to 18 μm. (v) BET surface area is 20m 2 It is less than / g (vi) The 7-day hydrogen activity is less than 40 μmol per gram of silicon, preferably less than 30 μmol per gram of silicon.

[0209] More preferably, in the composite particles of the present invention, (i) The porous particle framework is 0.6 cm 3 / g~1.4cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 2.5 nm or less. 50 Pore ​​size, and preferably PD of 8 nm or less. 90 Having a pore size, (ii) Z is 10% or less, preferably Y is at least 25%, (iii) The oxygen content is less than 3.5% by weight, (iv)D 50 The particle size is in the range of 1.5 μm to 12 μm. (v) BET surface area is 15m 2 It is less than / g (vi) The 7-day hydrogen activity is less than 25 μmol per gram of silicon, preferably less than 20 μmol per gram of silicon.

[0210] More preferably, in the composite particles of the present invention, (i) The porous particle framework is 0.65 cm 3 / g~1.3cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 2 nm or less. 50 Pore ​​diameter, and preferably PD of 6 nm or less. 90 Having a pore size, (ii) Z is 8% or less, preferably Y is at least 28%, (iii) The oxygen content is less than 3.2% by weight, (iv)D 50 The particle size is in the range of 2 μm to 10 μm. (v) BET surface area is 10m 2 It is less than / g (vi) The 7-day hydrogen activity is less than 15 μmol per gram of silicon, preferably less than 12 μmol per gram of silicon.

[0211] More preferably, in the composite particles of the present invention, (i) The porous particle framework is 0.7 cm 3 / g~1.2cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 1.8 nm or less. 50 Pore ​​diameter, and preferably PD of 5 nm or less. 90 Having a pore size, (ii) Z is 7% or less, preferably Y is at least 30%, (iii) The oxygen content is less than 3.2% by weight, (iv)D 50 The particle size is in the range of 2.5 μm to 8 μm. (v) BET surface area is 8m 2 It is less than / g (vi) The hydrogen activity over 7 days is less than 10 μmol per gram of silicon, preferably less than 8 μmol per gram of silicon.

[0212] More preferred composite particles of the present invention include the following: (i) The porous particle framework is 0.4 cm 3 / g~1.8cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 10 nm or less. 50 Pore ​​diameter, and preferably PD of 20 nm or less. 90 Having a pore size, (ii) Z is 10% or less, preferably Y is at least 30%, (iii) D 50 The particle size is in the range of 1 μm to 20 μm. (iv) BET surface area is 25m 2 It is less than / g (v) The 7-day hydrogen activity is less than 20 μmol per gram of silicon, preferably less than 15 μmol per gram of silicon.

[0213] More preferred composite particles of the present invention include the following: (i) The porous particle framework is 0.5 cm 3 / g~1.6cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 8 nm or less. 50 Pore ​​diameter, and preferably PD of 15 nm or less. 90 Having a pore size, (ii) Z is 10% or less, preferably Y is at least 30%, (iii) D 50The particle size is in the range of 1 μm to 18 μm. (iv) BET surface area is 25m 2 It is less than / g (v) The 7-day hydrogen activity is less than 15 μmol per gram of silicon, preferably less than 12 μmol per gram of silicon.

[0214] More preferred composite particles of the present invention include the following: (i) The porous particle framework is 0.6 cm 3 / g~1.5cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 6 nm or less. 50 Pore ​​diameter, and preferably PD of 12 nm or less. 90 Having a pore size, (ii) Z is 8% or less, preferably Y is at least 35%, (iii) D 50 The particle size is in the range of 1.5 μm to 15 μm. (iv) BET surface area is 20m 2 It is less than / g (v) The 7-day hydrogen activity is less than 12 μmol per gram of silicon, preferably less than 10 μmol per gram of silicon.

[0215] More preferred composite particles of the present invention include the following: (i) The porous particle framework is 0.65 cm 3 / g~1.4cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 2.5 nm or less. 50 Pore ​​diameter, and preferably PD of 10 nm or less. 90 Having a pore size, (ii) Z is 8% or less, preferably Y is at least 35%, (iii) D 50 The particle size is in the range of 1.5 μm to 12 μm. (iv) BET surface area is 20m 2 It is less than / g (v) The 7-day hydrogen activity is less than 10 μmol per gram of silicon, preferably less than 8 μmol per gram of silicon.

[0216] More preferred composite particles of the present invention include the following: (i) The porous particle framework is 0.7 cm 3 / g~1.3cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 4 nm or less. 50 Pore ​​size, and preferably PD of 8 nm or less. 90 Having a pore size, (ii) Z is 5% or less, preferably Y is at least 40%, (iii) D 50 The particle size is in the range of 2 μm to 10 μm. (iv) BET surface area is 15m 2 It is less than / g (v) The 7-day hydrogen activity is less than 10 μmol per gram of silicon, preferably less than 8 μmol per gram of silicon.

[0217] More preferred composite particles of the present invention include the following: (i) The porous particle framework is 0.75 cm 3 / g~1.2cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 3 nm or less. 50 Pore ​​diameter, and preferably PD of 6 nm or less. 90 Having a pore size, (ii) Z is 5% or less, preferably Y is at least 40%, (iii) D 50 The particle size is in the range of 2 μm to 10 μm. (iv) BET surface area is 15m 2 It is less than / g (v) The 7-day hydrogen activity is less than 8 μmol per gram of silicon, preferably less than 7 μmol per gram of silicon.

[0218] More preferred composite particles of the present invention include the following: (i) The porous particle framework is 0.8 cm 3 / g~1.2cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 2 nm or less. 50 Pore ​​diameter, and preferably PD of 5 nm or less. 90 Having a pore size, (ii) Z is 2% or less, preferably Y is at least 45%, (iii) D 50 The particle size is in the range of 2.5 μm to 8 μm. (iv) BET surface area is 10m 2 It is less than / g (v) The 7-day hydrogen activity is less than 7 μmol per gram of silicon, preferably less than 6 μmol per gram of silicon.

[0219] More preferred composite particles of the present invention include the following: (i) The porous particle framework is 0.6 cm 3 / g~1.5cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 3 nm or less. 50 Pore ​​diameter, and preferably PD of 10 nm or less. 90 Having a pore size, (ii) Z is 10% or less, preferably Y is at least 20%, (iii) The oxygen content is less than 4% by weight, (iv)D 50 The particle size is in the range of 1 μm to 18 μm. (v) BET surface area is 20m 2 It is less than / g (vi) The 7-day hydrogen activity is less than 6 μmol per gram of silicon, preferably less than 5.5 μmol per gram of silicon.

[0220] More preferred composite particles of the present invention include the following: (i) The porous particle framework is 0.6 cm 3 / g~1.4cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 2.5 nm or less. 50 Pore ​​size, and preferably PD of 8 nm or less. 90 Having a pore size, (ii) Z is 10% or less, preferably Y is at least 25%, (iii) The oxygen content is less than 3.5% by weight, (iv)D 50 The particle size is in the range of 1.5 μm to 12 μm. (v) BET surface area is 15m 2 It is less than / g (vi) The hydrogen activity over 7 days is less than 5 μmol per gram of silicon, preferably less than 4.5 μmol per gram of silicon.

[0221] More preferred composite particles of the present invention include the following: (i) The porous particle framework is 0.65 cm 3 / g~1.3cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 2 nm or less. 50 Pore ​​diameter, and preferably PD of 6 nm or less. 90 Having a pore size, (ii) Z is 8% or less, preferably Y is at least 28%, (iii) The oxygen content is less than 3.2% by weight, (iv)D 50 The particle size is in the range of 2 μm to 10 μm. (v) BET surface area is 10m 2 It is less than / g (vi) The hydrogen activity over 7 days is less than 4 μmol per gram of silicon, preferably less than 3.5 μmol per gram of silicon.

[0222] More preferred composite particles of the present invention include the following: (i) The porous particle framework is 0.7 cm 3 / g~1.2cm 3Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 1.8 nm or less. 50 Pore ​​diameter, and preferably PD of 5 nm or less. 90 Having a pore size, (ii) Z is 7% or less, preferably Y is at least 30%, (iii) The oxygen content is less than 3.2% by weight, (iv)D 50 The particle size is in the range of 2.5 μm to 8 μm. (v) BET surface area is 8m 2 It is less than / g (vi) The hydrogen activity over 7 days is less than 3 μmol per gram of silicon, preferably less than 2.5 μmol per gram of silicon.

[0223] More preferred composite particles of the present invention include the following: (i) The porous particle framework is 0.4 cm 3 / g~1.8cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 10 nm or less. 50 Pore ​​diameter, and preferably PD of 20 nm or less. 90 Having a pore size, (ii) Z is 10% or less, preferably Y is at least 30%, (iii) D 50 The particle size is in the range of 1 μm to 20 μm. (iv) BET surface area is 25m 2 It is less than / g (v) The 7-day hydrogen activity is less than 3.5 μmol per gram of silicon, preferably less than 3 μmol per gram of silicon.

[0224] More preferred composite particles of the present invention include the following: (i) The porous particle framework is 0.5 cm 3 / g~1.6cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 8 nm or less. 50Pore ​​diameter, and preferably PD of 15 nm or less. 90 Having a pore size, (ii) Z is 10% or less, preferably Y is at least 30%, (iii) D 50 The particle size is in the range of 1 μm to 18 μm. (iv) BET surface area is 25m 2 It is less than / g (v) The 7-day hydrogen activity is less than 3 μmol per gram of silicon, preferably less than 2.5 μmol per gram of silicon.

[0225] More preferred composite particles of the present invention include the following: (i) The porous particle framework is 0.6 cm 3 / g~1.5cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 6 nm or less. 50 Pore ​​diameter, and preferably PD of 12 nm or less. 90 Having a pore size, (ii) Z is 8% or less, preferably Y is at least 35%, (iii) D 50 The particle size is in the range of 1.5 μm to 15 μm. (iv) BET surface area is 20m 2 It is less than / g (v) The 7-day hydrogen activity is less than 2.5 μmol per gram of silicon, preferably less than 2 μmol per gram of silicon.

[0226] More preferred composite particles of the present invention include the following: (i) The porous particle framework is 0.65 cm 3 / g~1.4cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 2.5 nm or less. 50 Pore ​​diameter, and preferably PD of 10 nm or less. 90 Having a pore size, (ii) Z is 8% or less, preferably Y is at least 35%, (iii) D 50 The particle size is in the range of 1.5 μm to 12 μm. (iv) BET surface area is 20m 2 It is less than / g (v) The 7-day hydrogen activity is less than 2 μmol per gram of silicon, preferably less than 1.5 μmol per gram of silicon.

[0227] More preferred composite particles of the present invention include the following: (i) The porous particle framework is 0.7 cm 3 / g~1.3cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 4 nm or less. 50 Pore ​​size, and preferably PD of 8 nm or less. 90 Having a pore size, (ii) Z is 5% or less, preferably Y is at least 40%, (iii) D 50 The particle size is in the range of 2 μm to 10 μm. (iv) BET surface area is 15m 2 It is less than / g (v) The 7-day hydrogen activity is less than 1.5 μmol per gram of silicon, preferably less than 1.2 μmol per gram of silicon.

[0228] More preferred composite particles of the present invention include the following: (i) The porous particle framework is 0.75 cm 3 / g~1.2cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 3 nm or less. 50 Pore ​​diameter, and preferably PD of 6 nm or less. 90 Having a pore size, (ii) Z is 5% or less, preferably Y is at least 40%, (iii) D 50 The particle size is in the range of 2 μm to 10 μm. (iv) BET surface area is 15m 2 It is less than / g (v) The 7-day hydrogen activity is less than 1.2 μmol per gram of silicon, preferably less than 1 μmol per gram of silicon.

[0229] More preferred composite particles of the present invention include the following: (i) The porous particle framework is 0.8 cm 3 / g~1.2cm 3 Total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the range of / g, and PD of 2 nm or less. 50 Pore ​​diameter, and preferably PD of 5 nm or less. 90 Having a pore size, (ii) Z is 2% or less, preferably Y is at least 45%, (iii) D 50 The particle size is in the range of 2.5 μm to 8 μm. (iv) BET surface area is 10m 2 It is less than / g (v) The 7-day hydrogen activity is less than 1 μmol per gram of silicon, preferably less than 0.8 μmol per gram of silicon.

[0230] The present invention further provides a composition comprising only composite particles of a third embodiment.

[0231] A fourth aspect of the present invention is a method for manufacturing an electrode, (a) A step of combining composite particles of the second or third embodiment with an aqueous liquid and at least one binder, (b) A step of casting the slurry onto the current collector, (c) A step of drying the cast slurry to form a coating layer on the current collector, The present invention provides a manufacturing method that includes the following:

[0232] The composite particles used in the fourth aspect of the present invention may be in the form of a composition consisting only of the composite particles of the second or third aspect.

[0233] As used herein, the term current collector refers to any conductive substrate capable of conducting electric current to and from electroactive particles in a 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 take the form of foil or mesh having a thickness of 3 μm to 500 μm. The particulate material of the present invention can be applied to one or both 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.

[0234] The electrodes are prepared by forming a slurry by combining composite particles with an aqueous liquid, at least one binder, and optionally one or more viscosity-modifying additives. 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 any binder and / or calendering of the electrode layer can be performed as appropriate. The electrode layer preferably has a thickness in the range of 20 μm to 2 mm, preferably 20 μm to 1 mm, preferably 20 μm to 500 μm, preferably 20 μm to 200 μm, preferably 20 μm to 100 μm, and preferably 20 μm to 50 μm.

[0235] In an alternative manufacturing method, for example, the slurry formed in step (a) can be cast onto a suitable cast template, the solvent can be removed, and then the cast template can be removed to form the slurry into a self-supporting film or mat containing the particulate material of the present invention. The resulting film or mat has the form of self-supporting aggregates and can then be adhered to a current collector by known methods. [Examples]

[0236] Example 1: Preparation of composite particles A 5.0 L agitated pressurized reactor was filled with 300 g of porous carbon particles having the characteristics described in Table 1.

[0237] [Table 1]

[0238] The reactor was sealed and slowly placed under vacuum (10 mbar) to remove the air, then filled with oxygen-free dry nitrogen or argon. This process was repeated three times to remove all air from the porous carbon particles. The reactor was heated to 340°C, evacuated again, and filled with silane to a pressure of 1.2 MPa. The reactor was then heated to 400°C at a heating rate of 10°C / min and held at 400°C for 30 minutes. The reactor was then cooled to 340°C and slowly depressurized. The reactor was then refilled with silane to 1.2 MPa, heated again to 400°C at 10°C / min, and held for another 30 minutes. The cooling and refilling process was repeated a total of six times.

[0239] The reactor was depressurized and filled with nitrogen or argon, then heated to 450°C for 8 hours to anneal the composite particles.

[0240] Next, the reactor was cooled to 200°C, evacuated, and filled with gas to a pressure of 0.1 MPa. The composite particle product was then passed through air using a mixture of 10% air in nitrogen for 15 minutes. This process was repeated three times using a mixture of 10% air in nitrogen, three times using a mixture of 25% air in nitrogen, once using a mixture of 50% air in nitrogen, once using a mixture of 75% air in nitrogen, and finally with 100% air. The composite particle product had the properties described in Table 2.

[0241] Sample A is a composite particle product prepared from porous particle sample 1.

[0242] [Table 2]

[0243] Example 2: General procedure for water treatment using steam A 6.6 kg sample of composite particle product A obtained according to Example 1 was heated to 200°C in a stirred reactor under inert gas (nitrogen). Using a humidifier connected to the reaction vessel, water vapor-saturated air was supplied at a temperature of 80°C with a specific relative humidity (RH%) in the range of 50% to 100%. Once the desired temperature was reached, the reaction vessel was reduced to a set vacuum pressure (-0.9 bar), and humidified air was supplied by the humidifier to a set pressure (0.3 bar). The humidified air was maintained at the required pressure for a set time of 7 minutes, and then reduced again to vacuum pressure. This process was repeated for a specified number of pulses, i.e., a set duration, with a higher number of pulses resulting in a longer supply time of humidified air. After the desired number of cycles, the supply of humidified air was stopped by lowering RH%=0. Then, dry air for 10 cycles was passed through the reaction vessel to remove excess moisture, and the reactor was cooled to room temperature.

[0244] [Table 3]

[0245] [Table 4]

[0246] Example 3 - General procedure for measuring hydrogen activity The hydrogen activity of the samples is evaluated by storing 0.5 g of composite particles in 10 g of deionized water in a 20 mL vial equipped with an injectable vial cap at 25°C for 7 days (168 hours). The vial is stored upside down except during gas chromatography measurements.

[0247] Gas chromatography measurements were performed using a Perkin Elmer Clarus GC with an HTA headspace platform. The detector used was a pulsed discharge detector with helium as the ion source. The carrier gas used was grade 6.0 (99.9999%) gas (O2 < 0.01 ppm, H2O < 0.02 ppm, THC < 0.1 ppm, CO + CO2 < 0.1 ppm, N2 < 1 ppm, CFC < 0.001 ppm). The column used for gas chromatography was CP-Molsieve 5 Å (7536 fused silica; 25 m; 0.32 mm; 30 μm). The headspace was sampled by first extracting and reintroducing 2.5 mL of gas into a vial five times to ensure good mixing of the gas in the headspace. Then, 1 mL of gas was extracted and injected into the GC unit at 20 mL / min. The injection port temperature is set to 150°C, the detector temperature to 150°C, and the column oven temperature to 40°C. The carrier gas pressure is 82.74 kPa (12 psi).

[0248] The response at the GC unit's detector is calibrated against a commercial calibration standard gas, and the response is determined in ppm units. This is then converted to the number of moles of hydrogen gas (H2) under a conversion rate of 22.4 liters per mole and a known gas volume.

[0249] The composite and water vials were continuously stored in a controlled environment at 25°C. The vial caps were carefully crimped and secured to prevent gas leakage. When they were not being measured or were not being prepared for measurement, the vials were stored upside down to isolate the vial caps from the gas phase, further preventing potential hydrogen gas loss due to leakage. After measurement, the vials were allowed to stand for at least one minute to allow hydrogen gas to escape before being re-capped and stored upside down (this avoids double counting of cumulative totals).

[0250] Each data point in the examples was measured two or three times, and the given value is the average of the repeated measurements.

[0251] Measurements were taken after 1 day (24 hours), 2 days (48 hours), 3 days (72 hours), and 7 days (168 hours). The 2-day, 3-day, and 7-day hydrogen activity values ​​are defined herein as the cumulative sum of measurements taken from the specified day to the specified day.

[0252] The results for samples A to C are shown in Table 5.

[0253] [Table 5]

[0254] Example 4: General procedure for water treatment using liquid water An 8 kg sample of composite particle product sample A obtained according to Example 1 was mixed with excess DI water at 20°C to form a slurry, which was stirred for 60 minutes until the composite particles were completely wet. The slurry was filtered to form a moist filter cake containing approximately 30% by weight of water (water + composite particles = 100% of total mass). The filter cake was then heated in an open container to a specified temperature and held at that temperature until the sample was dry (less than 1% by weight of water). The sample was then cooled to ambient temperature under dry air.

[0255] The reaction conditions are shown in Table 6, and the properties of the composite particles are shown in Table 7.

[0256] [Table 6]

[0257] [Table 7]

[0258] Example 5 - Measurement of Hydrogen Activity The hydrogen activity of composite particle samples A and D to G was evaluated using the method of Example 3. The results are shown in Table 8.

[0259] Table 8

Claims

1. A method for producing composite particles, (a) A step of preparing a plurality of porous particles including micropores and / or mesopores, wherein the total pore volume of the micropores and mesopores measured by nitrogen gas adsorption is 0.4 cm³. ３ / g ~ 2.2cm ３ Processes within the range of / g, (b) A step of bringing the porous particles into contact with a silicon-containing precursor at a temperature and pressure effective for depositing silicon in the pores of the porous particles to form silicon-containing composite particles, (c) Optionally, a step of bringing the silicon-containing composite particles derived from step (b) into contact with a passivating agent, (d) A step of bringing the silicon-containing composite particles derived from step (b) or step (c) into contact with liquid water or a gas containing water vapor, wherein the contact is carried out at a temperature of at least 30°C. A manufacturing method that includes this.

2. The manufacturing method according to claim 1, wherein the temperature in step (d) is in the range of 40°C to 400°C, or 100°C to 350°C, or 120°C to 300°C, or 140°C to 280°C.

3. The manufacturing method according to claim 1 or 2, wherein step (d) includes bringing the silicon-containing composite particles derived from step (b) or step (c) into contact with a gas containing water vapor.

4. The manufacturing method according to claim 3, wherein the gas comprises 1 mol% to 60 mol% of water vapor, or 2 mol% to 55 mol% of water vapor, or 3 mol% to 50 mol% of water vapor, or 4 mol% to 45 mol% of water vapor, or 5 mol% to 40 mol% of water vapor, or 8 mol% to 35 mol% of water vapor, or 10 mol% to 30 mol% of water vapor, or 12 mol% to 25 mol% of water vapor, or 15 mol% to 20 mol% of water vapor.

5. The manufacturing method according to claim 3 or 4, wherein the pressure in step (d) is in the range of 5 kPa to 5000 kPa, or 10 kPa to 2000 kPa, or 20 kPa to 1000 kPa, or 50 kPa to 500 kPa, or 80 kPa to 200 kPa, or 90 kPa to 150 kPa, or 95 kPa to 120 kPa, or about 100 kPa.

6. The manufacturing method according to any one of claims 3 to 5, wherein step (d) includes an initial step in which the gas contains 1 mol% to less than 10 mol% water vapor, and a subsequent step in which the water vapor content of the gas is increased to 10 mol% to 60 mol%.

7. The manufacturing method according to any one of claims 3 to 6, wherein the gas further contains oxygen, and optionally the gas is humidified air.

8. The manufacturing method according to claim 1, wherein step (d) includes bringing the silicon-containing composite particles derived from step (b) or step (c) into contact with liquid water.

9. The manufacturing method according to claim 8, wherein the temperature in step (d) is in the range of 30°C to 150°C, or 30°C to 99.5°C, or 40°C to 99°C, or 50°C to 98°C, or 60°C to 97°C, or 70°C to 96°C, or 80°C to 95°C.

10. The manufacturing method according to claim 8 or 9, wherein the pressure in step (d) is in the range of 1 kPa to 1000 kPa, or 1 kPa to 500 kPa, or 50 kPa to 200 kPa, or 80 kPa to 150 kPa, or 90 kPa to 120 kPa, or about 100 kPa.

11. The manufacturing method according to any one of claims 8 to 10, wherein the silicon-containing composite particles and water are in the form of an aqueous suspension (slurry) containing more than 60% by weight of water or more than 80% by weight of water relative to the total amount of water and silicon-containing composite particles, or in the form of a moist cake containing 2% to 60% by weight of water.

12. The manufacturing method according to any one of claims 8 to 11, wherein the total duration of contact in step (d) is in the range of 5 minutes to 24 hours, or 10 minutes to 12 hours, or 15 minutes to 6 hours, or 20 minutes to 5 hours, or 25 minutes to 3 hours, or 30 minutes to 2 hours.

13. The manufacturing method according to any one of claims 8 to 12, wherein the composite particles are dried after step (d).

14. The total pore volume of micropores and mesopores measured by nitrogen gas adsorption in the porous particles used in step (a) is 0.45 cm ３ / g to 2 cm ３ / g, or 0.5 cm ３ / g to 1.8 cm ３ / g, or 0.55 cm ３ / g to 1.6 cm ３ / g, or 0.6 cm ３ / g to 1.5 cm ３ / g, or 0.65 cm ３ / g to 1.4 cm ３ / g, or 0.7 cm ３ / g to 1.3 cm ３ / g, or 0.75 cm ３ / g to 1.2 cm ３ / g, and the manufacturing method according to any one of claims 1 to 13 is within this range.

15. The PD of the porous particles used in step (a) ５０ The manufacturing method according to any one of claims 1 to 14, wherein the pore diameter is 10 nm or less, or 8 nm or less, or 6 nm or less, or 5 nm or less, or 4 nm or less, or 3 nm or less, or 2.5 nm or less, or 2 nm or less, or 1.9 nm or less, or 1.8 nm or less, or 1.7 nm or less, or 1.6 nm or less.

16. The PD of the porous particles used in process (a) ９０ The manufacturing method according to any one of claims 1 to 15, wherein the pore diameter is 20 nm or less, or 15 nm or less, or 12 nm or less, or 10 nm or less, or 8 nm or less, or 6 nm or less, or 5 nm or less.

17. The manufacturing method according to any one of claims 1 to 16, wherein the micropore volume fraction of the porous particles used in step (a) is at least 0.4, at least 0.45, at least 0.5, at least 0.55, or at least 0.6 with respect to the total volume of micropores and mesopores in the porous particles.

18. The manufacturing method according to any one of claims 1 to 17, wherein the micropore volume fraction of the porous particles used in step (a) is 0.85 or less, or 0.8 or less, or 0.75 or less, or 0.7 or less, relative to the total volume of micropores and mesopores in the porous particles.

19. The porous particles are 500 m ２ / g to 4000m ２ / g, or 750m ２ / g to 3500m ２ / g, or 1000m ２ / g ~ 3250m ２ / g, or 1000m ２ / g to 3000m ２ / g, or 1000m ２ / g to 2500m ２ / g, or 1000m ２ / g to 2000m ２ A manufacturing method according to any one of claims 1 to 18, having a BET surface area in the range of / g.

20. The manufacturing method according to any one of claims 1 to 19, wherein the porous particles are conductive porous particles, preferably conductive porous carbon particles, more preferably conductive porous carbon particles containing at least 80% by weight of carbon, or at least 85% by weight of carbon, or at least 90% by weight of carbon, or at least 95% by weight of carbon.

21. The silicon-containing precursor used in step (b) is in gaseous form, and optionally the silicon-containing precursor is silane (SiH ４ ), disilane (Si ２ H ６ ), trisilane (Si ３ H ８ A method for producing a product according to any one of claims 1 to 20, selected from methylsilane, dimethylsilane, and chlorosilane.

22. The manufacturing method according to any one of claims 1 to 21, wherein the temperature in step (b) is in the range of 340°C to 500°C, or 350°C to 480°C, or 350°C to 450°C, or 350°C to 420°C, or 350°C to less than 400°C, or 355°C to 395°C, or 360°C to 390°C, or 365°C to 385°C, or 370°C to 380°C.

23. The manufacturing method according to any one of claims 1 to 22, wherein the pressure in step (b) is in the range of 10 kPa to 10,000 kPa, or 20 kPa to 5,000 kPa, or 50 kPa to 2,000 kPa, or 60 kPa to 1,500 kPa, or 70 kPa to 1,000 kPa, or 80 kPa to 800 kPa, or 90 kPa to 600 kPa.

24. The manufacturing method according to any one of claims 1 to 23, wherein the particles formed in step (b) contain, with respect to the total mass of the particles, at least 26% by weight of silicon, or at least 28% by weight of silicon, or at least 30% by weight of silicon, or at least 32% by weight of silicon, or at least 34% by weight of silicon, or at least 36% by weight of silicon, or at least 38% by weight of silicon, or at least 40% by weight of silicon, or at least 42% by weight of silicon, or at least 44% by weight of silicon.

25. The weight ratio of the silicon deposited in step (b) to the porous particles is [0.50 × P １ ~1.9 x P １ ]: 1, or [0.6 × P １ ~1.8 x P １ ]: 1, or [0.7 × P １ ~1.7 x P １ ]: 1, or [0.8 × P １ ~1.6 x P １ ]: is in the range of 1, where P １ is, cm ３ The manufacturing method according to any one of claims 1 to 24, wherein the dimensionless number is the same as the total pore volume of micropores and mesopores in the porous particles, as measured by gas adsorption, and is expressed as / g.

26. The manufacturing method according to any one of claims 1 to 25, wherein step (c) is included.

27. The manufacturing method according to claim 26, wherein step (c) comprises contacting the silicon-containing composite particles derived from step (b) with a passivating agent selected from (i) an oxygen-containing gas, (ii) ammonia, (iii) a gas containing ammonia and oxygen, and (iv) phosphine.

28. Step (c) involves the silicon-containing composite particles derived from step (b), (i)R １ -CH=CH-R １ 、 ())) １ .≡.!R １ 、 (iii)O=CR １ R １ 、 (iv) HX-R ２ , and, (v)HX-C(O)-R １ (In the formula, X is O, S, NR) １ or PR １ This represents, Each R １ can independently represent H, or an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 carbon atoms, or two R １ The group forms an unsubstituted or substituted ring structure containing 3 to 8 carbon atoms in the ring. R ２ R represents an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 carbon atoms, or R １ and R ２ The manufacturing method according to claim 26, comprising contacting the two with a passivating agent selected from (together, they form an unsubstituted or substituted ring structure containing 3 to 8 carbon atoms in the ring).

29. The manufacturing method according to any one of claims 1 to 28, further comprising the step of subjecting the particles derived from step (b) to heat treatment at a temperature of at least 400°C in the presence of an inert atmosphere before a subsequent step.

30. The manufacturing method according to any one of claims 1 to 29, wherein the composite particles obtained from step (d) have a total oxygen content of less than 6% by weight, or less than 5% by weight, or less than 4.5% by weight, or less than 4% by weight, or less than 3.5% by weight, or less than 3.2% by weight, or less than 3% by weight, or less than 2% by weight, or less than 1% by weight, or less than 0.5% by weight, relative to the total mass of the composite particles.

31. The composite particles obtained from step (d) contain less than 40 μmol per gram of silicon, or less than 35 μmol per gram of silicon, or less than 30 μmol per gram of silicon, or less than 25 μmol per gram of silicon, or less than 20 μmol per gram of silicon, or less than 15 μmol per gram of silicon, or less than 12 μmol per gram of silicon, or less than 10 μmol per gram of silicon, or less than 8 μmol per gram of silicon, or less than 7 μmol per gram of silicon. A manufacturing method according to any one of claims 1 to 30, having a 7-day hydrogen activity in water of less than 6 μmol per gram of silicon, or less than 5.5 μmol per gram of silicon, or less than 5 μmol per gram of silicon, or less than 4.5 μmol per gram of silicon, or less than 3.5 μmol per gram of silicon, or less than 3 μmol per gram of silicon, or less than 2.5 μmol per gram of silicon, or less than 2 μmol per gram of silicon.

32. The manufacturing method according to any one of claims 1 to 31, wherein the composite particles obtained from step (d) have a hydrogen activity in water for 7 days of at least 0.1 μmol per gram of silicon, or at least 0.2 μmol per gram of silicon, or at least 0.3 μmol per gram of silicon, or at least 0.4 μmol per gram of silicon, or at least 0.5 μmol per gram of silicon, or at least 0.6 μmol per gram of silicon, or at least 0.8 μmol per gram of silicon, or at least 1 μmol per gram of silicon.

33. Composite particles that can be obtained by the manufacturing method described in any one of claims 1 to 32.

34. A composite particle comprising a porous particle skeleton and silicon, (a) The porous particle framework includes micropores and / or mesopores, and the total pore volume of the micropores and mesopores, as measured by nitrogen gas adsorption, is 0.4 cm³. ３ / g ~ 2.2cm ３ It is within the range of / g, (b) The silicon is located within the micropores and / or mesopores of the porous particle skeleton, The composite particles have a hydrogen activity of less than 40 μmol per gram of silicon for 7 days in water.

35. The composite particle according to claim 34, wherein the composite particle has a 7-day hydrogen activity in water of less than 35 μmol per gram of silicon, or less than 30 μmol per gram of silicon, or less than 25 μmol per gram of silicon, or less than 20 μmol per gram of silicon, or less than 15 μmol per gram of silicon, or less than 12 μmol per gram of silicon, or less than 10 μmol per gram of silicon, or less than 8 μmol per gram of silicon, or less than 7 μmol per gram of silicon, or less than 6 μmol per gram of silicon, or less than 5.5 μmol per gram of silicon, or less than 5 μmol per gram of silicon, or less than 4.5 μmol per gram of silicon, or less than 4 μmol per gram of silicon, or less than 3.5 μmol per gram of silicon, or less than 3 μmol per gram of silicon, or less than 2.5 μmol per gram of silicon, or less than 2 μmol per gram of silicon.

36. The composite particles according to claim 34 or 35, wherein the composite particles obtained from step (d) have a 7-day hydrogen activity in water of at least 0.1 μmol per gram of silicon, or at least 0.2 μmol per gram of silicon, or at least 0.3 μmol per gram of silicon, or at least 0.4 μmol per gram of silicon, or at least 0.5 μmol per gram of silicon, or at least 0.6 μmol per gram of silicon, or at least 0.8 μmol per gram of silicon, or at least 1 μmol per gram of silicon.

37. The composite particle according to any one of claims 34 to 36, wherein the composite particle has a total oxygen content of less than 5% by weight, or less than 4.5% by weight, or less than 4% by weight, or less than 3.5% by weight, or less than 3.2% by weight, or less than 3% by weight, or less than 2% by weight, or less than 1% by weight, or less than 0.5% by weight, relative to the total mass of the composite particle.

38. The total pore volume of micropores and mesopores in the porous particle skeleton, as measured by nitrogen gas adsorption, is 0.45 cm³. ３ / g to 2cm ３ / g, or 0.5cm ３ / g to 1.8cm ３ / g, or 0.55cm ３ / g ~ 1.6cm ３ / g, or 0.6cm ３ / g to 1.5cm ３ / g, or 0.65cm ３ / g to 1.4cm ３ / g, or 0.7cm ３ / g ~ 1.3cm ３ / g, or 0.75cm ３ / g to 1.2cm ３ The composite particles according to any one of claims 34 to 37, wherein the particle size is in the range of / g.

39. The PD of the porous particle skeleton ５０ The composite particle according to any one of claims 34 to 38, wherein the pore diameter is 10 nm or less, or 8 nm or less, or 6 nm or less, or 5 nm or less, or 4 nm or less, or 3 nm or less, or 2.5 nm or less, or 2 nm or less, or 1.9 nm or less, or 1.8 nm or less, or 1.7 nm or less, or 1.6 nm or less.

40. The PD of the porous particle skeleton ９０ The composite particle according to any one of claims 34 to 39, wherein the pore diameter is 20 nm or less, or 15 nm or less, or 12 nm or less, or 10 nm or less, or 8 nm or less, or 6 nm or less, or 5 nm or less.

41. The composite particle according to any one of claims 34 to 40, wherein the micropore volume fraction of the porous particle skeleton is at least 0.4, or at least 0.45, or at least 0.5, or at least 0.55, or at least 0.

6.

42. The composite particle according to any one of claims 34 to 41, wherein the micropore volume fraction of the porous particle skeleton is 0.85 or less, or 0.8 or less, or 0.75 or less, or 0.7 or less, with respect to the total volume of micropores and mesopores in the porous particle.

43. The porous particle skeleton has a BET surface area in the range of 100 m ２ / g to 4000 m ２ / g, or 500 m ２ / g to 4000 m ２ / g, or 750 m ２ / g to 3500 m ２ / g, or 1000 m ２ / g to 3250 m ２ / g, or 1000 m ２ / g to 3000 m ２ / g, or 1000 m ２ / g to 2500 m ２ / g, or 1000 m ２ / g to 2000 m ２ / g, and is the composite particle according to any one of claims 34 to 42.

44. The composite particle according to any one of claims 34 to 43, wherein the porous particle skeleton is a conductive porous particle skeleton, preferably a conductive porous carbon particle skeleton, more preferably a conductive porous carbon particle skeleton containing at least 80% by weight of carbon, or at least 85% by weight of carbon, or at least 90% by weight of carbon, or at least 95% by weight of carbon.

45. A composite particle according to any one of claims 34 to 44, comprising at least 26% by weight of silicon, or at least 28% by weight of silicon, or at least 30% by weight of silicon, or at least 32% by weight of silicon, or at least 34% by weight of silicon, or at least 36% by weight of silicon, or at least 38% by weight of silicon, or at least 40% by weight of silicon, or at least 42% by weight of silicon, or at least 44% by weight of silicon.

46. A composite particle according to any one of claims 34 to 45, comprising 64% by weight or less of silicon, or 62% by weight or less of silicon, or 60% by weight or less of silicon, or 58% by weight or less of silicon, or 56% by weight or less of silicon, or 54% by weight or less of silicon.

47. The composite particle according to any one of claims 34 to 46, wherein at least 25% by weight of the silicon, or at least 30% by weight, or at least 35% by weight, or at least 40% by weight of the silicon, is surface silicon determined by thermogravimetric analysis (TGA).

48. The composite particle according to any one of claims 34 to 47, wherein 10% by weight or less of the silicon, or 8% by weight or less of the silicon, or 6% by weight or less of the silicon, or 5% by weight or less, or 4% by weight or less, or 3% by weight or less, or 2% by weight or less, or 1.5% by weight or less of the silicon is crude bulk silicon determined by thermogravimetric analysis (TGA).

49. D in the range of 1 μm to 25 μm ５０ A composite particle according to any one of claims 34 to 48, having a particle size.

50. 100 m ２ / g or less, or 80 m ２ / g or less, or 60 m ２ / g or less, or 50 m ２ / g or less, or 40 m ２ / g or less, or 30 m ２ / g or less, or 25 m ２ / g or less, or 20 m ２ / g or less, or 15 m ２ / g or less, or 10 m ２ The composite particle according to any one of claims 34 to 49, having a BET surface area of / g or less.

51. A composition comprising only the composite particles described in any one of claims 33 to 50.

52. A method for manufacturing electrodes, (a) A step of forming a slurry by combining the composite particles according to any one of claims 33 to 50 with an aqueous liquid and at least one binder, (b) A step of casting the slurry onto the current collector, (c) A step of drying the cast slurry to form a coating layer on the current collector, A manufacturing method that includes this.

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