Electroactive materials for metal ion batteries

Abstract

A process for preparing composite particles for use as electroactive materials for metal-ion batteries is provided, the process comprising: (a) providing a porous particle framework comprising micropores and / or mesopores and optionally a polyvalent metal; (b) optionally impregnating the porous particle framework with the polyvalent metal; (c) depositing elemental silicon and / or elemental germanium in the pores of the porous particle framework, wherein the porous particle framework in step (a) comprises the polyvalent metal, or step (b) is performed, or both, thereby providing an impregnated porous particle framework comprising the polyvalent metal and silicon and / or germanium; and (d) contacting the impregnated porous particle framework with the monovalent metal while applying a potential effective in causing the formation of an intermetallic phase comprising the polyvalent metal, silicon and / or germanium, and a monovalent metal, thereby providing composite particles.

Description

[Technical Field]

[0001] introduction This invention relates to composite particles for use as an anode electroactive material in metal-ion batteries such as lithium-ion batteries, and to a process for producing the same. This invention also relates to intermediate particles useful for producing composite particles. [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 with a layer of electroactive material, which is defined herein as 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 intercalated lithium atoms. Thus, herein the terms “cathode” and “anode” are used in the sense that the battery is positioned relative to the load such that the anode is the negative electrode. herein the term “battery” is used to refer to both a device containing a single cell (e.g., a lithium-ion cell or a sodium-ion cell) and a device containing multiple connected cells.

[0003] Conventional lithium-ion batteries (LIBs) use graphite as the electroactive anode material. A graphite anode can accommodate up to one lithium atom for every six carbon atoms, giving a theoretical maximum specific capacity of 372 mAh / g for lithium-ion batteries, although the actual capacity is slightly lower (approximately 340-360 mAh / g). Silicon is a promising alternative to graphite due to its very high lithium capacity (see, for example, Insertion Electrodematerials for Rechargeable Lithium Batteries, Winter, M. et al. in Adv. Mater. 1998, 10, No. 10). The theoretical maximum specific capacity of silicon is... (Lithium-ion battery)15 The capacity is approximately 3,600 mAh / g (Si4-based). However, due to the very high ratio of intercalated lithium to silicon, the silicon material expands up to 400% of its original volume. Repeated charge and discharge cycles place significant mechanical stress on the silicon material, leading to breakage and structural failure. Furthermore, when the anode of a LIB is charged, a solid electrolyte interface (SEI) layer is formed. This SEI layer is an ionically conductive yet insulating layer formed by the reductive decomposition of the electrolyte on the electrode surface exposed during the initial charge. In graphite anodes, this SEI layer remains relatively stable during subsequent charge / discharge cycles. However, due to the expansion and contraction of the silicon anode, the SEI layer breaks and peels off, exposing a new silicon surface. As a result, the decomposition of the electrolyte progresses further, increasing the thickness of the SEI layer and irreversibly consuming lithium. Furthermore, lithium silicide, especially in a highly lithified state, also deteriorates. 15 Si4 is thermodynamically metastable, and further reactions occur upon contact with the electrolyte. These failure mechanisms work together to cause unacceptable losses of electrochemical capacity throughout continuous charge and discharge cycles.

[0004] One approach taken to address these problems is to use Si-based alloy anodes, which are prepared before lithiation at the anode and include so-called Si / Li active systems (Si-Mg, Si-Ge, and Si-Zn) and Si / Li inactive systems (Si-Fe, Si-Ni, Si-Ti, and Si-Cu) (Feng et al., Int. J. Mineral Metall. Mater., 28(10)(2021), 1549-1564). Other alloys under study include Si-Al-Fe (Umirov et al. ACS Appl. Mater. Interfaces 2020, 12, 17406-17414). Alloy anodes have been reviewed in Obrovac, Chem. Rev. 2014, 114, 23, 11444-11502.

[0005] Another approach is to add polyvalent metal salts (Mg 2+ , Zn 2+ , Al 3+ , Ca 2+ ) to the electrolyte so that alloying occurs when lithium is inserted into silicon (Li et al., Chem. Mater. 2021, 33, 13, 4960 - 4970; Li et al., ACS Appl. Energy Mater. 2020, 3, 12, 11534 - 11539; Han et al., ACS Appl. Mater. Interfaces 2019, 11, 33, 29780 - 29790). As a result, it is said that a Li-M-Si ternary alloy with low chemical reactivity and relatively high stability is formed in situ in the battery. In one study, based on single crystals fabricated in the laboratory, Li 15-x Al x Si4 was said to be thermodynamically stable, in contrast to the metastability of the above-mentioned Li 15 Si4 (Zeilinger et al., Chem. Mater. 2013, 25, 20, 4113 - 4121).

[0006] One approach previously reported by the inventors is to develop a class of electroactive materials having composite structures in which electroactive materials such as silicon are deposited within a pore network of highly porous particles, such as porous carbon materials, with a carefully controlled pore size distribution. For example, WO2020 / 095067, WO2020 / 128495, and WO2022 / 029422 report that the improved electrochemical performance of these materials is due to the electroactive material forming small domains on the order of a few nanometers or less in size within the pore network of porous particles, which function as a framework for the composite particles. Since the fine electroactive structures are thought to have lower resistance to elastic deformation and higher resistance to fracture than larger electroactive structures, lithiation and delithiation are possible without excessive structural stress. As a result, the electroactive materials exhibit good reversible capacity retention over multiple charge-discharge cycles. Furthermore, by controlling the silicon filling within the porous particle framework, so that only a portion of the pore volume is occupied by silicon in the uncharged state, the pore volume of the porous particle framework can accommodate a considerable amount of silicon expansion internally. Excessive expansion is limited by the particle framework. In addition, only a small area of ​​the electroactive material surface can access the electrolyte, significantly preventing SEI formation.

[0007] However, porous carbon materials used to produce composite particles naturally contain impurities that are usually considered undesirable, depending on the raw materials and processing conditions. Therefore, carbonaceous raw materials are typically treated and / or processing conditions are adjusted to reduce the level of impurities, but this increases the complexity and cost of production. For example, WO2020 / 056368 proposes obtaining high-purity porous carbon derived from biomass using a combination of chemical purification (e.g., treatment with acid) and thermal purification (e.g., heat treatment at temperatures of about 800-2000°C to cause evaporation of impurities). WO2013 / 120011 proposes forming porous carbon with low levels of impurities by thermal decomposition of specially prepared polymer gel particles.

[0008] In this technical field, there remains a need to further improve the electroactive composite particles of the above type in order to improve the electrochemical performance and material lifespan over multiple charge-discharge cycles and to broaden the range of porous materials suitable for the manufacture of such particles. [Overview of the project]

[0009] In a first aspect, the present invention provides a process for preparing composite particles for use as an electroactive material for metal-ion batteries, the process being: (a) Providing a porous particle framework comprising micropores and / or mesopores and optionally a polyvalent metal, (b) an optional step of impregnating the porous particle framework with a polyvalent metal, (c) A step of depositing elemental silicon and / or elemental germanium in the pores of a porous particle framework, Either the porous particle framework in step (a) contains a polyvalent metal, or step (b) is performed, or both are performed. A deposition step provides a porous particle framework containing polyvalent metals and silicon and / or germanium, (d) The step of bringing an impregnated porous particle framework into contact with a monovalent metal while applying a potential effective in causing the formation of an intermetallic phase containing a polyvalent metal, silicon and / or germanium, and a monovalent metal, thereby providing a composite particle.

[0010] In a second aspect, the present invention provides composite particles for use as an electroactive material for metal-ion batteries, wherein the composite particles are A porous particle framework including micropores and / or mesopores, The system includes a polyvalent metal, silicon and / or germanium, and an intermetallic phase containing a monovalent metal.

[0011] The intermetallic phase is Li 15It is believed that the resulting composite particles are more stable than the two-component silicon and / or germanium alloys formed when typical composite particles such as Si4 are lithium-ionized in a battery, resulting in less reaction with both liquid and solid electrolytes. Furthermore, in typical composite particles, silicon can be terminated with hydride groups, resulting in hydrogen generation during the formation cycle. In this invention, the presence of polyvalent metals is thought to favorably alter the termination chemistry of the silicon and / or germanium deposited in step (c), resulting in fewer hydride groups and a material that is less susceptible to oxidation. A further advantage is that the invention encompasses the use of many sources of porous particle backbone, such as activated carbon, without requiring additional processing steps used to remove polyvalent metals, which are typically considered undesirable impurities. Rather, the inventors recognized that the presence of polyvalent metals in this invention is advantageous because it promotes the formation of intermetallic phases.

[0012] Another advantage is that the potential in step (d) for forming the intermetallic phase can be easily applied without modifying existing battery manufacturing processes. For example, this can be applied during the electrochemical prelithiation of the anode or during the battery formation cycle, which means that the advantages of the present invention can be offered as a “drop-in” solution to existing manufacturing lines.

[0013] The present invention also provides an electrode containing composite particles and an electrochemical cell, such as a rechargeable metal-ion battery, which includes the electrode as an anode. Processes for preparing the electrode and the electrochemical cell are also provided.

[0014] In a third aspect, the present invention provides a process for producing an impregnated porous particle skeleton, the process following the method of the first aspect, but omitting step (d).

[0015] In a fourth aspect, the present invention provides an impregnated porous particle skeleton comprising micropores and / or mesopores, a polyvalent metal, and elemental silicon and / or elemental germanium within the pores.

[0016] Impregnated porous particles represent a convenient intermediate material for producing composite particles having the advantages provided by the first and second embodiments. Furthermore, they can be used as a “drop-in” solution in existing manufacturing lines, which is typically for applying a potential during a battery formation cycle or electrochemical pre-lithiation of an anode to form a desired intermetallic phase. Thus, the present invention also provides electrodes comprising an impregnated porous particle framework and electrochemical cells such as rechargeable metal-ion batteries, which include the electrode as an anode, for example. Processes for preparing electrodes and electrochemical cells are also provided.

[0017] The present invention is carried out, for example, using silicon and / or germanium in step (c), but most preferably using silicon. Furthermore, the present invention is carried out using a monovalent metal such as a Group 1 metal, preferably Li or Na, i.e., the present invention is carried out in the context of a Li-ion battery or a Na-ion battery. Most preferably the monovalent metal is Li. [Modes for carrying out the invention]

[0018] It will be understood that the process steps in this specification are labeled for ease of reference. The steps can be performed in any order, with or without other intervening steps, unless obviously incompatible. The following descriptions of porous particle skeletons, impregnated porous particle skeletons, composite particles, electrodes, cells, etc., apply equally when they are provided as products themselves or used as part of a process.

[0019] Step (a) includes providing a porous particle skeleton comprising micropores and / or mesopores and optionally a polyvalent metal. Providing a porous particle skeleton includes synthesizing the skeleton and obtaining the skeleton from a supplier.

[0020] Porous particle frameworks typically provide a silicon and / or germanium framework deposited in the form of multiple electroactive material domains. The term “electroactive material domain” refers to the body of the electroactive material (e.g., elemental silicon), whose maximum dimension is determined by the dimensions of the micropores and / or mesopores in the porous particle framework in which they reside. Thus, electroactive domains can be described as nanoscale electroactive material domains, and the term “nanoscale” is generally understood to refer to dimensions less than 100 nm, however, due to the dimensions of micropores and mesopores, electroactive material domains typically have a maximum dimension of less than 50 nm in any direction, and are usually well below 50 nm. Domains can take the form of, for example, regular or irregular particles, or layers or regions with coating boundaries.

[0021] Porous particle frameworks generally consist of a three-dimensionally interconnected network of open pores, including micropores and / or mesopores, and optionally a small amount of large pores. According to conventional IUPAC terminology, in this specification, the term "micropore" refers to pores with a diameter of less than 2 nm, the term "mesopore" refers to pores with a diameter of 2 to 50 nm, and the term "large pore" refers to pores with a diameter greater than 50 nm.

[0022] References herein to the volumes of micropores, mesopores, and coarse pores within a porous particle framework, as well as to the distribution of pore volumes within a porous particle framework, relate to the internal pore volume of the porous particle framework used as a starting material in step (a) of the claimed process, i.e., before the electroactive material is deposited into the pore volume in step (c).

[0023] Porous particle frameworks can be characterized by the total volume of micropores and mesopores (i.e., the total pore volume in the pore size range of 0–50 nm). Typically, porous particle frameworks contain both micropores and mesopores. However, the use of porous particle frameworks containing micropores but not mesopores, or conversely, containing mesopores but not micropores, is not ruled out.

[0024] The total volume of micropores and mesopores in the porous particle framework is preferably at least 0.4 cm³. 3 / g, or at least 0.5cm 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 / g, or at least 0.8cm 3 The value is / g. Using highly porous particles can be advantageous because it allows for the accommodating of more electroactive material within the pore volume.

[0025] The internal pore volume of the porous particle framework is appropriately limited to a value where the increased fragility of the framework structure outweighs the benefits of increased pore volume in accommodating more electroactive material. Preferably, the total volume of micropores and mesopores in the porous particle framework is 1.8 cm³. 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 1.1cm 3 It is less than / g.

[0026] Preferably, the total volume of micropores and mesopores in the porous particle framework is 0.4 to 1.8 cm³. 3 / g, or 0.4-1.7cm 3 / g, or 0.5-1.6cm 3 / g, or 0.5-1.55cm 3 / g, or 0.6-1.5cm 3 / g, or 0.6-1.45cm 3 / g, or 0.65-1.4cm 3 / g, or 0.65-1.35cm 3 / g, or 0.7-1.3cm 3 / g, or 0.7-1.25cm 3 / g, or 0.75-1.2cm 3 / g, or 0.75-1.1cm 3 / g, or 0.8-1.2cm 3 / g, or 0.8-1.1cm 3 It is within the range of / g.

[0027] In this specification, "PD" n The general term "pore diameter" refers to the volume-based n-th percentile pore diameter, which is based on the total volume of micropores and mesopores. For example, as used herein, "PD 50 The term "pore diameter" refers to the pore diameter below which 50% of the total volume of micropores and mesopores resides. To avoid ambiguity, PD n For the purpose of determining the value, large pore volume (pore diameter exceeding 50 nm) is not considered.

[0028] Porous particle skeleton PD 90 The pore size is preferably 50 nm or less, or 30 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. Preferably, the porous particle skeleton is PD 90 The pore size is at least 3 nm, or at least 4 nm, or at least 5 nm, or at least 6 nm. For example, PD of a porous particle skeleton. 90 The pore size is preferably in the range of 3 to 20 nm, 4 to 15 nm, 5 to 10 nm, or 6 to 8 nm.

[0029] Porous particle skeleton PD 50 The pore size is preferably 30 nm or less, or 15 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.

[0030] Based on the total volume of micropores and mesopores in the porous particle framework, the micropore volume fraction is at least 0.3, or at least 0.4, or at least 0.45, or at least 0.5, or at least 0.55, or at least 0.6, and / or 0.95 or less, or 0.9 or less, or 0.85 or less, or 0.8 or less. If step (b) is performed, most preferably the micropore volume fraction is 0.95 or less, based on the total volume of micropores and mesopores in the porous particle framework. In this way, the mesopore volume is greater than 0.05, ensuring pores large enough to impregnate the polyvalent metal into the porous particle framework.

[0031] P 1 is, cm 3 Expressed as / g, this is the total volume of micropores and mesopores in the porous particle framework. VP07 is P 1 This is the volume of pores with a diameter of 0.7 nm or less in the porous particle framework, expressed as a percentage. VP07 is preferably in the range of 5.1-40%, or 5.5-35%, or 7-30%, or 10-27%, or most preferably 15-25%.

[0032] VP07 is expressed as the total volume of micropores and mesopores in the porous particle framework. However, in some applications, it is advantageous to specify the minimum absolute volume of pores with a diameter of 0.7 nm or less. Therefore, the volume of pores with a diameter of 0.7 nm or less in the porous particle framework should be at least 0.05 cm³ when measured by nitrogen adsorption. 3 / g, preferably 0.08-0.5cm 3 / g, most preferably 0.1-0.3cm 3 It is / g.

[0033] VP1, VP2, and VP5 are P 1These are the volumes of pores in the porous particle framework with pore diameters of 1.0 nm or less, 2.0 nm or less, and 5.0 nm or less, respectively, expressed as a percentage of the total volume. VP1, VP2, and VP5 are measured by nitrogen gas adsorption. Preferably, VP1 is at least 1.5 × VP07, or at least 2 × VP07. Preferably, VP2 is at least 2.5 × VP07, or at least 3 × VP07, or at least 4 × VP07. Preferably, VP5 is at least 55%, or at least 60%, or at least 70%, or at least 80%, or at least 90%, or at least 92%, or at least 93%.

[0034] Preferably, VP2 is at least 20%. In some applications, VP2 is at least 40%, at least 50%, at least 55%, or at least 60%, at least 70%, at least 80%, or at least 85%, i.e., micropores form the majority of the volume of micropores and mesopores. Alternatively, VP2 is less than 50%, or 45% or less, or 40% or less, i.e., mesopores form the majority of the volume of micropores and mesopores.

[0035] VP2 may be less than 99%, or less than 98%, or less than 95%, or preferably less than 90%, for example, 40-90%.

[0036] VP2 may range from 45 to 98%, or 45 to 90%, or 45 to 85%, or 45 to 80%, or 45 to 78%, or 45 to 75%, or 45 to 70%, or 45 to 60%, or 50 to 98%, or 50 to 90%, or 50 to 85%, or 50 to 80%, or 50 to 78%, or 50 to 75%, or 50 to 70%, or 55 to 98%, or 55 to 90%, or 55 to 85%, or 55 to 80%, or 55 to 78%, or 55 to 75%, or 55 to 70%, or 55 to 69%.

[0037] By controlling the pore volume at larger pore sizes, the properties of the framework and the resulting composite particles can be further improved. VP20 and VP10 are P 1 VP10 and VP20 are defined as the volume of pores in the porous particle framework with a pore diameter of 20.0 nm or less or 10.0 nm or less, respectively, expressed as a percentage of the total volume. VP10 and VP20 are measured by nitrogen gas adsorption. VP20 may be at least 80%, or at least 90%, or at least 95%, or at least 97%, or at least 98%. VP10 may be at least 70%, or at least 80%, or at least 90%, or at least 95%, or at least 97%.

[0038] VP20-VP5 is P 1 This represents the pore volume of porous particle skeletons with a pore diameter greater than 5.0 nm and less than or equal to 20.0 nm, expressed as a percentage of the total volume. VP20-VP5 may be less than 20%, less than 15%, preferably less than 12%, preferably less than 10%, or more preferably less than 9%. Optionally, VP20-VP5 may be at least 0.5%, or at least 1%, or at least 2%. VP20-VP5 may be 0.5-20%, 0.5-15%, or 1-12%, or 2-10%, or 2-9%, or 3-9%.

[0039] VP20-VP2 may be at least 45%, or at least 50%, or at least 55%.

[0040] The pore size distribution of a porous particle framework can be unimodal, bimodal, or multimodal. As used herein, the term “pore size distribution” refers to the distribution of pore sizes relative to the cumulative total internal pore volume of a porous particle framework. Bimodal or multimodal pore size distributions may be preferred because the proximity between micropores and large pores provides the advantage of efficient ion transport through the porous network to the electroactive material.

[0041] The total volume of micropores and mesopores, as well as the pore size distribution of micropores and mesopores, were determined using rapid solid density functional theory (QSDFT) with nitrogen gas adsorption at 77K, assuming a relative pressure p / p0 of 10 -6 The pore size distribution is determined, preferably according to the standard methodology specified in ISO 15901-2 and ISO 15901-3, most preferably ISO 15901-2:2022. Nitrogen gas adsorption is a technique for characterizing the porosity and pore size distribution of a material by condensing a gas into the pores of a solid. As the pressure increases, the gas first condenses in the smallest diameter pores, and the pressure increases until it reaches a saturation point where all pores are filled with liquid. The pressure of the nitrogen gas is then gradually decreased, causing the liquid to evaporate from the system. By analyzing the adsorption isotherms and desorption isotherms, and the hysteresis between them, the pore volume and pore size distribution can be determined. Suitable instruments for measuring pore volume and pore size distribution by nitrogen gas adsorption include the TriStar II and TriStar II Plus porosity analyzers available from Micromeritics Instrument Corporation, USA, and the Autosorb IQ porosity analyzer available from Quantachrome Instruments.

[0042] Nitrogen gas adsorption is effective for measuring pore volume and pore size distribution for pores with a diameter of up to 50 nm, but its reliability is low for pores with much larger diameters. Therefore, for the purposes of this invention, nitrogen adsorption is used to determine pore volume and pore size distribution only for pores with a diameter of 50 nm or less (i.e., micropores and mesopores). PD 50 Similarly, the value is determined based solely on the total volume of micropores and mesopores.

[0043] Given the limitations of available analytical techniques, it is impossible to measure pore volume and pore size distribution across the entire range of micropores, mesopores, and large pores using a single technique. When the porous particle framework contains large pores, the volume of pores with diameters ranging from 50 nm to 100 nm can be measured by mercury porosimetry, preferably 0.3 cm³.3 Less than / g, or 0.2cm 3 Less than / g, or 0.1cm 3 Less than / g, or 0.05cm 3 The amount is less than / g. Small amounts of large pores may be useful in facilitating access of electrolytes to the pore network, and performing step (b) promotes impregnation of the porous particle framework with polyvalent metals, but the advantages of the present invention are substantially obtained by housing the electroactive material in micropores and even smaller mesopores.

[0044] Pore ​​volumes measured by mercury porosimetry for pore sizes of 50 nm or less are ignored (as mentioned above, nitrogen adsorption is used to characterize mesopores and micropores). Pore volumes exceeding 100 nm measured by mercury porosimetry are considered to be interparticle porosity for the purposes of this invention and are therefore also ignored.

[0045] Mercury porosimetry is a technique for characterizing the porosity and pore size distribution of a material by applying varying levels of pressure to a sample of the 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 porosimetry method reported herein were obtained according to ASTM UOP578-11, with a surface tension γ of 480 mN / m and a contact angle φ of 140° for mercury at room temperature. The density of mercury at room temperature was 13.5462 g / cm³. 3 It is said that numerous high-precision mercury porosimetry meters are commercially available, such as the AutoPore IV series of automated mercury porosimetry meters sold by Micromeritics Instrument Corporation, USA. For a complete review of mercury porosimetry, see "Analytical Methods in Fine Particle Technology," 1997, Micromeritics Instrument Corporation, ISBN 0-9656783-0, by PAWebb and C. Orr.

[0046] It will be understood that penetration techniques such as gas adsorption and mercury porosimetry are only effective when determining the pore volume of pores that are accessible to nitrogen or mercury from outside the porous particle framework. The porosity values ​​defined herein will be understood to refer to open pores, i.e., pore volumes that are accessible to fluid from outside the porous particle framework. Completely enclosed pores that cannot be identified by nitrogen adsorption or mercury porosimetry are not considered herein when determining porosity values. Similarly, pore volumes in pores so small that they fall below the detection limit by nitrogen adsorption are not considered.

[0047] As used herein, the term “particle diameter” refers to the equivalent spherical diameter (ESD), i.e., the diameter of a sphere having the same volume as a given particle, and particle volume is understood to include the volume of pores within any particle. 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 volume of a particle population lies. 10 " and "D 10 The term "particle diameter" refers to the volume-based 10th percentile median particle diameter, i.e., the diameter below which 10% of the volume of a particle population lies. 90 " and "D 90 The term "particle diameter" refers to the 90th percentile median particle diameter based on volume, i.e., the diameter below which 90% of the volume of a particle population lies.

[0048] Particle diameter and particle size distribution can be determined by standard laser diffraction according to ISO 13320:2009. Laser diffraction is based on the principle that particles scatter light at different angles depending on their particle size, and the aggregate of particles generates a pattern of scattered light defined by intensity and angle, which correlates with the particle size distribution. Numerous laser diffraction devices are commercially available for rapid and reliable measurement of particle size distribution. Unless otherwise stated, the particle size distribution measurements specified or reported herein were measured using a conventional Malvernmastersizer™ 3000 particle size analyzer from Malvern Instruments™. The Malvernmastersizer™ 3000 particle size analyzer operates by projecting a helium-neon gas laser beam through a transparent cell containing target particles suspended in an aqueous solution. The light beam striking the particles is scattered at 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 different 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). The refractive index of the particles is assumed to be 2.68 for porous particle skeletons and 3.50 for composite particles, and the dispersant index is assumed to be 1.378. The particle size distribution is calculated using the Mie scattering model.

[0049] Generally, porous particle frameworks are in the range of 1 to 30 μm. 50 It has a particle size. Optionally, the porous particle skeleton D 50 The particle size may be at least 1 μm, or at least 1.5 μm, or at least 2 μm, or at least 2.5 μm, or at least 3 μm, or at least 4 μm, or at least 5 μm. Optionally, the porous particle framework D 50 The particle size may be 25 μm or less, or 20 μm or less, or 18 μm or less, or 15 μm or less, or 12 μm or less, or 10 μm or less, or 8 μm or less.

[0050] D of porous particle skeleton 10 The particle size is preferably at least 0.5 μm, or at least 0.8 μm, or at least 1 μm, or at least 1.5 μm, or at least 2 μm. 10 Maintaining a particle size of 0.5 μm or larger reduces the possibility of undesirable aggregation of submicron-sized particles, improving the dispersibility of the resulting composite particles.

[0051] D of porous particle skeleton 90 The particle size is preferably 50 μm or less, or 40 μm or less, or 30 μm or less, or 25 μm or less, or 20 μm or less, or 15 μm or less.

[0052] The porous particle skeleton preferably has a narrow size distribution span. For example, the particle size distribution span ((D 90 -D 10 ) / D 50 The size distribution (as defined) is preferably 5 or less, more preferably 4 or less, more preferably 3 or less, more preferably 2 or less, and most preferably 1.5 or less. Maintaining a narrow size distribution span makes it easier to efficiently pack particles into a high-density powder bed.

[0053] The porous particle framework may have an average sphericity (as defined herein) greater than 0.5. Preferably, they have an average sphericity of at least 0.55, or at least 0.6, or at least 0.65, or at least 0.7, or at least 0.75, or at least 0.8, or at least 0.85. Preferably, the porous particle framework has an average sphericity of at least 0.90, or at least 0.92, or at least 0.93, or at least 0.94, or at least 0.95. Spherical particles are thought to enhance depositional uniformity and promote high-density packing both in batch pressure reactors and in the final product incorporated into electrodes.

[0054] High-precision two-dimensional projections of micron-scale particles can be obtained by a scanning electron microscope (SEM) or by dynamic image analysis that records the shadows projected by the particles with a digital camera. As used herein, the term "sphericity" is understood as the ratio of the particle projected area (obtained from such imaging techniques) to the area of a circle, where the particle projection and the circumference of the circle are the same. Thus, the sphericity S of an individual particle can be defined as follows:

Number

Number

[0055] The porous particle skeleton preferably has a BET surface area of at least 100 m 2 / g, or at least 500 m 2 / g, or at least 750 m 2 / g, or at least 1,000 m 2 / g, or at least 1,250 m 2 / g, or at least 1,500 m 2 / g. As used herein, the term "BET surface area" is interpreted to refer to the surface area per unit mass calculated from the measurement of the physical adsorption of gas molecules on the solid surface using the Brunauer-Emmett-Teller theory in accordance with the ISO 9277 method (e.g., ISO 9277:2022). Preferably, the BET surface area of the porous particle skeleton is 4,000 m 2 / g or less, or 3,500 m 2 / g or less, or 3,250 m 2 / g or less, or 3,000 m<着 2 / g or less, or 2,500 m 2 / g or less, or 2,000 m 2 / g or less. For example, the porous particle skeleton is 100 m 2 / g 10 to 4,000 m 2 / g, or 500 m 2 / g to 4,000 m 2 / g, or 750 m 2 / g to 3,500 m 2 / g, or 1,000 m 2 / g to 3,250 m 2 / g, or 1,000 m 2 / g to 3,000 m 2 / g, or 1,000 m 2 / g to 2,500 m 2 / g, or 1,000 m 2 / g to 2,000 m 2 / g may have a BET surface area in the range of.

[0056] The porous particle skeleton preferably has a particle density of at least 0.35, 3 g / cm 3 It is preferably less than, 2 g / cm 3 It is more preferably less than, 1.5 g / cm 3 It is even more preferably less than, 0.35 to 1.2 g / cm 3 It is most preferably. As used herein, the term "particle density" refers to the "apparent particle density" measured by mercury porosimetry (i.e., the value obtained by dividing the mass of the particles by the volume of the particles, where the particle volume is the sum of the volume of the solid material and the closed pores or blind pores (the "blind pores" are pores that are too small to be measured by mercury porosimetry)). Preferably, the porous particle skeleton is 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 3It has a particle density of 1.15 g / cm³. Preferably, the porous particle skeleton has a density of 1.15 g / cm³. 3 The following, or 1.1 g / cm³ 3 The following, or 1.05 g / cm³ 3 The following, or 1 g / cm³ 3 The following, or 0.95 g / cm³ 3 The following, or 0.9 g / cm³ 3 It has the following particle density.

[0057] Preferably, the porous particle skeleton is (i) Measured by nitrogen gas adsorption, 0.4-1.8 cm 3 The total pore volume of micropores and mesopores within the range of / g. (ii) PD of 30nm or less 50 PD with a pore size of preferably 50 nm or less 90 Pore ​​diameter, and (iii) D in the range of 1 to 30 μm 50 The particle size is small.

[0058] More preferably, the porous particle skeleton is (i) Measured by nitrogen gas adsorption, 0.5-1.6 cm 3 The total pore volume of micropores and mesopores within the range of / g. (ii) PD of 15nm or less 50 PD with a pore size of preferably 30 nm or less 90 Pore ​​diameter, and (iii) D in the range of 1 to 25 μm 50 The particle size is small.

[0059] More preferably, the porous particle skeleton is (i) Measured by nitrogen gas adsorption, 0.6-1.5 cm 3 The total pore volume of micropores and mesopores within 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 to 20 μm 50 The particle size is small.

[0060] More preferably, the porous particle skeleton is (i) Measured by nitrogen gas adsorption, 0.65-1.4 cm 3 The total pore volume of micropores and mesopores within 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 to 18 μm 50 The particle size is small.

[0061] More preferably, the porous particle skeleton is (i) Measured by nitrogen gas adsorption, 0.7-1.3 cm 3 The total pore volume of micropores and mesopores within 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 to 15 μm 50 The particle size is small.

[0062] More preferably, the porous particle skeleton is (i) Measured by nitrogen gas adsorption, 0.75-1.2 cm 3 The total pore volume of micropores and mesopores within 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, and (iii) D in the range of 2 to 12 μm 50 The particle size is small.

[0063] More preferably, the porous particle skeleton is (i) Measured by nitrogen gas adsorption, 0.8-1.2 cm 3 The total pore volume of micropores and mesopores within 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, and (iii) D in the range of 2.5 to 10 μm 50 The particle size is small.

[0064] In certain examples, the porous particle framework is a porous carbon particle framework containing micropores and optionally mesopores. P 1 is, cm 3 Expressed as / g, this is the total volume of micropores and mesopores in the porous carbon particle framework, P 1 It is at least 0.35 and, optionally, less than 2.5. VP07 and VP2 are P 1 This is the volume of pores in porous carbon particle skeletons with pore diameters of 0.7 nm or less and 2.0 nm or less, expressed as a percentage of the total volume, where VP07 is in the range of 5.1 to 35%, and VP2 is at least 2.5 × VP07. The micropore volume of the porous carbon particle framework is at least 0.3 cm³. 3 / g P 1 VP07, VP2, and micropore volume are measured by nitrogen gas adsorption.

[0065] In another specific example, the porous particle skeleton is a porous carbon particle skeleton containing micropores and optionally mesopores. P 1 is, cm 3 Expressed as / g, this is the total volume of micropores and mesopores in the porous carbon particle framework, P 1 It is at least 0.35 and, optionally, less than 2.5. VP07, VP2, VP5, and VP20 are P 1 This is the volume of pores in porous carbon particle skeletons with pore diameters of 0.7 nm or less, 2.0 nm or less, 5.0 nm or less, and 20.0 nm or less, expressed as a percentage of the total volume. VP07 is in the range of 5.1-35%, VP2 is in the range of 40-90%, and VP20-VP5 are less than 20%. Optionally, the micropore volume of the porous carbon particle skeleton is at least 0.3 cm³. 3 / g P 1 VP07, VP2, VP5, VP20, and micropore volume are measured by nitrogen gas adsorption.

[0066] The porous particle framework preferably contains a conductive material. The use of a conductive porous particle framework is advantageous because it forms a conductive framework within the composite particles and facilitates the flow of electrons between the lithium atoms / ions inserted into the electroactive material and the current collector.

[0067] A preferred type of porous particle skeleton is a particle comprising or consisting of a carbon material, more preferably a conductive carbon material, which is referred to herein as a porous carbon particle skeleton, more preferably a conductive porous carbon particle skeleton.

[0068] The porous carbon particle framework preferably contains at least 80% by weight of carbon, more preferably at least 85% by weight of carbon, more preferably at least 90% by weight of carbon, more preferably at least 95% by weight of carbon, and optionally at least 98% by weight or at least 99% by weight of carbon. The carbon may be crystalline carbon, amorphous carbon, or a mixture of amorphous and crystalline carbon. The porous carbon particles may be hard carbon particles or soft carbon particles.

[0069] As used herein, the term “hard carbon” refers to a nanoscale polycyclic aromatic domain in which carbon atoms are primarily sp-coupled. 2 This refers to a disordered carbon matrix that exists in a hybrid state (three-way bond). Polycyclic aromatic domains are cross-linked by chemical bonds such as COC bonds. Due to the chemical cross-linking between polycyclic aromatic domains, hard carbon cannot be converted to graphite even at high temperatures. Hard carbon has large G bonds in its Raman spectrum (approximately 1600 cm⁻¹). -1 It has graphite-like properties, as evidenced by the following: However, the prominent D bond in the Raman spectrum (approximately 1350 cm⁻¹) -1 As evidenced by ), carbon is not perfectly graphitic.

[0070] As used herein, "soft carbon" refers to polycyclic aromatic domains having dimensions in the range of 5 to 200 nm, in which carbon atoms are mainly sp 2This also refers to a disordered carbon matrix that exists in a hybrid state (three-way bonding). In contrast to hard carbon, the polyaromatic domains of soft carbon are bound together by intermolecular forces but are not cross-linked by chemical bonds. This means that it graphitizes at high temperatures. The porous carbon particle skeleton has at least 50% sp² as measured by XPS. 2 It is preferable that it contains hybrid carbon. For example, the porous carbon particle skeleton preferably contains 50% to 98% sp 2 Hybrid carbon, 55%~95% sp 2 Hybrid carbon, 60%~90% sp 2 Hybrid carbon, or 70-85% sp 2 It may contain hybrid carbon.

[0071] The porous carbon particle framework used in the present invention is most preferably in the form of activated carbon. The term "activated carbon" refers to a carbonaceous material that has been physically or chemically treated to increase its porosity and surface area. Chemical or physical activation (e.g., high-temperature steam or CO2) mechanisms are one of the common methods used in the production of activated carbon. A suitable activation process involves contacting pyrolytic carbon with one or more of oxygen, steam, CO, and CO2 at temperatures ranging from 300 to 1500°C, 600 to 1200°C, or 600 to 1000°C.

[0072] Mesopores can also be obtained by known stenography processes using extractable pore-forming agents such as MgO and other colloidal or polymer templates, and these templates can be removed by thermal or chemical means after thermal decomposition or activation.

[0073] Depending on the starting materials and the conditions of the pyrolysis process, various different porous carbon particle skeletons are available in this art. Porous carbon particle skeletons of various different specifications are available from commercial suppliers.

[0074] Various different carbonaceous materials can be used to prepare a suitable porous carbon particle skeleton via pyrolysis. Preferably, plant sources are used. Examples of plant sources include seeds, nuts, and the shells and husks of fruits (including drupes, kernels, and seeds). Examples of these plant sources include coconut husks and shells (including coir), peanuts, walnuts, apricots, almonds, palm seeds, peaches, olives, hazelnuts, bamboo, and tree bark (e.g., the bark of conifers including pine, spruce, larch, and poplar, and the bark of broad-leaved trees including oak). A preferred plant source is coconut husk. Fossil carbon sources such as coal may be used. Examples of resins and polymer materials as carbonaceous materials 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.

[0075] The carbonaceous material, for example, a plant source, preferably has an elemental composition containing at least 40% by weight of carbon, at least 3% by weight of hydrogen, and at least 30% by weight of oxygen. Trace amounts of nitrogen, sulfur, and chlorine may also be present. More preferably, the carbonaceous material has an elemental composition containing about 50% by weight of carbon, about 5% by weight of hydrogen, and about 40% by weight of oxygen, with smaller amounts of nitrogen, sulfur, and chlorine present.

[0076] Porous carbon particle skeletons are typically obtained from carbonaceous materials in a two-step process. First, the carbonaceous material is heated and thermally decomposed in an inert atmosphere. The inert atmosphere can be nitrogen, CO2, noble gases, or mixtures thereof. The thermal decomposition is usually carried out at a temperature of about 400–900°C, or about 500–700°C, or about 550–700°C, so that dehydration and devolatilization of carbon occurs. Preferably, the temperature does not exceed about 700°C. Optionally, the carbonaceous material is pre-treated to remove impurities before heating. Optionally, the carbonaceous material is purified and / or washed and dried before heating. Optionally, the carbonaceous material is sieved, crushed or ground before heating to obtain particles of uniform size. Optionally, the carbonaceous material is pelletized before heating.

[0077] Next, the pyrolyzed material is activated by heating it at a temperature of 600°C to 1200°C in a flow of one or more of oxygen, steam, CO, and CO2. This causes a chemical reaction between the carbon and the flowing gas to occur on the internal surface of the carbon, removing carbon from the pore walls and increasing the pore volume. This gas activation process is also called a physical activation process and can easily change the pore size to produce activated carbon with the desired porosity. Preferably, the pyrolyzed material is activated with steam.

[0078] Physical activation can be appropriately carried out in a rotary furnace, fixed-bed reactor, or fluidized-bed reactor. Optionally, additional washing, cleaning, or purification steps may be performed after activation. Optionally, the pyrolysis and activation steps may be combined into a continuous process. Optionally, the activated material may be crushed (e.g., ground) and / or sieved after the activation step to obtain particles of the desired size.

[0079] The combustion rate of the pyrolysis material during activation is preferably at least 30%, or at least 40%. The combustion rate is preferably 80% or less, or 75% or less, or 70% or less. The combustion rate is the mass fraction of the pyrolysis material removed during the physical activation step, and is expressed as a percentage of the material mass before the physical activation was initiated.

[0080] In chemical activation methods, carbonaceous materials are impregnated with chemical activators (e.g., NaOH, KOH, K2CO3, H3PO4, CaCl2, ZnCl2, and mixtures thereof). While carbonaceous materials may be carbonized before chemical impregnation, typically, they are impregnated before thermal decomposition, with the thermal decomposition step occurring simultaneously with the activation. Thermal decomposition for chemical activation can be carried out at 250–1000°C or 500–950°C. When porous carbon is formed using a chemical activation process, in addition to pore generation by thermal decomposition of carbon, the activation mechanism functions by expanding existing pores or spreading (exfoliating) the graphene sheet, and does not help maintain a high percentage of micropore space accessible through narrow channels / openings. This is thought to result in a relatively reduced electrochemical performance of composite materials prepared from chemically activated porous carbon materials. Therefore, particulate porous carbon skeletons are preferably prepared by physical activation.

[0081] It has been found that impregnating carbonaceous materials with polyvalent metals that act as catalysts allows the activation process to be carried out at lower temperatures and / or in shorter times, thereby reducing costs. Typically, residual polyvalent metals in such processes are washed away, increasing manufacturing complexity and negating cost advantages. However, in the present invention, such a washing step is unnecessary because the residual polyvalent metals act to form an intermetallic phase in step (d). Therefore, step (a) may include impregnating the carbonaceous material with a polyvalent metal and activating the impregnated carbonaceous material to form a porous carbon particle skeleton containing micropores and / or mesopores and the polyvalent metal, and it is most preferable that step (a) does not include a washing step after activating the impregnated carbonaceous material. Impregnation is preferably achieved using a salt or complex of the polyvalent metal, preferably a salt. The salt or complex of the polyvalent metal can be dissolved in a pore-forming agent such as ethylene glycol. The polyvalent metal may be selected from group 2 metals, transition metals, and mixtures thereof, preferably from calcium, magnesium, nickel, molybdenum, copper, and mixtures thereof, most preferably from calcium. For example, impregnation can be achieved using calcium acetate. Activation may involve heating at a temperature of 500°C to 1200°C in a stream of one or more of oxygen, nitrogen, vapor, CO, and CO2.

[0082] A typical example of activated carbon synthesis is as follows:

[0083] Synthetic activated carbon is prepared from a mixture of novolac resin and 11% hexamethylenetetramine powder (Bakelite PF 6705 FP, purchased from Hexion GmbH). This starting material is crosslinked at 150°C for 1 hour, and the resulting solid block of crosslinked material is crushed to a size of 2-3 cm, and then crushed into particles of approximately 100 μm. Next, this cured resin powder is thermally decomposed at 800°C for 10 minutes under a nitrogen gas flow of 1 L / min. The carbon yield obtained from this precursor is 57-59%. After carbonization, the carbon is ball-milled to a particle size of 3-4 μm, and the resulting carbon material is 0.20-0.22 cm². 30.25-0.3 cm² containing fine porosity / g 3 Total pore volume per gram and 650-700 m 2 It has a surface area of ​​0.8-0.9 cm². Next, this carbon is activated with vapor or CO₂ to achieve the desired pore volume. 3 The typical activation temperature used for CO2 activation to achieve the total pore volume per gram is 950–980°C, with a residence time of 5–8 hours depending on the amount of carbon being activated, the CO2 flow rate, and the type of furnace used. The temperature used for steam activation is lower than that for CO2, typically 850°C, because steam is more reactive. The residence time at the steam activation temperature varies depending on the type and amount of charcoal being activated, the steam flow rate, and the type of furnace used, but is typically 6–9 hours.

[0084] Examples of activated carbon produced by steam activation are as follows:

[0085] Total pore volume is 0.79 cm³ 3 To produce a vapor-activated synthesis scaffold at / g, vapor is introduced via a humidifier consisting of a nitrogen atomizer (3 bar injection pressure) through a 1 mm orifice positioned perpendicular to a 1 mm orifice, water is added to the atomization chamber in droplet form, and atomization is induced by the high-pressure nitrogen flow causing the high-pressure gas to collide with the water droplets. To prevent accidental vapor condensation, heating tapes are used at the inlet and outlet. Carbohydrate phenolic resin is processed using a planetary ball mill. 50The material is ball-milled to 3μm (60g load, 105, 10mm balls, 300RPM, 20-minute intervals). Next, 15g of the ground carbide phenol resin is placed in a short alumina crucible, and the material is spread evenly along the crucible. Steam activation is performed in a tubular furnace with the crucible placed in the center of the heating zone. The furnace is purged with 0.8L / min of N2 for 10-30 minutes. A heating rate of 8.7°C / min is used with a set point of 850°C. When the temperature reaches 840°C, water is injected into the spray nozzle at a rate of 0.25mL / min (water injection rate), and the temperature stabilizes when it reaches 850°C. This is held for 345 minutes. Once the holding is complete, the steam flow rate is set to zero and the heating tape is turned off.

[0086] Alternatives to carbon-based particle frameworks include porous particle frameworks comprising titanium nitride, titanium carbide, silicon carbide, boron carbide, nickel oxide, silicon oxide, silicon dioxide, aluminum oxide, silicon-aluminum ternary oxide, magnesium oxide, lead oxide, zirconium oxide, silicon nitride, titanium silicon nitride, nickel nitride, molybdenum nitride, titanium oxynitride, silicon carbide oxycarbide, boron nitride, or vanadium nitride. Preferred alternatives to particulate porous carbon frameworks are particulate porous frameworks of titanium nitride, silicon carbide oxycarbide, or boron nitride.

[0087] The porous particle framework optionally contains polyvalent metals. As mentioned above, polyvalent metals are often considered undesirable impurities in the porous carbon framework used in LIBs. Therefore, the porous carbon framework is typically subjected to additional processes to remove polyvalent metals or minimize their amount before being used in LIB manufacturing. One commonly used process is washing, which can be performed using acidic, basic, or neutral liquids. Other processes include gas purification, which involves removing volatile polyvalent metals as metal chlorides by reaction with chlorine gas. An advantage of the present invention is that such additional processes may not be necessary because polyvalent metal impurities promote the formation of desired intermetallic phases and reduce the complexity of manufacturing. Therefore, the porous particle framework in step (a) may not have been treated to remove impurities naturally present in the raw material used to synthesize the porous particle framework. For example, the porous particle framework in step (a) may not have been subjected to a washing step aimed at removing impurities naturally present in the raw material used to synthesize the porous particle framework.

[0088] The raw materials used in the production of porous particle skeletons are affected by the type and level of impurities. One economical raw material is biomass. However, since biomass raw materials contain impurities such as Ca and Mg, they are typically washed to remove such impurities. The present invention enables the use of biomass raw materials without requiring such additional processing. Therefore, preferably, the porous particle skeleton in step (a) is derived from biomass and is obtained without a washing step aimed at removing impurities, most preferably.

[0089] The porous particle framework may contain Ca, Mg, and S at concentrations of 50 to 5,000 ppm, respectively, relative to the mass of the porous particle framework. These are impurities that are typically present when biomass raw materials are used.

[0090] The porous particle framework may contain 100-10,000 ppm, 250-8,000 ppm, or 500-5,000 ppm of Ca relative to the mass of the porous particle framework.

[0091] The porous particle framework may contain at least one transition metal and Al at concentrations of 50 to 1,000 ppm, respectively, relative to the mass of the porous particle framework. These are impurities that are typically present when synthetic polymer raw materials are used.

[0092] P can also be present within the porous particle framework, typically resulting from the chemical activation of the raw materials (e.g., when H3PO4 is used as an activator). For example, the porous particle framework may contain 200–25,000 ppm, 500–20,000 ppm, or 1,000–16,000 ppm of P relative to the mass of the porous particle framework.

[0093] In certain cases, the porous particle framework is Ca at concentrations of 100-10,000 ppm, 250-8,000 ppm, or 500-5,000 ppm relative to the mass of the porous carbon particle framework, and The porous carbon particle framework contains 200-25,000 ppm, 500-20,000 ppm, or 1,000-16,000 ppm of P relative to its mass. Preferably, the porous carbon particle skeleton contains 500 to 5,000 ppm of Ca and 1,000 to 16,000 ppm of P relative to the mass of the porous carbon particle skeleton.

[0094] Such a framework may be provided as part of step (a) of the process, preferably by using H3PO4 to activate a biomass-derived carbonaceous material, and step (a) preferably does not include a washing step after the activation of the carbonaceous material.

[0095] One method for providing a porous particle skeleton containing a desired polyvalent metal is to introduce the polyvalent metal into the raw materials used to manufacture the skeleton before activation. A polymer raw material such as lignin (e.g., kraft lignin obtained from the wood pulping process) can be dissolved in a suitable solvent together with an aqueous solution of the desired polyvalent metal precursor. Non-aqueous systems can also be used, such as dissolving a phenolic resin in an organic solvent such as isopropyl alcohol or acetone containing a suitable polyvalent metal precursor. The aqueous or non-aqueous solution may also contain an activator for subsequent chemical activation. The aqueous or non-aqueous solution may also contain a suitable crosslinking agent such as hexamine. The solution is mixed until all components are dissolved. The solvent is then removed by thermal evaporation and / or vacuum drying (e.g., in the case of water, the excess is evaporated at 80°C and then vacuum-dried at 100°C to remove residual water). The polymer can then be further crosslinked at high temperature in another step, if necessary. The dried polymer / polyvalent metal precursor mixture can be heated to induce a thermal crosslinking process. The material can then be carbonized and activated according to conventional methods known in the art, such as those described above.

[0096] The desired polyvalent metal can be introduced into the carbonization raw material before activation. The carbonization raw material can be pulverized in the presence of the polyvalent metal precursor. Alternatively, the raw material can be immersed in a solution of the polyvalent metal precursor, and then the solvent can be removed. Next, the mixture is further heated and residual volatiles are removed in an inert atmosphere (e.g., 500°C in N2). Then, the mixture is heated to the activation temperature in an inert atmosphere, and if physical activation is required, the atmosphere is switched to another atmosphere (e.g., CO2 / N2 at 900°C) for an appropriate time (e.g., 3 hours). The activated carbon mat can then be subjected to post-treatment as needed, such as jet milling to reduce particle size or washing to remove excess metal compounds.

[0097] Optional step (b) includes impregnating the porous particle framework with a polyvalent metal. Step (b) is performed if the porous particle framework in step (a) does not contain an appropriate amount or type of polyvalent metal to cause the formation of the intermetallic phase in step (d). Thus, the present invention enables the use of a wide variety of porous particle frameworks, with or without polyvalent metals.

[0098] Step (b) is typically performed at temperatures below 1000°C. Step (b) is typically performed in an inert atmosphere, optionally in an atmosphere of nitrogen, CO2, a noble gas, or a mixture thereof.

[0099] If step (b) is performed, it may be performed before or after step (c).

[0100] Step (b) typically involves impregnating a porous particle framework with a polyvalent metal precursor, such as a salt or complex of a polyvalent metal. The polyvalent metal precursor may be selected from oxides, carbonates, nitrates, hydroxides, hydrides, sulfates, carboxylates, halides, oxalates, bisoxalatoborates, bis(trifluoromethanesulfonyl)imides, citrates, phosphates, complexes containing EDTA, complexes containing rotaxanes, and mixtures thereof. Step (b) can be achieved by several standard techniques known in the art, including wet impregnation, spray drying, rotary evaporation, grinding, powder mixing, and melt penetration. Other methods for achieving step (b) include the use of CVD and / or CVI. The polyvalent metal precursor may be selected from acetates.

[0101] For example, a porous particle framework, such as activated carbon from a physical or chemical activation process, is impregnated with polyvalent metals by exposing the carbon to a solution of polyvalent metal precursors such as chlorides or nitrates for a predetermined period, e.g., 24 hours, thereby enabling wet impregnation of carbon with the precursors. The excess solution is filtered, and the resulting wet cake is dried overnight at 70-80°C. The resulting solid is placed in a suitable reactor, such as a tubular furnace, and heated to a high temperature (e.g., 750°C) to decompose the precursors under an inert atmosphere. The material is then recovered and stored in a sealed container, drying oven, or desiccator.

[0102] In another example, a porous particle skeleton is pulverized to a desired size in a solvent in the presence of a polyvalent metal precursor in solution, and then recovered by spray-drying the resulting suspension at a temperature higher than the boiling point of the solvent, so that, for example, the polyvalent metal precursor moves into the pores of the skeleton. The skeleton with impregnated polyvalent metal can be heat-treated as described above to release the desired dopant form.

[0103] In another example, the initial wetting technique can be used to fill a porous particle skeleton with a polyvalent metal precursor. A predetermined amount of the polyvalent metal precursor is dissolved in a predetermined amount of solvent, which is determined by the porous volume of the skeleton. Excess solvent is removed by heating, followed by calcination under an N2 atmosphere to remove volatile substances. The resulting impregnated skeleton powder is recovered as described above.

[0104] Step (c) includes depositing elemental silicon and / or elemental germanium within the pores of the porous particle framework. Step (c) typically includes contacting the porous particle framework with a silicon-containing precursor and / or germanium-containing precursor, most preferably a silicon-containing precursor, at a temperature effective in causing the deposition of elemental silicon and / or elemental germanium, most preferably elemental silicon, within the pores of the porous particle framework.

[0105] Step (c) is appropriately carried out via chemical vapor infiltration (CVI) of a gaseous silicon and / or germanium-containing precursor into the pore structure of the porous particle framework. As used herein, CVI refers to the process by which a gaseous precursor is thermally decomposed on the surface, forming elemental silicon and / or germanium and gaseous byproducts on the surface.

[0106] Suitable gaseous silicon-containing precursors include silane (SiH4), disilane (Si2H6), trisilane (Si3H8), and tetrasilane (Si4H 10 ), Pentasilane (Si5H 12 ), Hexasilane (Si6H 14 ), methylsilane (CH3SiH3), dimethylsilane ((CH3)2SiH2), or chlorosilane, for example trichlorosilane (HSiCl3) or dichlorosilane (H2SiCl2) or chlorosilane (H3SiCl), or methylchlorosilane, for example methyltrichlorosilane (CH3SiCl3) or dimethyldichlorosilane ((CH3)2SiCl2). Preferably, the silicon-containing precursor is silane (SiH4), disilane (Si2H6), trisilane (Si3H8), tetrasilane (Si4H 10 A selection is made from the group consisting of the following. A particularly preferred silicon precursor is silane.

[0107] Suitable gaseous germanium-containing precursors include germane (GeH4), hexamethyldigermanium ((CH3)3GeGe(CH3)3), tetramethylgermanium ((CH3)4Ge), tributylgermanium hydride ([CH3(CH2)3]3GeH), triethylgermanium hydride ((C2H5)3GeH), and triphenylgermanium hydride ((C6H5)3GeH). Preferably, the germanium-containing precursor is germane.

[0108] When the precursor is a chlorinated compound such as chlorosilane, the precursor is used in mixture with hydrogen gas, preferably in such a way that the atomic ratio of hydrogen to chlorine is at least 1:1.

[0109] Optionally, the precursor is chlorine-free. Chlorine-free means that the amount of chlorine-containing compound in the precursor is less than 1% by weight, preferably less than 0.1% by weight, and preferably less than 0.01% by weight.

[0110] The gaseous precursor in step (c) may be used in a pure form (or substantially pure form) or as a diluted mixture with an inert carrier gas such as nitrogen or argon. Preferably, step (c) involves contacting a porous particle skeleton 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 gaseous precursor, based on the total volume of the gas.

[0111] In accordance with conventional procedures for working in an inert atmosphere, the presence of oxygen in step (c) should be avoided to prevent undesirable oxidation of the deposited electroactive material. Preferably, the oxygen content is less than 0.01% by volume, and more preferably less than 0.001% by volume, based on the total volume of gas used in step (c).

[0112] The temperature in step (c) is preferably in the range of 180 to 520°C, or 340 to 500°C, or 350 to 480°C, or 350 to 450°C, or 350 to 420°C, or less than 350 to 400°C, or 355 to 395°C, or 360 to 390°C, or 360 to 385°C, or 360 to 380°C.

[0113] The pressure in step (c) is preferably in the range of 1 to 5000 kPa, more preferably 200 to 2000 kPa, or 20 to 500 kPa, or 40 to 200 kPa, or 50 to 150 kPa, or 60 to 120 kPa, or 80 to 100 kPa. Preferably, the pressure in step (b) is maintained at 200 kPa or less, or 150 kPa or less, or 120 kPa or less, or 110 kPa or less, or 100 kPa or less, or 90 kPa or less, or 80 kPa or less. Any reference to pressure in any step of the claimed process refers to the absolute pressure within the reaction zone, which may include any suitable form of reactor vessel.

[0114] The deposition of electroactive material by CVI removes byproducts, particularly byproduct gases such as hydrogen. Step (c) preferably further includes separating the byproducts from the particles formed in step (c). Separation of byproducts can be carried out by flushing the reactor with an inert gas and / or by reducing the pressure and evacuating the reactor. For example, separation of byproducts from the particles formed in step (c) can be carried out 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 may be effective not only in removing byproducts in the gas phase but also in desorbing byproducts that may be adsorbed on the surface of the deposited silicon and / or germanium.

[0115] Either the porous particle framework in step (a) contains polyvalent metals, or step (b) is performed, or both are performed. Thus, the impregnated porous particle framework contains polyvalent metals from step (a) (e.g., as naturally occurring impurities), polyvalent metals added in step (b), or both. More than one polyvalent metal may be present.

[0116] If elemental silicon is deposited in step (c), it will be understood that the polyvalent metals will include polyvalent metals other than silicon. If elemental germanium is deposited in step (c), the polyvalent metals will include polyvalent metals other than germanium.

[0117] To avoid ambiguity, the term “polyvalent metal” includes elements that may be classified as “metalloids” in some literature, such as B, Si, Ge, As, and Sb. In this invention, polyvalent metals may be defined as those selected from the metals and metalloids of the 1st to 5th periods of groups 2 to 14, As, Sb, and mixtures thereof. Polyvalent metals may be selected from the 1st to 5th periods of group 2, B, the metals and metalloids of the 4th and 5th periods of groups 3 to 14, and mixtures thereof, preferably from Mg, Ca, Sn, B, Ge, Zn, Zr, and mixtures thereof, most preferably from Ca, Mg, B, Sn, and mixtures thereof.

[0118] Polyvalent metals can be selected from metals and metalloids of the 1st to 5th periods of Group 2, metals and metalloids of the 4th and 5th periods of Groups 3 to 14, Al, Sb, and mixtures thereof, or Mg, Ca, Sn, Ge, Zn, Al, Sb, and mixtures thereof.

[0119] Polyvalent metals such as Mg and / or Ca are particularly preferred. For reference, phase diagrams of Mg-Si and Ca-Si binary alloys are described in Seth et al., RSC Adv., 2020, 10, 37327-37345 and Okamoto, Journal of Phase Equilibria and Diffusion Vol.28 No.4 2007.

[0120] As a result of steps (a), (b), and (c), an impregnated porous particle skeleton containing a polyvalent metal and silicon and / or germanium is formed. The silicon and / or germanium is preferably in the form of nanoscale electroactive domains as described above. The particle size distribution of the porous particle skeleton in step (a) is assumed not to change with the process of forming the impregnated porous particle skeleton. Therefore, the particle size distribution parameter defined for the porous particle skeleton can also be used to define the impregnated porous particle skeleton (e.g., D 50 (etc.)

[0121] If no opposing instructions exist, the pore structure of the impregnated porous particle skeleton (e.g., pore volume, PD) is specified. n Pore ​​diameter, etc., is defined by measuring the pore structure of the porous particle skeleton in isolation, i.e., in the absence of electroactive material (or other material) occupying the pores of the porous particle skeleton. Thus, the pore structure parameters defined for the porous particle skeleton in step (a) can also be used to define the impregnated porous particle skeleton.

[0122] The polyvalent metal is present in the impregnated porous particle framework at a concentration of preferably 30 atomic% or less, optionally 0.001 atomic% or more, or 0.1 to 25 atomic% or 1 to 20 atomic% relative to the total amount of polyvalent metal and silicon and / or germanium in the impregnated porous particle framework. When silicon is deposited in step (c), the amount of polyvalent metal can be expressed relative to the total amount of polyvalent metal and silicon in the impregnated porous particle framework using the same atomic percentage. For example, when silicon is deposited in step (c), the polyvalent metal is present in the impregnated porous particle framework at a concentration of preferably 30 atomic% or less, optionally 0.001 atomic% or more, or 0.1 to 25 atomic% or 1 to 20 atomic% relative to the total amount of polyvalent metal and silicon in the impregnated porous particle framework. When silicon and germanium are deposited in step (c), the amount of polyvalent metal can be expressed relative to the total amount of polyvalent metal, silicon, and germanium in the impregnated porous particle framework, using the same atomic percentages.

[0123] In other words, polyvalent metals may be present in the impregnated porous particle framework at concentrations of 5 ppm or more, 50 ppm or more, 500 ppm or more, 1,100 ppm or more, 11,000 ppm or more, and optionally 200,000 ppm or less, 100,000 ppm or less, or 50,000 ppm or less, relative to the mass of the impregnated porous particle framework.

[0124] The impregnated porous particle skeleton is preferably, Mg at concentrations of 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less, relative to the total amount of Mg and silicon in the impregnated porous particle framework. Ca at concentrations of 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less, relative to the total amount of Ca and silicon in the impregnated porous particle framework. The total amount of Sn and silicon in the impregnated porous particle skeleton is 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less of Sn. Ge at concentrations of 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less, relative to the total amount of Ge and silicon in the impregnated porous particle framework. A concentration of Zn of 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less, relative to the total amount of Zn and silicon in the impregnated porous particle framework. Al at concentrations of 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less, relative to the total amount of Al and silicon in the impregnated porous particle framework, and The impregnated porous particle skeleton contains at least one of the following concentrations of Sb: 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less, relative to the total amount of Sb and silicon. The polyvalent metal is present in the impregnated porous particle framework at a concentration of preferably 30 atomic percent or less relative to the total amount of polyvalent metal and silicon in the impregnated porous particle framework. In this way, a favorable amount of intermetallic phase can be formed during step (d). Most preferably, the impregnated porous particle framework contains Mg and / or Ca in the above concentration range.

[0125] While the presence of some polyvalent metals is suitable for forming the intermetallic phases described herein, it may be undesirable for other reasons depending on the desired end use of the composite particles. For example, some battery manufacturers may want to minimize the concentration of certain elements to avoid harmful side reactions with other battery components. Therefore, in some cases, impregnated porous particles may be undesirable. Fe at concentrations of 0.5 atomic% or less, 0.1 atomic% or less, 0.01 atomic% or less, or 0.001 atomic% or less relative to the total amount of Fe and silicon in the impregnated porous particle framework. Co at concentrations of 0.5 atomic% or less, 0.1 atomic% or less, 0.01 atomic% or less, or 0.001 atomic% or less relative to the total amount of Co and silicon in the impregnated porous particle framework. Cu at concentrations of 0.5 atomic% or less, 0.1 atomic% or less, 0.01 atomic% or less, or 0.001 atomic% or less relative to the total amount of Cu and silicon in the impregnated porous particle framework. Ni at concentrations of 0.5 atomic% or less, 0.1 atomic% or less, 0.01 atomic% or less, or 0.001 atomic% or less relative to the total amount of Ni and silicon in the impregnated porous particle framework, and The impregnated porous particle framework may contain at least one, or optionally all, of the following concentrations of Mn: 0.5 atomic% or less, 0.1 atomic% or less, 0.01 atomic% or less, or 0.001 atomic% or less, relative to the total amount of Mn and silicon.

[0126] For example, an impregnated porous particle skeleton is Mg at concentrations of 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less, relative to the total amount of Mg and silicon in the impregnated porous particle framework, With respect to the total amount of Ca and silicon in the impregnated porous particle framework, one or two of the following concentrations of Ca are present: 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less, and Fe at a concentration of 0.01 atomic% or less, or 0.001 atomic% or less, relative to the total amount of Fe and silicon in the impregnated porous particle framework. Co at a concentration of 0.01 atomic% or less, or 0.001 atomic% or less, relative to the total amount of Co and silicon in the impregnated porous particle framework. Cu at a concentration of 0.01 atomic% or less, or 0.001 atomic% or less, relative to the total amount of Cu and silicon in the impregnated porous particle framework. Ni at a concentration of 0.01 atomic% or less, or 0.001 atomic% or less, relative to the total amount of Ni and silicon in the impregnated porous particle framework, The impregnated porous particle skeleton may contain at least one, or optionally all, of Mn at a concentration of 0.01 atomic% or less, or 0.001 atomic% or less, relative to the total amount of Mn and silicon. The polyvalent metal is preferably present in the impregnated porous particle framework at a concentration of 30 atomic percent or less relative to the total amount of the polyvalent metal and silicon in the impregnated porous particle framework.

[0127] For example, an impregnated porous particle skeleton is The total amount of Mg and silicon in the impregnated porous particle framework is 0.1 to 25 atomic percent of Mg, and One or two of the Ca atoms in a concentration of 0.1 to 25 atomic percent relative to the total amount of Ca and silicon in the impregnated porous particle framework, and Fe at a concentration of 0.001 atomic percent or less relative to the total amount of Fe and silicon in the impregnated porous particle framework. Co at a concentration of 0.001 atomic percent or less relative to the total amount of Co and silicon in the impregnated porous particle framework. Cu at a concentration of 0.001 atomic percent or less relative to the total amount of Cu and silicon in the impregnated porous particle framework. Ni at a concentration of 0.001 atomic percent or less relative to the total amount of Ni and silicon in the impregnated porous particle framework, and The impregnated porous particle skeleton may contain at least one, or optionally all, of Mn at a concentration of 0.001 atomic percent or less relative to the total amount of Mn and silicon. The polyvalent metals are present in the impregnated porous particle framework at a concentration of 30 atomic percent or less relative to the total amount of polyvalent metals and silicon in the impregnated porous particle framework.

[0128] A range of silicon and / or germanium filling amounts can be obtained in the impregnated porous particle framework. The impregnated porous particle framework preferably contains at least 26 wt% silicon and / or germanium, or at least 28 wt% silicon and / or germanium, or at least 30 wt% silicon and / or germanium, or at least 32 wt% silicon and / or germanium, or at least 34 wt% silicon and / or germanium, or at least 36 wt% silicon and / or germanium, or at least 38 wt% silicon and / or germanium, or at least 40 wt% silicon and / or germanium, or at least 42 wt% silicon and / or germanium, or at least 44 wt% silicon and / or germanium. Most preferably, the impregnated porous particle framework contains elemental silicon, where these amounts refer to the amount of silicon.

[0129] The amount of elemental silicon and / or elemental germanium in the impregnated composite particles is preferably selected such that, after step (c), elemental silicon and / or elemental germanium occupies at least 20% and up to 90% of the internal pore volume of the porous particle framework. For example, elemental silicon and / or elemental germanium 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 particle framework. Most preferably, the impregnated porous particle framework contains elemental silicon, where these amounts refer to the amount of silicon. Within these preferred ranges, the remaining pore volume of the porous particle framework is effective in accommodating the expansion of the electroactive material during charging and discharging without a large excess pore volume that does not contribute to the volumetric capacity of the particulate particles. However, the amount of electroactive material is also not so large that it hinders effective lithiation due to insufficient metal ion diffusion rate or mechanical resistance to lithiation due to insufficient expansion volume.

[0130] If the impregnated porous particle skeleton contains elemental silicon, the amount of silicon in the impregnated porous particle skeleton is such that the mass ratio of silicon to the porous particle skeleton is [0.5 × P 1 ~1.9×P 1 The requirement that ]:1 can be related to the available pore volume in the porous particle skeleton, P 1 is, cm 3 It is a dimensionless quantity expressed in / g that represents the magnitude of the total pore volume of micropores and mesopores within a porous particle framework (for example, the total volume of micropores and mesopores in a porous particle framework is 1.2 cm³). 3 In the case of / g, P 1 =1.2). This relationship defines the weight ratio of silicon where the pore volume accounts for approximately 20% to 82%, taking into account the silicon density and the pore volume of the porous particle skeleton. Preferably, the weight ratio of silicon deposited in step (c) to the porous particle skeleton 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 ]: The range is 1.

[0131] The amount of silicon in the impregnated porous particle framework can be determined by elemental analysis. Preferably, elemental analysis is used to determine the elemental composition of the porous particle framework, the impregnated porous particle framework, and the composite particles.

[0132] The silicon and polyvalent metal content is preferably determined by ICP-OES (inductively coupled plasma atomic emission spectrometry). Numerous ICP-OES instruments are commercially available, such as the iCAP® 7000 series ICP-OES analyzers available from ThermoFisher Scientific. The carbon content of the impregnated porous particle skeleton and the carbon content of the porous particle skeleton alone (and hydrogen, nitrogen, and oxygen content as needed) are preferably determined by IR absorption. A suitable instrument for determining the carbon, hydrogen, nitrogen, and oxygen content is the TruSpec® Micro elemental analyzer available from Leco Corporation.

[0133] Preferably, at least 90% by weight, more preferably at least 95% by weight, and even more preferably at least 98% by weight of the elemental silicon and / or elemental germanium material in the impregnated porous particle framework is located within the internal pore volume of the porous particles such that there is no electroactive material present at all, or only a very small amount, on the outer surface of the impregnated porous particle framework. As described above, the deposition of the electroactive material in the CVI process occurs on the surface of the porous particles. Given the very large internal surface area of ​​the porous particles, the reaction kinetics of the CVI process ensure that the deposition of the electroactive material occurs almost completely within the pores of the porous particles.

[0134] Internal deposition of the electroactive material is further improved by the requirement that the pressure in step (c) is maintained below 200 kPa or within the more preferable pressure range described above.

[0135] The impregnated porous particle skeleton obtained by the process of the present invention can be characterized by its performance under thermogravimetric analysis (TGA) in air. This analytical method is based on the principle that an increase in weight is observed when electroactive materials are oxidized in air and at high temperatures.

[0136] Generally, atoms on a material's surface are known to have different bonding interactions than atoms within the material, and this difference is usually explained by the material's surface energy. In the case of silicon deposited by chemical vapor deposition (CVI), the free valence of silicon atoms on the surface generally includes hydride groups. When this hydride-terminated silicon surface is exposed to air, it reacts with oxygen to form a native oxide surface. However, surfaces not exposed to air remain in the hydride-terminated state.

[0137] As used herein, "surface silicon" is calculated from the initial mass increase from the minimum value in the TGA trace between 150°C and 500°C to the maximum mass measured in the temperature range of 550°C and 650°C, where the TGA is performed in air at a temperature increase rate of 10°C / min. Since this mass increase is thought to be due to oxidation of surface silicon, the percentage of surface silicon to the total amount of silicon can be determined according to the following formula. Y = 1.875 × [(M 最大 -M 最小 ) / M f ] × 100%

[0138] In the formula, Y is the percentage of surface silicon relative to the total silicon in the sample, M 最大 This is the maximum mass of the sample measured in the temperature range of 550°C to 650°C, M 最小 This is the minimum mass of a sample between 150°C and 500°C, M f is the mass of the sample when oxidation is complete at 1400°C. For completeness, it should be understood that 1.875 is the molar mass ratio of SiO2 to O2 (i.e., the ratio of the mass of SiO2 formed to the mass increase due to the addition of oxygen). Typically, TGA analysis is performed using a sample size of 10 mg ± 2 mg.

[0139] It has been found that when the surface silicon measured by the TGA method described above is at least 20% by weight of the total silicon amount in the impregnated porous particle framework, reversible capacity retention over multiple charge / discharge cycles is significantly improved. Preferably, at least 22% by weight, or at least 25% by weight, or at least 30% by weight, or at least 35% by weight, or at least 40% by weight, or at least 45% by weight of the silicon in the impregnated porous particle framework is surface silicon determined by thermogravimetric analysis (TGA).

[0140] The fact that a significant proportion of hydride-terminated silicon can be measured in the particulate material even after passivation in air indicates that the composite particles contain internal silicon surfaces inaccessible to air. This suggests that the internal pore spaces of the porous carbon framework are first covered with silicon and then capped, forming internal void spaces with hydride-terminated silicon surfaces facing closed internal void spaces. This indicates that the silicon domains have a characteristic length scale that is much smaller than the pores themselves.

[0141] Because the electrolyte cannot access the internal voids, the silicon surface is protected from SEI formation, thereby minimizing irreversible lithium loss during the initial charge cycle. Further exposure of the electroactive material in subsequent charge-discharge cycles is also significantly prevented, so SEI formation does not become a critical failure mechanism leading to capacity loss. At the same time, this silicon is hydrostatically constrained during lithiation, allowing the voids to be utilized during the expansion induced by lithiation.

[0142] The impregnated porous particle skeleton is preferably low in rough bulk silicon content, as determined by TGA, in addition to the surface silicon content. Rough bulk silicon is defined herein as silicon oxidized above 800°C as determined by TGA, and TGA is performed in air at a temperature rise rate of 10°C / min. Thus, the rough bulk silicon content is determined according to the following formula. Z = 1.875 × [(Mf -M 800 ) / M f ] × 100%

[0143] In the formula, Z is the percentage of unoxidized silicon at 800°C, M 800 M is the mass of the sample at 800°C. f This is the mass of the ash when oxidation is complete at 1400°C. For the purposes of this analysis, it is assumed that the mass increase above 800°C corresponds to the oxidation of silicon to SiO2, and that the total mass at the completion of oxidation is SiO2.

[0144] Silicon that oxidizes above 800°C is undesirable. Preferably, rough bulk silicon is 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, as determined by TGA.

[0145] Preferably, at least 30% by weight of silicon is surface silicon and 10% by weight or less of silicon is rough bulk silicon, both determined by TGA. More preferably, at least 35% by weight of silicon is surface silicon and 8% by weight or less of silicon is rough bulk silicon, both determined by TGA. More preferably, at least 40% by weight of silicon is surface silicon and 5% by weight or less of silicon is rough bulk silicon, both determined by TGA. More preferably, at least 45% by weight of silicon is surface silicon and 2% by weight or less of silicon is rough bulk silicon, both determined by TGA.

[0146] The impregnated porous particle skeleton is preferably 300 m 2 / g or less, or 250m 2 / g or less, or 200m 2 / g or less, or 150m 2 It has a BET surface area of ​​100m² or less. More preferably, 100m². 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 is less than or equal to / g. Generally, a low BET surface area is preferable to minimize the formation of a solid electrolyte interface (SEI) layer on the surface of the composite particles during the first charge-discharge cycle of the anode. However, if the BET surface area is too low, the majority of the electroactive material cannot access the metal ions in the surrounding electrolyte, resulting in unacceptably low charging speed and capacity. 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 ​​composite particles is 0.1 to 100 m². 2 / g, or 0.1-80m 2 / g, or 0.5-60m 2 / g, or 0.5-40m 2 / g, or 1-30m 2 / g, or 1-25m 2 / g, or 2-20m 2 It could be in the range of / g.

[0147] This process may include an annealing step prior to step (d), in which the impregnated porous particle framework is annealed at a high temperature under an inert or reducing atmosphere.

[0148] The annealing step involves several interrelated thermal induction processes that stabilize silicon and / or germanium and extend the cycle life of the composite particles in the LIB. These processes include the removal of hydrogen from terminal Si-H and / or Ge-H bonds, volume contraction of Si and / or Ge domains resulting in the reopening of some pore spaces, and the promotion of covalent bonding between silicon and the inner surface of the porous particle framework (e.g., Si-C bonds if the porous particle framework is a porous carbon particle framework).

[0149] For example, the temperature of the annealing step may be at least 450°C, or at least 500°C, or at least 510°C, or at least 520°C, or at least 540°C, or at least 560°C, or at least 580°C, or at least 600°C, or at least 610°C, or at least 620°C, or at least 630°C, or at least 640°C, or at least 650°C. Preferably, the temperature of the annealing step is 900°C or less, or 850°C or less, or 800°C or less, or 750°C or less, or 700°C or less, or 680°C or less, or 660°C or less, or 650°C or less.

[0150] The temperature of the annealing step may be in the range of 200°C to 1000°C, 400°C to 900°C, 500°C to 900°C, or 600°C to 900°C. The temperature of the annealing step may be in the range of 500°C to 800°C, 510°C to 800°C, 520°C to 750°C, 540°C to 700°C, 560°C to 680°C, 580°C to 660°C, or 600°C to 650°C.

[0151] The temperature of the annealing step may be higher than the temperature of step (c). Preferably, the temperature of the annealing step 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 of step (c).

[0152] The duration of the annealing step is preferably at least 1 minute, or at least 2 minutes, or at least 5 minutes, or at least 10 minutes, or at least 15 minutes, or at least 20 minutes, or at least 30 minutes, or at least 45 minutes, or at least 1 hour, or at least 2 hours. Preferably, the duration of the annealing step is 72 hours or less, or 48 hours or less, or 24 hours or less, or 12 hours or less, or 6 hours or less, or 5 hours or less, or 4 hours or less, or 3 hours or less.

[0153] The duration of an annealing step can range from 1 minute to 72 hours, or 2 minutes to 48 hours, or 5 minutes to 24 hours, or 10 minutes to 12 hours, or 15 minutes to 6 hours, or 20 minutes to 5 hours, or 30 minutes to 4 hours, or 1 hour to 4 hours, or 1 hour to 3 hours.

[0154] The annealing step is carried out under an inert or reducing atmosphere. Preferably, the atmosphere is selected from a nitrogen atmosphere, a hydrogen-containing atmosphere, a noble gas atmosphere, or a mixture thereof.

[0155] Preferably, the annealing step is performed at a temperature in the range of 400°C to 900°C for 1 minute to 72 hours, or at a temperature in the range of 500°C to 900°C for 30 minutes to 4 hours, or at a temperature in the range of 600°C to 900°C for 1 hour to 4 hours.

[0156] The ratio of the BET surface area of ​​the particles formed after the annealing step to the BET surface area of ​​the impregnated porous particle skeleton may be at least 1.1:1, or at least 1.2:1, or at least 1.3:1, or at least 1.4:1, or at least 1.5:1, or at least 2:1, or at least 3:1, or at least 4:1, or at least 5:1.

[0157] The ratio of the BET surface area of ​​the particles formed after the annealing step to the BET surface area of ​​the impregnated porous particle skeleton may be 15:1 or less, 14:1 or less, 13:1 or less, or 12:1 or less.

[0158] The ratio of the total pore volume of micropores and mesopores measured by gas adsorption of particles formed after the annealing step to the total pore volume of micropores and mesopores measured by gas adsorption of the impregnated porous particle skeleton may be at least 2:1, or at least 3:1, or at least 4:1, or at least 5:1, or at least 6:1, or at least 7:1, or at least 8:1.

[0159] The ratio of the total pore volume of micropores and mesopores measured by gas adsorption of particles formed after the annealing step to the total pore volume of micropores and mesopores measured by gas adsorption of the impregnated porous particle skeleton may be 20:1 or less, or 19:1 or less, or 18:1 or less, or 17:1 or less, or 16:1 or less, or 15:1 or less.

[0160] The ratio of the total hydrogen content of the particles formed after the annealing step to the total hydrogen content of the impregnated porous particle skeleton may be 0.8:1 or less, 0.7:1 or less, 0.6:1 or less, or 0.5:1 or less.

[0161] The ratio of the total hydrogen content of the particles formed after the annealing step to the total hydrogen content of the impregnated porous particle skeleton may be at least 0.1:1, or at least 0.2:1, or at least 0.3:1.

[0162] This process may include a passivation step prior to step (d), in which the impregnated porous particle skeleton is brought into contact with a passivating agent.

[0163] As defined herein, a passivating agent is a compound or mixture of compounds that can react with the surface of silicon and / or germanium deposited in step (c) to form a modified surface. In particular, the passivating agent as defined herein is a material that can react with the surface of silicon to further reduce its surface energy.

[0164] Preferably, the passivation step is carried out after the annealing step. As explained above, one of the effects of the annealing step is to reopen the pore spaces that were previously blocked or covered by the silicon nanostructures, allowing the passivating gas to access the pore spaces and enabling more extensive passivation of the silicon surface and removal of the hydrogen-terminated silicon surface.

[0165] One type of preferred passivation layer is the native oxide layer. The native oxide layer can be formed, for example, by exposing the silicon and / or germanium surface to a passivating agent selected from air or other oxygen-containing gases. The passivation layer may contain silicon oxide of the formula SiO x where 0 < x ≦ 2. The silicon oxide is preferably amorphous silicon oxide. Since the formation of the native oxide layer is exothermic, careful process control is required to prevent overheating or combustion of the particulate material. When the passivating agent is an oxygen-containing gas, the passivation step may include cooling the impregnated porous particles to a temperature below 300°C, preferably below 200°C, optionally below 100°C, before contacting the impregnated porous particles with the oxygen-containing gas.

[0166] The passivating agent can be liquid water or a gas containing water vapor. The passivation step may include contacting the impregnated porous particle skeleton with liquid water or a gas containing water vapor at a temperature of at least 30°C, optionally below 400°C or below 300°C.

[0167] The passivation step preferably includes a first step of contacting the impregnated porous particle skeleton with an oxygen-containing gas at a temperature below 300 °C, and a second step of contacting the skeleton obtained from the first step with a gas containing liquid water or steam at a temperature of at least 30 °C, optionally below 400 °C, or preferably below 300 °C.

[0168] Another type of passivation layer is, for example, a nitride layer formed by exposing a silicon and / or germanium surface to a passivating agent selected from ammonia or other nitrogen-containing molecules. The passivation layer may contain silicon nitride of the formula SiN x where 0 < x ≤ 4 / 3. The silicon nitride is preferably amorphous silicon nitride. The nitride layer can be formed by contacting the silicon and / or germanium surface with ammonia at a temperature of 200 - 700 °C, preferably 400 - 700 °C, more preferably 400 - 600 °C. Next, if necessary, the temperature is raised to the range of 500 - 1000 °C to form a nitride surface (e.g., a silicon nitride surface of the formula SiN x where x ≤ 4 / 3). Nitride passivation may be preferred over oxide passivation. Nitrides with a sub-stoichiometric ratio (such as SiN x etc., where 0 < x ≤ 4 / 3) are conductive, so the nitride passivation layer can function as a conductive network that enables faster charging and discharging of electroactive materials. Phosphine, as a phosphorus analogue of ammonia, can also be used as a passivating agent. Another type of passivation layer is, for example, an oxynitride layer formed by exposing a silicon and / or germanium surface to a passivating agent containing ammonia (or other nitrogen-containing molecules) 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 silicon nitride is preferably amorphous silicon oxynitride. [[ID=]]

[0169] Another type of passivation layer is a carbide layer. The passivation layer has the formula SiC xmay contain silicon carbide, where 0 < x ≦ 1. The silicon carbide is preferably amorphous silicon carbide. The carbide layer can be formed by contacting the silicon and / or germanium surface with a passivating agent selected from carbon-containing precursors such as methane or ethylene at a high temperature in the range of, for example, 250 to 700 °C. At low temperatures, covalent bonds are formed between the silicon surface and the carbon-containing precursor, and as the temperature rises, it is converted into a single layer of crystalline silicon carbide. The chemical formula of silicon carbide is SiC x where 0 < x ≦ 1.

[0170] Other suitable passivating agents include alkenes, alkynes or carbonyl functional groups, more preferably compounds containing terminal alkenes, terminal alkynes, aldehyde or ketone groups. Preferred passivating agents include one or more compounds of the following formulae, (i) R 1 -CH=CH-R 1 , (ii) R 1 -C≡C-R 1 , and (iii) O=CR 1 R 1 , where each R 1 independently represents H or an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 carbon atoms, or two R 1 groups form an unsubstituted or substituted ring structure containing 3 to 8 carbon atoms in the ring.

[0171] Particularly preferred passivating agents include one or more compounds of the following formulae, (i) CH2=CH-R 1 , and <00009​​​​​​​​​​​​Examples of 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]octo-2-ene. Optionally, mixtures of different passivators may also be used.

[0173] Passivating agents containing alkenes, alkynes, or carbonyl groups are thought to undergo insertion reactions with Si-H groups on the silicon surface, forming a covalently passivated surface that is resistant to oxidation by air. Therefore, the passivation reaction between the silicon surface and the passivating agent can be understood as a form of hydrosilylation, as schematically shown below. [ka]

[0174] Other suitable passivators include compounds containing active hydrogen atoms bonded to oxygen, nitrogen, sulfur, or phosphorus. For example, passivators may be alcohols, amines, thiols, or phosphines. It is understood that the reaction between the hydride groups on the silicon surface and the -XH groups results in the elimination of H2, forming a direct bond between X and the silicon surface.

[0175] Suitable passivators in this category include compounds of the following formula: (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 These are defined independently as 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 These elements combine to form an unsubstituted or substituted ring structure containing 3 to 8 carbon atoms within the ring.

[0176] Preferably, X represents O or NH.

[0177] Preferably, R 2 represents an optionally substituted aliphatic or aromatic group having 2 to 10 carbon atoms. Amine groups can also be incorporated into 4 to 10-membered aliphatic or aromatic ring structures such as pyrrolidine, pyrrole, imidazole, piperazine, indole, or purine.

[0178] Contact between the impregnated porous particle skeleton and the passivating agent is carried out in a temperature range of 25 to 500°C, preferably in a temperature range of 50 to 450°C, and more preferably in a temperature range of 100 to 400°C.

[0179] This process may further include a deposition step prior to step (d), in which a lithium-ion permeable material is deposited within and / or on the outer surface of the impregnated porous particle framework. In this way, in step (d), a metallic interphase is formed within the shell of the lithium-ion permeable material, and the metallic interphase is protected from subsequent dissolution in the electrolyte. This minimizes the risk of lithium plating and dendrite formation.

[0180] Preferably, the lithium-ion permeable material is a pyrolysis carbon material, and the deposition step includes combining an impregnated porous particle skeleton with a pyrolysis carbon precursor and heating the pyrolysis carbon precursor to a temperature effective for depositing the conductive pyrolysis carbon material inside and / or on the outer surface of the impregnated porous particle skeleton. If the process includes an annealing step, the deposition step may optionally be performed before or after the annealing step. If a passivation step is performed, most preferably the deposition step is performed after the passivation step.

[0181] The pyrolysis carbon precursor is preferably a hydrocarbon. Suitable hydrocarbons include polycyclic hydrocarbons containing 10 to 25 carbon atoms and optionally 1 to 3 heteroatoms, and optionally, polycyclic aromatic hydrocarbons are selected from naphthalene, substituted naphthalenes such as dihydroxynaphthalene, anthracene, tetracene, pentacene, fluorene, acenaphthene, phenanthrene, fluoranthrene, pyrene, chrysene, perylene, coronene, fluorenone, anthraquinone, anthrone, and their alkyl-substituted derivatives. Suitable pyrolysis carbon precursors also include bicyclic monoterpenoids, and optionally, bicyclic monoterpenoids are selected from camphor, borneol, eucalyptol, camphene, carene, sabinene, thujene, and pinene. Furthermore, suitable pyrolysis carbon precursors include C2-C10 hydrocarbons, optionally selected from alkanes, alkenes, alkynes, cycloalkanes, cycloalkenes, and arenes, such as methane, ethylene, propylene, limonene, styrene, cyclohexane, cyclohexene, α-terpinene, and acetylene. Other suitable pyrolysis carbon precursors include phthalocyanines, sucrose, starch, graphene oxide, reduced graphene oxide, pyrene, perhydropyrene, triphenylene, tetracene, benzopyrene, perylene, coronene, and chrysene. The preferred carbon precursor is acetylene.

[0182] The suitable temperature for depositing pyrolysis carbon material in the deposit step is in the range of 300-800°C or 400-700°C. For example, the temperature may be 680°C or lower, or 660°C or lower, or 640°C or lower, or 620°C or lower, or 600°C or lower, or 580°C or lower, or 560°C or lower, or 540°C or lower, or 520°C or lower, or 500°C or lower. The minimum temperature depends on the type of carbon precursor used. Preferably, the temperature is at least 300°C, or at least 350°C, or at least 400°C, or at least 450°C, or at least 500°C.

[0183] The carbon-containing precursor used in the deposition step can be used in its pure form or as a diluted mixture with an inert carrier gas such as nitrogen or argon. For example, the carbon-containing precursor can be used in an amount ranging from 0.1 to 100% by volume, or 0.5 to 20% by volume, or 1 to 10% by volume, or 1 to 5% by volume, based on the total volume of the precursor and the inert carrier gas.

[0184] When depositing a pyrolytic carbon material, the same compound can function as both the passivating agent in the passivation step and the pyrolytic carbon precursor in the deposition step. For example, if styrene is selected as the pyrolytic carbon precursor, styrene will also function as a passivating agent if the impregnated porous particle skeleton has not been exposed to another passivating agent before contacting styrene. In this case, the passivation and deposition of the conductive carbon material can be carried out simultaneously in a stepwise manner, for example, in a temperature range of 300 to 700°C. Alternatively, the passivation and deposition of the conductive carbon material can be carried out continuously using the same material as the passivating agent and the pyrolytic carbon precursor, but the deposition step is carried out at a higher temperature after the passivation step. For example, passivation can be carried out in a temperature range of 25°C to less than 300°C, and the deposition of pyrolytic carbon can be carried out in a temperature range of 300 to 700°C. These two steps can be appropriately carried out continuously by raising the temperature while maintaining contact with the compound that functions as both the passivating agent and the pyrolytic carbon precursor. At a lower temperature (e.g., in the range of 25°C to less than 300°C), passivation becomes the main process. As the temperature rises (e.g., 300 to 700°C), the deposition of pyrolytic carbon occurs.

[0185] Step (d) involves contacting the impregnated porous particle framework with a monovalent metal. The monovalent metal is typically selected from Li, Na, K, Rb, and mixtures thereof. Preferably, the monovalent metal is Li or Na, these metals are routinely used as charge carriers in lithium-ion and sodium-ion batteries. Most preferably, the monovalent metal is Li. However, as mentioned above, the impregnated porous particles themselves are a convenient intermediate material for producing composite particles for metal-ion batteries. Therefore, step (d) can be omitted, and the impregnated porous particles can be provided for subsequent downstream use.

[0186] Preferably, step (d) includes contacting the impregnated porous particle skeleton with an electrolyte containing a monovalent metal. Suitable electrolytes are non-aqueous electrolytes containing a monovalent metal, for example, in the form of a lithium salt, and may include, but are not limited to, non-aqueous electrolytes, organic solid electrolytes, and inorganic solid electrolytes. Examples of usable non-aqueous electrolytes include aprotic organic solvents, such as propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, sulfolane, methylsulfolane, and 1,3-dimethyl-2-imidazolidinone.

[0187] Examples of organic solid electrolytes include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate ester polymers, polyester sulfides, polyvinyl alcohol, polyvinylidene fluoride, and polymers containing ionic dissociation groups.

[0188] Examples of inorganic solid electrolytes include nitrides, halides, and sulfides of lithium salts, such as Li5NI2, Li3N, LiI, LiSiO4, Li2SiS3, Li4SiO4, LiOH, and Li3PO4.

[0189] Lithium salts dissolve well in selected solvents or mixtures of solvents. Examples of suitable lithium salts include LiCl, LiOH, LiBr, LiI, LiClO4, LiBF4, LiBC4O8, LiPF6, LiCF3SO3, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, and CF3SO3Li. Equivalent sodium salts may also be used.

[0190] In an alternative approach, step (d) may involve chemically introducing a monovalent metal. Thus, step (d) may involve contacting the impregnated porous particle skeleton with a monovalent metal precursor. The monovalent metal precursor may be a salt, complex, or organic compound of a monovalent metal. For example, the monovalent metal precursor may be selected from oxides, carbonates, nitrates, hydroxides, hydrides, sulfates, carboxylates, halides, oxalates, bisoxalatoborates, bis(trifluoromethanesulfonyl)imides, citrates, phosphates, complexes containing EDTA, complexes containing rotaxanes, organolithium compounds, and mixtures thereof. For example, step (d) may involve contacting the impregnated porous particle skeleton with butyllithium, preferably t This may involve contact with an organolithium compound such as BuLi, or with LiAlH4. The monovalent metal precursor may be selected from acetates.

[0191] Step (d) involves applying a potential. When an appropriate potential is applied to an electroactive material such as silicon in the presence of a monovalent metal such as Li, an insertion reaction or lithiation reaction occurs, forming an intermetallic phase (also called the Zintol phase) containing Si and Li. When Li insertion reaches its maximum level, Li 15 Si4(Li 3.75 Si) is formed. In an electrochemical cell, a reverse potential is applied and delithiation occurs, for example, Li 3.75-x Si is formed. By reversing the potential again, the cell can be charged and discharged.

[0192] In this invention, because polyvalent metals are present, when a potential is applied, an intermetallic phase is formed containing silicon and / or germanium, monovalent metals, and polyvalent metals. This intermetallic phase is thought to be formed following a reaction in which, for example, Li and Mg co-insert into Si. Alternatively, an ion exchange reaction may occur, leading to the formation of the intermetallic phase. For example, Mg and fully or excessively lithium-ionized binary domains (Li 3.75+x This includes ion exchange of silicon (Si). For example, if the polyvalent metal is magnesium, then Li 3.55 Mg 0.1 A Si phase may be formed. Reversing the potential inside the cell can lead to delithiation (e.g., Li 3.55-x Mg 0.1 Si formation occurs, and the cell can be charged and discharged accordingly. The intermetallic phase is considered more stable than the two-component silicon and / or germanium alloy formed when typical composite particles are lithium-ionized in a battery, resulting in less reaction with both the liquid and solid electrolytes.

[0193] Step (d) is particularly preferable to be achieved as part of the battery formation cycle. As is widely known, a battery undergoes at least one controlled charge / discharge cycle called the formation cycle before it is ready for use after assembly. During the formation cycle, numerous reactions typically occur between the electrolyte and the anode (formation of the anode solid electrolyte interface SEI), between the electrolyte and the cathode (formation of the cathode electrolyte interface CEI), and between the charge carriers (e.g., Li or Na) and the electroactive material. Since the formation cycle is already carried out in battery manufacturing, performing step (d) as part of this cycle is advantageous because it minimizes the changes required for the battery manufacturing process. Contact between the impregnated porous particle backbone and the monovalent metal is achieved during the formation cycle via the monovalent metal present in the electrolyte (e.g., Li-containing electrolyte) and / or the monovalent metal present in the cathode (e.g., Li-containing cathode (or, if the present invention is carried out in the context of a Na-ion battery, the Na equivalent)). The application of a potential effective in causing the formation of the intermetallic phase is also achieved during the formation cycle. Therefore, the impregnated porous particle framework can be used as a "drop-in" solution in place of existing composite particles before the existing formation cycle is performed, and can form the desired intermetallic phase as part of the existing process.

[0194] Therefore, the process of the first aspect of the present invention preferably includes, prior to step (d), the step of forming an electrochemical cell such as a rechargeable metal-ion battery, which includes an anode, a cathode, and an electrolyte between the anode and the cathode, the cathode and / or electrolyte comprising a monovalent metal. Step (d) is then achieved as part of the electrochemical cell formation cycle.

[0195] Another advantageous process for achieving step (d), in which impregnated porous particles can be used as a drop-in solution, is to pre-lithify the electrodes before incorporating them into a lithium-ion battery (or pre-sodium the electrodes before incorporating them into a sodium-ion battery). Electrodes typically take the form of a composition containing an active material deposited on a current collector such as copper or aluminum foil. Electrodes can be pre-lithified to replenish lithium lost during initial cycles, such as the formation cycle. Pre-lithification can be achieved by electrochemical methods, and the potentials applied during these methods can be utilized as the potential in step (d). For example, one electrochemical process involves placing the electrodes in an electrolytic cell of a lithium-containing electrolyte. This process can be carried out in a roll-to-roll process in which the electrode layer passes through the electrolytic bath. Other electrochemical processes include forming a cell containing the electrodes, electrolyte, and a lithium-containing counter electrode such as metallic lithium foil, and then polarization of the cell. A direct contact method has also been envisioned in which the metallic lithium foil is polarized by directly contacting it with the electrode. Since each of these pre-lithiation processes involves bringing electrodes into contact with lithium and applying a potential, step (d) can be carried out as part of each of these processes, and therefore the present invention can be implemented without requiring additional manufacturing steps. When the present invention is applied in the context of sodium-ion batteries, equivalents to each of these processes can be used for pre-sodiumization.

[0196] A specific example of the pre-lithiumization process involves forming electrodes by coating one or both sides of a current collector, such as copper foil, with an electrode composition containing a silicon-containing electroactive material. The electrodes are mounted on a frame between carbon-pair electrodes at 2 cm intervals. The system is immersed in a non-aqueous solvent such as gamma-butyrolactone containing a 0.5 M lithium salt such as LiCl, and is typically kept at room temperature (25°C). CO2 may be blown into the system. The current is 0.9 mA / cm at a cell voltage of 6 V. 2The reduced current density is applied for 150 seconds, followed by a 30-second pause at 0V. This cycle is repeated four times, after which a forward / reverse cycle is performed with a 30-second pause and a current density of 1.0 mAh / cm². 2 This is replaced by a current reversal (oxidation) step. Forward / reverse pulses are repeated until the desired lithium dose to the electrode composition is achieved.

[0197] Accordingly, the process of the first aspect of the present invention preferably includes a step of forming an electrode comprising impregnated porous particles deposited on a current collector prior to step (d). Step (d) is preferably achieved as part of an electrochemical pre-lithiumization or pre-sodiumization step of the electrode. This electrode is then typically used as the anode of a lithium-ion battery or a sodium-ion battery.

[0198] Generally, the formation cycles and potentials used in pre-lithiation described above are effective in inducing the formation of the intermetallic phase. Effective conditions include constant current / constant voltage cycling at C / n (n≧5, lower cutoff voltage≧10mV).

[0199] Step (d) can also be performed independently of the formation cycle or the pre-lithiation step. For example, impregnated porous particles may be deposited on an electrode, step (d) may be performed, and the resulting composite particles may be recovered from the electrode for use in a downstream process.

[0200] Step (d) forms an intermetallic phase containing a polyvalent metal, silicon and / or germanium, and a monovalent metal. It will be understood that the polyvalent metal is present in addition to silicon and / or germanium. If the intermetallic phase contains silicon, it contains a polyvalent metal that is not silicon. If the intermetallic phase contains germanium, it contains a polyvalent metal that is not germanium.

[0201] The intermetallic phase is preferably an alloy of a polyvalent metal, silicon and / or germanium with a monovalent metal. The intermetallic phase may incorporate further elements such as H, Li, Na, K, Rb, N, P, S and mixtures thereof, or H, N, P, S and mixtures thereof, or H, P and mixtures thereof. These further elements may be present in the porous particle framework and may be incorporated into the intermetallic phase when it is formed during step (d). Furthermore, H may be introduced during step (c) because the deposition of elemental silicon and / or elemental germanium often forms hydride end surfaces (e.g., Si-H).

[0202] The presence of intermetallic phases can be verified by various standard methods. These include ion etching by scanning spreading resistance microscopy (SSRM), Raman spectroscopy, XPS, HAADF-TEM, TEM-EDS, and solid-state NMR (e.g., 7 Li and / or 29 It includes Si NMR, and XPS and solid-state NMR are preferred.

[0203] Mg is a particularly preferred polyvalent metal. Mg is relatively small. 2+ The cation is Li + It has an ionic radius equivalent to that of a cation. Therefore, it is believed that when Mg is used as a polyvalent metal, a uniform reaction is promoted throughout the elemental silicon and / or germanium of the impregnated porous particle framework, resulting in the formation of a uniform intermetallic phase.

[0204] Ca is another particularly preferred polyvalent metal. 2+ The cation is Mg 2+ and Li + Its ionic radius is larger than that of [another element]. Therefore, it is thought to promote reactions on the surface of the elemental silicon and / or germanium in the impregnated porous particle framework, resulting in the formation of a rich layer on the surface of the intermetallic phase.

[0205] The intermetallic phase is formed from polyvalent metals and elemental silicon and / or elemental germanium present in the impregnated porous particle framework and from the monovalent metal present in step (d). Since the intermetallic phase itself is an electroactive material, the present invention encompasses a process in which all elemental silicon and / or elemental germanium in the impregnated porous particle framework is consumed to form the intermetallic phase. However, while the resulting composite particles may have excellent lifetime, they are disadvantageous in terms of capacity because the capacity of the intermetallic phase is reduced compared to the original electroactive material (e.g., elemental silicon). Therefore, most preferably, the composite particles contain elemental silicon and / or elemental germanium and the intermetallic phase. This can be achieved by controlling the amount of polyvalent metal in the impregnated porous particles so that not all of the silicon and / or germanium is consumed by the formation of the intermetallic phase. In this specification, the intermetallic phase may be closely bonded to elemental silicon and / or elemental germanium.

[0206] Since elemental silicon and / or elemental germanium are deposited in the pores of the porous particle framework, typically the metallic interphase resides within the pores of the composite particle. However, as will be discussed later, elemental silicon and / or elemental germanium can be further deposited on the outer surface of the porous particle framework, and as a result, the metallic interphase may reside on the outer surface of the composite particle.

[0207] In step (d), a composite particle is formed comprising a porous particle framework containing micropores and / or mesopores, and an intermetallic phase containing a polyvalent metal, silicon and / or germanium, and a monovalent metal. It is assumed that the particle size distribution of the porous particle framework in step (a) does not change during the process of forming the composite particle. Therefore, the particle size distribution parameters defined for the porous particle framework in step (a) can also be used to define the composite particle (e.g., D 50 (etc.)

[0208] If no opposing instructions exist, the pore structure of the composite particle (e.g., pore volume, PD) is determined. nPore ​​diameter, etc., is defined by measuring the pore structure of the porous particle skeleton in isolation, i.e., in the absence of electroactive material (or other material) occupying the pores of the porous particle skeleton. Thus, the pore structure parameters defined for the porous particle skeleton in step (a) can also be used to define the impregnated porous particle skeleton.

[0209] It is believed that the polyvalent metals within the impregnated porous particle framework are retained within the composite particles after the formation of the intermetallic phase. Therefore, the elemental composition of the composite particles can be defined using the same values ​​shown herein for the impregnated porous particle framework. For example, the amount of polyvalent metals in the composite particles can be expressed relative to the total amount of polyvalent metals and silicon in the composite particles, using the same values ​​shown herein for the total amount of polyvalent metals and silicon in the impregnated porous particle framework.

[0210] Similarly, the silicon and / or germanium content in the composite particles can be defined using the same values ​​as those specified herein for the impregnated porous particle framework.

[0211] Elemental silicon and / or elemental germanium are deposited within the pores of a porous particle framework, i.e., micropores and / or mesopores, because this is favorable for the formation of small domains with dimensions on the order of a few nanometers or less. Small domains are thought to be able to lithify and delithiate without excessive structural stress. Furthermore, the pore volume of the porous particle framework can accommodate a considerable amount of expansion of electroactive material internally. Generally, depositing electroactive material on the outer surface of a porous particle framework has been considered undesirable because the formation of small domains is less desirable. Instead, larger, bulkier, or coarser domains are preferred, and are thought to withstand greater structural stress during lithification and delithiation. However, this limits the amount of electroactive material that can be deposited within the framework. As the amount of electroactive material increases, deposition on the outer surface becomes increasingly favorable ("overfilling"). The present invention mitigates this problem and provides a method to minimize the detrimental effects of bulky outer surface regions of electroactive material, enabling higher loads while maintaining lifespan.

[0212] In particular, when elemental silicon and / or elemental germanium are also deposited on the outer surface of the porous particle framework, the presence of polyvalent metals forms an intermetallic phase on the outer surface of the framework, thereby reducing the instability of the bulky outer surface domains of silicon and / or germanium. This allows for extending the lifespan of "overpacked" composite particles while maintaining the advantage of high capacity provided by high packing of electroactive materials. A further advantage is that the intermetallic phase present on the outer surface of the framework serves as a convenient alternative to carbon coatings, which are commonly used to reduce the reactivity of the outer surface. The intermetallic phase on the outer surface also reduces the surface area, which can lower the level of side reactions with electrolytes and other electrode components.

[0213] Accordingly, the process of the first embodiment can be carried out such that step (c) further includes depositing elemental silicon and / or elemental germanium on the outer surface of the porous particle framework, and the intermetallic phase in step (d) is formed on the outer surface of the porous particle framework. This can be achieved if the porous particle framework in step (a) contains a polyvalent metal on its outer surface. This can also be achieved by carrying out step (b) to impregnate the outer surface of the porous particle framework with a polyvalent metal. Preferably, when step (b) is carried out in this manner, a polyvalent metal precursor is deposited on the outer surface of the porous particle framework and an annealing step is performed. The annealing step reduces the polyvalent metal precursor and promotes the formation of the intermetallic phase in step (d).

[0214] Preferably, the process of the first embodiment is such that step (c) further comprises depositing elemental silicon and / or elemental germanium on the outer surface of the porous particle skeleton, and step (d) is carried out such that the intermetallic phase is formed on the outer surface of the porous particle skeleton, then the porous particle skeleton is a porous carbon particle skeleton in which the micropore volume fraction is at least 0.5, or at least 0.55, or at least 0.6, based on the total volume of micropores and mesopores in the porous particle skeleton. More preferably, the porous particle skeleton is a porous carbon particle skeleton comprising micropores and optionally mesopores. P 1 is, cm 3 Expressed as / g, this is the total volume of micropores and mesopores in the porous carbon particle framework, P 1 It is at least 0.35 and, optionally, less than 2.5. VP07, VP2, VP5, and VP20 are P 1 This is the volume of pores in porous carbon particle skeletons with pore diameters of 0.7 nm or less, 2.0 nm or less, 5.0 nm or less, and 20.0 nm or less, expressed as a percentage of the total volume. VP07 is in the range of 5.1-35%, VP2 is in the range of 40-90%, and VP20-VP5 are less than 20%. Optionally, the micropore volume of the porous carbon particle skeleton is at least 0.3 cm³. 3 / g P 1 VP07, VP2, VP5, VP20, and micropore volume are measured by nitrogen gas adsorption.

[0215] The process of the first embodiment may be carried out according to the following modifications.

[0216] In order, step (a), optional step (b), step (c), passivation step, formation of an electrode containing impregnated porous particles, optionally formation of an electrochemical cell containing the electrode, and step (d).

[0217] In order, step (a), step (c), optional step (b), passivation step, formation of an electrode containing impregnated porous particles, optionally formation of an electrochemical cell containing an electrode, and step (d).

[0218] In order, step (a), optional step (b), step (c), annealing step, passivation step, formation of an electrode containing impregnated porous particles, optionally formation of an electrochemical cell containing the electrode, and step (d).

[0219] In order, step (a), optional step (b), step (c), passivation step, annealing step, formation of an electrode containing impregnated porous particles, optionally formation of an electrochemical cell containing the electrode, and step (d).

[0220] Step (a) further comprising depositing elemental silicon and / or elemental germanium on the outer surface of a porous particle framework; step (c) optionally step (b) passivation step; formation of an electrode comprising impregnated porous particles; optionally formation of an electrochemical cell comprising an electrode; and step (d) forming a metallic interphase on the outer surface of the porous particle framework.

[0221] Step (a) further comprising depositing elemental silicon and / or elemental germanium on the outer surface of a porous particle framework; step (c) optionally step (b), annealing step, passivation step, formation of an electrode containing impregnated porous particles, optionally formation of an electrochemical cell containing an electrode, and a metallic interphase being formed on the outer surface of the porous particle framework; step (d).

[0222] In order, step (a), optional step (b), step (c), passivation step, deposition step, annealing step, formation of an electrode containing impregnated porous particles, optionally formation of an electrochemical cell containing an electrode, and step (d).

[0223] In order, step (a), optional step (b), step (c), passivation step, annealing step, deposition step, formation of an electrode containing impregnated porous particles, optionally formation of an electrochemical cell containing an electrode, and step (d).

[0224] The impregnated porous particle skeleton or composite particles (for example, those recovered after step (d) and not yet part of the electrode) can be incorporated into a composition comprising at least one other component. In particular, a composition is provided comprising the impregnated porous particle skeleton or composite particles and at least one other component selected from (i) a binder, (ii) a conductive additive, and (iii) an additional particulate electroactive material. This composition is useful as an electrode composition and can therefore be used to form the active layer of an electrode.

[0225] The composition may be a hybrid electrode composition comprising an impregnated porous particle skeleton or composite particles and at least one additional particulate electroactive material. Examples of additional particulate electroactive materials include graphite, hard carbon, silicon, tin, germanium, aluminum, and lead. The at least one additional particulate electroactive material is preferably selected from graphite and hard carbon, and most preferably the at least one additional particulate electroactive material is graphite.

[0226] In the case of a hybrid electrode composition, the composition preferably contains 3 to 60% by weight, or 3 to 50% by weight, or 5 to 50% by weight, or 10 to 50% by weight, or 15 to 50% by weight, of impregnated porous particle skeletons or composite particles, based on the total dry weight of the composition. At least one additional particulate electroactive material is appropriately present in an amount of 20 to 95% by weight, or 25 to 90% by weight, or 30 to 75% by weight, based on the total dry weight of the composition.

[0227] At least one additional particulate electroactive material is preferably 10-50 μm, preferably 10-40 μm, more preferably 10-30 μm, most preferably 10-25 μm, for example, in the range of 15-25 μm. 50 It has a particle size.

[0228] D of at least one additional particulate electroactive material 10 The particle size is preferably at least 5 μm, more preferably at least 6 μm, more preferably at least 7 μm, more preferably at least 8 μm, more preferably at least 9 μm, and even more preferably at least 10 μm.

[0229] D of at least one additional particulate electroactive material 90 The particle size is preferably 100 μm or less, more preferably 80 μm or less, more preferably 60 μm or less, more preferably 50 μm or less, and most preferably 40 μm or less.

[0230] At least one additional particulate electroactive material is preferably selected from carbon-containing particles, graphite particles and / or hard carbon particles, the graphite and hard carbon particles being in the range of 10 to 50 μm. 50 The particles have a particle size. More preferably, at least one additional particulate electroactive material is selected from graphite particles, and the graphite particles are in the range of 10 to 50 μm. 50 It has a particle size.

[0231] The composition may also be a non-hybrid (or “high-load”) electrode composition substantially free of additional particulate electroactive material. In this context, the term “substantially free of additional particulate electroactive material” should be interpreted as meaning that, based on the total dry weight of the composition, the composition contains less than 15% by weight, preferably less than 10% by weight, preferably less than 5% by weight, preferably less than 2% by weight, more preferably less than 1% by weight, and more preferably less than 0.5% by weight of additional electroactive material (i.e., additional material that can insert and release metal ions during charging and discharging of the battery).

[0232] This type of "high-load" electrode composition preferably contains at least 50% by weight, or at least 60% by weight, or at least 70% by weight, or at least 80% by weight, or at least 90% by weight of impregnated porous particle skeletons or composite particles, based on the total dry weight of the composition.

[0233] The composition may optionally contain a binder. The binder has the function of adhering the composition to the current collector and maintaining the integrity of the composition. Examples of binders include polyvinylidene fluoride (PVDF), polyacrylic acid (PAA) and its alkali metal salts, modified polyacrylic acid (mPAA) and its alkali metal salts, carboxymethylcellulose (CMC), modified carboxymethylcellulose (mCMC), sodium carboxymethylcellulose (Na-CMC), polyvinyl alcohol (PVA), alginates and their alkali metal salts, styrene-butadiene rubber (SBR), and polyimide. The composition may contain a mixture of binders. Preferably, the binder contains a polymer selected from polyacrylic acid (PAA) and its alkali metal salts, modified polyacrylic acid (mPAA) and its alkali metal salts, SBR, and CMC.

[0234] The binder may be present in an amount of 0.5 to 20% by weight, preferably 1 to 15% by weight, preferably 2 to 10% by weight, and most preferably 5 to 10% by weight, based on the total dry weight of the composition.

[0235] The binder may optionally be present in combination with one or more additives that modify the properties of the binder, such as crosslinking promoters, coupling agents, and / or adhesion promoters.

[0236] The composition may optionally contain one or more conductive additives. Preferred conductive additives are non-electroactive materials included to improve electrical conductivity between the electroactive components of the composition and between the electroactive components of the composition and the current collector. Conductive additives may be selected from carbon black, carbon fibers, carbon nanotubes, graphene, acetylene black, Ketjenblack, metal fibers, metal powders, and conductive metal oxides. Preferred conductive additives include carbon black and carbon nanotubes.

[0237] One or more conductive additives may be present in a total amount of 0.5 to 20% by weight, preferably 1 to 15% by weight, preferably 2 to 10% by weight, and most preferably 5 to 10% by weight, based on the total dry weight of the composition.

[0238] The present invention also provides an electrode comprising an impregnated porous particle skeleton or composite particle and a current collector, wherein the impregnated porous particle skeleton or composite particle is in electrical contact with the current collector. The particulate material used to prepare the electrode may be in the form of a composition comprising the impregnated porous particle skeleton or composite particle and at least one other component as defined above.

[0239] As used herein, the term current collector refers to a conductive substrate that can conduct electric current with respect to 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 are typically in the form of foil or mesh having a thickness of 3 to 500 μm. Impregnated porous particle skeletons or composite particles can be coated on one or both sides of the current collector, preferably with a thickness ranging from 10 μm to 1 mm, for example, 20 to 500 μm, or 50 to 200 μm.

[0240] The electrodes may be manufactured by forming a slurry by combining an impregnated porous particle skeleton or composite particles with a solvent and optionally one or more viscosity-modifying additives. The slurry is then cast onto the surface of a current collector, the solvent is removed, and thereby an electrode layer is formed on the surface of the current collector. If necessary, further steps such as heat treatment and / or calendering of the electrode layer to cure any binder may be performed. The electrode layer 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.

[0241] Alternatively, the slurry may be formed into a self-supporting film or mat containing the particulate material of the present invention by, for example, casting the slurry onto a suitable casting template, removing the solvent, and then removing the casting template. The resulting film or mat is cohesive and in the form of self-supporting clumps, which can then be bonded to a current collector by known methods.

[0242] The electrode can be used as the anode of a metal-ion battery. Therefore, the present invention provides a rechargeable metal-ion battery that includes the electrode as the anode. Lithium ions are preferred as the metal ions. More preferably, the rechargeable metal-ion battery is a lithium-ion battery.

[0243] The cathode of a rechargeable metal-ion battery typically includes a current collector and a cathode active material capable of releasing and reabsorbing metal ions. The cathode active material is preferably a metal oxide composite material. Examples of suitable cathode active materials include LiCoO2, LiCo 0.99 Al 0.01 O2, LiNiO2, LiMnO2, LiCo 0.5 Ni 0.5 O2, LiCo 0.7 Ni 0.3 O2, LiCo 0.8 Ni 0.2 O2, LiCo 0.82 Ni 0.18 O2, LiCo0.8 Ni 0.15 Al 0.05 O2, LiLiLi 0.4 Co 0.3 Mn 0.3 O2 and LiNi 0.33 Co 0.33 Mn 0.34 It contains O2. The thickness of the cathode current collector is typically 3 to 500 μm. Examples of materials that can be used as cathode current collectors include aluminum, stainless steel, nickel, titanium, and sintered carbon.

[0244] Electrolytes suitable for rechargeable metal-ion batteries are described above in relation to the step of bringing an impregnated porous particle framework into contact with an electrolyte containing a monovalent metal.

[0245] When the electrolyte is a non-aqueous organic solution, rechargeable metal-ion batteries are preferably provided with a separator interposed between the anode and the cathode. The separator is typically formed from an insulating material with high ion permeability and high mechanical strength. The separator typically has a pore size of 0.01 to 100 μm and a thickness of 5 to 300 μm. An example of a suitable electrode separator includes a microporous polyethylene film. The separator can be replaced with a polymer electrolyte material, in which case the polymer electrolyte material is present in both the composite anode layer and the composite cathode layer. The polymer electrolyte material may be a solid polymer electrolyte or a gel-type polymer electrolyte.

Claims

1. A process for preparing composite particles for use as an electroactive material for metal ion batteries, wherein the process is: (a) Providing a porous particle framework comprising micropores and / or mesopores and optionally a polyvalent metal, (b) optionally impregnating the porous particle framework with a polyvalent metal, (c) A step of depositing elemental silicon and / or elemental germanium in the pores of the porous particle skeleton, The porous particle skeleton in step (a) contains the polyvalent metal, or step (b) is performed, or both are performed. The deposit step provides an impregnated porous particle skeleton containing the polyvalent metal and the silicon and / or the germanium, (d) The step of bringing the impregnated porous particle framework into contact with the monovalent metal while applying a potential effective in causing the formation of an intermetallic phase comprising the polyvalent metal, the silicon and / or the germanium, and the monovalent metal, thereby providing the composite particles, The process including the process described above.

2. Step (b) is the process according to claim 1, which is performed before step (c).

3. Step (b) is the process according to claim 1, which is performed after step (c).

4. The process according to any of the prior claims, step (c) is to deposit elemental silicon in the pores of the porous particle framework.

5. The aforementioned polyvalent metals are Metals and metalloids of the 1st to 5th periods of groups 2 to 14, As, Sb, and mixtures thereof, Metals and metalloids of Group 2, Group B (periods 1-5), Groups 3-14 (periods 4 and 5), and mixtures thereof, or Mg, Ca, B, Sn, Ge, Zn, Zr, and mixtures thereof, Mg, Ca, B, Sn, and mixtures thereof, A process according to any of the prior claims, selected from Mg, Ca, and mixtures thereof.

6. The process according to any of the prior claims, wherein the polyvalent metal is Mg.

7. The process according to any of the prior claims, wherein the polyvalent metal is Ca.

8. The aforementioned intermetallic phase is H, Li, Na, K, Rb, N, P, S, and mixtures thereof, H, N, P, S, and mixtures thereof, The process according to any of the prior claims, further comprising H, P, and mixtures thereof.

9. Step (b) comprises impregnating the porous particle skeleton with a polyvalent metal precursor, optionally the polyvalent metal precursor being a salt or complex of the polyvalent metal, optionally the polyvalent metal precursor being selected from oxides, carbonates, acetates, nitrates, hydroxides, hydrides, sulfates, carboxylates, halides, oxalates, bisoxalatoborates, bis(trifluoromethanesulfonyl)imides, citrates, phosphates, complexes containing EDTA, complexes containing rotaxanes, and mixtures thereof, the process according to any of the prior claims.

10. The process according to any of the prior claims, wherein the polyvalent metal is present in the impregnated porous particle skeleton at a concentration of 5 ppm or more, 50 ppm or more, 500 ppm or more, 1,100 ppm or more, 11,000 ppm or more, and optionally 200,000 ppm or less, 100,000 ppm or less, or 50,000 ppm or less, relative to the mass of the impregnated porous particle skeleton.

11. The process according to any of the prior claims, wherein the polyvalent metal is present in the impregnated porous particle framework at a concentration of 30 atomic% or less, optionally 0.001 atomic% or more, or 0.1 to 25 atomic% or 1 to 20 atomic% relative to the total amount of the polyvalent metal and silicon and / or germanium in the impregnated porous particle framework.

12. The process according to any of the prior claims, step (c) is to deposit elemental silicon in the pores of the porous particle framework, wherein the polyvalent metal is present in the impregnated porous particle framework at a concentration of 30 atomic% or less, optionally 0.001 atomic% or more, or 0.1 to 25 atomic%, or 1 to 20 atomic%, relative to the total amount of polyvalent metal and silicon in the impregnated porous particle framework.

13. The impregnated porous particle skeleton is With respect to the total amount of Mg and silicon in the impregnated porous particle framework, Mg is present in concentrations of 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less. With respect to the total amount of Ca and silicon in the impregnated porous particle skeleton, Ca at concentrations of 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less. With respect to the total amount of Sn and silicon in the impregnated porous particle skeleton, Sn is present in concentrations of 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less. With respect to the total amount of Ge and silicon in the impregnated porous particle skeleton, Ge is present in concentrations of 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less. With respect to the total amount of Zn and silicon in the impregnated porous particle skeleton, Zn is present in concentrations of 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less. Al at concentrations of 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less, relative to the total amount of Al and silicon in the impregnated porous particle framework, and The impregnated porous particle skeleton contains at least one of the following concentrations of Sb: 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less, relative to the total amount of Sb and silicon in the impregnated porous particle skeleton. The process according to any of the prior claims, wherein the polyvalent metal is present in the impregnated porous particle skeleton at a concentration of preferably 30 atomic percent or less relative to the total amount of the polyvalent metal and silicon in the impregnated porous particle skeleton.

14. The impregnated porous particles are Fe at a concentration of 0.5 atomic% or less, 0.1 atomic% or less, 0.01 atomic% or less, or 0.001 atomic% or less, relative to the total amount of Fe and silicon in the impregnated porous particle skeleton. With respect to the total amount of Co and silicon in the impregnated porous particle skeleton, the concentration of Co is 0.5 atomic% or less, 0.1 atomic% or less, 0.01 atomic% or less, or 0.001 atomic% or less. Cu at a concentration of 0.5 atomic% or less, 0.1 atomic% or less, 0.01 atomic% or less, or 0.001 atomic% or less, relative to the total amount of Cu and silicon in the impregnated porous particle skeleton. Ni at a concentration of 0.5 atomic% or less, 0.1 atomic% or less, 0.01 atomic% or less, or 0.001 atomic% or less, relative to the total amount of Ni and silicon in the impregnated porous particle skeleton, and The process according to any of the prior claims, wherein the Mn in the impregnated porous particle skeleton comprises at least one, or optionally all, of the following concentrations of Mn: 0.5 atomic% or less, 0.1 atomic% or less, 0.01 atomic% or less, or 0.001 atomic% or less, relative to the total amount of Mn and silicon.

15. Step (b) is a process according to any of the prior claims, comprising wet impregnation, spray drying, rotary evaporation, grinding, powder mixing, or melt penetration.

16. Step (b) is the process described in any of the prior claims, which is performed at a temperature below 1000°C.

17. Step (b) is performed under an inert atmosphere and optionally with nitrogen, CO2 ２ The process according to any of the prior claims, carried out in an atmosphere of noble gases and mixtures thereof.

18. The process according to any of the prior claims, wherein step (c) comprises contacting the porous particle skeleton with a silicon-containing precursor at a temperature effective for depositing elemental silicon in the pores of the porous particle.

19. The silicon-containing precursor is a gaseous silicon-containing precursor, and optionally, the gaseous silicon-containing precursor is silane (SiH ４ ), disilane (Si ２ H ６ ), trisilane (Si ３ H ８ ), tetrasilane (Si ４ H １０ ), methylsilane (CH ３ SiH ３ ), pentasilane (Si ５ H １２ ), hexasilane (Si ６ H １４ ), dimethylsilane ((CH ３ ) ２ SiH ２ ), and chlorosilane, such as trichlorosilane (HSiCl ３ ), or dichlorosilane (H ２ SiCl ２ ), or chlorosilane (H ３ SiCl), or methylchlorosilane, such as methyltrichlorosilane (CH ３ SiCl ３ ), or dimethyldichlorosilane ((CH ３ ) ２ SiCl ２ ), the process according to claim 18.

20. The process according to any of the prior claims, step (c) comprising contacting the porous particle skeleton with the gas containing at least 30 volume% or at least 40 volume% or at least 50 volume% or at least 60 volume% or at least 70 volume% or at least 80 volume% or at least 90 volume% or at least 95 volume% or at least 97 volume% or at least 99 volume% of a silicon-containing precursor, based on the total volume of the gas.

21. The process according to any of the prior claims, wherein the temperature in step (c) is in the range of 180 to 520°C, or 340 to 500°C, or 350 to 480°C, or 350 to 450°C, or 350 to 420°C, or 355 to 400°C, or 355 to 395°C, or 360 to 390°C, or 360 to 385°C, or 360 to 380°C.

22. The process according to any of the prior claims, wherein the pressure in step (c) is in the range of 1 to 5000 kPa, or 200 to 2000 kPa, or 20 to 500 kPa, or 40 to 200 kPa, or 50 to 150 kPa, or 60 to 120 kPa, or 80 to 100 kPa.

23. The process according to any of the prior claims, wherein the composite particles comprise elemental silicon and / or elemental germanium and the intermetallic phase, and optionally, the composite particles comprise elemental silicon and / or elemental germanium in the pores of the porous particle framework and the intermetallic phase in the pores of the porous particle framework.

24. The process according to claim 23, wherein the intermetallic phase is closely bonded to the element silicon and / or the element germanium.

25. Step (c) includes depositing elemental silicon and / or elemental germanium on the outer surface of the porous particle framework, The process according to any of the prior claims, wherein the intermetallic phase in step (d) is formed on the outer surface of the porous particle framework.

26. Step (c) is a process according to any of the prior claims, comprising depositing nanoscale elemental silicon domains within the pores of the porous particle framework.

27. The process according to any of the prior claims, comprising a passivation step of bringing the impregnated porous particle skeleton into contact with a passivating agent prior to step (d).

28. The process according to claim 27, wherein the passivation step comprises a first step of contacting the impregnated porous particle skeleton with an oxygen-containing gas at a temperature of less than 300°C, and a second step of contacting the skeleton obtained from the first step with a gas containing liquid water or water vapor at a temperature of at least 30°C, optionally less than 400°C or less than 300°C.

29. The process according to claim 27, wherein the passivating agent is selected from an oxygen-containing gas, ammonia, a gas containing ammonia and oxygen, and phosphine.

30. The passivating agent is R １ -CH=CH-R １ 、 R １ -C≡C-R １ 、 O=CR １ R １ 、 O=CR １ R ２ 、 HX-R ２ , and HX-C(O)-R １ Selected from, In the formula, X is O, S, NR １ or PR １ This represents, In the formula, each R １ represents independently 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 within the ring. In the formula, 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 process according to claim 27, wherein the elements come together to form an unsubstituted or substituted ring structure containing 3 to 8 carbon atoms within the ring.

31. The process according to any of the prior claims, comprising an annealing step of annealing the impregnated porous particle skeleton at a high temperature in an inert or reducing atmosphere prior to step (d).

32. The process according to claim 31, wherein the high temperature is at least 200°C, 300 to 800°C, 400 to 700°C, and / or less than 1000°C.

33. The process according to claim 31 or 32, wherein the inert atmosphere or the reducing atmosphere is a nitrogen atmosphere, or an atmosphere containing hydrogen, or a noble gas atmosphere, or a mixture thereof.

34. The process according to any one of claims 31 to 33, wherein the annealing step is performed for at least 1 minute, 10 minutes to 10 hours, 30 minutes to 5 hours, and / or less than 72 hours.

35. The process according to claims 27 and 31, wherein the passivation step is performed before the annealing step.

36. The process according to claims 27 and 31, wherein the annealing step is performed before the passivation step.

37. The aforementioned monovalent metal is Selected from Li, Na, K, Rb, and mixtures thereof, or Selected from Li, Na, and mixtures thereof, A process according to any of the prior claims, wherein Li.

38. The process according to any of the prior claims, comprising the step of depositing a lithium-ion permeable material inside and / or on the outer surface of the impregnated porous particle skeleton prior to step (d).

39. The process according to any of the prior claims, comprising, prior to step (d), a step of combining the impregnated porous particle skeleton with a pyrolysis carbon precursor and heating the pyrolysis carbon precursor to a temperature effective for depositing a conductive pyrolysis carbon material in the pores and / or on the outer surface of the impregnated porous particle skeleton.

40. The process according to any of the prior claims, comprising the step of forming an electrode containing the impregnated porous particle skeleton prior to step (d).

41. The process according to claim 40, wherein step (d) is achieved as part of an electrochemical prelithiation or presodiumization step of the electrode.

42. Step (d) comprises contacting the impregnated porous particle skeleton with a monovalent metal precursor, optionally the monovalent metal precursor being a salt, complex, or organic compound of the monovalent metal, optionally the monovalent metal precursor being selected from oxides, carbonates, acetates, nitrates, hydroxides, hydrides, sulfates, carboxylates, halides, oxalates, bisoxalatoborates, bis(trifluoromethanesulfonyl)imides, citrates, phosphates, complexes containing EDTA, complexes containing rotaxanes, organolithium compounds, and mixtures thereof, the process according to any of the prior claims.

43. The process according to any of the prior claims, wherein step (d) comprises bringing the impregnated porous particle skeleton into contact with the monovalent metal-containing electrolyte.

44. Prior to step (d), the step includes forming an electrochemical cell comprising an anode, a cathode, and an electrolyte between the anode and the cathode, wherein the cathode and / or the electrolyte comprises the monovalent metal. The process according to any of the prior claims, wherein the electrochemical cell is optionally a rechargeable metal-ion battery.

45. The process according to claim 44, wherein step (d) is achieved as part of the electrochemical cell formation cycle.

46. The process according to any one of claims 43 to 45, wherein the electrolyte comprises a polyvalent metal, optionally the same polyvalent metal as in step (a) and / or (b), or a polyvalent metal different from the polyvalent metal in step (a) and (b).

47. The process according to any of the prior claims, wherein the potential in step (d) includes a constant current / constant voltage cycle of C / n, n ≥ 5, and the lower limit cutoff voltage is 10 mV or greater.

48. The process according to any of the prior claims, wherein the porous particle skeleton in step (a) is a porous carbon particle skeleton, optionally comprising 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.

49. The porous particle skeleton in step (a) is a porous carbon particle skeleton, and the porous carbon particle skeleton is With respect to the mass of the porous carbon particle skeleton, the amount of Ca is 100 to 10,000 ppm, 250 to 8,000 ppm, or 500 to 5,000 ppm, and The process according to any one of the prior claims, comprising 200 to 25,000 ppm, 500 to 20,000 ppm, or 1,000 to 16,000 ppm of P with respect to the mass of the porous carbon particle skeleton.

50. The porous particle skeleton in step (a) is a porous carbon particle skeleton that includes micropores and optionally mesopores. P １ is, cm ３ The total volume of micropores and mesopores in the porous carbon particle framework, expressed as P / g, １ It is at least 0.35, and optionally less than 2.5, VP07, VP2, VP5, and VP20 are, respectively, P １ This is the volume of pores in the porous carbon particle skeleton with pore diameters of 0.7 nm or less, 2.0 nm or less, 5.0 nm or less, and 20.0 nm or less, expressed as a percentage of the total volume, where VP07 is in the range of 5.1 to 35%, VP2 is in the range of 40 to 90%, and VP20-VP5 is less than 20%. Optionally, the micropore volume of the porous carbon particle skeleton is at least 0.3 cm². ３ / g, P １ The process according to any of the prior claims, wherein VP07, VP2, VP5, VP20, and the micropore volume are measured by nitrogen gas adsorption.

51. The process according to any of the prior claims, wherein the porous particle skeleton in step (a) has not been subjected to any treatment aimed at removing naturally occurring impurities in the raw material used to synthesize the porous particle skeleton.

52. The process according to any of the prior claims, wherein the porous particle skeleton in step (a) is not subjected to a washing step aimed at removing naturally occurring impurities in the raw material used to synthesize the porous particle skeleton.

53. The process according to any of the prior claims, wherein the porous particle skeleton in step (a) is derived from biomass.

54. In step (a), the porous particle skeleton has a total volume of micropores and mesopores measured by gas adsorption of 0.4 to 1.8 cm³. ３ / g, or 0.6-1.4cm ３ / g, or 0.75–1.1cm ３ The process described in any of the prior claims, wherein the process is / g.

55. In step (a), the porous particle skeleton is a PD of 50 nm or less. ９０ Pore ​​size and / or PD of 30 nm or less ５０ A process according to any of the prior claims, having a pore size.

56. The process according to any of the prior claims, wherein the porous particle skeleton in step (a) has a micropore volume fraction of at least 0.45 and / or 0.95 or less, based on the total volume of micropores and mesopores.

57. The process according to any of the prior claims, wherein the porous particle skeleton in step (a) has a bimodal or multimodal pore size distribution.

58. The porous particle skeleton in step (a) is 1200 to 3000 m ２ A process according to any of the prior claims, having a BET surface area of ​​1 / g.

59. In step (a), the porous particle skeleton is 1 to 30 μm, or 1 to 20 μm, or 2 to 8 μm. ５０ A process according to any of the prior claims, having particle size.

60. The process according to any of the prior claims, wherein the impregnated porous particle skeleton comprises 30 to 70% by weight of silicon, 35 to 65% by weight of silicon, or 40 to 60% by weight of silicon.

61. The process according to any of the prior claims, wherein, as measured by thermogravimetric analysis (TGA), at least 20% by weight, at least 30% by weight, or at least 40% by weight of the silicon in the impregnated porous particle skeleton is surface silicon.

62. The process according to any of the prior claims, wherein, as measured by thermogravimetric analysis (TGA), 6% by weight or less, or 5% by weight or less, or 4% by weight or less, or 3.5% by weight or less, or 3% by weight or less, or 2.5% by weight or less, or 2% by weight or less, or 1.5% by weight or less of the silicon in the impregnated porous particle skeleton is coarse bulk silicon.

63. A composite particle obtained by the method described in any of the prior claims.

64. Composite particles for use as an electroactive material for metal ion batteries, wherein the composite particles are A porous particle framework including micropores and / or mesopores, The composite particle comprises a polyvalent metal, silicon and / or germanium, and an intermetallic phase containing a monovalent metal.

65. The composite particle according to claim 64, wherein the intermetallic phase is present within the pores of the porous particle skeleton.

66. The composite particle according to claim 64 or 65, wherein the metallic interphase is present on the outer surface of the porous particle skeleton.

67. A composite particle according to any one of claims 64 to 66, comprising elemental silicon and / or elemental germanium deposited in the pores of the porous particle framework, wherein optionally the intermetallic phase is closely bonded to the elemental silicon and / or elemental germanium in the pores of the porous particle framework.

68. A composite particle according to any one of claims 64 to 67, comprising elemental silicon and / or elemental germanium deposited on the outer surface of the porous particle framework, wherein optionally the intermetallic phase is closely bonded to the elemental silicon and / or elemental germanium on the outer surface of the porous particle framework.

69. The aforementioned composite particles are With respect to the total amount of Mg and silicon in the composite particles, Mg is present in concentrations of 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less. With respect to the total amount of Ca and silicon in the composite particles, Ca is present in concentrations of 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less. With respect to the total amount of Sn and silicon in the composite particles, Sn is present in concentrations of 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less. With respect to the total amount of Ge and silicon in the composite particles, Ge is present in concentrations of 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less. With respect to the total amount of Zn and silicon in the composite particles, Zn is present in concentrations of 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less. Al in the composite particles at concentrations of 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less, relative to the total amount of Al and silicon, and The composite particle contains at least one of the following concentrations of Sb: 0.001 atomic% or more, 0.01 atomic% or more, 0.1 atomic% or more, or 1 atomic% or more, and optionally 30 atomic% or less, 25 atomic% or less, or 20 atomic% or less, relative to the total amount of Sb and silicon in the composite particle. The composite particle according to any one of claims 64 to 68, wherein the polyvalent metal is present in the impregnated porous particle skeleton at a concentration of preferably 30 atomic percent or less relative to the total amount of the polyvalent metal and silicon in the composite particle.

70. The aforementioned composite particles are Fe in the composite particle at a concentration of 0.5 atomic% or less, 0.1 atomic% or less, 0.01 atomic% or less, or 0.001 atomic% or less, relative to the total amount of Fe and silicon in the composite particle. With respect to the total amount of Co and silicon in the composite particles, the concentration of Co is 0.5 atomic% or less, 0.1 atomic% or less, 0.01 atomic% or less, or 0.001 atomic% or less. Cu at a concentration of 0.5 atomic% or less, 0.1 atomic% or less, 0.01 atomic% or less, or 0.001 atomic% or less relative to the total amount of Cu and silicon in the composite particles. Ni at a concentration of 0.5 atomic% or less, 0.1 atomic% or less, 0.01 atomic% or less, or 0.001 atomic% or less relative to the total amount of Ni and silicon in the composite particles, and The composite particle according to any one of claims 64 to 69, wherein the composite particle contains at least one, or all of, Mn at a concentration of 0.5 atomic% or less, 0.1 atomic% or less, 0.01 atomic% or less, or 0.001 atomic% or less, relative to the total amount of Mn and silicon in the composite particle.

71. An electrode comprising composite particles according to any one of claims 64 to 70.

72. A rechargeable metal-ion battery comprising the electrode described in claim 71, wherein the electrode is an anode.

73. A method for producing an impregnated porous particle skeleton, wherein the method follows the method of any one of claims 1 to 62, but includes omitting step (d).

74. An impregnated porous particle skeleton obtained by the method described in claim 73.

75. An impregnated porous particle framework containing micropores and / or mesopores, polyvalent metals, and elemental silicon and / or elemental germanium within the pores.

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