Method for preparing electroactive materials for metal ion batteries - Patents.com

Abstract

The present invention relates to a method of preparing composite particles comprising contacting a plurality of particles in a reaction zone with a gas comprising at least 25% by volume of a silicon-containing precursor at a temperature effective to cause deposition of silicon within the pores of the porous particles, wherein during the contacting step, a controlled temperature differential is maintained between the maximum temperature of the interior surface of the reaction zone and the minimum temperature within the plurality of porous particles at the same time.

Description

[Technical field]

[0001] The present invention relates to a method and system for preparing electroactive materials suitable for use in metal-ion batteries, in which silicon is deposited into the pores of a porous particulate material using chemical vapor infiltration (CVI). [Background technology]

[0002] The present inventors have previously reported the development of a class of electroactive materials having composite structures in which a nanoscale electroactive material, such as silicon, is deposited within the pores of a highly porous particulate material, such as a porous carbon material.

[0003] For example, US Pat. No. 5,399,633 discloses such a particulate material comprising a plurality of composite particles.

[0004] The material described in the '693 patent was synthesized using CVI. Porous particles are contacted with silane gas at temperatures between 400°C and 500°C. Low concentrations of silane are used, such as 1.25% by volume. Such previous CVI methods are sufficient for laboratory scale production but are not suitable for large scale production.

[0005] For example, the use of such low concentrations of silicon-containing precursors means that production times for composite particles are unacceptable on a large scale.

[0006] Additionally, previous methods of depositing silicon within the pores of porous particles using CVI techniques have been found to result in uncontrolled fouling of the reaction zone, in particular, relatively large flakes of silicon-rich composites can form on the interior surfaces of the reaction zone.

[0007] Such flaking is detrimental to manufacturing because the contaminating material can fragment and become mixed into the particulate material even after post-manufacturing processing such as sieving, which can reduce the quality of the particulate material and can have undesirable effects on the electrode formulation, such as uneven expansion and loss of contact.

[0008] It has also been identified that the formation of silicon flakes on the inner surface of the reaction zone correlates with the formation of composite particles having a high content of coarse silicon as defined herein. The inventors understand that coarse silicon is one manifestation of non-uniform silicon deposition. Thus, it is believed that reaction zone fouling correlates with poorly controlled silicon deposition in the porous particles.

[0009] In large scale manufacturing, contamination can completely halt production, with interruptions to remove contaminated material causing unacceptable delays and cumbersome cleaning procedures.

[0010] Some CVI processes, such as fixed bed, conveyor bed and vibrating fluidized bed, rely on a high ratio of reactor surface area per mass of porous particles and a thin bed thickness to achieve sufficient heat transfer to the porous particles. In addition to the risk of fouling, such processes are limited in scale-up. In order to increase the throughput of techniques that rely on a relatively high ratio of reactor surface area to mass of porous particles, a proportional increase in reactor surface area is required. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] International Publication No. 2020 / 128495 Summary of the Invention [Problem to be solved by the invention]

[0012] Therefore, there is a need to solve the above problems. [Means for solving the problem]

[0013] In a first aspect, the present invention provides a method for preparing a composite particle, comprising the steps of: (a) providing a plurality of porous particles within a reaction zone, the reaction zone having an interior surface; (b) contacting the plurality of particles in a reaction zone with a gas comprising at least 25 volume percent of a silicon-containing precursor at a temperature effective to cause deposition of silicon within the pores of the porous particles; Including, The method further comprises maintaining ΔT≦+90° C. during step (b), where ΔT represents the temperature difference between the maximum temperature at the inner surface of the reaction zone and the minimum temperature within the plurality of porous particles at the same time, with a positive ΔT value indicating that the maximum temperature at the inner surface of the reaction zone is greater than the minimum temperature within the plurality of particles.

[0014] In another aspect, the present invention provides a system for preparing composite particles, comprising: (a) a reaction zone configured to retain a plurality of porous particles, (i) at least one heat source configured to heat the plurality of porous particles; (ii) at least one gas inlet for receiving a gas comprising at least 25 volume percent of a silicon-containing precursor; (iii) at least one gas outlet for recovering exhaust gas from the reaction zone; a reaction zone having (b) at least one sensor configured to obtain temperature data within the plurality of porous particles; and (c) at least one sensor configured to obtain temperature data of an interior surface of the reaction zone; and (d) a processor; Including, A system is provided, in which at least one sensor configured to obtain temperature data within the plurality of porous particles and at least one sensor configured to obtain temperature data of an internal surface of a reaction zone are configured to transmit the respective temperature data to a processor, and the processor is configured to control a heat source to maintain ΔT≦+90° C., ΔT representing the temperature difference between a maximum temperature of the internal surface of the reaction zone and a minimum temperature within the plurality of porous particles at the same time, with a positive ΔT value indicating that the maximum temperature of the internal surface of the reaction zone is higher than the minimum temperature within the plurality of particles. The system can be used to carry out the method of the present invention.

[0015] The method and system of the present invention have been developed to provide simultaneous control of product quality while avoiding undesirable silicon deposition on reactor surfaces.

[0016] The deposition of silicon in the process of the present invention occurs due to the thermal decomposition of a silicon-containing precursor on the surface. The relative amounts of silicon deposited on the pore surfaces of the porous particles and on the interior surfaces of the reaction zone are (i) the relative surface areas of the porous particles and the interior surface of the reaction zone; and (ii) the relative temperatures of the porous particles and the interior surfaces of the reaction zone; Depends on.

[0017] Porous particles are materials with a very large surface area, and therefore, at equal temperatures, silicon deposition is expected to occur on almost the entire inner surface of the porous particles. However, porous particles, especially porous carbon particles, have very poor thermal conductivity, and therefore a large temperature difference can occur between the reactor surface, which serves as the heat source for the reaction, and the porous particles. This temperature difference is believed to explain the formation of silicon flakes on the inner surface of the reaction zone. Another consequence of the temperature difference is that a large temperature gradient is associated within many porous particles in the reaction zone. Particles adjacent to the inner surface of the reactor are overheated, resulting in uncontrolled silicon deposition (due to the excessive coarse silicon formation described herein), while particles further away from the inner surface of the reactor cool significantly, resulting in minimal or even non-existent silicon deposition.

[0018] The above problem is exacerbated when the loading of porous particles in the reactor is increased, since the bed depth of the particles increases, thereby increasing the maximum distance between the particles and the inner surface of the reactor that serves as the heat source. The problem is also exacerbated when the concentration of silicon precursor in the gas fed to the reactor is increased. Both of these factors are necessary to ensure high throughput in the reaction zone, but both increase the possibility of reactor fouling and product non-uniformity.

[0019] The process of the present invention addresses these problems by controlling the temperature difference between the porous particles and the interior surfaces of the reaction zone to be no more than +90° C. This temperature has been found to be the practical upper limit above which the relatively large surface area of ​​the porous particles becomes the dominant factor in determining where silicon is deposited. As the loading of the reactor and / or the surface area of ​​the porous particles begins to increase, the balance tips further in favor of the porous particles being deposited on the pore surfaces.

[0020] According to the present invention, during step (b), a ΔT of +90° C. or less is maintained, such that the temperature of the inner surface of the reaction zone does not exceed the minimum temperature within the plurality of porous particles by more than 90° C. This is achieved by maintaining the gas containing the silicon-containing precursor in contact with the plurality of porous particles under the conditions: T IS ≦[T P +90℃] (Here, T IS is the maximum temperature on the inner surface of the reaction zone, T P It can also be expressed as a requirement to maintain a temperature of 100° C. (where 100° C. is the minimum temperature within the particles at any one time).

[0021] Therefore, ΔT is T IS -T P is equal to.

[0022] Without being bound by theory, it is believed that when the reaction conditions are controlled in this manner, the relatively large surface area of ​​the porous particles compared to the interior surface of the reaction zone results in preferential deposition within the pores of the porous particles, even when the maximum temperature at the interior surface of the reaction zone is up to 90° C. greater than the minimum temperature within the particles.

[0023] Therefore, it is observed that maintaining ΔT≦+90° C. reduces flake formation in the reaction zone. [Brief description of the drawings]

[0024] [Figure 1] 1 is a graph showing temperatures on the interior surface of a representative reaction zone and temperatures within a number of particles for a comparative process. [Diagram 2] 2 is a graph showing temperatures at the interior surface of a representative reaction zone and temperatures within a number of particles during one cycle of silicon deposition of the comparative process shown in FIG. 1 . [Diagram 3] 1 is a graph showing temperatures on the interior surface of a representative reaction zone and temperatures within a number of particles for a comparative process. [Figure 4]4 is a graph showing temperatures at the interior surface of a representative reaction zone and temperatures within multiple particles during one cycle of silicon deposition of the comparative process shown in FIG. 3. [Diagram 5] 1 is a graph showing temperatures at the interior surface of a representative reaction zone and temperatures within a plurality of particles of a process according to the present invention. [Figure 6] 6 is a graph showing temperatures at the interior surface of a representative reaction zone and temperatures within a number of particles during one cycle of silicon deposition of the method shown in FIG. 5. [Figure 7] 1 is a graph showing temperatures at the interior surface of a representative reaction zone and temperatures within a plurality of particles of a process according to the present invention. [Figure 8] 8 is a graph showing temperatures at the interior surface of a representative reaction zone and temperatures within a number of particles during one cycle of silicon deposition of the method shown in FIG. [Figure 9] 1 is a graph showing temperatures at the interior surface of a representative reaction zone and temperatures within a plurality of particles of a process according to the present invention. [Figure 10] 10 is a graph showing temperatures at the interior surface of a representative reaction zone and temperatures within a number of particles during one cycle of silicon deposition of the method shown in FIG. [Figure 11] 1 is a graph showing temperatures at the interior surface of a representative reaction zone and temperatures within a plurality of particles of a process according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] As used herein, "reaction zone" refers to an at least partially enclosed volume in which the deposition reaction occurs. The reaction zone may be a reactor vessel of any suitable form. The reaction zone may be a batch reactor or a continuous reactor. The reaction zone may be a tubular reactor, a fixed bed reactor, a fluidized bed reactor, or a continuous stirred tank reactor.

[0026] Preferably, ΔT≦+85° C., or ΔT≦+80° C., or ΔT≦+75° C., or ΔT≦+70° C., or ΔT≦+65° C., or ΔT≦+60° C., or ΔT≦+55° C. is maintained during step (b). More preferably, ΔT≦+50° C., or ΔT≦+45° C., or ΔT≦+40° C., or ΔT≦+35° C., or ΔT≦+30° C., or ΔT≦+25° C. is maintained during step (b). Even more preferably, ΔT≦+20° C., or ΔT≦+15° C., or ΔT≦+10° C., or ΔT≦+5° C. is maintained during step (b). Most preferably, ΔT≦0° C., or ΔT≦−5° C., or ΔT≦−10° C. is maintained during step (b).

[0027] ΔT≦+90° C. can be achieved in several ways.

[0028] The deposition reaction is exothermic, causing the temperature of the particles to increase.

[0029] The plurality of porous particles and / or the gas containing the silicon-containing precursor may be preheated, which may contribute to the temperature of the plurality of particles.

[0030] The plurality of porous particles and the gas containing silicon-containing precursor may be contacted, i.e., mixed together and preheated together. The plurality of porous particles and the gas containing silicon-containing precursor may be preheated together before providing the plurality of porous particles to the reaction zone. Alternatively, the plurality of porous particles and the gas containing silicon-containing precursor may be preheated together within the reaction zone.

[0031] The plurality of porous particles and / or the gas containing the silicon-containing precursor may be preheated separately.

[0032] The plurality of porous particles may be preheated prior to providing the plurality of porous particles to the reaction zone. For example, the porous particles may be moved through a heating zone prior to entering the reaction zone. The plurality of porous particles may be preheated to a temperature of 300°C to 480°C, or 320°C to 450°C, or 330°C to 400°C, or 340°C to 390°C, or 345°C to 390°C, or 350°C to 400°C, or 350°C to 390°C, or 350°C to 385°C, or 350°C to 380°C, or 355°C to 390°C, or 355°C to 385°C, or 355°C to 380°C, or 360°C to 390°C, or 360°C to 385°C, or 360°C to 380°C.

[0033] The reaction zone may include a heat source, and step (a) may include operating the heat source to heat the plurality of porous particles. The heat source may be operable to heat the plurality of porous particles to a temperature of 340° C. to 400° C., or 340° C. to less than 395° C., or 340° C. to 390° C., or 345° C. to 400° C., or 345° C. to less than 395° C., or 345° C. to 390° C., or 350° C. to 400° C., or 350° C. to less than 395° C., or 350° C. to 390° C., or 350° C. to 385° C., or 350° C. to 380° C., or 355° C. to 400° C., or 355° C. to less than 395° C., or 355° C. to 390° C., or 355° C. to 385° C., or 355° C. to 380° C. It can be heated to a temperature of 0°C, or 360°C to 400°C, or less than 360°C to 395°C, or 360°C to 390°C, or 360°C to 385°C, or 360°C to 380°C, or 365°C to 400°C, or less than 365°C to 395°C, or 365°C to 390°C, or 365°C to 385°C, or 365°C to 380°C, or 370°C to 400°C, or less than 370°C to 395°C, or 370°C to 390°C, or 370°C to 385°C, or 370°C to 380°C. The heat source may be a convection heat source or a conduction heat source. A temperature range of 370°C to less than 395°C is particularly preferred.

[0034] The gas containing the silicon-containing precursor may be preheated prior to the contacting step. Step (b) may include preheating the gas to a temperature of 100°C to 350°C, or 110°C to 340°C, or 120°C to 330°C, or 130°C to 320°C, or 140°C to 310°C, or 150°C to 300°C prior to the contacting step. Preheating the gas prior to contacting reduces temperature fluctuations within the plurality of porous particles that would otherwise be caused by contact between the particles and the gas. Thus, preheating the gas may contribute to maintaining the temperature of the plurality of particles.

[0035] The ΔT maintained during step (b) is +90°C to -110°C, or +85°C to -110°C, or +80°C to -110°C, or +75°C to -110°C, or +70°C to -110°C, or +65°C to -110°C, or +60°C to -110°C, or +55°C to -110°C, or +50°C to -110°C, or +45°C to -110°C, or +40°C to -110°C, or +35°C to -110°C, or +30°C to -110°C, or +25°C to -110°C, or +20°C to -110°C, or +15°C to -110°C, or +10°C to -110°C, or +5°C to -110°C, or 0°C to -110°C It is preferably in the range of -110°C, or -5°C to -110°C, or -5°C to -105°C, or -5°C to -100°C, or -5°C to -95°C, or -5°C to -90°C, or -5°C to -85°C, or -5°C to -80°C, or -5°C to -75°C, or -5°C to -70°C, or -5°C to -65°C, or -5°C to -60°C, or -5°C to -55°C, or -5°C to -50°C, or -5°C to -45°C, or -5°C to -40°C, or -5°C to -35°C, or -5°C to -30°C, or -5°C to -25°C, or -5°C to -20°C, or -5°C to -15°C, or -5°C to -10°C.

[0036] In some cases, it is possible to deposit sufficient silicon into the pores of the porous particles in one cycle of deposition. In other cases, it is desirable to operate the method as a multi-cycle deposition in which successive deposition steps are used to deposit a target amount of silicon. In such a multi-cycle deposition, the method comprises: (c) interrupting the deposition of silicon to form intermediate particles and, optionally, separating by-products from the intermediate particles; (d) contacting the intermediate particles from step (c) with a gas containing a silicon-containing precursor in a reaction zone at a temperature effective to cause further deposition of silicon within the pores of the intermediate particles; may include wherein during step (d), ΔT≦+90°C is maintained, ΔT representing the temperature difference between the maximum temperature at the inner surface of the reaction zone and the minimum temperature within the plurality of porous particles, with a positive ΔT value indicating that the maximum temperature at the inner surface of the reaction zone is higher than the minimum temperature within the plurality of particles.

[0037] The reaction zone of step (d) may be the same reaction zone as step (b), or steps (b) and (d) may be carried out in different reaction zones.

[0038] Each of steps (c) and (d) can be repeated as many times as necessary to deposit a target amount of silicon. For example, each of steps (c) and (d) can be performed 2 to 15 times, resulting in a total of 3 to 16 silicon deposition steps, including the repetition of steps (b) and (d). When steps (c) and (d) are repeated, each stage of steps (c) and (d) is independently as described herein. For example, the silicon-containing precursor used in each repetition of step (d) can be the same or different. Preferably, the silicon-containing precursor used in each repetition of step (d) is a silane.

[0039] The interruption of deposition in step (c) can be achieved in several ways. The interruption of deposition can be achieved by completely consuming the silicon-containing precursor by deposition reaction. Alternatively, deposition can be interrupted while unreacted silicon-containing precursor remains, for example, by lowering the temperature. In this case, the gas containing silicon-containing precursor used in step (d) can contain the silicon-containing precursor that is not consumed in step (b).

[0040] Preferably, ΔT≦+85° C., or ΔT≦+80° C., or ΔT≦+75° C., or ΔT≦+70° C., or ΔT≦+65° C., or ΔT≦+60° C., or ΔT≦+55° C. is maintained during step (d). More preferably, ΔT≦+50° C., or ΔT≦+45° C., or ΔT≦+40° C., or ΔT≦+35° C., or ΔT≦+30° C., or ΔT≦+25° C. is maintained during step (d). Even more preferably, ΔT≦+20° C., or ΔT≦+15° C., or ΔT≦+10° C., or ΔT≦+5° C. is maintained during step (d). Most preferably, ΔT≦0° C., or ΔT≦−5° C., or ΔT≦−10° C. is maintained during step (d).

[0041] In step (b) and / or step (d), the minimum temperature in the plurality of porous particles is 340°C to 400°C, or 340°C to 395°C, or 340°C to 390°C, or 345°C to 400°C, or 345°C to 395°C, or 345°C to 390°C, or 350°C to 400°C, or 350°C to 395°C, or 350°C to 390°C, or 350°C to 385°C, or 350°C to 380°C, or 355°C to 400°C, or 355°C to 395°C, or 355°C to 390°C, or 355°C to 385°C. The temperature may be maintained within the range of 355° C. to 380° C., 360° C. to 400° C., 360° C. to 395° C., 360° C. to 390° C., 360° C. to 385° C., 360° C. to 380° C., 365° C. to 400° C., 365° C. to 395° C., 365° C. to 390° C., 365° C. to 385° C., 365° C. to 380° C., 370° C. to 400° C., 370° C. to 395° C., 370° C. to 390° C., 370° C. to 385° C., or 370° C. to 380° C. It is particularly preferred that the minimum temperature in the plurality of porous particles is maintained at a temperature of less than 370° C. to 395° C. during step (b), step (c) and / or step (d).

[0042] More preferably, in step (b) and / or step (d), all of the plurality of porous particles are heated to 340°C to 400°C, or 340°C to 395°C, or 340°C to 390°C, or 345°C to 400°C, or 345°C to 395°C, or 345°C to 390°C, or 350°C to 400°C, or 350°C to 395°C, or 350°C to 390°C, or 350°C to 385°C, or 350°C to 380°C, or 355°C to 400°C, or 355°C to 395°C, or 355°C to 390°C, or 355°C to 355°C. The temperature is maintained within the range of 385°C to 380°C, 360°C to 400°C, 360°C to 395°C, 360°C to 390°C, 360°C to 385°C, 360°C to 380°C, 365°C to 400°C, 365°C to 395°C, 365°C to 390°C, 365°C to 385°C, 365°C to 380°C, 370°C to 400°C, 370°C to 395°C, 370°C to 390°C, 370°C to 385°C, or 370°C to 380°C. It is particularly preferred that the minimum temperature in the plurality of porous particles is maintained at a temperature of less than 370°C to 395°C during step (b), step (c) and / or step (d).

[0043] Reducing or eliminating temperature fluctuations in the multiple porous particles can reduce energy consumption and contribute to improved production efficiency, especially for large-scale systems.

[0044] Conventional CVI processes using silanes are carried out at temperatures above 400°C. Surprisingly, it has been discovered that CVI can be carried out at lower temperatures. Carrying out CVI at such high temperatures (e.g., 420°C-450°C) results in insufficient penetration of the silicon. Furthermore, the use of such high temperatures requires the operation of heating and cooling cycles in the reaction zone, which can exacerbate uncontrolled fouling of the reaction zone. Overall, these problems limit production rates. The use of the above temperatures solves these problems.

[0045] The maximum temperature of the inner surface of the reaction zone during the above contacting in step (b) and / or step (d) may be 150°C to 480°C, or 150°C to 460°C, or 150°C to 440°C, or 150°C to 420°C, or 150°C to 400°C, or 150°C to 390°C, or 200°C to 390°C, or 250°C to 390°C, or 300°C to 390°C, or 340°C to 375°C, or 340°C to 370°C, or 345°C to 370°C, or 345°C to 365°C, or 350°C to 400°C, or 350°C to 390°C, or 350°C to 380°C, or 350°C to 370°C, or 350°C to 365°C.

[0046] The maximum temperature of the interior surface of the reaction zone during said contacting in step (b) and / or step (d) may be 480°C or less, or 460°C or less, or 440°C or less, or 420°C or less, or 400°C or less, or 395°C or less, or 390°C or less, or 385°C or less, or 380°C or less.

[0047] Step (d) may include preheating the gas to a temperature of from 100°C to 350°C, or from 110°C to 340°C, or from 120°C to 330°C, or from 130°C to 320°C, or from 140°C to 310°C, or from 150°C to 300°C prior to said contacting.

[0048] Step (a) may include providing a plurality of batches of porous particles in a reaction zone.

[0049] The process may be operated in a batch mode, in which case step (b) or step (d) may comprise interrupting the deposition of silicon to form the composite particles and recovering the composite particles from the reaction zone.

[0050] The process may be operated in a continuous mode, in which case step (a) comprises: providing a chemical vapor infiltration unit including a reaction zone; Providing a feedstock comprising porous particles; continuously introducing porous particles into a reaction zone; It may include, Step (b) is continuously introducing a gas containing a silicon-containing precursor into a reaction zone; providing conditions in a reaction zone effective to cause deposition of silicon within the pores of the porous particles; continuously withdrawing composite particles comprising a porous particulate framework and elemental silicon within the pores of the porous particulate framework from the reaction zone; continuously withdrawing exhaust gas from the reaction zone; may include:

[0051] The process may be operated batchwise with respect to the porous particles and continuously with respect to the silicon precursor. Step (a) may comprise providing a batch of a plurality of porous particles within a reaction zone. Step (b) may comprise continuously introducing a gas comprising a silicon-containing precursor into the reaction zone.

[0052] Preferably, step (b) and / or step (d) comprise continuously stirring the porous particles. More preferably, step (b) and / or step (d) may comprise continuously mechanically stirring the porous particles during said contacting. Preferably, stirring is achieved by a high shear mixer.

[0053] Agitation of the porous particles is preferred in the method of the present invention because it reduces temperature gradients within the multiple porous particles and also promotes uniform penetration of the silicon precursor gas throughout the multiple porous particles, both of which contribute to improved uniformity of silicon deposition throughout the multiple porous particles, thereby reducing both flake formation on the reactor surfaces and the formation of coarse silicon within the composite particles.

[0054] The reaction zone preferably includes an agitator for continuously agitating the porous particles during said contacting. Any suitable agitator can be used, such as a turbine agitator, a paddle agitator, an anchor agitator, a propeller agitator, or a helical agitator. The agitator is preferably a high shear mixer.

[0055] Mechanical agitation of the porous particles decouples the feed rate of the silicon precursor gas from the efficiency of mixing of the porous particles. With a vertical fluidized bed reactor, agitation of the porous particles is achieved only by feeding the silicon precursor gas at a rate sufficient to fluidize the porous particles. Thus, the use of mechanical agitation allows the process to work with silicon precursor gas at lower rates than the vertical fluidized bed reactor method, and allows the residence time of the silicon precursor to be adjusted independently of the agitation.

[0056] The use of a high shear mixer provides continuous mechanical agitation, effectively breaking down the agglomerates that inevitably form due to the cohesive nature of the porous particles, thus addressing both heat and mass transfer challenges.

[0057] The combination of temperature control of the present invention, i.e., maintaining ΔT≦+90° C. with continuous stirring, minimizes the risk of uneven silicon penetration and reactor fouling.

[0058] The plurality of porous particles in the reaction zone in step (a) is at least 100 cm 3 of reaction zone volume per liter (cm 3 / L RV ), or at least 150 cm 3 / L RV , or at least 200 cm 3 / L RV , or at least 250 cm 3 / L RV , or at least 300 cm 3 / L RV , or at least 400 cm 3 / L RV , or at least 500 cm 3 / L RV , or at least 600 cm 3 / L RV , or at least 700 cm 3 / L RV , or at least 800 cm 3 / L RV, or at least 900 cm 3 / L RV It is preferred that the compound has the formula:

[0059] The plurality of porous particles are at least 500 cm 3 / L RV and in some embodiments, optionally, a volume sufficient to substantially fill the volume of the reaction zone.

[0060] As used herein, the volume of a porous particle refers to the equivalent volume of the porous particle as determined from the mass and tap density of the particle. For example, 200 g of a porous particle material having a tap density of 1000 g / L has a volume of 200 cm 3 is considered to be a porous particulate material.

[0061] In the case of a continuous reactor where the porous particles move through the reaction zone, an equal volume of porous particles in the reactor is equal to the feed rate of the porous particles to the reaction zone, g min -1 , the average residence time of the particles in the reaction zone, and the tap density of the porous particles as described above.

[0062] The ratio of the internal surface area of ​​the reaction zone to the mass of the porous particles in the reaction zone is 1 m 2 / kg or less, or 0.9m 2 / kg or less, or 0.8m 2 / kg or less, or 0.7m 2 / kg or less, or 0.6m 2 / kg or less, or 0.5m 2 / kg or less, or 0.4m 2 / kg or less, or 0.3m 2 / kg or less, or 0.2m 2 / kg or less, or 0.1m 2 / kg or less.

[0063] The ratio of the internal surface area of ​​the reaction zone to the mass of the porous particles in the reaction zone is at least 0.001 m 2 / kg, or at least 0.002m 2 / kg, or at least 0.003m2 / kg, or at least 0.004m 2 / kg, or at least 0.006m 2 / kg, or at least 0.008m 2 / kg, or at least 0.01m 2 / kg.

[0064] For example, the ratio of the internal surface area of ​​the reaction zone to the mass of the porous particles in the reaction zone is 0.001 m 2 / kg~1m 2 / kg, or 0.002m 2 / kg~0.9m 2 / kg, or 0.003m 2 / kg~0.8m 2 / kg, or 0.004m 2 / kg~0.7m 2 / kg, or 0.006m 2 / kg~0.6m 2 / kg, or 0.008m 2 / kg~0.5m 2 / kg, or 0.01m 2 / kg~0.4m 2 / kg, or 0.01m 2 / kg~0.3m 2 / kg.

[0065] The bed depth of the porous particles in the reaction zone may be at least 11 cm, or at least 15 cm, or at least 20 cm, or at least 25 cm, or at least 30 cm.

[0066] It is preferred to combine the above-mentioned porous particle volumes per liter of reaction zone, ratios of the internal surface area of ​​the reaction zone to the mass of the porous particles in the reaction zone, and / or bed depths of the porous particles in the reaction zone with continuous agitation as described herein.

[0067] The plurality of porous particles in the reaction zone of step (a) is at least 100 cm 3 / L RVand the bed depth of the porous particles within the reaction zone may be at least 11 cm.

[0068] The plurality of porous particles in the reaction zone of step (a) is at least 200 cm 3 / L RV and the bed depth of the porous particles within the reaction zone may be at least 15 cm.

[0069] The plurality of porous particles in the reaction zone of step (a) is at least 300 cm 3 / L RV and the bed depth of the porous particles in the reaction zone may be at least 20 cm.

[0070] The plurality of porous particles in the reaction zone of step (a) is at least 400 cm 3 / L RV and the bed depth of the porous particles within the reaction zone may be at least 25 cm.

[0071] The plurality of porous particles in the reaction zone of step (a) is at least 500 cm 3 / L RV and the bed depth of the porous particles in the reaction zone may be at least 30 cm.

[0072] The plurality of porous particles in the reaction zone of step (a) is at least 100 cm 3 / L RV and the ratio of the internal surface area of ​​the reaction zone to the mass of the porous particles in the reaction zone is 1 m 2 / kg or less.

[0073] The plurality of porous particles in the reaction zone of step (a) is at least 200 cm 3 / L RV and the ratio of the internal surface area of ​​the reaction zone to the mass of the porous particles in the reaction zone is 0.9 m 2 / kg or less.

[0074] The plurality of porous particles in the reaction zone of step (a) is at least 300 cm 3 / L RV and the ratio of the internal surface area of ​​the reaction zone to the mass of the porous particles in the reaction zone is 0.8 m 2 / kg or less.

[0075] The plurality of porous particles in the reaction zone of step (a) is at least 400 cm 3 / L RV and the ratio of the internal surface area of ​​the reaction zone to the mass of the porous particles in the reaction zone is 0.7 m 2 / kg or less.

[0076] The plurality of porous particles in the reaction zone of step (a) is at least 500 cm 3 / L RV and the ratio of the internal surface area of ​​the reaction zone to the mass of the porous particles in the reaction zone is 0.6 m 2 / kg or less.

[0077] The plurality of porous particles in the reaction zone of step (a) is at least 600 cm 3 / L RV and the ratio of the internal surface area of ​​the reaction zone to the mass of the porous particles in the reaction zone is 0.5 m 2 / kg or less.

[0078] Suitable silicon precursors include silane (SiH4), disilane (Si2H6), trisilane (Si3H8), tetrasilane (Si4H 10 ), methylsilane (CH3SiH3), dimethylsilane ((CH3)2SiH2), or chlorosilanes such as trichlorosilane (HSiCl3), or methylchlorosilanes such as methyltrichlorosilane (CH3SiCl3), or dimethyldichlorosilane ((CH3)2SiCl2). The preferred precursor of silicon is silane.

[0079] The silicon-containing precursors used in steps (b) and (d) may be the same or different. It is preferred that the silicon-containing precursor used in each of steps (b) and (d) is a silane.

[0080] The pressure in step (b) and / or step (d) may be 10 kPa to 10,000 kPa, or 100 kPa to 5,000 kPa, or 100 kPa to 4,000 kPa, or 100 kPa to 3,000 kPa, or 100 kPa to 2,000 kPa, or 100 kPa to 1,000 kPa, or 100 kPa to 500 kPa.

[0081] The pressure in step (b) and / or step (d) may be 10 kPa to 15,000 kPa, or 50 kPa to 10,000 kPa, or 120 kPa to 5,000 kPa, or 150 kPa to 2,000 kPa, or 200 kPa to 1,800 kPa, or 200 kPa to 1,600 kPa, or 250 kPa to 1,500 kPa, or 300 kPa to 1,200 kPa, or 400 kPa to 1,000 kPa, or 500 kPa to 900 kPa, or 600 kPa to 800 kPa.

[0082] References to pressure in any step of the claimed process refer to the absolute pressure in the reaction zone, which may comprise a reactor vessel of any suitable form.

[0083] The silicon-containing precursor of step (b) and / or step (d) may be used either in pure form (or substantially pure form) or as a mixture diluted with an inert carrier gas such as nitrogen or argon. The carrier gas may be hydrogen, which is inert under the conditions of the reaction. When in a mixture diluted with a carrier gas, the silicon-containing precursor of step (b) is used in an amount of at least 25% by volume. The gas may contain at least 30% by volume of the silicon-containing precursor based on the total volume of the gas, or at least 40% by volume, or at least 50% by volume, or at least 60% by volume, or at least 70% by volume, or at least 80% by volume, or at least 90% by volume, or at least 95% by volume, or at least 97% by volume, or at least 99% by volume of the silicon-containing precursor based on the total volume of the gas. The volume percent of the silicon-containing precursor based on the total volume of the gas refers to the concentration of the silicon-containing precursor in the gas supplied to the reaction zone.

[0084] When in a mixture diluted with an inert carrier gas, the silicon-containing precursor of step (d) may be used in an amount ranging from 1% to 95% by volume, or 1% to 85% by volume, or 1% to 70% by volume, or 1% to 50% by volume, or 2% to 40% by volume, or 5% to 30% by volume, or 5% to 25% by volume, based on the total volume of the precursor and inert carrier gas. The gas used in step (d) may comprise at least 25% by volume of the silicon-containing precursor, based on the total volume of the gas, or at least 30% by volume, or at least 40% by volume, or at least 50% by volume, or at least 60% by volume, or at least 70% by volume, or at least 80% by volume, or at least 90% by volume, or at least 95% by volume, or at least 97% by volume, or at least 99% by volume of the silicon-containing precursor, based on the total volume of the gas.

[0085] The presence of oxygen should be minimized in accordance with conventional procedures for working under inert atmospheres to prevent undesired oxidation of the deposited silicon. Preferably, the oxygen content is less than 0.01% by volume, more preferably less than 0.001% by volume, relative to the total volume of gas used in steps (b) and (d).

[0086] The term "BET surface area" as used herein should be taken to refer to the surface area per unit mass calculated from measurements of the physical adsorption of gas molecules on a solid surface using the Brunauer-Emmett-Teller theory and in accordance with ISO 9277.

[0087] The porous particles are 100m 2 / g~4000m 2 The BET surface of the porous particles may be in the range of 500 m / g. 2 / g~4000m 2 / g, or 750m 2 / g~3500m 2 / g, or 1000m 2 / g~3250m 2 / g, or 1000m 2 / g~3000m 2 / g, or 1000m 2 / g~2500m 2 / g, or 1000m 2 / g~2000m 2 / g. The large surface area of ​​the porous particles compared to the internal surface of the reactor results in preferential deposition within the pores of the porous particles relative to the volume and internal surface area of ​​the reactor, especially at high particle loadings.

[0088] The porous particles include a three-dimensionally interconnected open pore network. The porous particles may include micropores and / or mesopores. Typically, the porous particles include both micropores and mesopores. However, it is not excluded that porous particles containing micropores and no mesopores, or containing mesopores and no micropores, may be used. In accordance with conventional IUPAC terminology, the term "micropore" is used herein to refer to pores with a diameter of less than 2 nm, the term "mesopore" is used herein to refer to pores with a diameter of 2 nm to 50 nm, and the term "macropore" is used herein to refer to pores with a diameter of more than 50 nm.

[0089] References herein to the volume of micropores, mesopores and macropores in a porous particle, and any references to the distribution of pore volume within the porous particle, likewise relate to the internal pore volume of the porous particle used as starting material for step (a) of the claimed method, i.e. prior to the deposition of silicon in the pore volume in step (b).

[0090] The total volume of micropores and mesopores, as well as the pore size distribution of micropores and mesopores, were determined using quenched solid-state density functional theory (QSDFT) at 77 K for 10°C according to standard methodologies specified in ISO 15901-2 and ISO 15901-3. -6The pore volume and pore size distribution are determined using nitrogen gas adsorption up to a relative pressure p / p0 of 1000 MPa. Nitrogen gas adsorption is a technique for characterizing the porosity and pore size distribution of a material by condensing a gas in the pores of a solid. As the pressure is increased, the gas condenses initially in the pores with the smallest diameters until a saturation point is reached where all pores are filled with liquid. The nitrogen gas pressure is then reduced in stages to allow the liquid to evaporate from the system. The pore volume and pore size distribution can be determined by analysis of the adsorption and desorption isotherms and the hysteresis between them. Suitable instruments for measuring the 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.

[0091] Nitrogen gas adsorption is effective for measuring the pore volume and pore size distribution of pores with diameters up to 50 nm, but is less reliable for pores with much larger diameters. Therefore, for the purposes of the present invention, nitrogen adsorption is used to determine the pore volume and pore size distribution of only pores with diameters up to 50 nm (i.e., only micropores and mesopores). Similarly, PD 50 The value of is determined for the total volume of micropores and mesopores only.

[0092] Given the limitations of available analytical techniques, it is not possible to measure the pore volume and pore size distribution over the full range of micropores, mesopores, and macropores using a single technique. When the porous particles contain macropores, the volume of pores with diameters greater than 50 nm and ranging up to 100 nm can be measured by mercury intrusion porosimetry, preferably at 0.3 cm. 3 / g or less, or 0.2 cm 3 / g or less, or 0.1cm 3 / g or less, or 0.05 cm 3 / g or less. A small proportion of macropores can be useful to facilitate electrolyte access into the pore network.

[0093] Any pore volume measured by mercury porosimetry at pore diameters of 50 nm or less is disregarded (as described above, nitrogen adsorption is used to characterize mesopores and micropores). Pore volume measured by mercury porosimetry above 100 nm is assumed to be interparticle porosity for purposes of this invention, and this pore volume is also disregarded.

[0094] Mercury porosimetry is a technique for characterizing the porosity and pore size distribution of a material by applying various levels of pressure to a sample of the material immersed in mercury. The pressure required to force mercury into the pores of the sample is inversely proportional to the pore size. Mercury porosimetry values ​​reported herein were obtained according to ASTM UOP578-11, with a surface tension of mercury at room temperature, γ, of 480 mN / m and a contact angle, φ, of 140°. The density of mercury at room temperature is 13.5462 g / cm 3 There are many high-precision mercury intrusion instruments available commercially, such as the AutoPore IV series of automated mercury intrusion meters available from Micromeritics Instrument Corporation, USA. For a complete report on mercury intrusion methods, refer to "Analytical Methods in Fine Particle Technology, 1997, Micromeritics Instrument Corporation" by PA Webb and C. Orr (ISBN 0-9656783-0).

[0095] It will be understood that intrusion techniques such as gas adsorption and mercury porosimetry are only effective for determining the pore volume of pores accessible to nitrogen or mercury from the exterior of the porous particle. The porosity values ​​defined herein should be understood to refer to the open pores, i.e., the volume of pores accessible to fluids from the exterior of the porous particle. Completely enclosed pores that cannot be identified by nitrogen adsorption or mercury porosimetry shall not be considered in determining the porosity values ​​herein. Similarly, any pore volume located within pores that are small enough to be below the detection limit by nitrogen adsorption shall not be considered.

[0096] The total pore volume of the micropores and mesopores as measured by nitrogen gas adsorption is 0.4 cm 3 / g~2.2cm 3 / g, or 0.45 cm 3 / g~2.2cm 3 / g, or 0.5 cm 3 / g~2cm 3 / g, or 0.55 cm 3 / g~2cm 3 / g, or 0.6 cm 3 / g~1.8cm 3 / g, or 0.65 cm 3 / g~1.8cm 3 / g, or 0.7 cm 3 / g~1.6cm 3 / g, or 0.7 cm 3 / g~1.5cm 3 / g, or 0.7 cm 3 / g~1.4cm 3 / g. The use of highly porous particles may be preferred as they allow for greater amounts of silicon to be accommodated within the pore volume.

[0097] "P.D. n The collective term "pore size" as used herein refers to the nth percentile pore size on a volume basis relative to the total volume of micropores and mesopores. For example, "PD 50 The term "pore size" refers to the pore size below which 50% of the total volume of the micropores and mesopores is found.

[0098] PD of porous particles 50 The pore size may be 30 nm or less, or 25 nm or less, or 20 nm or less, or 15 nm or less, or 12 nm or less, or 10 nm or less, or 8 nm or less, or 6 nm or less, or 5 nm or less, or 4 nm or less, or 3 nm or less, or 2.5 nm or less, or 2 nm or less, or 1.5 nm or less.

[0099] PD of porous particles 30 The pore size may be 25 nm or less, or 20 nm or less, or 15 nm or less, or 12 nm or less, or 10 nm or less, or 8 nm or less, or 6 nm or less, or 5 nm or less, or 4 nm or less, or 3 nm or less, or 2.5 nm or less, or 2 nm or less, or 1 nm or less.

[0100] As used herein, the term "particle size" refers to the equivalent spherical diameter (esd), i.e., the diameter of a sphere having the same volume as a given particle, where the volume of the particle is understood to include the volume of the pores within the particle. 50 " and "D 50 The term "particle size" refers to the median particle size on a volume basis, i.e., the diameter below which 50% by volume of the particle population lies.

[0101] Particle size and size distribution can be determined by standard laser diffraction techniques according to ISO 13320:2009. Laser diffraction is based on the principle that particles scatter light at angles that vary with particle size, and a collection of particles produces a scattered light pattern defined by intensity and angle that can be correlated to particle size distribution. Many laser diffraction instruments are commercially available for rapid and reliable determination of particle size distribution. Unless otherwise stated, particle size distribution measurements specified or reported herein are measured by a conventional Malvern Mastersizer™ 3000 particle size analyzer manufactured by Malvern Instruments™. The Malvern Mastersizer™ 3000 particle size analyzer works by projecting a helium neon gas laser beam through a transparent cell containing particles of interest suspended in an aqueous solution. The light that strikes the particles is scattered at angles that are inversely proportional to the particle size, and a photodetector array measures the light intensity at several predetermined angles, and the measured intensities at the various angles are processed by a computer using standard theoretical principles to determine the particle size distribution. Laser diffraction values ​​as reported herein are obtained using a wet dispersion of particles in 2-propanol with the addition of 5% by volume of the surfactant SPAN™-40 (sorbitan monopalmitate). The particle refractive index is taken to be 2.68 for porous particles and 3.50 for composite particles, and the dispersant refractive index is taken to be 1.378. The Mie scattering model is used to calculate the particle size distribution.

[0102] Generally, porous particles have a D in the range of 0.5 μm to 200 μm. 50 The porous particles may have a particle size D 50 The particle size may be in the range of 0.5 μm to 30 μm, or 1 μm to 25 μm, or 1 μm to 20 μm, or 2 μm to 25 μm, or 2 μm to 20 μm, or 2 μm to 18 μm, or 2 μm to 15 μm, or 2 μm to 12 μm, or 2.5 μm to 15 μm, or 2.5 μm to 12 μm, or 2 μm to 10 μm.

[0103] The porous particles function as a skeleton for the silicon that is typically deposited in the form of a plurality of silicon domains. The term "silicon domains" as used herein refers to bodies of silicon, e.g., elemental silicon, with a maximum dimension determined by the dimensions of the pores (e.g., micropores and / or mesopores) of the porous particles in which they are located. Silicon domains can therefore also be described as nanoscale silicon domains, where the term "nanoscale" is generally understood to refer to dimensions less than 100 nm. However, due to the dimensions of the micropores and mesopores, silicon domains typically have a maximum dimension in any direction that is less than, and usually significantly less than, 50 nm. The domains can take the form of, for example, regular or irregular particles or bounded layers or coated regions.

[0104] The porous particles preferably comprise a conductive material. The use of conductive porous particles is preferred because the porous particles form a conductive framework within the composite particle, which facilitates the flow of electrons between the lithium atoms / ions intercalated within the silicon and the current collector.

[0105] A preferred type of conductive porous particle is a particle that includes or consists of a conductive carbon material, referred to herein as a conductive porous carbon particle.

[0106] The conductive porous carbon particles preferably comprise at least 80% by weight carbon, more preferably at least 90% by weight carbon, more preferably at least 95% by weight carbon, optionally at least 98% by weight or at least 99% by weight carbon. The carbon may be crystalline or amorphous carbon, or a mixture of amorphous and crystalline carbon. The porous carbon particles may be either hard or soft carbon particles.

[0107] As used herein, the term "hard carbon" refers to carbon atoms that are primarily distributed in nanoscale polyaromatic domains. 2It refers to a disordered carbon matrix that adopts a hybridized (three-way bond) state. The polyaromatic domains are cross-linked by chemical bonds, e.g., COC bonds. Because the polyaromatic domains are chemically cross-linked, the hard carbon cannot be converted to graphite at high temperatures. The high G band (approx. 1600 cm) in the Raman spectrum -1 ), hard carbon has graphite-like properties. However, the high D band in the Raman spectrum (approximately 1350 cm -1 ), carbon is not completely graphitic. The graphiticity of a carbon material can be assessed by monitoring the ratio of the D band to the G band peak intensities (ID / IG). Porous carbon particles can have an ID / IG of 0.84 or less.

[0108] The term "soft carbon" as used herein also refers to carbon atoms that are primarily dispersed in polyaromatic domains having dimensions in the range of 5 nm to 200 nm. 2 It refers to a disordered carbon matrix that adopts a hybridized (three-way bond) state. In contrast to hard carbon, the polyaromatic domains in soft carbon are not cross-linked by chemical bonds but are held together by intermolecular forces; that is, at high temperatures, soft carbon can be graphitized. The porous carbon particles preferably have at least 50% sp 2 For example, the porous carbon particles preferably contain 50% to 98% sp 2 Hybrid carbon, 55%-95% sp 2 Hybrid carbon, 60%-90% sp 2 Hybrid carbon, or 70% to 85% sp 2 It may contain hybridized carbon.

[0109] A variety of different materials can be used to prepare suitable porous carbon particles through pyrolysis. Examples of organic materials that can be used include plant biomass, including lignocellulosic materials (coconut shells, rice husks, wood, etc.), and fossil carbon sources such as coal. Examples of resins and polymeric materials that form porous carbon particles upon pyrolysis include phenolic resins, novolac resins, pitch, melamine, polyacrylates, polystyrene, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and various copolymers that contain monomer units of acrylates, styrene, α-olefins, vinylpyrrolidone, and other ethylenically unsaturated monomers. Depending on the starting materials and the conditions of the pyrolysis process, a variety of different carbon materials are available in the art. A variety of different specifications of porous carbon particles are available from suppliers.

[0110] To increase the mesopore and micropore volume, the porous carbon particles can be subjected to a chemical or gas activation process. Suitable activation processes include contacting the pyrolyzed carbon with one or more of oxygen, steam, CO, CO2, and KOH at temperatures ranging from 600°C to 1000°C.

[0111] Mesopores can also be obtained by known templating processes using extractable pore-forming agents such as MgO and other colloidal or polymeric templates, which can be removed by thermal or chemical means after pyrolysis or activation.

[0112] Alternatives to carbon-based conductive particles include titanium nitride (TiN), titanium carbide (TiC), silicon carbide (SiC), and nickel oxide (NiO x ), titanium silicon nitride (TiSiN), nickel nitride (NiN), molybdenum nitride (MoN), titanium oxynitride (TiO x N 1-xThe porous particles include those comprising titanium nitride (TiN), silicon oxycarbide (SiOC), boron nitride (BN), or vanadium nitride (VN). Preferably, the porous particles comprise titanium nitride (TiN), silicon oxycarbide (SiOC), or boron nitride (BN).

[0113] The total volume of the micropores and mesopores in the porous particles is at least 0.45 cm 3 / g, or at least 0.5 cm 3 / g, at least 0.55 cm 3 / g, or at least 0.6 cm 3 / g, or at least 0.65 cm 3 / g, or at least 0.7 cm 3 / g, or at least 0.75 cm 3 / g, or at least 0.8 cm 3 / g, at least 0.85 cm 3 / g, or at least 0.9 cm 3 / g, or at least 0.95 cm 3 / g, or at least 1 cm 3 / g.

[0114] The internal pore volume of the porous particles may be appropriately limited such that the increased fragility of the particle structure outweighs the benefit of increased pore volume to accommodate a larger amount of electroactive material. Preferably, the total volume of micropores and mesopores in the porous particles is less than 2 cm 3 / g or less, or 1.8 cm 3 / g or less, or 1.6 cm 3 / g or less, or 1.5cm 3 / g or less, or 1.45 cm 3 / g or less, or 1.4cm 3 / g or less, or 1.35 cm 3 / g or less, or 1.3 cm 3 / g or less, or 1.25 cm 3 / g or less, or 1.2 cm 3 / g or less, or 1.1cm 3 / g or less, or 1cm 3 / g or less, or 0.95 cm 3 / g or less.

[0115] Preferably, the total volume of the micropores and mesopores in the porous particles is less than 0.45 cm 3 / g~2.2cm 3 / g, or 0.5 cm 3 / g~2cm 3 / g, or 0.55 cm 3 / g~2cm 3 / g, or 0.6 cm 3 / g~1.8cm 3 / g, or 0.65 cm 3 / g~1.8cm 3 / g, or 0.7 cm 3 / g~1.6cm 3 / g, or 0.7 cm 3 / g~1.5cm 3 / g, or 0.7 cm 3 / g~1.4cm 3 / g range.

[0116] The total volume of micropores and mesopores in the porous particle is also 0.55 cm 3 / g~1.4cm 3 / g, or 0.6 cm 3 / g~1.4cm 3 / g, or 0.6 cm 3 / g~1.3cm 3 / g, or 0.65 cm 3 / g~1.3cm 3 / g, or 0.65 cm 3 / g~1.2cm 3 / g, or 0.7 cm 3 / g~1.2cm 3 / g, or 0.7 cm 3 / g~1.1cm 3 / g, or 0.7 cm 3 / g~1cm 3 / g, or 0.75 cm 3 / g~0.95cm 3 / g.

[0117] The total volume of micropores and mesopores in the porous particle is also 0.4 cm 3 / g~0.75cm 3 / g, or 0.4 cm3 / g~0.7cm 3 / g, or 0.4 cm 3 / g~0.65cm 3 / g, or 0.45 cm 3 / g~0.75cm 3 / g, or 0.45 cm 3 / g~0.7cm 3 / g, or 0.45 cm 3 / g~0.65cm 3 / g, or 0.45 cm 3 / g~0.6cm 3 / g.

[0118] The total volume of micropores and mesopores in the porous particle is also 0.6 cm 3 / g~2cm 3 / g, or 0.6 cm 3 / g~1.8cm 3 / g, or 0.7 cm 3 / g~1.8cm 3 / g, or 0.7 cm 3 / g~1.6cm 3 / g, or 0.8 cm 3 / g~1.6cm 3 / g, or 0.8 cm 3 / g~1.5cm 3 / g, or 0.8 cm 3 / g~1.4cm 3 / g, or 0.9 cm 3 / g~1.5cm 3 / g, or 0.9 cm 3 / g~1.4cm 3 / g or 1cm 3 / g~1.4cm 3 / g.

[0119] PD of porous particles 90 The pore size may be 35 nm or less, or 30 nm or less, or 25 nm or less, or 20 nm or less, or 15 nm or less, or 12 nm or less, or 10 nm or less, or 8 nm or less, or 6 nm or less, or 5 nm or less, or 4 nm or less, or 3 nm or less, or 2.5 nm or less, or 2 nm or less. 90The pore size is at least 2.5 nm, or at least 3 nm, or at least 3.5 nm, or at least 4 nm. For example, the PD of the porous particles 90 The pore diameter is preferably in the range of 2.5 nm to 20 nm, or 3 nm to 15 nm, or 3.5 nm to 10 nm, or 4 nm to 8 nm.

[0120] PD of porous particles 10 The pore size may be 10 nm or less, or 9 nm or less, or 8 nm or less, or 7 nm or less, or 6 nm or less, or 5 nm or less, or 4 nm or less, or 3 nm or less, or 2.5 nm or less, or 2 nm or less, or 1.5 nm or less, or 1 nm or less. 10 The pore size is at least 0.3 nm, or at least 0.4 nm, or at least 0.5 nm. For example, the PD of the porous particles 10 The pore diameter is preferably in the range of 0.3 nm to 10 nm, or 0.3 nm to 5 nm, or 0.3 nm to 1 nm, or 0.4 nm to 1 nm, or 0.5 nm to 1 nm.

[0121] To avoid any misunderstanding, P.D. n For purposes of determining the value, any macropore volume (pore diameters greater than 50 nm) is not taken into account.

[0122] The volume ratio of micropores to mesopores in the porous particles can in principle be in the range of 100:0 to 0:100. Preferably, the volume ratio of micropores to mesopores is 90:10 to 55:45, or 90:10 to 60:40, or 85:15 to 65:35.

[0123] The pore size distribution of the porous particles may be unimodal, bimodal or multimodal. The term "pore size distribution" as used herein refers to the pore size distribution relative to the cumulative total internal pore volume of the porous particle. A bimodal or multimodal pore size distribution may be preferred, since the proximity of the micropores and larger diameter pores provides the advantage of efficient transport of ions through the porous network to the electroactive material.

[0124] As used herein, "D 10 " and "D 10 The term "particle size" refers to the 10th percentile median particle size on a volume basis, i.e., the diameter below which 10% by volume of the particle population lies. 90 " and "D 90 The term "particle size" refers to the volume-based 90th percentile median particle diameter, i.e., the diameter below which 90% of the particle population falls, by volume.

[0125] Optionally, the D of the porous particles 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 D of the porous particles 50 The particle size may be 150 μm or less, or 100 μm or less, or 70 μm or less, or 50 μm or less, or 40 μm or less, or 30 μm or less, or 25 μm or less, or 20 μm or less, or 18 μm or less, or 15 μm or less, or 12 μm or less, or 10 μm or less, or 8 μm or less.

[0126] For example, the porous particles may have a diameter of 0.5 μm to 150 μm, or 0.5 μm to 100 μm, or 0.5 μm to 50 μm, or 0.5 μm to 30 μm, or 1 μm to 25 μm, or 1 μm to 20 μm, or 2 μm to 25 μm, or 2 μm to 20 μm, or 2 μm to 18 μm, or 2 μm to 15 μm, or 2 μm to 12 μm, or 2.5 D in the range of μm to 15 μm, or 2.5 μm to 12 μm, or 2 μm to 10 μm, or 3 μm to 20 μm, or 3 μm to 18 μm, or 3 μm to 15 μm, or 4 μm to 18 μm, or 4 μm to 15 μm, or 4 μm to 12 μm, or 5 μm to 15 μm, or 5 μm to 12 μm, or 5 μm to 10 μm, or 5 μm to 8 μm 50 Particles within these size ranges and having porosities and pore size distributions as set forth herein are ideally suited for the preparation of composite particles for use in anodes for metal ion batteries by the CVI process.

[0127] D of porous particles 10 The particle size is preferably at least 0.2 μm, or at least 0.5 μm, or at least 0.8 μm, or at least 1 μm, or at least 1.5 μm, or at least 2 μm. 10 Maintaining the particle size at or above 0.2 μm reduces the likelihood of undesirable agglomeration of submicron sized particles and improves the dispersibility of the composite particles formed.

[0128] D of porous particles 90 The particle size is preferably 300 μm or less, or 250 μm or less, or 200 μm or less, or 150 μm or less, or 100 μm or less, or 80 μm or less, or 60 μm or less, or 40 μm or less, or 30 μm or less, or 25 μm or less, or 20 μm or less.

[0129] The porous particles preferably have a narrow particle size distribution span. For example, the particle size distribution span (D 90 -D 10 ) / D 50 (defined as) is preferably 5 or less, more preferably 4 or less, more preferably 3 or less, more preferably 2 or less, and most preferably 1.5 or less. By maintaining a narrow particle size distribution span, efficient packing of particles into a dense powder bed is more easily achievable.

[0130] The porous particles may have an average sphericity (as defined above) of greater than 0.5. Preferably, the porous particles have an average sphericity of at least 0.55, or at least 0.6, or at least 0.65, or at least 0.7, or at least 0.75, or at least 0.8, or at least 0.85. Preferably, the porous particles have an average sphericity of at least 0.90, or at least 0.92, or at least 0.93, or at least 0.94, or at least 0.95. It is believed that spherical particles aid in the uniformity of deposition and promote denser packing of the final product when captured in the reaction zone and within the electrodes.

[0131] Highly accurate two-dimensional projections of micron-scale particles can be obtained by scanning electron microscopy (SEM) or dynamic image analysis, where the shadows cast by the particles are recorded using a digital camera. The term "sphericity" as used herein is to be understood as the ratio of the area of ​​the particle projection (obtained from such imaging technique) to the area of ​​a circle, where the particle projection and the circle have the same circumference. Thus, for an individual particle, the sphericity S can be defined as:

number

number

[0132] The porous particles are at least 100m 2 / g, or at least 500m 2 / g, or at least 750m 2 / g, or at least 1000m 2 / g, or at least 1250m 2 / g, or at least 1500m 2 The BET surface area of ​​the porous particles is 4000 m 2 / g or less, or 3500m 2 / g or less, or 3250m 2 / g or less, or 3000m 2 / g or less, or 2500m 2 / g or less, or 2000m 2 For example, the porous particles have a particle size of 100 m 2 / g~4000m 2 / g, or 500m2 / g~4000m 2 / g, or 750m 2 / g~3500m 2 / g, or 1000m 2 / g~3250m 2 / g, or 1000m 2 / g~3000m 2 / g, or 1000m 2 / g~2500m 2 / g, or 1000m 2 / g~2000m 2 / g.

[0133] The porous particles preferably have a density of at least 0.35 g / cm 3 and preferably 3 g / cm 3 less than 2 g / cm 3 less than 1.5 g / cm 3 less than 0.35 g / cm 3 ~1.2g / cm 3 The term "particle density" as used herein refers to the "apparent particle density" as measured by mercury intrusion (i.e., particle mass divided by particle volume, where particle volume is taken to be the sum of the volume of solid material and any closed or blind pores ("blind pores" are pores that are too small to be measured by mercury intrusion). Preferably, the porous particles have a particle density of at least 0.4 g / cm. 3 , or at least 0.45 g / cm 3 , or at least 0.5 g / cm 3 , or at least 0.55 g / cm 3 , or at least 0.6 g / cm 3 , or at least 0.65 g / cm 3 , or at least 0.7 g / cm 3 Preferably, the porous particles have a particle density of 1.15 g / cm 3 or less than 1.1g / cm 3 or less than 1.05g / cm 3 or less than 1g / cm 3 or less than 0.95g / cm3 or less than 0.9g / cm 3 It has the following particle density:

[0134] Preferably, the porous particles are (i) 0.4 cm 3 / g~2.2cm 3 the total pore volume of micropores and mesopores as measured by nitrogen gas adsorption in the range of 1 / g; (ii) PD less than 20 nm 50 Pore ​​diameter, preferably PD of 30 nm or less 90 Pore ​​size, preferably PD of 15 nm or less 30 Pore ​​size, and (iii) D in the range of 0.5 μm to 30 μm 50 Particle size, has.

[0135] More preferably, the BET surface area of ​​the porous particles is greater than 1000 m 2 / g~3000m 2 / g.

[0136] More preferably, the porous particles are (i) 0.6 cm 3 / g~1.8cm 3 the total pore volume of micropores and mesopores as measured by nitrogen gas adsorption in the range of 1 / g; (ii) PD less than 10 nm 50 Pore ​​diameter, preferably PD of 20 nm or less 90 Pore ​​diameter, preferably 8 nm or less PD 30 Pore ​​size, and (iii) D in the range of 1 μm to 25 μm 50 Particle size, has.

[0137] More preferably, the BET surface area of ​​the porous particles is greater than 1000 m 2 / g~3000m 2 / g.

[0138] More preferably, the porous particles are (i) 0.7 cm 3 / g~1.6cm 3 the total pore volume of micropores and mesopores as measured by nitrogen gas adsorption in the range of 1 / g; (ii) PD less than 10 nm 50 Pore ​​diameter, preferably PD of 20 nm or less 90 Pore ​​diameter, preferably 8 nm or less PD 30 Pore ​​size, and (iii) D in the range of 1 μm to 20 μm 50 Particle size, has.

[0139] More preferably, the BET surface area of ​​the porous particles is greater than 1000 m 2 / g~3000m 2 / g.

[0140] More preferably, the porous particles are (i) 0.7 cm 3 / g~1.5cm 3 the total pore volume of micropores and mesopores as measured by nitrogen gas adsorption in the range of 1 / g; (ii) PD less than 5 nm 50 Pore ​​diameter, preferably PD of 10 nm or less 90 Pore ​​size, preferably 3 nm or less PD 30 Pore ​​size, and (iii) D in the range of 2 μm to 20 μm 50 Particle size, has.

[0141] More preferably, the BET surface area of ​​the porous particles is greater than 1000 m 2 / g~3000m 2 / g.

[0142] More preferably, the porous particles are (i) 0.7 cm 3 / g~1.4cm 3 the total pore volume of micropores and mesopores as measured by nitrogen gas adsorption in the range of 1 / g; (ii) PD less than 5 nm 50 Pore ​​diameter, preferably PD of 10 nm or less 90Pore ​​size, preferably 3 nm or less PD 30 Pore ​​size, and (iii) D in the range of 2 μm to 20 μm 50 Particle size, has.

[0143] More preferably, the BET surface area of ​​the porous particles is greater than 1000 m 2 / g~2500m 2 / g.

[0144] More preferably, the porous particles are (i) 0.7 cm 3 / g~1.4cm 3 the total pore volume of micropores and mesopores as measured by nitrogen gas adsorption in the range of 1 / g; (ii) PD less than 5 nm 50 Pore ​​diameter, preferably PD of 10 nm or less 90 Pore ​​size, preferably 3 nm or less PD 30 Pore ​​size, and (iii) D in the range of 2 μm to 18 μm 50 Particle size, has.

[0145] More preferably, the BET surface area of ​​the porous particles is greater than 1000 m 2 / g~2500m 2 / g.

[0146] More preferably, the porous particles are (i) 0.7 cm 3 / g~1.4cm 3 the total pore volume of micropores and mesopores as measured by nitrogen gas adsorption in the range of 1 / g; (ii) PD less than 2 nm 50 Pore ​​size, preferably 5 nm or less PD 90 Pore ​​diameter, preferably PD of 1 nm or less 30 Pore ​​size, and (iii) D in the range of 2 μm to 15 μm 50 Particle size, has.

[0147] More preferably, the BET surface area of ​​the porous particles is greater than 1000 m 2 / g~2500m 2 / g.

[0148] When the silicon-containing precursor is a chlorinated compound, such as a chlorosilane, the silicon-containing precursor can be used in a mixture with hydrogen gas, preferably at least a 1:1 atomic ratio of hydrogen to chlorine.

[0149] Optionally, the silicon-containing precursor is chlorine-free. By chlorine-free, it is meant that the silicon-containing precursor contains less than 1 wt.%, preferably less than 0.1 wt.%, preferably less than 0.01 wt.% of chlorine-containing compounds.

[0150] The temperature effective to cause deposition of silicon in steps (b) and (d) is any temperature effective to decompose the silicon-containing precursor to form silicon. The temperature effective to cause deposition of silicon in steps (b) and (d) is from 340°C to 400°C, or from 340°C to 395°C, or from 340°C to 390°C, or from 345°C to 400°C, or from 345°C to 395°C, or from 345°C to 390°C, or from 350°C to 400°C, or from 350°C to 395°C, or from 350°C to 390°C, or from 350°C to 385°C, or from 350°C to 380°C, or from 355°C to 400°C, or from 355°C to 395°C, or from 355°C to 390 ... Preferably, the temperature range is 5°C to 385°C, or 355°C to 380°C, or 360°C to 400°C, or 360°C to 395°C, or 360°C to 390°C, or 360°C to 385°C, or 360°C to 380°C, or 365°C to 400°C, or 365°C to 395°C, or 365°C to 390°C, or 365°C to 385°C, or 365°C to 380°C, or 370°C to 400°C, or 370°C to 395°C, or 370°C to 390°C, or 370°C to 385°C, or 370°C to 380°C. A temperature range of less than 370°C to 395°C is particularly preferred.

[0151] Deposition of silicon by CVI results in the removal of by-products, in particular by-product gases such as hydrogen. Step (c) preferably includes at least the separation of the by-products from the intermediate particles formed. Separation of the by-products from the intermediate particles formed can be achieved by flushing the reaction zone with an inert gas and / or by evacuating the reaction zone by reducing the pressure. For example, separation of the by-products from the intermediate particles formed can be achieved by evacuating the reaction zone 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. Evacuation of the reaction zone to a low pressure can be effective not only to remove gas phase by-products, but also to desorb any by-products that may be adsorbed on the surface of the deposited silicon.

[0152] According to a preferred embodiment of the present invention, (i) Multiple porous particles are 500m 2 / g~4000m 2 / g, (ii) ΔT in step (b) is +80° C. or less; (iii) the plurality of porous particles is maintained within a temperature range of 340° C. to 395° C. during step (b); (iv) the plurality of porous particles in the reaction zone of step (a) is at least 100 cm 3 / L RV and having a volume of (v) Step (b) comprises continuously stirring the porous particles.

[0153] According to another preferred embodiment of the invention, (i) Multiple porous particles are 750m 2 / g~3500m 2 / g, (ii) ΔT in step (b) is +60° C. or less; (iii) the plurality of porous particles is maintained within a temperature range of 350° C. to 395° C. during step (b); (iv) the plurality of porous particles in the reaction zone of step (a) is at least 200 cm 3 / L RV and having a volume of (v) Step (b) comprises continuously stirring the porous particles.

[0154] According to another preferred embodiment of the invention, (i) Multiple porous particles are 1000m 2 / g~3250m 2 / g, (ii) ΔT in step (b) is +40° C. or less; (iii) the plurality of porous particles is maintained within a temperature range of 360° C. to 395° C. during step (b); (iv) the plurality of porous particles in the reaction zone of step (a) is at least 300 cm 3 / L RV and having a volume of (v) Step (b) comprises continuously stirring the porous particles.

[0155] According to another preferred embodiment of the invention, (i) Multiple porous particles are 1000m 2 / g~3000m 2 / g, (ii) ΔT in step (b) is +20° C. or less; (iii) the plurality of porous particles is maintained within a temperature range of 370° C. to 395° C. during step (b); (iv) the plurality of porous particles in the reaction zone of step (a) is at least 400 cm 3 / L RV and having a volume of (v) Step (b) comprises continuously stirring the porous particles.

[0156] According to another preferred embodiment of the invention, (i) Multiple porous particles are 1000m 2 / g~2500m 2 / g, (ii) ΔT in step (b) is +10° C. or less; (iii) the plurality of porous particles is maintained within a temperature range of 370° C. to 390° C. during step (b); (iv) the plurality of porous particles in the reaction zone of step (a) is at least 500 cm 3 / L RV and having a volume of (v) Step (b) comprises continuously stirring the porous particles.

[0157] According to a preferred embodiment of the present invention, (i) Multiple porous particles are 500m 2 / g~4000m 2 / g, (ii) ΔT in step (b) is +80° C. or less; (iii) the plurality of porous particles is maintained within a temperature range of 340° C. to 395° C. during step (b); (iv) The ratio of the internal surface area of ​​the reaction zone in step (a) to the mass of the porous particles in the reaction zone is less than 1 m 2 / kg or less, (v) Step (b) comprises continuously stirring the porous particles.

[0158] According to another preferred embodiment of the invention, (i) Multiple porous particles are 750m 2 / g~3500m 2 / g, (ii) ΔT in step (b) is +60° C. or less; (iii) the plurality of porous particles is maintained within a temperature range of 350° C. to 395° C. during step (b); (iv) the ratio of the internal surface area of ​​the reaction zone in step (a) to the mass of the porous particles in the reaction zone is 0.8 m 2 / kg or less, (v) Step (b) comprises continuously stirring the porous particles.

[0159] According to another preferred embodiment of the invention, (i) Multiple porous particles are 1000m 2 / g~3250m 2 / g, (ii) ΔT in step (b) is +40° C. or less; (iii) the plurality of porous particles is maintained within a temperature range of 360° C. to 395° C. during step (b); (iv) the ratio of the internal surface area of ​​the reaction zone in step (a) to the mass of the porous particles in the reaction zone is 0.6 m 2 / kg or less, (v) Step (b) comprises continuously stirring the porous particles.

[0160] According to another preferred embodiment of the invention, (i) Multiple porous particles are 1000m 2 / g~3000m 2 / g, (ii) ΔT in step (b) is +20° C. or less; (iii) the plurality of porous particles is maintained within a temperature range of 370° C. to 395° C. during step (b); (iv) the ratio of the internal surface area of ​​the reaction zone to the mass of the porous particles in the reaction zone in step (a) is 0.4 m 2 / kg or less, (v) Step (b) comprises continuously stirring the porous particles.

[0161] According to another preferred embodiment of the invention, (i) Multiple porous particles are 1000m 2 / g~2500m 2 / g, (ii) ΔT in step (b) is +10° C. or less; (iii) the plurality of porous particles is maintained within a temperature range of 370° C. to 390° C. during step (b); (iv) the ratio of the internal surface area of ​​the reaction zone to the mass of the porous particles in the reaction zone in step (a) is less than or equal to 0.2 m 2 / kg or less, (v) Step (b) includes continuously stirring the porous particles.

[0162] The method of the present invention may further include forming a modifier material on the surface of the silicon deposited in step (b) and / or step (d).

[0163] The modifier material may be a passivation layer formed on the surface of the silicon deposited in step (b) or step (d). Thus, the method may further include contacting the particles from step (b) or step (d) with a passivating agent. As defined herein, a passivating agent is a compound or mixture of compounds capable of reacting with the surface of the deposited silicon to form a modified surface.

[0164] One type of passivation layer is a native oxide layer. The native oxide layer can be formed, for example, by exposing the surface of the silicon to a passivating agent selected from air or another oxygen-containing gas. The passivation layer may include silicon oxide of the formula SiO x (where 0 < x ≦ 2). The silicon oxide is preferably amorphous silicon oxide. The formation of the native oxide layer is exothermic, and thus careful process control is required to prevent overheating or even combustion of the particulate material. When the modifier material formed is a native oxide layer, the method may include cooling the material formed in step (b) or step (d) to a temperature below 300°C, preferably below 200°C, optionally below 100°C, before contacting the surface of the silicon domain with an oxygen-containing gas.

[0165] Another type of passivation layer is a nitride layer formed, for example, by exposing the surface of the silicon to a passivating agent selected from ammonia or another nitrogen-containing molecule. The passivation layer has the formula SiN xIt may contain silicon nitride of (wherein, 0 < x ≦ 4 / 3). The silicon nitride is preferably amorphous silicon nitride. The nitride layer can be formed by bringing the surface of the silicon domain into contact with ammonia at a temperature in the range of 200°C to 700°C, preferably 400°C to 700°C, more preferably 400°C to 600°C. Then, if necessary, the temperature is raised to the range of 500°C to 1000°C to form a nitride surface (for example, the surface of silicon nitride of the formula SiN x (wherein, x ≦ 4 / 3)). Nitride passivation may be preferable to oxide passivation. Since stoichiometric nitrides (for example, SiN x (wherein, 0 < x ≦ 4 / 3), etc.) are conductive, the nitride intermediate layer functions as a conductive network that enables more rapid charging and discharging of silicon. Phosphine can also be used as a passivating agent as a phosphorus analog of ammonia.

[0166] Another type of passivation layer is, for example, an oxynitride layer formed by exposing the surface of silicon to a passivating agent containing ammonia (or another nitrogen-containing molecule) and oxygen gas. The passivation layer may contain silicon oxynitride of the formula SiO x N y (wherein, 0 < x < 2, 0 < y < 4 / 3, and 0 < (2x + 3y) ≦ 4). The silicon nitride is preferably amorphous silicon oxynitride.

[0167] Another type of passivation layer is a carbide layer. The passivation layer may contain silicon carbide of the formula SiC x (wherein, 0 < x ≦ 1). The silicon carbide is preferably amorphous silicon carbide. The carbide layer can be formed by bringing the surface of silicon into contact with a passivating agent selected from carbon-containing precursors such as methane or ethylene at an elevated temperature, for example, in the range of 250°C to 700°C. At lower temperatures, covalent bonds are formed between the surface of silicon and the carbon-containing precursor, which is converted into a single layer of crystalline silicon carbide as the temperature rises. The modified material domain may contain silicon carbide of the formula SiC x (wherein, 0 < x ≦ 1).

[0168] Other suitable passivating agents include compounds that contain an alkene, alkyne or carbonyl functionality, more preferably a terminal alkene, terminal alkyne, aldehyde or ketone group.

[0169] Preferred passivating agents include those having the following formula: (i)R 1 -CH=CH-R 1 , (ii)R 1 -C≡CR 1 , and (iii) O=CR 1 R 1 , (In the formula, each R 1 independently represent H or an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 carbon atoms, or two R 1 The group includes one or more compounds that form an unsubstituted or substituted ring structure containing 3 to 8 carbon atoms in the ring.

[0170] Particularly preferred passivators include those having the following formula: (i) CH2=CH-R 1 , and (ii) HC≡CR 1 、 (In the formula, R 1 is as defined above. 1 is non-substitutive.

[0171] 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]oct-2-ene. Optionally, mixtures of different passivators can also be used.

[0172] It is believed that passivating agents containing alkene, alkyne or carbonyl groups undergo an insertion reaction with MH groups (wherein M represents a silicon atom) on the silicon surface to form a covalently passivated surface that is resistant to oxidation by air. The passivating reaction between the silicon surface and the passivating agent can be understood as a form of hydrosilylation as shown diagrammatically below. [ka]

[0173] Other suitable passivation agents include compounds that contain an active hydrogen atom bonded to oxygen, nitrogen, sulfur, or phosphorus. For example, the passivation agent may be an alcohol, an amine, a thiol, or a phosphine. It is understood that the reaction of the -XH group with a hydride group on the silicon surface results in the elimination of H2 and the formation of a direct bond between X and the silicon surface.

[0174] Suitable passivators in this category include those having the following formula: (iv) HX-R 2 , and (v) HX-C(O)-R 1 、 (wherein X is O, S, NR 1 Or PR 1 Each R 1 are independently as defined above, and R 2 represents an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 carbon atoms, or R 1 and R 2 taken together form an unsubstituted or substituted ring structure containing 3 to 8 carbon atoms in the ring.

[0175] Preferably, X represents O or NH.

[0176] Preferably, R 2represents an optionally substituted aliphatic or aromatic group having from 2 to 10 carbon atoms. Amine groups may also be incorporated into 4- to 10-membered aliphatic or aromatic ring structures, such as in pyrrolidine, pyrrole, imidazole, piperazine, indole, or purine.

[0177] Contact of the silicon with the passivating agent may be carried out at a temperature in the range of 25°C to 700°C, preferably 50°C to 500°C, more preferably 100°C to 300°C.

[0178] The modifier material formed may optionally comprise a pyrolytic carbon material deposited on the silicon surface by pyrolysis of a carbon-containing precursor, i.e., by chemical vapor infiltration (CVI). Deposition of pyrolytic carbon material may be preferred because it forms a conductive network between silicon domains that may facilitate electron transport within the composite particle. The method may thus comprise contacting the intermediate particles from step (b) or step (d) with a carbon-containing precursor, preferably a hydrocarbon, at a temperature effective to cause deposition of pyrolytic carbon material in the pores of the intermediate particles.

[0179] Suitable hydrocarbons include polycyclic hydrocarbons containing 10 to 25 carbon atoms and optionally 1 to 3 heteroatoms, optionally the polycyclic aromatic hydrocarbons being selected from naphthalene, substituted naphthalenes such as dihydroxynaphthalene, anthracene, tetracene, pentacene, fluorene, acenaphthene, phenanthrene, fluoranthene, pyrene, chrysene, perylene, coronene, fluorenone, anthraquinone, anthrone and alkyl-substituted derivatives thereof. Suitable pyrolytic carbon precursors also include bicyclic monoterpenoids, optionally the bicyclic monoterpenoids being selected from camphor, borneol, eucalyptol, camphene, careen, sabinene, thujene and pinene. Further suitable pyrolytic carbon precursors include C2-C 10Included are 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 pyrolytic carbon precursors include phthalocyanine, sucrose, starch, graphene oxide, reduced graphene oxide, pyrene, perhydropyrene, triphenylene, tetracene, benzopyrene, perylene, coronene, and chrysene. A preferred carbon precursor is acetylene.

[0180] Suitable temperatures for the deposition of pyrolytic carbon materials range from 300°C to 800°C, or from 400°C to 700°C. For example, the temperature may be 680°C or less, or 660°C or less, or 640°C or less, or 620°C or less, or 600°C or less, or 580°C or less, or 560°C or less, or 540°C or less, or 520°C or less, or 500°C or less. The minimum temperature varies depending on the type of carbon precursor used. Preferably, the temperature is at least 300°C, or at least 350°C, or at least 400°C, or at least 450°C, or at least 500°C.

[0181] The carbon-containing precursors used may be used in pure form or in a mixture diluted with an inert carrier gas such as nitrogen or argon. For example, the carbon-containing precursors may be used in an amount ranging from 0.1% to 100% by volume, or from 0.5% to 20% by volume, or from 1% to 10% by volume, or from 1% to 5% by volume, based on the total volume of the precursor and the inert carrier gas. The presence of oxygen should be minimized to prevent undesired oxidation of the deposited electroactive material. Preferably, the oxygen content is less than 0.01% by volume, more preferably less than 0.001% by volume, based on the total volume of the gas.

[0182] When a pyrolytic carbon material is deposited, the same compound can function as both the passivator and the pyrolytic carbon precursor. For example, if styrene is selected as the pyrolytic carbon precursor, it will also function as the passivator, provided that the intermediate particles from step (b) are not exposed to oxygen prior to contact with the styrene. In this case, the passivation and deposition of the conductive carbon material in the process can be carried out simultaneously, for example at a temperature in the range of 300°C to 700°C. Alternatively, the passivation and deposition of the conductive carbon material can be carried out sequentially, if the passivator and the pyrolytic carbon precursor are the same material, but the deposition of the pyrolytic carbon precursor is carried out at a higher temperature than the passivation. For example, the passivation can be carried out at a temperature in the range of 25°C to less than 300°C, and the deposition of the pyrolytic carbon can be carried out at a temperature in the range of 300°C to 700°C. These two steps can be suitably carried out sequentially by increasing the temperature while maintaining contact with the compound that functions as both the passivator and the pyrolytic carbon precursor. At lower temperatures (e.g., in the range of 25°C to less than 300°C), passivation would be the predominant process. As the temperature increases (e.g., to 300°C to 700°C), deposition of pyrolytic carbon would likely ensue.

[0183] A range of different silicon loadings in the composite particles may be obtained using the method of the present invention. For example, the amount of silicon in the composite particles may range from 5% to 85% by weight, based on the total mass of the composite particles. Preferably, the amount of silicon in the composite particles is 10% to 85% by weight, or 15% to 85% by weight, or 20% to 80% by weight, or 25% to 80% by weight, or 30% to 75% by weight, or 35% to 75% by weight, or 40% to 70% by weight, or 45% to 65% by weight, based on the total mass of the composite particles. The total silicon loading in the composite particles is the sum of the silicon deposited in steps (b) and (d) (including repetitions of step (d)).

[0184] The amount of silicon in the composite particles is preferably selected such that at least 20% and up to 90% of the internal pore volume of the porous particles is occupied by silicon. For example, silicon may occupy 20%-80%, or 25%-75%, or 30%-70%, or 35%-65%, or 40%-60%, or 45%-55% of the internal pore volume of the porous particles. Within these preferred ranges, the remaining pore volume of the porous particles is effective to accommodate the expansion of silicon during charging and discharging, without excess pore volume that does not contribute to the volumetric capacity of the particulate particles. However, the amount of silicon is also not so high as to prevent effective lithiation due to inadequate metal ion diffusion rates or inadequate expansion volume resulting in mechanical resistance to lithiation.

[0185] The amount of silicon in the composite particles is determined by the mass ratio of silicon to porous particles [0.5 × P 1 ~1.9×P 1 ]:1, where P 1 is cm 3 Pore ​​volume is a dimensionless quantity that has a measure of the total pore volume of micropores and mesopores in a porous particle, expressed as pore volume per gram (e.g., if a porous particle has a volume of 1.2 cm 3 / g, then P 1 = 1.2). This relationship takes into account the density of silicon and the pore volume of the porous particles and defines the weight ratio of silicon at which the pore volume is approximately 20% to 82% occupied.

[0186] The amount of silicon in the composite particles can be determined by elemental analysis. Preferably, elemental analysis is used to determine the elemental composition of only the porous particles, and the composition of the composite particles.

[0187] The silicon content is preferably determined by ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy). Many ICP-OES instruments are commercially available, such as the iCAP™ 7000 series of ICP-OES analyzers available from ThermoFisher Scientific. The carbon content (and optionally the hydrogen, nitrogen and oxygen content) in the composite particles and in the porous carbon particles alone is preferably determined by IR absorption. A suitable instrument for determining the carbon, hydrogen, nitrogen and oxygen content is the TruSpec™ Micro elemental analyzer available from Leco Corporation.

[0188] Preferably, at least 90% by weight of the silicon in the composite particles is located within the interior pore volume of the porous particles, more preferably at least 95% by weight, and even more preferably at least 98% by weight, such that none or little silicon is located on the exterior surfaces of the composite particles. As discussed above, deposition of silicon during the CVI process occurs at the porous particle surfaces.

[0189] The method of the present invention comprises the steps of: (e) forming a plurality of modifier material domains in the pores and / or on the exterior surface of the composite particles resulting from step (b) or step (d); It may further include.

[0190] Step (e) is performed immediately after the last silicon deposition step (i.e. step (b) or step (d), or the last iteration of step (d) if steps (c) and (d) are repeated). The formation of the modifier material domains is similar to the steps described above, except that step (e) is performed after the last silicon deposition step, whereas the previous steps may be performed between successive electroactive material deposition steps.

[0191] Any of the modifier materials and deposition conditions disclosed herein apply to both processes.

[0192] The modifier material domains formed in step (e) may comprise the same or a different modifier material as the modifier material domains formed in the previous step.

[0193] Optionally, step (e) comprises contacting the composite particles from step (b) or step (d) with a passivating agent. Preferred passivating agents and passivating conditions are as set forth above.

[0194] Optionally, step (e) comprises depositing a lithium-ion permeable material within the pores and / or on the outer surface of the composite particles from step (b) or step (d), which provides further improvement in the performance of the composite particles when used as electroactive materials for lithium-ion batteries by reducing the surface area of ​​the composite particles and by blocking electroactive material domains from access to electrolyte.

[0195] The lithium ion permeable material may be deposited immediately after the last electroactive material deposition step, or alternatively, the passivation step in step (e) may be performed first, as discussed above, followed by deposition of the lithium ion permeable material.

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

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

[0198] The preferred pyrolytic carbon precursors and pyrolysis conditions are as set forth above.

[0199] When the lithium ion permeable material is a pyrolytic carbon material, the same compound may function as both the passivator and the pyrolytic carbon precursor in step (e). Suitable conditions for passivating and forming the pyrolytic carbon material using the same compound as the passivator and the pyrolytic carbon precursor in step (e) are as set forth above.

[0200] Alternatively, different compounds may be used as the passivating agent and as the pyrolytic carbon precursor in step (e), for example the passivating agent may be styrene and the pyrolytic carbon precursor may be a compound such as cyclohexane that is capable of forming a pyrolytic carbon material but is unable to passivate the silicon surface.

[0201] The composite particles obtained by the method of the present invention may be characterized by their performance under thermogravimetric analysis (TGA) in air, which is based on the principle that when silicon is oxidized in air and at elevated temperatures, a weight gain is observed.

[0202] As defined herein, "surface silicon" is calculated from the initial mass increase in a TGA trace from a minimum between 150°C and 500°C to a maximum mass measured in the temperature range between 550°C and 650°C, the TGA being performed in air at a heating rate of 10°C / min. This mass increase is assumed to result from oxidation of the surface silicon and is therefore calculated according to the following formula: Y = 1.875 × [(M max -M min ) / M f ]×100% where Y is the percentage of surface silicon as a proportion of the total silicon in the sample, and M max is the maximum mass of the sample measured in the temperature range between 550°C and 650°C, and M min is the minimum mass of the sample at temperatures greater than 150°C and less than 500°C, and M fThe percentage of surface silicon as a proportion of the total amount of silicon can be determined according to (where 1.875 is the mass of the sample at the completion of oxidation at 1400°C). For completeness, it will be understood that 1.875 is the molar mass ratio of SiO2 to O2 (i.e., the mass ratio 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.

[0203] It has been found that reversible capacity retention over multiple charge / discharge cycles is significantly improved when the surface silicon, as determined by the TGA method described above, is at least 20% by weight of the total amount of silicon in the material.Preferably, at least 22% by weight of the silicon, or at least 25% by weight, at least 30% by weight, or at least 35% by weight of the silicon, or at least 40% by weight of the silicon, or at least 45% by weight of the silicon is surface silicon, as determined by thermogravimetric analysis (TGA).

[0204] In addition to surface silicon content, the silicon-containing composite particles obtained by the method of the present invention preferably have a low content of coarse bulk silicon as determined by TGA. Coarse bulk silicon is defined herein as silicon that undergoes oxidation above 800°C as determined by TGA, where the TGA is performed in air at a heating rate of 10°C / min. Thus, the coarse bulk silicon content is calculated according to the following formula: Z = 1.875 × [(M f -M 800 ) / M f ]×100% (where Z is the percentage of unoxidized silicon at 800°C, M 800 is the mass of the sample at 800 °C, M f is the mass of ash at completion of oxidation at 1400°C). For the purposes of this analysis, any mass increase above 800°C corresponds to the oxidation of silicon to SiO2, and it is assumed that the total mass at completion of oxidation is SiO2.

[0205] Silicon that undergoes oxidation above 800° C. is less desirable. Preferably, crude bulk silicon is no more than 10% by weight of the silicon, or no more than 8%, or no more than 6%, or no more than 5%, or no more than 4%, or no more than 3%, or no more than 2%, or no more than 1.5% by weight, as determined by TGA.

[0206] Preferably, at least 20% by weight of the silicon is surface silicon and not more than 10% by weight of the silicon is crude bulk silicon, both as determined by TGA. More preferably, at least 25% by weight of the silicon is surface silicon and not more than 10% by weight of the silicon is crude bulk silicon, both as determined by TGA. More preferably, at least 30% by weight of the silicon is surface silicon and not more than 10% by weight of the silicon is crude bulk silicon, both as determined by TGA. More preferably, at least 35% by weight of the silicon is surface silicon and not more than 8% by weight of the silicon is crude bulk silicon, both as determined by TGA. More preferably, at least 40% by weight of the silicon is surface silicon and not more than 5% by weight of the silicon is crude bulk silicon, both as determined by TGA. More preferably, at least 45% by weight of the silicon is surface silicon and not more than 2% by weight of the silicon is crude bulk silicon, both as determined by TGA.

[0207] The composite particles obtained according to the method of the present invention are preferably 2 / g or less, or 250m 2 / g or less, or 200m 2 / g or less, or 150m 2 / g or less. More preferably, it has a BET surface area of ​​100 m 2 / g or less, or 80m 2 / g or less, or 60m 2 / g or less, or 40m 2 / g or less, or 30m 2 / g or less, or 25m 2 / g or less, or 20m 2 / g or less, or 15m 2 / g or less, or 10m 2 / g or less, or 5m 2 / g or less. Generally, a low BET surface area is preferred to minimize the formation of a solid electrolyte interfacial (SEI) layer on the surface of the composite particles during the first charge-discharge cycles of the anode. However, an excessively low BET surface area will result in unacceptably low charge rates and capacities due to the inaccessibility of large amounts of silicon to metal ions in the surrounding electrolyte. The BET surface area is preferably at least 0.1 m 2 / g, or at least 1m 2 / g, or at least 2m 2 / g, or at least 5m 2 For example, the BET surface area of ​​a composite particle is 0.1 m 2 / g~100m 2 / g, or 0.1m 2 / g~80m 2 / g, or 0.5m 2 / g~60m 2 / g, or 0.5m 2 / g~40m 2 / g, or 1m 2 / g~30m 2 / g, or 1m 2 / g~25m 2 / g, or 2m 2 / g~20m 2 / g.

[0208] In a third aspect, the present invention provides composite particles obtainable according to the method of the first aspect of the invention.

[0209] In a fourth aspect of the invention, there is provided a composition comprising a composite particle according to the third aspect of the invention and at least one other component. In particular, there is provided a composition comprising a composite particle according to the third aspect of the invention and at least one other component selected from (i) a binder, (ii) a conductive additive, and (iii) an additional particulate electroactive material. The composition according to the fourth aspect of the invention is useful as an electrode composition and can thus be used to form the active layer of an electrode.

[0210] In a fifth aspect, the present invention provides an electrode comprising composite particles according to the third aspect of the invention in electrical contact with a current collector. The particulate material used to manufacture the electrode of the fifth aspect of the invention may be in the form of a composition according to the fourth aspect of the invention.

[0211] The term current collector as used herein refers to any conductive substrate capable of conducting electrical current to and from the electroactive particles in the composition. Examples of materials that can be used as current collectors include copper, aluminum, stainless steel, nickel, titanium, and sintered carbon. Copper is a preferred material. Current collectors typically have the form of a foil or mesh having a thickness of 3 μm to 500 μm. The particulate material of the present invention can be applied to one or both sides of the current collector, preferably to a thickness ranging from 10 μm to 1 mm, for example, from 20 μm to 500 μm, or from 50 μm to 200 μm.

[0212] The electrode of the fifth aspect of the invention may be used as the anode of a metal-ion battery.Thus, in a sixth aspect, the invention provides a rechargeable metal-ion battery comprising an anode comprising an electrode as described above, a cathode comprising a cathode active material capable of releasing and reabsorbing metal ions, and an electrolyte between the anode and the cathode.

[0213] The metal ions are preferably lithium ions. More preferably, the rechargeable metal ion batteries of the present invention are lithium ion batteries and the cathode active material is capable of releasing and accepting lithium ions. EXAMPLES

[0214] Example 1 Silicon-carbon composite particles were prepared by placing porous carbon particles inside a stainless steel autoclave equipped with an agitator and gas inlet and outlet lines. The autoclave was purged with nitrogen gas and then set to a furnace temperature of 500°C. Before the temperature of the particle bed reached 500°C, the gas supply was switched from nitrogen to pure monosilane. After 1 hour, the furnace was switched off and the autoclave was slowly depressurized. The autoclave was then refilled with monosilane and heated again to 500°C and held for another hour. The furnace was switched off, refilled and heated as many times as necessary for the target silicon content. After dosing was completed, the autoclave was purged using nitrogen and exposed to increasing concentrations of oxygen to passivate the composite particles, followed by cooling to room temperature.

[0215] FIG. 1 shows the temperatures at the interior surfaces of a representative reaction zone and within several particles in this example.

[0216] FIG. 2 shows the temperatures at the interior surfaces of a representative reaction zone and within several particles during one cycle of silicon deposition in this example.

[0217] At most times during contact of the gas containing silicon-containing precursor with the porous particles, the temperature of the interior surface of a typical reaction zone is observed to significantly exceed the temperature within a number of particles. Under these conditions, significant fouling of the reaction zone occurs, and large flakes of silicon-rich composite are formed. It is expected that shutdown and cleaning of the reaction zone will be required after the process, rendering the process inoperable.

[0218] Example 2 Silicon-carbon composite particles were prepared by placing porous carbon particles inside a stainless steel autoclave equipped with an agitator and gas inlet and outlet lines. The autoclave was purged with nitrogen gas and then the furnace temperature was set to 430°C. Monosilane was added to the autoclave before the temperature of the particle bed reached 370°C. After 1 hour, the furnace was switched off and the autoclave was slowly depressurized. The autoclave was then refilled with monosilane and heated again to 430°C and held for another hour. The furnace was switched off, refilled and heated as many times as necessary for the target silicon content. After dosing was completed, the autoclave was purged using nitrogen and exposed to increasing concentrations of oxygen to passivate the composite particles, followed by cooling to room temperature.

[0219] FIG. 3 shows the temperatures at the interior surface of a representative reaction zone and within several particles in this example.

[0220] FIG. 4 shows the temperatures at the interior surfaces of a representative reaction zone and within several particles during one cycle of silicon deposition in this example.

[0221] It is observed that at the majority of times during contact of the gas containing silicon-containing precursor with the porous particles, the temperature of the interior surface of the representative reaction zone exceeds the temperature within the particles. Compared to the deposition conditions shown in FIG. 1, the difference between the temperature of the interior surface of the reaction zone and the temperature within the particles at any time is smaller. Under these conditions, significant fouling of the reaction zone occurs and large flakes of silicon-rich composite are formed. It is expected that a shutdown and cleaning of the reaction zone will be required after the process, rendering the process inoperable.

[0222] Example 3 Silicon-carbon composite particles were prepared by placing porous carbon particles inside a stainless steel autoclave equipped with an agitator and gas inlet and outlet lines. The autoclave was purged with nitrogen gas and then the furnace temperature was set to 400°C. When the particle bed temperature reached 350°C, monosilane was added to the autoclave. After 1 hour, the autoclave was slowly depressurized. The autoclave was then refilled with monosilane and held for another hour. Depressurization and refilling were each repeated as many times as necessary for the target silicon content. After dosing was completed, the autoclave was purged using nitrogen and exposed to increasing concentrations of oxygen to passivate the composite particles, followed by cooling to room temperature.

[0223] FIG. 5 shows the temperatures at the interior surface of a representative reaction zone and within several particles in this example.

[0224] FIG. 6 shows the temperatures at the interior surfaces of a representative reaction zone and within several particles during one cycle of silicon deposition in this example.

[0225] Compared to the deposition conditions shown in Figures 1-4, when the temperature of the inner surface of the reaction zone exceeded the temperature within the particles in Figures 5 and 6, the difference between the temperature of the inner surface of the reaction zone and the temperature within the particles at any time was smaller. Under these conditions, fouling of the reaction zone occurred, but the silicon-rich composite flakes were smaller and within acceptable limits compared to Examples 1 and 2. It is expected that the process will be operable, but that shutdowns and cleaning of the reaction zone will be required.

[0226] Example 4 Silicon-carbon composite particles were prepared by placing porous carbon particles inside a stainless steel autoclave equipped with an agitator and gas inlet and outlet lines. The autoclave was purged with nitrogen gas and then the furnace temperature was set to 350°C. Once the particle bed temperature reached 350°C, monosilane was added to the autoclave. After 1 hour, the autoclave was slowly depressurized. The autoclave was then refilled with monosilane and held for another hour. Depressurization and refilling were each repeated as many times as necessary for the target silicon content. After dosing was completed, the autoclave was purged using nitrogen and exposed to increasing concentrations of oxygen to passivate the composite particles, followed by cooling to room temperature.

[0227] FIG. 7 shows the temperatures at the interior surface of a representative reaction zone and within several particles in this example.

[0228] FIG. 8 shows the temperatures at the interior surface of a representative reaction zone and within several particles during one cycle of silicon deposition in this example.

[0229] It is observed that the temperature within the particles exceeds the temperature of the interior surface of the reaction zone at the majority of times during contact of the gas containing silicon-containing precursor with the porous particles. In comparison to the deposition conditions shown in Figures 1-6, when the temperature of the interior surface of the reaction zone exceeded the temperature within the particles in Figures 7 and 8, the difference between the temperature of the interior surface of the reaction zone and the temperature within the particles at any time was much smaller. Under these conditions, the reaction zone did not foul. It is likely that the method can be operated without the need for shutdowns and cleaning of the reaction zone for extended periods of time.

[0230] Example 5 Silicon-carbon composite particles were prepared by placing porous carbon particles inside a stainless steel autoclave equipped with an agitator and gas inlet and outlet lines. The autoclave was purged with nitrogen gas and then the furnace temperature was set to 350°C. When the temperature of the particle bed reached 350°C, monosilane was added to the autoclave. After 1 hour, the autoclave was slowly depressurized. The autoclave was then refilled with monosilane and held for another hour. Each depressurization and refill was repeated. After 25 hours, the furnace was switched off and left under an inert nitrogen atmosphere. After approximately 8 hours, the furnace temperature was set to 350°C. When the temperature of the particle bed reached 350°C, monosilane was added to the autoclave and each depressurization and refill step was repeated as many times as necessary for the target silicon content. After dosing was completed, the autoclave was purged using nitrogen and exposed to increasing concentrations of oxygen to passivate the composite particles, followed by cooling to room temperature.

[0231] FIG. 9 shows the temperatures at the interior surface of a representative reaction zone and within several particles in this example.

[0232] FIG. 10 shows the temperatures of the heat sources in a representative reaction zone and the temperatures within several particles during one cycle of silicon deposition in this example.

[0233] It is observed that the temperature within the particles exceeds the temperature of the interior surface of the reaction zone at the majority of times during contact of the gas containing silicon-containing precursor with the porous particles. In comparison to the deposition conditions shown in Figures 1-6, when the temperature of the interior surface of the reaction zone exceeded the temperature within the particles in Figures 9 and 10, the difference between the temperature of the interior surface of the reaction zone and the temperature within the particles at any time was much smaller. Under these conditions, the reaction zone did not foul. It is likely that the method can be operated without the need for shutdowns and cleaning of the reaction zone for extended periods of time.

[0234] Example 6 Silicon-carbon composite particles were prepared by placing the porous carbon particles inside a stainless steel autoclave equipped with an agitator and gas inlet and outlet lines. The autoclave was purged with nitrogen gas and then the furnace temperature was set to 395°C. Once the particle bed temperature reached 395°C, monosilane was added continuously to the autoclave. After dosing was completed, the autoclave was purged using nitrogen and exposed to increasing concentrations of oxygen to passivate the composite particles, and then cooled to room temperature.

[0235] FIG. 11 shows the temperatures at the interior surface of a representative reaction zone and within several particles in this example during the continuous addition of monosilane to the autoclave.

[0236] During contact of the gas containing the silicon-containing precursor with the porous particles, the temperature within the particles is observed to exceed the temperature of the interior surface of the reaction zone. Under these conditions, the reaction zone does not foul. It is likely that the method can be operated for extended periods of time without the need for shutdowns and cleaning of the reaction zone.

[0237] The table below summarizes the maximum temperature (maximum temperature on the internal surface of the reaction zone at a given time minus the minimum temperature within multiple particles at that same time) throughout the entire reaction for each of the above examples, and also includes the degree of reactor fouling.

[0238] [Table 1]

Claims

1. A method for preparing composite particles, (a) A step of providing a plurality of porous particles in a reaction zone, wherein the reaction zone has an internal surface, (b) A step of bringing the plurality of particles in the reaction zone into contact with a gas containing at least 25 volume% of a silicon-containing precursor at a temperature effective in causing silicon to deposit into the pores of the porous particles, Includes, A method wherein, during step (b), ΔT ≤ +90°C is maintained, where ΔT represents the temperature difference between the highest temperature on the inner surface of the reaction zone and the lowest temperature within the plurality of porous particles at the same time, and a positive ΔT value indicates that the highest temperature on the inner surface of the reaction zone is higher than the lowest temperature within the plurality of particles.

2. The method according to claim 1, wherein during step (b), ΔT ≤ +85°C, or ΔT ≤ +80°C, or ΔT ≤ +75°C, or ΔT ≤ +70°C, or ΔT ≤ +65°C, or ΔT ≤ +60°C, or ΔT ≤ +55°C, or ΔT ≤ +50°C, or ΔT ≤ +45°C, or ΔT ≤ +40°C, or ΔT ≤ +35°C, or ΔT ≤ +30°C, or ΔT ≤ +25°C, or ΔT ≤ +20°C, or ΔT ≤ +15°C, or ΔT ≤ +10°C, or ΔT ≤ +5°C, or ΔT ≤ -5°C, or ΔT ≤ -10°C.

3. During step (b), ΔT is between +90°C and -110°C, or +85°C and -110°C, or +80°C and -110°C, or +75°C and -110°C, or +70°C and -110°C, or +65°C and -110°C, or +60°C and -110°C, or +55°C and -110°C, or +50°C and -110°C, or +45°C and -110°C, or +40°C and -110°C, or +35°C and -110°C, or +30°C and -110°C, or +25°C and -110°C, or +20°C and -110°C, or +15°C and -110°C, or +10°C and -110°C, or +5°C and -110°C, or 0°C and -110°C. The method according to claim 1 or 2, wherein the temperature is maintained in the range of -5°C to -110°C, or -5°C to -105°C, or -5°C to -100°C, or -5°C to -95°C, or -5°C to -90°C, or -5°C to -85°C, or -5°C to -80°C, or -5°C to -75°C, or -5°C to -70°C, or -5°C to -65°C, or -5°C to -60°C, or -5°C to -55°C, or -5°C to -50°C, or -5°C to -45°C, or -5°C to -40°C, or -5°C to -35°C, or -5°C to -30°C, or -5°C to -25°C, or -5°C to -20°C, or -5°C to -15°C, or -5°C to -10°C.

4. The lowest temperature within the plurality of porous particles during contact is 340°C to 400°C, or 340°C to 395°C, or 340°C to 390°C, or 345°C to 400°C, or 345°C to 395°C, or 345°C to 390°C, or 350°C to 400°C, or 350°C to 395°C, or 350°C to 390°C, or 350°C to 385°C, or 355°C to 380°C, or 355°C to 400°C, or 355°C to 395°C, or 355°C to 390°C, or 355°C to 385°C, or 3 The method according to claim 1, wherein the temperature range is 55°C to 380°C, or 360°C to 400°C, or 360°C to 395°C, or 360°C to 390°C, or 360°C to 385°C, or 360°C to 380°C, or 365°C to 400°C, or 365°C to 395°C, or 365°C to 390°C, or 365°C to 385°C, or 365°C to 380°C, or 370°C to 400°C, or 370°C to 395°C, or 370°C to 390°C, or 370°C to 385°C, or 370°C to 380°C.

5. The method according to claim 1, wherein step (a) includes preheating the plurality of porous particles before providing the plurality of porous particles to the reaction zone.

6. The method according to claim 5, wherein the plurality of porous particles are preheated to a temperature of 300°C to 480°C, or 320°C to 450°C, or 330°C to 400°C, or 340°C to 390°C, or 345°C to 390°C, or 350°C to 400°C, or 350°C to 390°C, or 350°C to 385°C, or 350°C to 380°C, or 355°C to 390°C, or 355°C to 385°C, or 355°C to 380°C, or 360°C to 390°C, or 360°C to 385°C, or 360°C to 380°C.

7. The reaction zone includes a heat source, and step (a) operates the heat source to heat the plurality of porous particles to 340°C to 400°C, or 340°C to 395°C, or 340°C to 390°C, or 345°C to 400°C, or 345°C to 395°C, or 345°C to 390°C, or 350°C to 400°C, or 350°C to 395°C, or 350°C to 390°C, or 350°C to 385°C, or 355°C to 380°C, or 355°C to 400°C, or 355°C to 395°C, or 355°C to 390°C, or 355°C to 385°C The method according to claim 1, comprising heating to a temperature of ℃, or 355℃ to 380℃, or 360℃ to 400℃, or 360℃ to 395℃, or 360℃ to 390℃, or 360℃ to 385℃, or 360℃ to 380℃, or 365℃ to 400℃, or 365℃ to 395℃, or 365℃ to 390℃, or 365℃ to 385℃, or 365℃ to 380℃, or 370℃ to 400℃, or 370℃ to 395℃, or 370℃ to 390℃, or 370℃ to 385℃, or 370℃ to 380℃.

8. The method according to claim 7, wherein the heat source is a convective heat source or a conductive heat source.

9. The method according to claim 1, wherein step (b) includes preheating the gas to a temperature of 100°C to 350°C, or 110°C to 340°C, or 120°C to 330°C, or 130°C to 320°C, or 140°C to 310°C, or 150°C to 300°C before contact.

10. The method according to claim 1, wherein the maximum temperature of the inner surface of the reaction zone during contact is 150°C to 480°C, or 150°C to 460°C, or 150°C to 440°C, or 150°C to 420°C, or 150°C to 400°C, or 150°C to 390°C, or 200°C to 390°C, or 250°C to 390°C, or 300°C to 390°C, or 340°C to 375°C, or 345°C to 370°C, or 345°C to 365°C, or 350°C to 400°C, or 350°C to 390°C, or 350°C to 380°C, or 350°C to 370°C, or 350°C to 365°C.

11. The method according to claim 1, wherein step (a) includes providing a batch of the plurality of porous particles into the reaction zone.

12. (c) A step of interrupting the deposition of silicon to form intermediate particles, (d) A step of bringing the intermediate particles derived from step (c) and a gas containing a silicon-containing precursor into contact in a reaction zone at a temperature effective to cause further deposition of the silicon into the pores of the intermediate particles, It further includes, During step (d), ΔT ≤ +90°C, or ΔT ≤ +85°C, or ΔT ≤ +80°C, or ΔT ≤ +75°C, or ΔT ≤ +70°C, or ΔT ≤ +65°C, or ΔT ≤ +60°C, or ΔT ≤ +55°C, or ΔT ≤ +50°C, or ΔT ≤ +45°C, or ΔT ≤ +40°C, or ΔT ≤ +35°C, or ΔT ≤ +30°C, or ΔT ≤ +25°C, or ΔT ≤ +20°C, or ΔT ≤ +15 The method according to claim 1, wherein a temperature of °C, or ΔT ≤ +10°C, or ΔT ≤ +5°C, or ΔT ≤ 0°C, or ΔT ≤ -5°C, or ΔT ≤ -10°C is maintained, and ΔT represents the temperature difference between the highest temperature on the inner surface of the reaction zone and the lowest temperature within the plurality of porous particles, and a positive ΔT value indicates that the highest temperature on the inner surface of the reaction zone is higher than the lowest temperature within the plurality of particles.

13. The method according to claim 12, wherein step (c) further comprises a step of separating by-products from the intermediate particles.

14. The method according to claim 12, wherein the maximum temperature of the internal surface of the reaction zone during contact in step (b) and / or step (d) is 150°C to 480°C, or 150°C to 460°C, or 150°C to 440°C, or 150°C to 420°C, or 150°C to 400°C, or 150°C to 390°C, or 200°C to 390°C, or 250°C to 390°C, or 300°C to 390°C, or 340°C to 375°C, or 345°C to 370°C, or 345°C to 365°C, or 350°C to 400°C, or 350°C to 390°C, or 350°C to 380°C, or 350°C to 370°C, or 350°C to 365°C.

15. During steps (b), (c), and (d), the lowest temperature within the plurality of porous particles is 340°C to 400°C, or 340°C to 395°C, or 340°C to 390°C, or 345°C to 400°C, or 345°C to 395°C, or 345°C to 390°C, or 350°C to 400°C, or 350°C to 395°C, or 350°C to 390°C, or 350°C to 385°C, or 355°C to 380°C, or 355°C to 400°C, or 355°C to 395°C, or 355°C to 390°C, or 355°C to 385°C, The method according to claim 12 or 14, wherein the temperature is maintained within the range of 355°C to 380°C, or 360°C to 400°C, or 360°C to 395°C, or 360°C to 390°C, or 360°C to 385°C, or 365°C to 380°C, or 365°C to 400°C, or 365°C to 395°C, or 365°C to 390°C, or 365°C to 385°C, or 370°C to 400°C, or 370°C to 395°C, or 370°C to 390°C, or 370°C to 385°C, or 370°C to 380°C.

16. The method according to claim 12, wherein step (d) includes preheating the gas to a temperature of 100°C to 350°C, or 110°C to 340°C, or 120°C to 330°C, or 130°C to 320°C, or 140°C to 310°C, or 150°C to 300°C before contact.

17. The method according to claim 12, wherein steps (b) and (d) are carried out in the same reaction zone, or steps (b) and (d) are carried out in different reaction zones.

18. The method according to claim 12, wherein the gas containing the silicon-containing precursor used in step (d) contains the silicon-containing precursor that is not consumed in step (b).

19. The method according to claim 1, wherein step (b) includes continuously introducing the gas containing the silicon precursor into the reaction zone.

20. The method according to claim 1 or 12, wherein step (b) or step (d) includes interrupting the deposition of the silicon to form the composite particles and recovering the composite particles from the reaction zone.

21. Step (a) is, To provide a chemical vapor phase immersion unit including the aforementioned reaction zone, To provide a supply material containing the aforementioned porous particles, The porous particles are continuously introduced into the reaction zone, Includes, Step (b) is, The gas containing the silicon precursor is continuously introduced into the reaction zone, To provide conditions within the reaction zone that are effective in causing silicon to deposit within the pores of the porous particles, Continuously recovering the porous particle skeleton and composite particles containing elemental silicon within the pores of the porous particle skeleton from the reaction zone, The exhaust gas is continuously recovered from the reaction zone, The method according to claim 1, including the method described in claim 1.

22. The method according to claim 1 or 12, wherein the maximum temperature of the internal surface of the reaction zone during contact in step (b) and / or step (d) is 480°C or less, or 460°C or less, or 440°C or less, or 420°C or less, or 400°C or less, or 395°C or less, or 390°C or less, or 385°C or less, or 380°C or less.

23. The method according to claim 1 or 12, wherein step (b) and / or step (d) comprises continuously stirring the porous particles during the contact.

24. The method according to claim 23, wherein step (b) and / or step (d) comprises mechanically and continuously stirring the porous particles during the contact.

25. The method according to claim 24, wherein the reaction zone includes a stirrer for continuously stirring the porous particles during contact.

26. The method according to claim 25, wherein the stirring is performed by a high-shear mixer.

27. The method according to claim 23, wherein stirring is performed by a stirrer selected from the group consisting of a turbine stirrer, a paddle stirrer, an anchor stirrer, a propeller stirrer, and a helical stirrer.

28. The plurality of porous particles in the reaction zone in step (a) have at least 100 cm ＲＶ , ＲＶ , ＲＶ , ＲＶ , ＲＶ , ＲＶ , ＲＶ , ＲＶ , ＲＶ , ＲＶ , ＲＶ of volume per liter of the reaction zone (cm ３ / L ＲＶ ), or at least 150 cm ３ / L ＲＶ ), or at least 200 cm ３ / L ＲＶ ), or at least 250 cm ３ / L ＲＶ ), or at least 300 cm ３ / L ＲＶ ), or at least 400 cm ３ / L ＲＶ ), or at least 500 cm ３ / L ＲＶ ), or at least 600 cm ３ / L ＲＶ ), or at least 700 cm ３ / L ＲＶ ), or at least 800 cm ３ / L ＲＶ ), or at least 900 cm ３ / L ＲＶ The method according to claim 1, having.

29. In step (a), the ratio of the internal surface area of ​​the reaction zone to the mass of porous particles in the reaction zone is 1 m ２ / kg or less, or 0.9m ２ / kg or less, or 0.8m ２ / kg or less, or 0.7m ２ / kg or less, or 0.6m ２ / kg or less, or 0.5m ２ / kg or less, or 0.4m ２ / kg or less, or 0.3m ２ / kg or less, or 0.2m ２ / kg or less, or 0.1m ２ The method according to claim 1, wherein the amount is less than or equal to / kg.

30. The ratio of the internal surface area of ​​the reaction zone to the mass of porous particles within the reaction zone is at least 0.001 m². ２ / kg, or at least 0.002m ２ / kg, or at least 0.003m ２ / kg, or at least 0.004m ２ / kg, or at least 0.006m ２ / kg, or at least 0.008m ２ / kg, or at least 0.01m ２ The method according to claim 1, wherein the amount is / kg.

31. The method according to claim 1, wherein the bed depth of the porous particles in the reaction zone is at least 11 cm, or at least 15 cm, or at least 20 cm, or at least 25 cm, or at least 30 cm.

32. The silicon-containing precursor is silane (SiH ４ ), disilane (Si ２ H ６ ), trisilane (Si ３ H ８ ), tetrasilane (Si ４ H １０ The method according to claim 1, wherein the method is selected from the group consisting of methylsilane, dimethylsilane, and chlorosilane, and mixtures thereof.

33. The method according to claim 1 or 12, wherein the pressure in step (b) and / or step (d) is 10 kPa to 10,000 kPa, or 100 kPa to 5,000 kPa, or 100 kPa to 4,000 kPa, or 100 kPa to 3,000 kPa, or 100 kPa to 2,000 kPa, or 100 kPa to 1,000 kPa, or 100 kPa to 500 kPa.

34. The method according to claim 1 or 12, wherein the pressure in step (b) and / or step (d) is 10 kPa to 15,000 kPa, or 50 kPa to 10,000 kPa, or 120 kPa to 5,000 kPa, or 150 kPa to 2,000 kPa, or 200 kPa to 1,800 kPa, or 200 kPa to 1,600 kPa, or 250 kPa to 1,500 kPa, or 300 kPa to 1,200 kPa, or 400 kPa to 1,000 kPa, or 500 kPa to 900 kPa, or 600 kPa to 800 kPa.

35. The method according to claim 1, wherein the gas containing the silicon-containing precursor contains at least 30 volume% of the silicon-containing precursor relative to the total volume of the gas, 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 the silicon-containing precursor relative to the total volume of the gas.

36. The porous particles are 100 m ２ / g to 4000m ２ / g, or 500m ２ / g to 4000m ２ / g, or 750m ２ / g to 3500m ２ / g, or 1000m ２ / g ~ 3250m ２ / g, or 1000m ２ / g to 3000m ２ / g, or 1000m ２ / g to 2500m ２ / g, or 1000m ２ / g to 2000m ２ The method according to claim 1, having a BET surface area in the range of / g.

37. The method according to claim 1, wherein the porous particles include micropores and / or mesopores.

38. The porous particles include micropores and / or mesopores, and the total pore volume of the micropores and mesopores, as measured by nitrogen gas adsorption, is 0.4 cm³. ３ / g ~ 2.2cm ３ / g, or 0.45cm ３ / g ~ 2.2cm ３ / g, or 0.5cm ３ / g to 2cm ３ / g, or 0.55cm ３ / g to 2cm ３ / g, or 0.6cm ３ / g to 1.8cm ３ / g, or 0.65cm ３ / g to 1.8cm ３ / g, or 0.7cm ３ / g ~ 1.6cm ３ / g, or 0.7cm ３ / g to 1.5cm ３ / g, or 0.7cm ３ / g to 1.4cm ３ The method according to claim 1, wherein the range is / g.

39. The PD of the porous particles ５０ The method according to claim 1, wherein the pore diameter is 30 nm or less, or 25 nm or less, or 20 nm or less, or 15 nm or less, or 12 nm or less, or 10 nm or less, or 8 nm or less, or 6 nm or less, or 5 nm or less, or 4 nm or less, or 3 nm or less, or 2.5 nm or less, or 2 nm or less, or 1.5 nm or less.

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

41. The porous particles are in the range of 0.5 μm to 200 μm, or 0.5 μm to 150 μm, or 0.5 μm to 100 μm, or 0.5 μm to 50 μm, or 0.5 μm to 30 μm, or 1 μm to 25 μm, or 1 μm to 20 μm, or 2 μm to 25 μm, or 2 μm to 20 μm, or 2 μm to 18 μm, or 2 μm to 15 μm, or 2 μm to 12 μm, or 2.5 μm to 15 μm, or 2.5 μm to 12 μm, or 2 μm to 10 μm. ５０ The method according to claim 1, having a particle size.

42. The method according to claim 1, wherein at least 20% by weight of the silicon in the composite particles is surface silicon (Y), and 10% by weight or less of the silicon is crude bulk silicon (Z), and the content of surface silicon and crude bulk silicon is determined by TGA according to the method described in the specification.

43. The method according to claim 1, wherein ΔT ≤ +40°C is maintained during step (b), and the lowest temperature in the plurality of porous particles during contact in step (b) is in the range of 360°C to 395°C.

44. (i) The plurality of porous particles are 1000 m ２ / g ~ 3250m ２ Having a BET surface area in the range of / g, (ii) The ΔT in step (b) is +40°C or lower, (iii) The plurality of porous particles are maintained within a temperature range of 360°C to 395°C during step (b), (iv) The ratio of the internal surface area of ​​the reaction zone in step (a) to the mass of porous particles in the reaction zone is 0.6 m ２ It is less than or equal to / kg, and (v) Step (b) includes continuously stirring the porous particles, The method according to claim 1.

45. (i) The plurality of porous particles are 1000 m ２ / g to 3000m ２ Having a BET surface area in the range of / g, (ii) The ΔT in step (b) is +20°C or less, (iii) The plurality of porous particles are maintained within a temperature range of 370°C to 395°C during step (b), (iv) The ratio of the internal surface area of ​​the reaction zone in step (a) to the mass of porous particles in the reaction zone is 0.4 m ２ It is less than or equal to / kg, and (v) Step (b) includes continuously stirring the porous particles, The method according to claim 1.

46. A step of forming a passivation layer on the surface of silicon deposited in step (b) and / or step (d) by contacting particles derived from step (b) or step (d) with a passivation agent. The method according to claim 1 or 12, further comprising:

47. The method according to claim 46, wherein the contact between the particles and the passivating agent is carried out at a temperature in the range of 50°C to 500°C.

48. The method according to claim 46, wherein the passivation layer is selected from the group consisting of a natural oxide layer, a nitride layer, an oxynitride layer, and a carbide layer.

49. The method according to claim 46, wherein the passivating agent is a compound containing an active hydrogen atom bonded to oxygen, nitrogen, sulfur, or phosphorus.

50. The passivating agent is (i)R １ -CH=CH-R １ 、 ())) １ .≡.!R １ 、 (iii)O=CR １ R １ (iv) HX-R ２ , and, (v)HX-C(O)-R １ (wherein, X represents O, S, NR １ or PR １ and) 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 in the ring, R ２ R represents an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 carbon atoms, or R １ and R ２ The method according to claim 46, wherein the elements are selected from the group consisting of (which together form an unsubstituted or substituted ring structure containing 3 to 8 carbon atoms in the ring).

51. A step of bringing particles derived from step (b) or step (d) into contact with a carbon-containing precursor at a temperature effective in causing the deposition of a pyrolytic carbon material in the pores of the particles, The method according to claim 1 or 12, further comprising:

52. The method according to claim 51, wherein the temperature effective for causing the deposition of a pyrolytic carbon material in the pores of the particles is in the range of 300°C to 800°C or 400°C to 700°C.

53. The method according to claim 51, wherein the carbon-containing precursor is a hydrocarbon.

54. The method according to claim 51, wherein the carbon-containing precursor is used in a mixture diluted with an inert carrier gas, and the carbon-containing precursor is 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, relative to the total volume of the carbon-containing precursor and the inert carrier gas.

55. A step of forming a passivation layer on the surface of silicon deposited in step (b) and / or step (d) by contacting particles derived from step (b) or step (d) with a passivation agent, and A step of bringing the passivated particles and the carbon-containing precursor into contact at a temperature effective in causing the deposition of a pyrolytic carbon material in the pores of the particles, The method according to claim 1 or 12, further comprising:

56. The method according to claim 55, wherein the passivating agent and the carbon-containing precursor are compounds that are both a passivating agent and a carbon-containing precursor, and the deposition of the pyrolytic carbon material is carried out at a temperature higher than that of passivation.

57. A step of depositing a lithium-ion permeable material into the pores and / or on the outer surface of composite particles derived from step (b) or step (d), The method according to claim 1 or 12, further comprising:

58. The method according to claim 57, wherein the ion-permeable material is a thermally decomposable carbon material.

59. The method according to claim 1, wherein the silicon-containing precursor contains less than 1% by weight, or less than 0.1% by weight, or less than 0.01% by weight of a chlorine-containing compound.

60. The method according to claim 1 or 12, wherein the oxygen content of the gas containing the silicon precursor used in step (b) and / or step (d) is less than 0.01% by volume or less than 0.001% by volume, relative to the total volume of the gas used in step (b) or step (d).

61. The method according to claim 1, wherein the ΔT maintained during step (b) is in the range of +40°C to -50°C or +20°C to -50°C.

62. A system for preparing composite particles, (a) A reaction zone configured such that a plurality of porous particles are held, (i) at least one heat source configured to heat the plurality of porous particles, (ii) at least one gas inlet that accepts a gas containing at least 25 volume percent of a silicon-containing precursor, (iii) At least one gas outlet for recovering the exhaust gas from the reaction zone, A reaction zone having, (b) at least one sensor configured to acquire temperature data within the plurality of porous particles, (c) At least one sensor configured to acquire temperature data of the internal surface of the reaction zone, (d) Processor and Includes, A system in which at least one sensor configured to acquire temperature data within the plurality of porous particles and at least one sensor configured to acquire temperature data on the inner surface of the reaction zone are configured to transmit their respective temperature data to the processor, the processor is configured to control the heat source so that ΔT ≤ +90°C is maintained, ΔT represents the temperature difference between the highest temperature on the inner surface of the reaction zone and the lowest temperature within the plurality of porous particles at the same time, and a positive ΔT value indicates that the highest temperature on the inner surface of the reaction zone is higher than the lowest temperature within the plurality of particles.

63. The system according to claim 62, wherein the reaction zone includes a stirrer for continuously stirring the plurality of porous particles.

64. The system according to claim 63, wherein the agitator is a turbine agitator, a paddle agitator, an anchor agitator, a propeller agitator, or a helical agitator.

65. The system according to claim 63, wherein the agitator is a high-shear mixer.

66. The system according to claim 62 or 63, wherein the reaction zone is a batch reactor or a continuous reactor.

67. The system according to claim 62 or 63, wherein the reaction zone is a tubular reactor, a fixed-bed reactor, a fluidized-bed reactor, or a continuous-stirred-tank reactor.

68. The system according to claim 62, wherein the processor is configured to control the heat source such that ΔT is maintained within the range of +90°C to -110°C.

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