Electroactive Materials for Metal-Ion Batteries

Abstract

The present invention relates generally to electroactive materials and methods for preparing the same. The electroactive particles have a porous particle skeleton with pores having pore diameters ranging from 3.5 to 100 nm and a total pore volume of 0.3 to 2.4 cm per gram of porous particle skeleton. 3 The pores of the porous particle are at least partially occupied by a multilayer coating disposed on the interior pore surfaces of the porous particle skeleton, the multilayer coating having at least a first electroactive material layer, a second electroactive material layer, and a first interlayer material disposed between the first and second electroactive material layers.

Description

Technical Field

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

Background Art

[0002] Rechargeable metal ion batteries are widely used in portable electronic devices such as mobile phones and laptop computers, and their application to electric vehicles and hybrid vehicles is increasing. A rechargeable metal ion battery generally has an anode in the form of a metal current collector provided with a layer of electroactive material, and the electroactive material is defined as a material capable of inserting and releasing metal ions during charge and discharge of the battery. The terms "cathode" and "anode" are used in the sense that the battery is arranged across a load and the anode becomes the negative electrode. When the metal ion battery is charged, metal ions are transported from the metal ion-containing cathode layer through the electrolyte to the anode and inserted into the anode material. The term "battery (or cell)" is used to represent both a device including a single anode and a single cathode, as well as a device including a plurality of anodes and / or a plurality of cathodes.

[0003] There is interest in improving the weight capacity and / or volume capacity of rechargeable metal ion batteries. To date, commercially available lithium ion batteries have mainly been limited to using graphite as the anode active material. When the graphite anode is charged, lithium is intercalated between the graphite layers, with the empirical formula Li x C 6Form a material having (where x is greater than 0 and less than or equal to 1). As a result, graphite exhibits a maximum theoretical capacity of 372 mAh / g in a lithium-ion battery, but the actual capacity is somewhat lower (about 340 - 360 mAh / g). Other materials such as silicon, tin, and germanium can intercalate significantly higher amounts of lithium compared to graphite, but are not widely used commercially because it is difficult to maintain sufficient capacity over charge / discharge cycles.

[0004] In particular, silicon has been identified as a promising alternative to graphite for the manufacture of rechargeable metal-ion batteries with high weight and volume capacities due to its extremely high capacity for lithium (see, for example, Winter, M. et al., "Insertion Electrode Materials for Rechargeable Lithium Batteries", Adv. Mater. 1998, 10, No. 10). At room temperature, silicon has a theoretical maximum specific capacity in a lithium-ion battery of about 3,600 mAh / g (based on Li 15 Si 4 ). However, the insertion of lithium into bulk silicon causes the volume of the silicon material to increase by 400% of its original volume when the silicon is lithiated to its maximum capacity. Repeated charge-discharge cycles cause significant mechanical stress in the silicon material, resulting in breakage and delamination of the silicon anode material. The volume shrinkage of silicon particles during delithiation leads to a loss of electrical contact between the anode material and the current collector. Another problem is that the solid electrolyte interphase (SEI) layer formed on the silicon surface does not have sufficient mechanical tolerance to accommodate the expansion and contraction of silicon. As a result, the newly exposed silicon surface causes further electrolyte decomposition and an increase in the thickness of the SEI layer, resulting in irreversible consumption of lithium. These failure mechanisms collectively lead to unacceptable loss of electrochemical capacity over continuous charge-discharge cycles.

[0005] To overcome the problems associated with the volume changes observed when charging a silicon-containing anode, many approaches have been proposed. Fine silicon structures with a cross-section of 150 nm or less, such as silicon films and silicon nanoparticles, have been reported to be more resistant to volume changes during charge and discharge compared to micron-sized silicon particles. However, none of these, in their unmodified form, are suitable for commercial-scale applications, the preparation and handling of nanoscale particles are difficult, and silicon thin films do not provide sufficient bulk capacity.

[0006] International Publication No. WO 2007 / 083155 discloses that improved capacity retention can be obtained in silicon particles with a high aspect ratio, i.e., a high ratio of the maximum dimension to the minimum dimension of the particles. The small cross-section of such particles reduces the structural stress on the material due to volume changes during charge and discharge. However, such particles are difficult to manufacture, costly, and brittle. Also, the large surface area can lead to excessive SEI formation and result in an excessive loss of capacity in the first charge-discharge cycle.

[0007] It is also generally known that an electroactive material such as silicon can be deposited within the pores of a porous carrier material such as an activated carbon material. These composite materials avoid the problems of handling nanoparticles and provide some of the beneficial charge-discharge characteristics of nanoscale silicon particles. Guo et al. (Journal of Materials Chemistry A, 2013, pp. 14075 - 14079) disclose a silicon-carbon composite material in which a porous carbon substrate provides a conductive skeleton with silicon nanoparticles deposited within the pore structure of the substrate having a uniform distribution. The composite material shows improved capacity retention over a plurality of charge-discharge cycles, but it has been shown that the initial capacity of the composite material in mAh / g is significantly lower than that of silicon nanoparticles. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] The inventors of the present application have previously reported the development of a class of electroactive materials having a composite structure in which a nanoscale electroactive material such as silicon is formed in a pore network of a highly porous, porous conductive particulate material such as a porous carbon material.

[0009] For example, International Publications Nos. 2020 / 095067 and 2020 / 128495 report that the improved electrochemical properties of these materials are due to the way in which the electroactive material is disposed within the porous material in the form of small domains having dimensions of a few nanometers or less. These fine electroactive structures are considered to have lower resistance to elastic deformation and higher fracture resistance compared to larger electroactive structures, and thus, in the absence of excessive structural low stress, lithiation and delithiation are possible. As a result, the electroactive material exhibits good reversible capacity retention over multiple charge-discharge cycles. Second, by controlling the filling of silicon within the porous carbon skeleton, only a portion of the pore volume is occupied by silicon in the uncharged state, and the unoccupied pore volume of the porous particle skeleton can accommodate a significant expansion of the silicon internally. Further, as described above, by disposing nanoscale silicon domains within small mesopores and / or micropores, only a small region of the silicon surface is accessible to the electrolyte, and the formation of the SEI is limited. Subsequent exposure of the silicon during charge-discharge cycles is substantially prevented, and SEI formation ceases to be a major failure mechanism leading to capacity loss. This is clearly in contrast to the excessive SEI formation characterizing the materials disclosed, for example, by Guo (see above).

[0010] The materials described in International Publication Nos. 2020 / 095067 and 2020 / 128495 are synthesized by chemical vapor infiltration (CVI) in different reactor systems (stationary, rotating, and FBR). The porous particles are contacted with a flow of a silicon-containing precursor (CVI), usually a silane gas, at atmospheric pressure and a temperature of 400 to 700 °C until the required amount of silicon is deposited on the micropores and small mesopores. In the materials described in International Publication Nos. 2020 / 095067 and 2020 / 128495, in order to obtain a fine electroactive structure capable of lithiation and delithiation with good reversible capacity retention over a plurality of charge-discharge cycles, it is necessary to carefully control the pore distribution of the porous particles and the amount of deposited silicon. In particular, the materials described in International Publication Nos. 2020 / 095067 and 2020 / 128495 include a porous particle skeleton in which a relatively high proportion of the pore volume is in the form of micropores (pore diameter < 2 nm) or fine mesopores (e.g., pore diameter < 20 nm or < 10 nm). In particular, International Publication Nos. 2020 / 095067 and 2020 / 128495 disclose that optimal results are obtained when the volume ratio of micropores is at least 50 vol% of the total pore volume of micropores and mesopores.

[0011] When preparing this type of composite particle, it has been found that using porous particles with a more open pore structure (i.e., a volume pore size distribution towards larger mesopores and macropores) results in poor electrochemical properties. The larger the pores, the rougher the silicon domain deposition is obtained, and it is considered that the exposed surface area of the deposited silicon increases. This leads to a decrease in the initial capacity due to oxidation of the exposed silicon surface, a high initial cycle loss due to initial SEI formation, and a decrease in reversible capacity retention due to excessive structural stress and uncontrollable SEI formation in subsequent charge-discharge cycles.

[0012] Therefore, it is desirable to use the techniques described in International Publications Nos. 2020 / 095067 and 2020 / 128495 to eliminate the aforementioned drawbacks and extend to a wider range of the porous particle skeleton. It has been found that this problem can be addressed when an electroactive material is present within the pores of a porous particle morphology of a multilayer structure in which multiple layers of the electroactive material are alternately arranged with spacer layers of different chemical species. The intercalated multilayer structure is formed using a CVI process, and the different chemical species are deposited layer by layer until the required multilayer structure is formed. A series of options regarding the number of layers, the chemical composition of each layer, and the thickness of each layer are provided within this general structure.

Means for Solving the Problems

[0013] In a first aspect, the present invention provides a particulate material comprising a plurality of composite particles. Here, the composite particles are (a) a porous particle skeleton having a total pore volume of pores with a pore diameter in the range of 3.5 to 100 nm, as determined by nitrogen gas adsorption, of P 1 cm 3 per gram of the porous particle skeleton, where P 1 represents a number in the range of 0.3 to 2.4, the porous particle skeleton, and (b) a multilayer coating disposed on the internal pore surface of the porous particle skeleton, the multilayer coating comprising at least (i) a first electroactive material layer, (ii) a second electroactive material layer, and (iii) a first intermediate layer material disposed between the first and second electroactive material layers and having a multilayer coating. having.

Mode for Carrying Out the Invention

[0014] When compared to materials prepared using a similar porous particle skeleton, many different factors contribute to the improvement of the properties of these materials, but the electroactive materials are formed into a film as a single homogeneous mass. Also, the multilayer structure can function as a filler to reduce the residual surface area and thus minimize the formation of SEI and oxygenation on the electroactive material surface. Further, the layered structure of the electroactive material suppresses the volume expansion in the thickness direction of the layer via mechanical buffering by the interlayer material, and the stress is released in the longitudinal direction. Also, the multilayer structure suppresses the formation of SEI. This is because the innermost layer of the electroactive material is not exposed to the electrolyte, and thus the formation of SEI on these layers is effectively prevented. Also, the intermediate layer material of the multilayer structure may act as a conductive component. For example, a conductive carbon layer may be used as the intermediate layer material. This is considered to improve the rate characteristics of the composite particles.

[0015] The terms "multilayer coating", "first electroactive material layer", "second electroactive material layer", and "first intermediate layer material" define a particle structure that is consistent with the continuous film formation of the first electroactive material, the first intermediate layer material, and the second electroactive material into the pore structure of the porous particle skeleton. Thus, the electroactive material does not form a network extending throughout the pore space but is blocked by the intermediate layer material. Thus, within at least a portion of the pore volume, there is an assembly of materials following the sequence: [First electroactive material domain] ↓ [Interlayer material region] ↓ [Second electroactive material domain] This sequence may be preferably extended both before and after by additional electroactive material domains and / or additional intermediate layer material domains as required. The intermediate layer material domain disposed between adjacent electroactive material domains may function as a barrier separating the electroactive material domains and limit the length scale of the continuous electroactive material domains within the composite particles.

[0016] The electroactive material layer and the intermediate layer material may form distinct domains having a sharp boundary between the two, or there may be a compositional gradient between the electroactive material layer and the intermediate layer material. The intermediate layer material may be chemically bonded (e.g., covalently, ionically, or metallically) to the first and / or second electroactive material layers. For example, the intermediate layer material may have a passivation layer on the surface of the first electroactive material layer, or may have an alloy of the electroactive material on the surface of the electroactive material, or may have a doped electroactive material on the surface of the electroactive material. Alternatively, the intermediate layer material may not be chemically bonded to the electroactive material layer.

[0017] As a result of the manufacturing method, the layered structure may not be uniform throughout the particles, for example, the thicknesses of the various layers may vary, and the layers need not be of the same phase. However, the composite particles exhibit the arrangement of layers / domains of the electroactive material and the intermediate layer material as described above, resulting from the process of the present invention.

[0018] The porous particle skeleton is preferably a conductive porous particle skeleton. The conductive porous particle skeleton improves the rate characteristics of the composite material particles by facilitating charge transfer during lithiation and delithiation of the electroactive material.

[0019] A preferred conductive porous particle skeleton is a conductive porous carbon particle skeleton. The conductive porous carbon particle skeleton preferably contains at least 80% by mass of carbon, more preferably at least 85% by mass of carbon, more preferably at least 90% by mass of carbon, more preferably at least 95% by mass of carbon, and, if necessary, at least 98% by mass or at least 99% by mass of carbon. The carbon may be crystalline carbon, amorphous carbon, or a mixture of amorphous and crystalline carbon. The conductive porous carbon particle skeleton may be either a hard carbon particle skeleton or a soft carbon particle skeleton.

[0020] The term "hard carbon" refers to a disordered carbon matrix in which carbon atoms are mainly found in the sp2 hybridized state (trigonal bonding) in nanoscale polyaromatic domains. The polyaromatic domains are cross-linked by chemical bonds, such as C-O-C bonds. Due to the chemical cross-linking between the polyaromatic domains, hard carbon cannot be converted into graphite at high temperatures. Hard carbon has graphite-like properties, as is evident from the large G band (~1600 cm -1 ) in the Raman spectrum. However, as is evident from the prominence of the D band (~1350 cm -1 ) in the Raman spectrum, the carbon is not fully graphitized.

[0021] The term "soft carbon" also refers to a disordered carbon matrix in which carbon atoms are mainly found in the sp2 hybridized state (trigonal bonding) in polyaromatic domains having dimensions in the range of 5 to 200 nm. In contrast to hard carbon, the polyaromatic domains of soft carbon are bonded by intermolecular forces but are not cross-linked by chemical bonds. This means that it graphitizes at high temperatures. The conductive porous carbon particle skeleton preferably contains at least 50% sp2 hybridized carbon when measured by XPS. For example, the conductive porous carbon particle skeleton may suitably contain 50% to 98% sp2 hybridized carbon, 55% to 95% sp2 hybridized carbon, 60% to 90% sp2 hybridized carbon, or 70% to 85% sp2 hybridized carbon.

[0022] Suitable conductive porous carbon particle skeletons may be prepared using a variety of different materials. Examples of organic materials that can be used include plant biomass and fossil carbon sources such as coal. Examples of resins and polymer materials that produce porous carbon particles upon pyrolysis include phenolic resins, novolac resins, pitch, melamine, polyacrylates, polystyrene, polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), and various copolymers containing monomer units of acrylates, styrenes, α-olefins, vinyl pyrrolidone, and other ethylenically unsaturated monomers. Depending on the starting materials and the conditions of the pyrolysis process, a variety of different carbon materials are available in the art. Porous carbon particles of various different specifications are available from commercial suppliers.

[0023] Mesopores and macropores can be obtained by known templating processes, which use extractable pore formers such as MgO, and other colloidal or polymeric templates that can be removed by thermal or chemical means after pyrolysis or activation.

[0024] Alternatives to carbon-based particle skeletons include porous particle skeletons containing titanium nitride (TiN), titanium carbide (TiC), and boron nitride (BN). Preferably, titanium nitride (TiN) and boron nitride (BN). Alternatively, the conductive porous particle skeleton may have a non-conductive porous particle skeleton, where a conductive coating such as a conductive pyrolytic carbon coating is provided on the internal pore surface of the porous particle skeleton.

[0025] The porous particle skeleton has a three-dimensionally interconnected open pore network containing macropores and / or mesopores, and optionally a small amount of micropores. According to the conventional IUPAC terminology, the term "micropore" is used to represent pores with a diameter of less than 2 nm, the term "mesopore" is used to represent pores with a diameter of 2 to 50 nm, and the term "macropore" is used to represent pores with a diameter of more than 50 nm.

[0026] In the present application, references to the volumes of micropores, mesopores, and macropores within the porous particle skeleton, as well as the pore volume distribution within the porous particle skeleton, are to be understood as relating to the internal pore volume of the isolated (i.e., before film formation of the multilayer coating) porous particle skeleton. References to the BET surface area of the porous particle skeleton are to be understood as relating to the isolated BET surface area porous particle skeleton.

[0027] The porous particle skeleton is characterized by the total volume of pores having a pore diameter in the range of 3.5 to 100 nm, as determined by the nitrogen gas adsorption method. The total volume of pores in this range is P 1 cm 3 per gram of the conductive porous particle skeleton, as determined by the nitrogen gas adsorption method, where P 1 represents a dimensionless number in the range of 0.3 to 2.4 (for example, when the total volume of pores in the range of 3.5 to 100 nm is 1.2 cm 3 / g, P 1 = 1.2). Preferably, P 1 is from 0.6 to 2.4.

[0028] Typically, the porous particle skeleton includes both macropores and mesopores. However, the use of a porous particle skeleton having a pore diameter distribution that includes macropores but not mesopores, or a pore diameter distribution that includes mesopores but not macropores, is not excluded. For the purposes of the present invention, any measured pore volume exceeding 100 nm is considered interparticle porosity and is ignored.

[0029] In the present application, references to the volume of pores in the range of 0 to 100 nm in diameter (including its sub-ranges) are determined by the Barrett-Joyner-Halenda (BJH) method in accordance with ISO 15901-2, the nitrogen gas adsorption method at 77 K, and a relative pressure range p / p -4 in the range of 1 to 10 0It should be understood to mean the pore volume measured using (referred to as the "BJH method" in the present application). The nitrogen gas adsorption method is a technique for characterizing the porosity and pore diameter distribution of a material by condensing a gas in the pores of a solid. As the pressure increases, the gas first condenses in the pores with the smallest diameter, and the pressure increases until a saturation point where all pores are filled with liquid is reached. Next, the nitrogen gas pressure is gradually decreased, and the liquid evaporates from the system. The pore volume and pore diameter distribution can be determined by analyzing the adsorption and desorption isotherms and the hysteresis between them. Apparatus suitable for measuring the pore volume and pore diameter distribution using the BJH method include the TriStar II and TriStar II Plus porosity analyzers available from Micromeritics, USA, and the Autosorb IQ porosity analyzer available from Quantachrome Instruments.

[0030] P 1 preferably has a value of at least 0.4, at least 0.5, at least 0.6, at least 0.7, at least 0.8, at least 0.85, at least 0.9, at least 0.95, at least 1, at least 1.05, at least 1.1, at least 1.15, or at least 1.2. Using a highly porous particulate backbone can be significant because a large amount of silicon can be accommodated within the pore structure.

[0031] The internal pore volume of the porous particulate backbone is preferably capped at a value where the increase in the fragility of the backbone outweighs the advantage of the increased pore volume for accommodating a large amount of silicon. Preferably, P 1 is 2.3 or less, 2.2 or less, 2.1 or less, 2 or less, 1.95 or less, 1.9 or less, 1.85 or less, or 1.8 or less.

[0032] P 1is preferably in the range of 0.6 to 2.4, or 0.7 to 2.4, or 0.8 to 2.3, or 0.9 to 2.2, or 0.95 to 2.1, or 1 to 2, or 1.05 to 1.95, or 1.1 to 1.9, or 1.15 to 1.85, or 1.2 to 1.8.

[0033] PD of the porous particle skeleton 50 The pore diameter is preferably at least 10 nm, at least 20 nm, at least 25 nm, at least 30 nm, at least 35 nm, at least 40 nm, at least 45 nm, or at least 50 nm. The term "PD" 50 The term "pore diameter" represents the volume-based median pore diameter based on the total volume of pores having a pore diameter in the range of 3.5 to 100 nm within the porous particle skeleton. Therefore, in the present invention, it is preferable that at least 50% of the total volume of pores having a pore diameter of 3.5 to 100 nm is in the form of pores having a diameter of at least 10 nm.

[0034] It is understood that gas adsorption is only effective when determining the pore volume of pores accessible to nitrogen from the outside of the porous material. It is understood that the value of porosity defined in the present application represents the volume of open pores, that is, the volume of pores accessible to fluid from the outside of the porous particles. Completely enclosed pores that cannot be identified by nitrogen adsorption are not considered when determining the porosity value.

[0035] The pore diameter distribution within the porous particle skeleton is preferably such that at least 50 vol% of the total volume of pores having a pore diameter in the range of 3.5 to 100 nm is within pores having a pore diameter in the range of 5 to 60 nm. Therefore, the volume ratio of pores having a pore diameter in the range of 5 to 60 nm is preferably at least 50 vol%, at least 55 vol%, at least 60 vol%, at least 65 vol%, at least 70 vol%, at least 75 vol%, at least 80 vol%, at least 85 vol%, or at least 90 vol% based on the total pore volume of pores having a pore diameter in the range of 3.5 to 100 nm in the porous particle skeleton.

[0036] More preferably, at least 50 vol% of the total volume of pores having a pore diameter in the range of 3.5 to 100 nm is in the form of pores having a pore diameter in the range of 10 to 50 nm. Accordingly, the volume ratio of pores having a pore diameter in the range of 10 to 50 nm is preferably at least 50 vol%, at least 55 vol%, at least 60 vol%, at least 65 vol%, at least 70 vol%, at least 75 vol%, at least 80 vol%, at least 85 vol%, or at least 90 vol% based on the total pore volume of pores having a pore diameter in the range of 3.5 to 100 nm in the porous particle skeleton.

[0037] The BJH method for analyzing pore volume and pore size distribution is effective for pores with a diameter of 3.5 nm or more, but is inappropriate for pore sizes less than 3.5 nm. The reference to the volume of pores with a diameter less than 3.5 nm (including its sub-range) is in accordance with the standard methods described in ISO15901-2 and ISO15901-3, using the quenched solid density functional theory (QSDFT) for the relative pressure p / p 0 =10 -6 It is understood to mean the pore volume measured by nitrogen gas adsorption at 77K hereinafter (referred to as the "QSDFT method" in this application). Apparatus suitable for QSDFT measurement includes the Autosorb IQ porosity analyzer available from Quantachrome Instruments.

[0038] The total volume of pores with a diameter less than 3.5 nm in the porous particle skeleton is defined as P per gram of the porous particle skeleton 2 cm 3 where P 2 preferably represents a dimensionless number having a value less than 0.5, less than 0.45, less than 0.4, less than 0.35, less than 0.3, less than 0.25, less than 0.2, less than 0.15, or less than 0.1 determined by the nitrogen gas adsorption method (for example, when the total volume of pores with a diameter less than 3.5 nm is 0.1 cm 3 / g, P 2 = 0.1).

[0039] If necessary, the value of P 2 may be determined with respect to the value of P 1 . Preferably, P 2 is [1 × P 1 or less, [0.8 × P 1 or less, [0.6 × P 1 or less, [0.5 × P 1 or less, [0.4 × P 1 or less, [0.3 × P 1 or less, [0.2 × P 1 or less, or [0.1 × P 1 or less.

[0040] The porous particle skeleton preferably has a BET surface area of at least 150 m 2 / g, more preferably at least 250 m 2 / g, optionally at least 500 m 2 / g, or at least 750 m 2 / g, or at least 1,000 m 2 / g, or at least 1,250 m 2 / g. The term "BET surface area" needs to be interpreted as representing the surface area per unit mass calculated from the measurement of the physical adsorption of gas molecules on the solid surface using the Brunauer-Emmett-Teller theory according to ISO 9277. Preferably, the BET surface area of the porous particle skeleton is 2,500 m 2 / g or less, preferably 2,000 m 2 / g or less, or 1,750 m 2 / g or less, or 1,500 m 2 / g or less. For example, the porous particle skeleton is from 250 m 2 / g to 2,500 m 2 / g, from 500 m 2 / g to 2,500 m 2 / g, from 750 m 2 / g to 2,000 m 2 / g, from 750 m 2 / g to 1,750 m 2 / g, from 750 m 2 / g to 1,500 m 2 / g, from 1,000 to 2,000 m 2 / g, 1,000 m 2 / g to 1,750 m 2 / g, 1,000 m 2 / g to 1,500 m 2 / g, 1,250 m 2 / g to 2,000 m 2 / g, 1,250 m 2 / g to 1,750 m 2 / g, 250 m 2 / g to 2,000 m 2 / g, 250 m 2 / g to 1,750 m 2 / g, 500 m 2 / g to 1,500 m 2 It may have a BET surface area in the range of / g.

[0041] The electroactive materials of the first and second electroactive material layers may be the same or different and, if necessary, may be independently selected from elemental silicon, elemental tin, elemental germanium, elemental aluminum, and mixtures and alloys thereof.

[0042] Preferably, the electroactive materials in the first and second electroactive material layers are elemental silicon, elemental tin, elemental germanium, and mixtures and alloys thereof, and, if necessary, the mixtures and alloys may contain aluminum.

[0043] A preferred electroactive material is silicon. Preferably, at least one of the first and second electroactive material layers contains elemental silicon or consists of elemental silicon. More preferably, both the first and second electroactive material layers contain elemental silicon or are composed of these.

[0044] The term "intermediate layer material" refers to a layer of material that is disposed between two adjacent electroactive material layers and has a distinct chemical composition different from that of the electroactive material layers. Thus, the multilayer coating has a periodic structure having alternating layers of electroactive material and intermediate layer material. The electroactive material layer and the intermediate layer material may be distinct layers having a sharp boundary therebetween, or there may be a composition gradient between the electroactive material layer and the intermediate layer material.

[0045] The first intermediate layer material preferably contains one or more of carbon, nitrogen, and / or oxygen.

[0046] The first intermediate layer material may include, or may be composed of, a passivation layer formed on the surface of the first electroactive material layer.

[0047] One type of passivation layer is a native oxide layer, which is formed, for example, by exposing the surface of the first electroactive material layer to air or another oxygen-containing gas prior to the deposition of the second electroactive material layer. When the first electroactive material layer is silicon, the first intermediate layer material may include silicon oxide of the general formula SiO x where 0 < x ≦ 2. The silicon oxide is preferably amorphous silicon oxide.

[0048] Another type of passivation layer is, for example, a nitride layer formed by exposing the surface of the first electroactive material layer to ammonia or another nitrogen-containing molecule prior to the deposition of the second electroactive material layer. When the first electroactive material layer is silicon, the first intermediate layer material may include silicon nitride of the general formula SiN x where 0 < x ≦ 4 / 3. The silicon nitride is preferably amorphous silicon nitride. The nitride intermediate layer material is more preferable than the oxide passivation layer. (SiN x : sub-stoichiometric nitrides such as 0 < x ≦ 4 / 3) are conductive, and the nitride intermediate layer functions as a conductive network, enabling faster charge and discharge of the electroactive material.

[0049] Another type of passivation layer is, for example, a oxynitride layer formed by exposing the surface of the first electroactive material layer to ammonia (or other nitrogen-containing molecules) and oxygen gas before forming the second electroactive material layer. When the first electroactive material layer is silicon, the first intermediate layer material may include silicon oxynitride with the general formula SiO x N y , where 0 < x < 2, 0 < y < 4 / 3, and 0 < (2x + 3y) ≤ 4. The silicon oxynitride is preferably amorphous silicon oxynitride.

[0050] Another type of passivation layer is a carbide layer. When the first electroactive material layer is silicon, the first intermediate layer may include silicon carbide with the general formula SiC x . Here, 0 < x ≤ 1. The silicon carbide is preferably amorphous silicon carbide. The silicon carbide layer may be formed by contacting the surface of the first electroactive material with a carbon-containing precursor, such as methane or ethylene, at a high temperature.

[0051] As a further alternative, the passivation layer may include a carbon-containing organic moiety covalently bonded to the surface of the first electroactive material layer. The covalently bonded organic intermediate layer may be formed by inserting an organic compound into the M-H groups (where M represents an atom of the electroactive material) on the surface of the electroactive material to form a covalently passivated surface resistant to oxidation by air. When silicon is the electroactive material, the passivation reaction between the silicon surface and the passivating agent can be understood as a form of hydrosilylation, as schematically shown below:

[0052]

Chemical formula

[0053] Particularly preferred passivating agents include one or more compounds of the following formulae: (i) CH 2 =CH-R 1 ; (ii) HC≡C-R 1 ; where R 1 is as described above. Preferably, R 1 is unsubstituted.

[0054] Specific examples of suitable organic compounds that can be used to form the first intermediate layer material through passivation of the surface of the first electroactive material layer include ethylene, propylene, 1-butene, butadiene, 1-pentene, 1,4-pentadiene, 1-hexene, 1-octene, styrene, divinylbenzene, acetylene, phenylacetylene, norbornene, norbornadiene bicyclo[2.2.2]oct-2-ene, camphene, 3-carene, sabinene, thujadiene, pinene, limonene, acetylene, phenylacetylene, anthraquinone, anthrone, and camphor. Also, a mixture of different passivating agents may be used.

[0055] Another example of an organic compound that can be used to form the first intermediate layer material through passivation of the surface of the first electroactive material layer includes compounds having an active hydrogen atom bonded to oxygen, nitrogen, sulfur, or phosphorus. For example, the passivating agent may be an alcohol, an amine, a thiol, or a phosphine. As a result of the reaction between the -XH group and the hydride group on the surface of the electroactive material, the removal of H 2 is understood to occur, and the formation of a direct bond between X and the surface of the electroactive material occurs.

[0056] Suitable passivating agents in this category include compounds of the following formula: (iv) HX-R 2 , (v) HX-C(O)-R 1 , where X represents O, S, NR, or PR, where each R 1 is independently defined as described above, and R 2 represents an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having from 1 to 20 carbon atoms, or R 1 and R 2 together form an unsubstituted or substituted hydrocarbyl ring structure containing from 3 to 8 carbon atoms in the ring.

[0057] Preferably, X represents O or NH.

[0058] Preferably, R 2 represents an aliphatic or aromatic group having 2 to 10 carbon atoms, optionally substituted. The amine group may also be incorporated into an aliphatic or aromatic ring structure of 4 to 10 members, such as pyrrolidine, pyrrole, imidazole, piperazine, indole, or purine.

[0059] The first intermediate layer material may include a conductive pyrolytic carbon material. The conductive pyrolytic carbon layer may be formed by CVI using a suitable carbon-containing precursor, as will be described in more detail below. Optionally, the first intermediate layer material may include a conductive pyrolytic carbon material layer on top of the passivation layer described above.

[0060] The first intermediate layer material may include a conductive metal element or a metal alloy. The conductive metal layer or metal alloy layer may be formed by CVI using a suitable metal-containing precursor, as will be described in more detail below. An example of a suitable conductive metal intermediate layer material is silver metal. Optionally, the first intermediate layer material may include a conductive metal layer or metal alloy layer on top of the passivation layer as described above.

[0061] The first intermediate layer material may have a lithium ion-permeable solid electrolyte. Examples of suitable lithium-permeable solid electrolytes include garnet-type solid electrolytes (Li 7 La 3 Zr 2 O 12 and Li 6.5 La 3 Ti 0.5 Zr 1.5 O 12 such as "LLZO" electrolytes); perovskite-type solid electrolytes (Li 0.33 La 0.57 TiO 3 such as "LLTO" electrolytes); LISICON-type solid electrolytes, NaSICON-type solid electrolytes (L i1.3 Al 0.3 T i1.7 (PO 4 ) 3etc.); lithium oxynitride phosphate (LiPON) solid electrolyte; Li 3 N-type solid electrolyte, lithium phosphate (Li 3 PO 4 ) solid electrolyte, lithium titanate (Li 4 Ti 5 O 12 ) solid electrolyte, lithium tantalate (LiTaO 3 ) solid electrolyte, sulfide-based solid electrolytes, argyrodite-type solid electrolytes, and anti-perovskite-type solid electrolytes. Also included are variants (e.g., those containing dopants) and combinations of these electrolyte types. Optionally, the first intermediate layer material may include a lithium-permeable solid electrolyte layer on top of the aforementioned passivation layer.

[0062] The multilayer coating may include additional electroactive material layers and the aforementioned intermediate layers. For example, the multilayer coating may include n electroactive material layers and (n - 1) intermediate layer materials disposed between each electroactive material layer. Here, n is an integer from 3 to 20, from 3 to 15, from 4 to 12, from 4 to 10, from 5 to 10, or from 5 to 8. Preferably, each of the n electroactive materials is independent of the first and second electroactive materials as described above. Preferably, each of the n electroactive materials is the same electroactive material, and more preferably, each of the n electroactive materials is elemental silicon. Preferably, each of the (n - 1) intermediate layer materials is independent of the first interlayer material as described above. If necessary, each of the (n - 1) interlayer materials is the same interlayer material.

[0063] The thickness of the intermediate layer material is preferably less than 5 nm, more preferably less than 2 nm, and most preferably less than 1 nm. It is understood that thicker intermediate layers reduce the amount of electroactive material that can be accommodated within the pore volume of the porous particle skeleton. Therefore, the average intermediate layer thickness is preferably less than 20%, or less than 10%, or less than 5% of the average thickness of the electroactive material layer.

[0064] The multilayer coating disposed on the internal pore surface of the porous particle skeleton may further include the following, if necessary: (iv) A coating layer disposed on the surface of the outermost electroactive material layer (i.e., the last-formed electroactive material layer and the electroactive material layer furthest distal from the pore wall of the porous particle skeleton).

[0065] If necessary, the coating layer (iv) may be formed from any of the materials used to form the aforementioned intermediate layer materials. The coating layer (iv) may be the same as or different from any intermediate layer material.

[0066] The particulate material of the present invention may have a range of electroactive material content. For example, the amount of silicon in the composite particles may be selected such that at least 25% and up to 80% or more of the internal pore volume of the porous particle skeleton is occupied by the electroactive material and the intermediate layer material. For example, the electroactive material may occupy 25% to 75%, 25% to 70%, 30% to 65%, 35% to 60%, 40% to 60%, 25% to 45%, 30% to 40% of the internal pore volume of the porous particle skeleton. Within these preferred ranges, the pore volume of the porous particle skeleton is effective in accommodating the expansion of the electroactive material during charge and discharge. However, excess pore volume that does not contribute to the volumetric capacity of the particles is avoided. However, the amount of electroactive material is not so high as to prevent effective lithiation due to an inappropriate lithium ion diffusion rate or an inappropriate expansion volume resulting in mechanical resistance to lithiation.

[0067] Preferably, at least 85% by mass, more preferably at least 90% by mass, more preferably at least 95% by mass, and even more preferably at least 98% by mass of the electroactive material in the composite particles is disposed within the internal pore volume of the porous particle skeleton, and the electroactive material disposed on the outer surface of the composite particles is extremely small or absent. The preferential deposition of silicon on the internal surface of the porous particle skeleton is ensured by the reaction rate of the CVI process.

[0068] When the electroactive material is silicon, the mass ratio of silicon to the porous particle skeleton needs to be in the range of [0.5×P 1 to 1.9×P 1 :1. Therefore, the amount of silicon in the composite particles can be correlated with the available pore volume. In this relationship, the density of silicon and the pore volume of the porous particle skeleton are considered, and the weight ratio of silicon is determined such that the pore volume occupied by silicon is about 20% to 80%.

[0069] When the electroactive material is silicon, the composite material particles preferably contain 35% to 75% by weight of silicon, 40% to 70% by weight of silicon, or 45% to 65% by weight of silicon.

[0070] Preferred composite material particles contain a conductive porous carbon particle skeleton as described above, and the composite material particles contain at least 80% by mass, or 80% to 98% by mass, in total of silicon and carbon.

[0071] The amount of silicon in the composite particles can be determined by elemental analysis. Preferably, using elemental analysis, the weight percentages of carbon (and optionally hydrogen, nitrogen, and oxygen) in the porous carbon particles alone and in the composite particles are determined. By determining the weight percentage of carbon in the porous carbon particles alone, the possibility that the porous carbon particles contain a small amount of heteroatoms, similar to any carbon present in the interlayer material, is considered. By performing both measurements together, the weight percentage of the electroactive material with respect to the porous carbon particles can be determined with high reliability.

[0072] The silicon content of the composite material particles is preferably measured by ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry). Many ICP-OES instruments are commercially available, such as the iCAP (registered trademark) 7000 series of ICP-OES analyzers available from ThermoFisher Scientific. The elemental composition of the composite particles and the porous particle skeleton alone (and the content of hydrogen, nitrogen, and oxygen as necessary) is preferably measured by IR absorption. An apparatus suitable for measuring the carbon, hydrogen, nitrogen, and oxygen content is the TruSpec (registered trademark) Micro elemental analyzer available from Leco.

[0073] The particulate material of the present invention can be further characterized by their properties under thermogravimetric analysis (TGA) in air. The particulate material preferably contains 10% or less unoxidized silicon at 800 °C when measured by TGA at a heating rate of 10 °C / min in air. More preferably, the particulate material contains 5% or less or 2% or less unoxidized silicon at 800 °C when measured by TGA at a heating rate of 10 °C / min in air.

[0074] The determination of the amount of unoxidized silicon is derived from the characteristic TGA traces of these materials. The mass increase at about 300 to 500 °C corresponds to the initial oxidation of Si to SiO 2 and then, since carbon is oxidized to CO 2 gas, a mass decrease occurs at about 500 to 600 °C. Above about 600 °C, there is a further mass increase corresponding to the continued conversion of silicon to SiO 2 and as the oxidation of silicon approaches completion, it rises towards an asymptote above 1000 °C.

[0075] In this analysis, the mass increase above 800 °C corresponds to the oxidation of Si to SiO 2 and the total mass at the end of oxidation is assumed to be due to SiO 2 Thus, the proportion of unoxidized silicon at 800 °C can be determined as a ratio to the total amount of silicon by the following equation: Z = 1.875 × [(M f - M 800 ) / M f × 100% Here, Z is the ratio of unoxidized silicon at 800 °C, M f is the mass of the sample at the end of oxidation, and M 800 is the sample mass at 800 °C.

[0076] Although not bound by theory, it is understood that the temperature at which silicon is oxidized under TGA broadly corresponds to the length scale of the oxide coating on silicon due to the diffusion of oxygen atoms through the thermally activated oxide layer. The size and arrangement of the silicon nanostructures limit the length scale of the thickness of the oxide coating. Thus, it is understood that silicon deposited within the pores oxidizes at a lower temperature than the silicon deposits on the particle surface due to the necessarily thinner oxide coatings present in these structures. Thus, the preferred materials according to the present invention exhibit substantially complete oxidation of silicon at low temperatures consistent with the small scale of the silicon nanostructures disposed within the micropores and smaller mesopores. For the purposes of the present invention, the oxidation of silicon at 800 °C is assumed to be the silicon on the outer surface of the porous particle skeleton.

[0077] The composite particles preferably have a low total oxygen content. Oxygen may be present in the composite particles, for example, as part of the porous particle skeleton or as an oxide layer on any exposed silicon surface. Preferably, the surface of the electroactive material is passivated to prevent or inhibit oxide formation.

[0078] Preferably, the total oxygen content of the composite particles is less than 15 wt%, more preferably less than 10 wt%, more preferably less than 5 wt%, for example less than 2 wt%, or less than 1 wt%, or less than 0.5 wt%.

[0079] The composite particles preferably have a D 50 particle diameter in the range of 0.5 to 200 μm. If necessary, the D 50The particle diameter is at least 1 μm, at least 1.5 μm, at least 2 μm, at least 3 μm, at least 4 μm, or at least 5 μm. If necessary, the D of the composite particles 50 The particle diameter may be 150 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 18 μm or less, 15 μm or less, 12 μm or less, or 10 μm or less.

[0080] For example, the composite particles have a D in the range of 0.5 to 200 μm, 0.5 to 150 μm, 0.5 to 100 μm, 0.5 to 50 μm, 0.5 to 30 μm, 1 to 25 μm, 1 to 20 μm, 2 to 25 μm, 2 to 20 μm, 2 to 18 μm, 3 to 20 μm, 3 to 18 μm, 3 to 15 μm, 4 to 18 μm, 4 to 15 μm, 4 to 12 μm, 5 to 15 μm, 5 to 12 μm, or 5 to 10 μm 50 and may have a particle diameter.

[0081] Particles within these preferred size ranges and having the porosity and pore diameter distribution as described in the present application are ideally suitable for the preparation of composite particles used for anodes in metal ion batteries by a fluidized bed process. In particular, particles having these properties have good dispersibility in a slurry, structural robustness, high capacity retention over repeated charge-discharge cycles, and are suitable for forming a dense electrode layer of uniform thickness in a conventional thickness range of 20 to 50 μm.

[0082] The D of the composite particles 10 The particle diameter is preferably at least 0.5 μm, at least 0.8 μm, at least 1 μm, at least 1.5 μm, or at least 2 μm. The D 10 By maintaining the particle diameter at 0.5 μm or more, the possibility of undesirable aggregation of submicron-sized particles is reduced, and as a result, the dispersibility of the composite particles in the slurry used for electrode manufacturing is improved.

[0083] The D of the composite particles 90The particle size is preferably 300 μm or less, 250 μm or less, 200 μm or less, 150 μm or less, 100 μm or less, 80 μm or less, 60 μm or less, 40 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less. The use of large composite particles results in non-uniform formation packing of the composite particles in the electrode active layer, thus inhibiting the formation of a dense electrode layer, particularly an electrode layer having a thickness in the range of 20 to 50 μm.

[0084] The composite particles preferably have a narrow size distribution span. For example, the particle size distribution span ((D 90 -D 10 ) / D 50 ) as defined) is preferably 5 or less, more preferably 4 or less, more preferably 3 or less, more preferably 2 or less, and most preferably 1.5 or less. By maintaining a narrow size distribution span, efficient packing of the particles into a dense electrode layer can be more easily achieved.

[0085] To avoid ambiguity, the term "particle diameter" refers to the equivalent spherical diameter (esd), i.e., the diameter of a sphere having the same volume as a given particle, where the particle volume is understood to include the volume of any internal pores of the particle. The terms "D 50 " and "D 50 particle diameter" as used in this application refer to the volume-based median particle diameter, i.e., the diameter at which less than 50% by volume of the particle population is found. The terms "D 10 " and "D 10 particle diameter" as used in this application refer to the 10% volume-based median particle diameter, i.e., the diameter at which less than 10% by volume of the particle population is found. The terms "D90" and "D90 particle diameter" as used in this application refer to the 90% volume-based median particle diameter, i.e., the diameter at which less than 90% by volume of the particle population is found.

[0086] The particle diameter and particle size distribution can be measured by a standard laser diffraction method in accordance with ISO13320:2009. The laser diffraction method is based on the principle that particles scatter light at angles that vary depending on the size of the particles, and the particles or their aggregates generate a pattern of scattered light defined by the intensity and angle that can be correlated with the particle size distribution. A number of laser diffraction devices are commercially available for measuring the particle size distribution quickly and with high reliability. Unless otherwise specified, the measured values of the particle size distribution described or reported in this application were measured with a conventional Malvern Mastersizer (trademark) 3000 particle size analyzer manufactured by Malvern Instruments. The Malvern Mastersizer (trademark) TM 3000 particle size analyzer operates by irradiating a transparent cell containing the target particles suspended in an aqueous solution with a helium-neon gas laser beam. The light rays that collide with the particles are scattered through angles inversely proportional to the particle size, and a photodetector array measures the intensity of the light at several predetermined angles. Using standard theoretical principles, the intensities measured at different angles are processed by a computer to determine the particle size distribution. The laser diffraction values described in this application are obtained using a wet dispersion of the particles in 2-propanol with 5 vol% of the surfactant SPAN (trademark)-40 (sorbitan monopalmitate) added. The particle refractive index is set at 3.50, and a dispersion index of 1.378 is adopted. The particle size distribution is calculated using the Mie scattering model.

[0087] The composite particles are preferably 100 m 2 / g or less, 80 m 2 / g or less, 60 m 2 / g or less, 40 m 2 / g or less, 30 m 2 / g or less, 25 m 2 / g or less, 20 m 2 / g or less, 15 m 2 / g or less, or 10 m 2It has a BET surface area of less than or equal to [value]. Generally, a low BET surface area is preferred to minimize the formation of the solid electrolyte interphase (SEI) layer on the surface of the composite particles during the first charge-discharge cycle of the anode. However, an overly low BET surface area may prevent access of the metal ions in the bulk of the electroactive material to the surrounding electrolyte, leading to unacceptable low charging rates and capacities. For example, the BET surface area of the composite particles is preferably at least 0.1 m 2 / g, at least 1 m 2 / g, at least 2 m 2 / g, or at least 5 m 2 / g. For example, the BET surface area may be in the range of 0.1 to 100 m 2 / g, 0.1 to 80 m 2 / g, 0.5 to 60 m 2 / g, 0.5 to 40 m 2 / g, 1 to 30 m 2 / g, 1 to 25 m 2 / g, or 2 to 20 m 2 / g.

[0088] The composite particles may optionally include a conductive coating. For example, the conductive coating may be a conductive pyrolytic carbon coating. When one or more intermediate layer materials are conductive pyrolytic carbon materials, the conductive carbon coating may be of the same type as the conductive pyrolytic carbon or a different type with respect to the intermediate layer material, and may be formed from different carbon-containing precursors, for example.

[0089] Preferably, the conductive pyrolytic carbon coating may be obtained by chemical vapor deposition (CVD). The thickness of the carbon coating may preferably be in the range of 2 to 30 nm. Optionally, the conductive pyrolytic carbon coating may be porous and / or may cover only a portion of the surface of the composite particles.

[0090] The carbon coating has the advantage of further reducing the BET surface area of the particulate material by smoothing any surface defects and filling any remaining surface microporosity, thereby further suppressing the first-cycle loss. Also, the carbon coating improves the conductivity of the surface of the composite material particles, suppresses the need for a conductive additive in the electrode composition, and forms an optimal surface for the formation of a more stable SEI layer, resulting in improved capacity retention during cycling.

[0091] The particulate material of the present invention preferably has a specific charge capacity of from 1400 to 2340 mAh / g upon the first lithiation. Preferably, the silicon-containing particulate material according to the present invention has a specific charge capacity of from 1600 to 2340 mAh / g upon the first lithiation.

[0092] In a second aspect of the present invention, a method for preparing composite particles is provided, the method comprising: (a) providing a plurality of porous particles, wherein the total pore volume of pores having a pore diameter in the range of 3.5 to 100 nm, as measured by nitrogen gas adsorption, is P per gram of the porous particles 1 cm 3 where P 1 represents a number in the range of 0.3 to 2.4; (b) forming a first layer of electroactive material on the internal pore surface of the porous particles; (c) forming a first intermediate layer material on the surface of the first layer of electroactive material; (d) depositing a second layer of electroactive material on the surface of the first intermediate layer material. Accordingly, in the method of the present invention, composite particles as described above are provided, and the porous particles form a backbone of a multilayer coating comprising at least first and second layers of electroactive material and at least a first intermediate layer material disposed between the first and second layers of electroactive material.

[0093] Thus, in the method of the present invention, composite particles as described above are provided, and the porous particles form a backbone of a multilayer coating comprising at least first and second layers of electroactive material and at least a first intermediate layer material disposed between the first and second layers of electroactive material.

[0094] In a second aspect of the present invention, the porous particles used in step (a) form a porous particle skeleton within the particles of the first aspect of the present invention. Thus, the porous particles in step (a) are considered to be equivalent to the porous particle skeleton in the above composite particles. Thus, any optional or preferred properties of the aforementioned porous particle skeleton according to the first aspect (in particular, the porous particle skeleton, the total pore volume of the porous particle skeleton, the PD 50 pore diameter, the pore size distribution of the porous particle skeleton, and the materials forming the BET surface area of the porous particle skeleton) are also understood to apply to the porous particles used in step (a) of the method according to the second aspect of the present invention.

[0095] The porous particles used in step (a) have preferred dimensions corresponding to the preferred dimensions of the composite particles described with respect to the first aspect of the present invention.

[0096] Thus, the porous particles used in step (a) appropriately have a D 50 particle diameter in the range of 0.5 to 200 μm. If necessary, the D 50 particle diameter of the composite particles may be at least 1 μm, at least 1.5 μm, at least 2 μm, at least 3 μm, at least 4 μm, or at least 5 μm. If necessary, the D 50 particle diameter of the porous particles may be 150 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 18 μm or less, 15 μm or less, 12 μm or less, or 10 μm or less.

[0097] For example, the porous particles used in step (a) have a D 50 particle diameter in the range of 0.5 to 200 μm, 0.5 to 150 μm, 0.5 to 100 μm, 0.5 to 50 μm, 0.5 to 30 μm, 1 to 25 μm, 2 to 25 μm, 2 to 20 μm, 2 to 18 μm, 3 to 20 μm, 3 to 18 μm, 3 to 15 μm, 4 to 18 μm, 4 to 15 μm, 4 to 12 μm, 5 to 15 μm, 5 to 12 μm, or 5 to 10 μm.

[0098] The D of the porous particles used in step (a) 10 The particle size is preferably at least 0.5 μm, at least 0.8 μm, at least 1 μm, at least 1.5 μm, or at least 2 μm. D 10 By maintaining the particle diameter of the particles at 0.5 μm or more, the possibility of undesirable aggregation of submicron-sized particles is reduced, and as a result, the dispersibility of the composite particles in the slurry used for electrode production is improved.

[0099] The D of the porous particles used in step (a) 90 The particle size is preferably 300 μm or less, 250 μm or less, 200 μm or less, 150 μm or less, 100 μm or less, 80 μm or less, 60 μm or less, 40 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

[0100] The porous particles used in step (a) preferably have a narrow size distribution span. For example, the particle size distribution span ((D 90 -D 10 ) / D 50 as defined) is preferably 5 or less, more preferably 4 or less, more preferably 3 or less, more preferably 2 or less, and most preferably 1.5 or less.

[0101] In steps (b) and (d), preferably, chemical vapor infiltration (CVI) is used, and the first and second electroactive material layers are formed on the pore surface of the porous particles. As described above, the chemical vapor infiltration (CVI) method is generally a process of infiltrating an additional phase into a porous substrate by passing a mixture of an inert carrier gas and a gas precursor at a high temperature through the porous substrate. As a result of the decomposition / reaction of the gas precursor on the pore surface, a solid phase is formed in the pore structure. When a gaseous precursor is referred to in the present application, it is understood that it includes a vapor-phase precursor that is liquid or solid at ambient temperature but vaporizes below the reaction temperature.

[0102] The electroactive materials in the first and second electroactive material layers formed in steps (b) and (d) may be the same or different, and may be independently selected from elemental silicon, elemental tin, elemental germanium, elemental aluminum, as well as mixtures and alloys thereof, as required. A preferred electroactive material is silicon. Preferably, at least one of the first and second electroactive material layers is an elemental silicon layer. More preferably, both the first and second electroactive material layers are elemental silicon layers.

[0103] Suitable silicon-containing precursors include silane (SiH 4 ), disilane (Si 2 H 6 ), trisilane (Si 3 H 8 ), tetrasilane (Si 4 H 10 ), or chlorosilanes such as trichlorosilane (HSiCl 3 ), or methylchlorosilanes such as methyltrichlorosilane (CH 3 SiCl 3 ) or dimethyldichlorosilane ((CH 3 ) 2 SiCl 2 ). Preferably, the silicon-containing precursor is silane.

[0104] Suitable tin-containing precursors include bis[bis(trimethylsilyl)amino]tin(II) ([(CH 3 ) 3 Si] 2 N) 2 Sn), tetraallyltin (((H 2 C=CHCH 2 ) 4 Sn), tetrakis(diethylamide)tin(IV) ([(C 2 H 5 ) 2 N] 4 Sn), tetrakis(dimethylamide)tin(IV) ([(CH 3 ) 2 N] 4 Sn), tetramethyltin (Sn(CH3 ) 4 )、 Tetravinyltin (Sn(CH=CH 2 ) 4 )、 Tin(II) acetylacetonate (C 10 H 14 O 4 Sn), Trimethyl(phenylethynyl)tin (C 6 H 5 C≡CSn(CH 3 ) 3 )、 and Trimethyl(phenyl)tin (C 6 H 5 Sn(CH 3 ) 3 ) are included. Preferably, the tin-containing precursor is tetramethyltin.

[0105] Suitable aluminum-containing precursors include aluminum tris(2,2,6,6-tetramethyl-3,5-heptanedionate) (Al(OCC(CH 3 ) 3 CHCOC(CH 3 ) 3 ) 3 ), Trimethylaluminum ((CH 3 ) 3 Al), and Tris(dimethylamide)aluminum(III) (Al(N(CH 3 ) 2 ) 3 ) are included. Preferably, the aluminum-containing precursor is trimethylaluminum.

[0106] Suitable germanium-containing precursors include germane (GeH 4 ), Hexamethyldigermane ((CH 3 ) 3 GeGe(CH 3 ) 3 ), Tetramethylgermane ((CH 3 ) 4 Ge), Tributylgermane hydride ([CH 3 (CH 2 ) 3 3 GeH), Triethylgermane hydride ((C 2 H​5 ) 3 GeH), and triphenylgermanium hydride ((C 6 H 5 ) 3 GeH) is included. Preferably, the germanium-containing precursor is germanium.

[0107] In the CVI processes of steps (b) and (d), if necessary, gaseous precursors of dopant materials are used, and the doped electroactive material may be formed on the micropores and / or mesopores of the porous particles. When the dopant is boron, suitable precursors are borane (BH 3 ), triisopropyl borate ([(CH 3 ) 2 CHO] 3 B), triphenylborane ((C 6 H 5 ) 3 B), and tris(pentafluorophenyl)borane (C 6 F 5 ) 3 B, and preferably borane. When the dopant is phosphorus, a suitable precursor is phosphine (PH 3 ).

[0108] Preferably, both the first and second electroactive materials are silicon. More preferably, the gaseous precursors used in steps (b) and (d) are, independently of each other, silane (SiH 4 ), disilane (Si 2 H 6 ), trisilane (Si 3 H 8 ), tetrasilane (Si 4 H 10 ), trichlorosilane (HSiCl 3 ), methyltrichlorosilane (CH 3 SiCl 3 ), and dimethyldichlorosilane ((CH 3 ) 2 SiCl 2) is selected. More preferably, the gaseous precursors used to form the first and second electroactive material layers in steps (b) and (d) are silane (SiH 4 ).

[0109] The precursors in steps (b) and (d) may be used in pure form or, more generally, as a diluted mixture with an inert carrier gas such as nitrogen or argon. For example, the precursor may be used in an amount in the range of 1 to 100 vol%, 1 to 50 vol%, 2 to 40 vol%, 5 to 30 vol%, or 5 to 25 vol% based on the total volume of the precursor and the inert carrier gas.

[0110] The CVI process in steps (b) and (d) is suitably carried out at a low partial pressure of the gaseous precursor, with the total pressure being 101.3 kPa (i.e., atmospheric pressure, 1 atm) or near it, using an inert padding gas such as hydrogen, nitrogen or argon so that the remaining partial pressure reaches atmospheric pressure. The presence of oxygen needs to be minimized, and following conventional procedures operating in an inert atmosphere, unwanted oxidation of the deposited electroactive material is prevented. Preferably, the oxygen content is less than 0.01 vol%, more preferably less than 0.001 vol% based on the total volume of the gas used in step (b).

[0111] The temperature of the CVI process in steps (b) and (d) may in principle be any temperature effective to pyrolyze the precursor to form the electroactive material. Preferably, the CVI process in steps (b) and (d) is carried out at a temperature in the range of 300 to 700 °C, 350 to 700 °C, 400 to 700 °C, 400 to 650 °C, 400 to 600 °C, 400 to 550 °C, 400 to 500 °C, 400 to 450 °C, or 450 to 500 °C. More preferably, the CVI process in steps (b) and (d) is carried out at a temperature in the range of 400 to 500 °C, preferably 450 to 500 °C.

[0112] The surface of the first electroactive material layer formed in step (b) is reactive to oxygen and forms a native oxide layer when exposed to oxygen. In the case of silicon, when the silicon surface is exposed to oxygen, an amorphous silicon dioxide film is formed. Therefore, the first intermediate layer material may be a native oxide layer formed by passivating the surface of the first electroactive material with air or another oxygen-containing gas such as nitrous oxide in step (c). The native oxide layer on the surface of silicon may be described by the chemical formula SiO x where 0 > x ≦ 2.

[0113] The formation of the native oxide layer is an exothermic reaction, and thus careful process control is required to prevent overheating or combustion of the particulate material during manufacturing. If the first intermediate layer material formed in step (c) is a native oxide layer, step (c) may include cooling the material formed in step (b) to a temperature below 300 °C, preferably below 200 °C, more preferably below 100 °C, before contacting the surface of the first electroactive material with an oxygen-containing gas.

[0114] The first intermediate layer material formed in step (c) may be a nitride of the first electroactive material instead of an oxide layer. The nitride layer is formed by passivating the surface of the first electroactive material with ammonia at a temperature in the range of 200 to 700 °C, preferably 400 to 700 °C, more preferably 400 to 600 °C, to form a nitride surface (e.g., a silicon nitride surface with the general formula SiN x where x ≦ 4 / 3). For example, when the passivating agent is ammonia, step (c) may be carried out at the same or a similar temperature as the temperature used to form the first electroactive material film in step (b). Since substoichiometric silicon nitride is conductive, as a result of this step, a conductive network is formed, which enables faster charge and discharge of the electroactive material.

[0115] The first intermediate layer material formed in step (c) may be an oxynitride layer formed on the surface of the first electroactive material layer. Step (c) may include a step of exposing the surface of the first electroactive material layer to ammonia (or other nitrogen-containing molecules) and oxygen gas. When the first electroactive material layer contains silicon, the intermediate layer material may contain silicon oxynitride with the general formula SiO x N y where 0 < x < 2, 0 < y < 4 / 3, and 0 < (2x + 3y) ≤ 4. The silicon oxynitride is preferably amorphous silicon oxynitride.

[0116] The first intermediate layer material formed in step (c) may be an amorphous or nanocrystalline carbide layer formed on the surface of the first electroactive material layer. Step (c) may include a step of contacting the surface of the first electroactive material layer with a carbon-containing precursor, such as methane or ethylene, at a temperature in the range of 250 to 700 °C. At low temperatures, covalent bonds are formed between the surface of the electroactive material and the carbon-containing precursor, and as the temperature rises, this is converted into a single layer of crystalline carbide. When the first electroactive material layer contains silicon, the intermediate layer material may contain silicon carbide with the general formula SiC x where 0 < x ≤ 1. The silicon carbide is preferably amorphous silicon carbide.

[0117] As a further option, the intermediate layer material formed in step (c) may include a carbon-containing organic moiety covalently bonded to the surface of the first electroactive material layer. Organic compounds containing certain functional groups, such as alkenes, alkynes, or carbonyl functional groups, more preferably terminal alkenes, terminal alkynes, or aldehyde groups, can passivate the surface of the first electroactive material layer, and covalent bonds are formed on its surface. Also, compounds containing active hydrogen atoms, such as alcohols, thiols, amines, and phosphines, may be used as passivating agents. For example, step (c) may include a step of passivating the surface of the first electroactive material layer using a passivating agent selected from one or more compounds of the following formula: (i) R1 -CH=CH-R 1 ; (ii)R 1 -C≡C-R 1 ; (iii)O=CH-R 1 ; Here, each R 1 independently represents H, or an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having from 1 to 20 carbon atoms, preferably from 2 to 10 carbon atoms, or two R groups of general formula (i) form an unsubstituted or substituted hydrocarbyl ring structure containing from 3 to 8 carbon atoms in the ring.

[0118] Particularly preferred passivating agents include one or more compounds of the following formula: (i)CH 2 =CH-R 1 ; (ii)HC≡C-R 1 ; Here, R 1 is as described above. Preferably, R 1 is unsubstituted.

[0119] Specific examples of suitable organic compounds that can be used to form a material domain modified through passivation of the surface of the electroactive material domain include ethylene, propylene, 1-butene, butadiene, 1-pentene, 1,4-pentadiene, 1-hexene, 1-octene, styrene, divinylbenzene, acetylene, phenylacetylene, norbornene, norbornadiene, bicyclo[2.2]oct-2-ene, camphene, 3-carene, sabinene, thujene, pinene, limonene, acetylene, phenylacetylene, anthraquinone, anthrone, and camphor. Also, mixtures of different passivating agents may be used.

[0120] Another example of an organic compound that can be used to form the first intermediate layer material through passivation of the surface of the first electroactive material layer includes compounds containing active hydrogen atoms bonded to oxygen, nitrogen, sulfur, or phosphorus. For example, the passivating agent may be an alcohol, an amine, a thiol, or a phosphine. As a result of the reaction between the -XH group and the hydride group on the surface of the electroactive material, the removal of H 2 is understood to occur, and the formation of a direct bond between X and the surface of the electroactive material occurs.

[0121] Suitable passivating agents in this category include compounds of the following formula: (iv) HX-R 2 , (v) HX-C(O)-R 1 , where X represents O, S, NR, or PR, and each R 1 is independently defined as described above, and R 2 represents an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having from 1 to 20 carbon atoms, or R 1 and R 2 together form an unsubstituted or substituted hydrocarbyl ring structure containing from 3 to 8 carbon atoms in the ring.

[0122] Preferably, X represents O or NH.

[0123] Preferably, R 2 represents, optionally, a substituted aliphatic or aromatic group having from 2 to 10 carbon atoms. Also, the amine group may be incorporated into a 4- to 10-membered aliphatic or aromatic ring structure, such as pyrrolidine, pyrrole, imidazole, piperazine, indole, or purine.

[0124] Examples of suitable compounds in this category include borneol, terpineol, sucrose, thiophenol, and aniline. Also, a mixture of different passivating agents may be used.

[0125] The combined organic intermediate layer material may be formed by passivating the surface of the first electroactive material with the above-described organic passivating agent at a temperature in the range of 200 to 700 °C, preferably 400 to 700 °C, more preferably 400 to 600 °C. For example, when the first intermediate layer material is formed using an organic passivating agent, step (c) may be carried out at the same or a similar temperature as the temperature used in forming the first electroactive material in step (b).

[0126] As a further option, an amorphous or nanocrystalline carbide layer may be formed by contacting the surface of the first electroactive material with a carbon-containing precursor, such as methane or ethylene, at a temperature of 250 to 700 °C. At low temperatures, covalent bonds are formed between the surface of the electroactive material and the carbon-containing precursor, which converts to a single layer of crystalline silicon carbide as the temperature increases.

[0127] As a further option, step (c) may include forming a layer of a conductive pyrolytic carbon material as the first intermediate layer material. Also, the pyrolytic carbon may be obtained by chemical vapor infiltration (CVI), i.e., by pyrolysis of a volatile carbon-containing gas (such as a hydrocarbon) on the surface of silicon-containing composite particles.

[0128] Suitable precursors for forming the conductive pyrolytic carbon material include polycyclic hydrocarbons containing 10 to 25 carbon atoms and, if necessary, 1 to 3 heteroatoms. Such polycyclic hydrocarbons are selected from naphthalene, substituted naphthalenes such as dihydroxynaphthalene, anthracene, tetracene, pentacene, fluorene, acenaphthene, phenanthrene, fluoranthene, pyrene, chrysene, perylene, coronene, fluorenone, anthraquinone, anthrone, and their alkyl-substituted derivatives. More suitable pyrolytic carbon precursors include bicyclic monoterpenoids, which, if necessary, are selected from camphor, borneol, eucalyptol, camphene, careen, sabinene, thujene, α-terpinene, and pinene. Another suitable pyrolytic carbon precursor is C 2 to C 10 hydrocarbons, which, if necessary, are selected from alkanes, alkenes, alkynes, cycloalkanes, cycloalkenes, and arenes, such as methane, ethylene, propylene, butane, butadiene, 1-pentene, 1,4-pentadiene, 1-hexene, 1-octene, limonene, styrene, cyclohexane, cyclohexene, and acetylenedivinylbenzene, norbornene, norbornadiene, cyclopentadiene, dicyclopentadiene, bicyclo[2.2.2]oct-2-ene. 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.

[0129] The pyrolytic carbon precursor used in step (c) may be used in pure form or as a mixture diluted with an inert carrier gas such as nitrogen or argon. For example, the pyrolytic carbon precursor may be used in an amount in the range of 0.1 to 50 vol%, 0.5 to 20 vol%, 1 to 10 vol%, or 1 to 5 vol% based on the total volume of the precursor and the inert carrier gas.

[0130] The formation of the conductive pyrolytic carbon layer in step (c) may be carried out following the passivation of the surface of the first electroactive material layer by one of the processes described above, if necessary. Thus, the intermediate layer material formed in step (c) may include both a passivation layer on the surface of the first electroactive material layer and a conductive pyrolytic carbon layer.

[0131] When the surface of the first electroactive material layer is passivated with an organic compound (in particular, an alkene or alkyne) and a covalently bonded organic moiety is formed on the surface of the first electroactive material layer, the same compound as the pyrolytic carbon precursor may be used for the passivation step. Thus, the covalently bonded organic moiety provides a substrate for the growth of the conductive pyrolytic carbon intermediate layer material.

[0132] As another option, step (c) may have a step of forming a layer of a conductive metal as the first intermediate layer material. Also, the conductive metal layer may be obtained by a chemical vapor infiltration (CVI) method. Examples of suitable conductive metals include silver, gold, copper, and titanium.

[0133] The formation of the conductive metal intermediate layer material in step (c) may be carried out after the passivation of the surface of the first electroactive material layer by one of the processes described above, if necessary. Thus, the intermediate layer material formed in step (c) may include both a passivation layer on the surface of the first electroactive material layer and a conductive metal layer.

[0134] As another option, step (c) may include forming a layer of a lithium-ion permeable solid electrolyte as the first intermediate layer material. The lithium-ion permeable solid electrolyte may be formed into a film by a CVI process similar to the method used in step (b) in step (c). For example, in step (c), a lithium phosphate solid electrolyte may be formed into a film using an atmosphere of tert-butyllithium and trimethyl phosphate. The CVI of the lithium-ion permeable solid electrolyte in step (c) is preferably carried out at a temperature of 700 °C or lower, 650 °C or lower, 600 °C or lower, 550 °C or lower, 500 °C or lower. The minimum temperature in step (c) depends on the type of lithium-ion permeable solid electrolyte used. The temperature of step (c) is preferably 300 °C or higher, 350 °C or higher, 400 °C or higher, or 450 °C or higher. For example, the temperature of step (c) may be in the range of 400 to 500 °C.

[0135] Steps (c) and (d) are optionally repeated one or more times to form a particulate material. This has three or more electroactive material layers, with a plurality of intermediate layer materials disposed between each of the adjacent electroactive material layers. For example, steps (c) and (d) are optionally repeated one or more times to form a particulate material including n electroactive material layers and (n - 1) intermediate layer materials disposed between each electroactive material layer. Here, n is an integer from 3 to 20, 3 to 15, 3 to 12, 3 to 10, 4 to 10, or 5 to 8.

[0136] Each repetition of step (d) is used to form an electroactive material layer, which may be the same as or different from any other electroactive material layer, and each repetition may independently have any of the characteristics of step (d) as described above. Preferably, each of the n electroactive material layers contains the same electroactive material. More preferably, each of the n electroactive material layers formed in each repetition of step (d) is a silicon layer.

[0137] Similarly, an intermediate layer material is formed using each iteration of step (c), which may be the same as or different from any other intermediate layer material. Each iteration may independently have any of the features of step (c) as described above. Preferably, each of the (n - 1) electroactive material layers contains the same intermediate layer material.

[0138] The method of the present invention may have an additional step (e) if necessary. Step (e) has the step of forming a coating layer on the surface of the final electroactive material layer to be formed (i.e., the layer formed in the final event of step (d)). The coating layer formed in step (e) may be formed in a similar manner to the intermediate layer formed in step (c), and in step (e), any of the above intermediate layer materials may be used to form the coating layer.

[0139] The method of the present invention may be carried out in any reactor capable of contacting the porous particles with a gas containing precursors of the electroactive material and the intermediate layer material. Suitable types of reactors include static furnaces, rotary kilns, or fluidized bed reactors (including jet fluidized bed reactors).

[0140] Preferably, each of steps (b), (c), (d), and any step (e) is carried out by contacting the porous particles with a continuous flow of a gas containing the respective precursors of the electroactive material, the intermediate layer material, and any coating material for a time sufficient to form the desired layer thickness. By circulating the atmosphere within the reactor between different precursors, a multilayer structure may be formed layer by layer until the required number of layers is formed.

[0141] Alternatively, each of steps (b), (c), (d) and optional step (e) may be carried out by contacting the porous particles with a constant charge of gas containing each respective precursor within a batch reactor. The use of a batch reactor has the advantage that the amounts of electroactive material, interlayer material and coating material can be accurately controlled by controlling the volume of precursor gas supplied to the reactor in each charge. The batch reactor may optionally have means for agitating the porous particles.

[0142] The reactor is preferably flushed with a suitable inert gas between each successive CVI process. The inert gas used to flush the reactor is preferably the same inert gas as that used as the carrier gas for each respective precursor of the electroactive material, interlayer material, and any coating material.

[0143] In a third aspect of the present invention, there is provided a composition comprising the particulate material according to the first aspect of the present invention and at least one other component optionally selected from (i) a binder, (ii) a conductive additive, and (iii) an additional particulate electroactive material. The composition of the third aspect of the present invention is useful as an electrode composition and may therefore be used to form the active layer of an electrode.

[0144] The composition preferably comprises from 1 to 95 wt%, from 2 to 90 wt%, from 5 to 85 wt%, or from 10 to 80 wt% of the particulate material according to the first aspect of the present invention, based on the total dry weight of the composition.

[0145] The composition may be a hybrid electrode composition comprising composite particles and at least one additional particulate electroactive material. Examples of additional particulate electroactive materials include graphite, hard carbon, silicon, tin, germanium, aluminum, and lead. At least one additional particulate electroactive material is preferably selected from graphite and hard carbon, and most preferably at least one additional particulate electroactive material is graphite.

[0146] In the case of a hybrid electrode composition, the composition preferably contains composite particles in an amount of 3 to 60% by weight, 3 to 50% by weight, 5 to 50% by weight, 10 to 50% by weight, or 15 to 50% by weight, based on the total dry weight of the composition.

[0147] At least one additional particulate electroactive material is preferably present in an amount of 20 to 95% by weight, 25 to 90% by weight, or 30 to 75% by weight of the at least one additional particulate electroactive material.

[0148] At least one additional particulate electroactive material preferably has a D particle diameter in the range of 10 to 50 μm, preferably 10 to 40 μm, more preferably 10 to 30 μm, most preferably 10 to 25 μm, for example 15 to 25 μm. 50 particle diameter.

[0149] The D of at least one additional particulate electroactive material 10 particle diameter is preferably at least 5 μm, more preferably at least 6 μm, more preferably at least 7 μm, more preferably at least 8 μm, more preferably at least 9 μm, even more preferably at least 10 μm.

[0150] The D of at least one additional particulate electroactive material 90 particle diameter is preferably at most 100 μm, more preferably at most 80 μm, more preferably at most 60 μm, more preferably at most 50 μm, most preferably at most 40 μm.

[0151] At least one additional particulate electroactive material is preferably selected from carbon-containing particles, graphite particles and / or hard carbon particles, and the graphite and hard carbon particles have a D particle diameter in the range of 10 to 50 μm. 50 particle diameter. More preferably, at least one additional particulate electroactive material is selected from graphite particles, and the graphite particles have a D particle diameter in the range of 10 to 50 μm. 50It has a particle diameter.

[0152] Also, the composition may be a non-hybrid (or "high loading") electrode composition that substantially does not contain additional particulate electroactive material. In this context, the term "substantially free of additional particulate electroactive material" means that the composition contains less than 15% by weight, preferably less than 10% by weight, preferably less than 5% by weight, preferably less than 2% by weight, more preferably less than 1% by weight, and even more preferably less than 0.5% by weight of any additional electroactive material (i.e., an additional material capable of inserting and releasing metal ions during battery charge and discharge) based on the total dry weight of the composition.

[0153] This type of "high loading" electrode composition preferably contains at least 50% by weight, at least 60% by weight, at least 70% by weight, at least 80% by weight, or at least 90% by weight of the composite particles obtained according to the first aspect of the present invention, based on the total dry weight of the composition.

[0154] The composition may optionally contain a binder. The binder functions to adhere the composition to the current collector and maintain the integrity of the composition. Examples of binders that can be used in the present invention include polyvinylidene fluoride (PVDF), polyacrylic acid (PAA) and its alkali metal salts, modified polyacrylic acid (mPAA) and its alkali metal salts, carboxymethyl cellulose (CMC), modified carboxymethyl cellulose (mCMC), sodium carboxymethyl cellulose (Na-mCMC), polyvinyl alcohol (PVA), alginates and their alkali metal salts, styrene-butadiene rubber (SBR), and polyimide. The composition may contain a mixture of binders. Preferably, the binder contains a polymer selected from polyacrylic acid (PAA) and its alkali metal salts, modified polyacrylic acid (mPAA) and its alkali metal salts, SBR, and CMC.

[0155] The binder may preferably be present in an amount of 0.5 to 20% by weight, preferably 1 to 15% by weight, preferably 2 to 10% by weight, and most preferably 5 to 10% by weight, based on the total dry weight of the composition.

[0156] The binder may, if necessary, be present in combination with one or more additives that modify the properties of the binder, such as a crosslinking accelerator, a coupling agent, and / or an adhesion promoter.

[0157] The composition may optionally contain one or more conductive additives. Preferred conductive additives are non-electrically active materials, which are included to improve the conductivity between the electroactive components of the composition and between the electroactive components of the composition and the current collector. The conductive additive may be selected from carbon black, carbon fiber, carbon nanotube, graphene, acetylene black, ketjen black, metal fiber, metal powder, and conductive metal oxide. Preferred conductive additives include carbon black and carbon nanotubes.

[0158] One or more conductive additives may preferably be present in a total amount of 0.5 to 20% by weight, preferably 1 to 15% by weight, preferably 2 to 10% by weight, and most preferably 5 to 10% by weight, based on the total dry weight of the composition.

[0159] In a fourth aspect, the present invention provides an electrode comprising the particulate material according to the first aspect of the present invention in electrical contact with a current collector. The particulate material used to prepare the electrode of the fourth aspect of the present invention may be in the form of the composition according to the third aspect of the present invention.

[0160] The term "current collector" as used in the present application refers to any conductive substrate capable of transporting current to or 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. The current collector is usually in the form of a thin or mesh having a thickness of 3 to 500 μm. The particulate material of the present invention may be provided on one or both surfaces of the current collector, preferably having a thickness in the range of 10 μm to 1 mm, such as 20 to 500 μm, or 50 to 200 μm.

[0161] The electrode of the fourth aspect of the present invention may be manufactured by combining the particulate material of the present invention with a solvent and any one or more viscosity modifying additives to form a slurry. Thereafter, the slurry is cast onto the surface of the current collector, the solvent is removed, thereby forming an electrode layer on the surface of the current collector. Optionally, another step such as heat treatment to cure any binder and / or calendaring of the electrode layer may be performed. Preferably, the electrode layer has a thickness of 20 μm to 2 mm, preferably 20 μm to 1 mm, preferably 20 μm to 500 μm, preferably 20 μm to 200 μm, preferably 20 μm to 100 μm, preferably 20 μm to 50 μm.

[0162] Alternatively, the slurry may be formed into a self-supporting thin film or mat containing the particulate material of the present invention, for example, by casting the slurry onto a suitable casting template, removing the solvent, and then removing the casting template. The resulting thin film or mat is in the form of an aggregated self-standing mass and may then be bonded to the current collector by conventional methods.

[0163] The electrode of the fourth aspect of the present invention may be used as the anode of a metal ion battery. Thus, in a fifth aspect, the present invention provides a rechargeable metal ion battery having an anode, a cathode, and an electrolyte therebetween, the anode having the aforementioned electrode and the cathode containing a cathode active material capable of releasing and reabsorbing metal ions.

[0164] The metal ions are preferably lithium ions. More preferably, the rechargeable metal ion battery of the present invention is a lithium ion battery, and the cathode active material can release and accept lithium ions.

[0165] The cathode active material is preferably a metal oxide-based composite material. Examples of suitable cathode active materials include LiCoO 2 , LiCo 0.99 Al 0.01 O 2 , LiNiO 2 , LiMnO 2 , LiCo 0.5 Ni 0.5 O 2 , LiCo 0.7 Ni 0.3 O 2 , LiCo 0.8 Ni 0.2 O 2 , LiCo 0.82 Ni 0.18 O 2 , LiCo 0.8 Ni 0.15 Al 0.05 O 2 , LiNi 0.4 Co 0.3 Mn 0.3 O 2 and LiNi 0.33 Co 0.33 Mn 0.34 O 2 are mentioned. The cathode current collector generally has a thickness of 3 to 500 μm. Examples of materials that can be used as the cathode current collector include aluminum, stainless steel, nickel, titanium, and sintered carbon.

[0166] The electrolyte is preferably a non-aqueous electrolyte containing a metal salt, such as a lithium salt, and may include, but is not limited to, non-aqueous electrolyte solutions, solid electrolytes, and inorganic solid electrolytes. Examples of non-aqueous electrolyte solutions that can be used include aprotic organic solvents such as propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, sulfolane, methyl sulfolane, and 1,3-dimethyl-2-imidazolidinone.

[0167] Examples of organic solid electrolytes include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate esters polymers, polyester sulfides, polyvinyl alcohol, polyvinylidene fluoride, and polymers containing ionic dissociation groups.

[0168] Examples of inorganic solid electrolytes include nitrides, halides, and sulfides of lithium salts such as Li 5 NI 2 、Li 3 N、LiI、LiSiO 4 、Li 2 SiS 3 、Li 4 SiO 4 、LiOH and Li 3 PO 4 。

[0169] The lithium salt is preferably dissolved in a selected solvent or mixture of solvents. Examples of suitable lithium salts include LiCl, LiBr, LiI, LiClO 4 、LiBF 4 、LiBC 4 O 8 、LiPF 6 、LiCF 3 SO 3 、LiAsF 6 、LiSbF6 , LiAlCl 4 , CH 3 SO 3 Li and CF 3 SO 3 contains Li.

[0170] When the electrolyte is a non-aqueous organic solution, a separator is preferably provided between the anode and the cathode in a metal ion battery. The separator is usually formed from an insulating material having high ion permeability and high mechanical strength. The separator usually has a pore diameter in the range of 0.01 to 100 μm and a thickness in the range of 5 to 300 μm. An example of a suitable electrode separator is a microporous polyethylene film.

[0171] The separator may be replaced with a polymer electrolyte material, and in such a case, the polymer electrolyte material is present inside both the composite anode layer and the composite cathode layer. The polymer electrolyte material may be a solid polymer electrolyte or a gel-type polymer electrolyte.

[0172] In a sixth aspect, the present invention provides the use of the particulate material according to the first aspect of the present invention as an anode active material. If necessary, the particulate material is in the form of a composition according to the third aspect of the present invention.

[0173] The following numbered descriptions provide further disclosure of the present invention: 1. A particulate material composed of a plurality of composite particles, wherein the composite particles (a) a porous particle skeleton having a pore diameter in the range of 3.5 to 100 nm determined by the nitrogen gas adsorption method, and the total pore volume of the pores is P 1 cm 3 per gram of the porous particle skeleton, where P 1 represents a number in the range of 0.3 to 2.4, a porous particle skeleton, and (b) a multilayer coating disposed on the inner pore surface of the porous particle skeleton, and at least (i) The first electroactive material layer, (ii) The second electroactive material layer, and (iii) The first intermediate layer material disposed between the first and second electroactive material layers, A multilayer coating having, A particulate material having.

[0174] 2. The particulate material according to disclosure 1, wherein the porous particle skeleton is a conductive porous particle skeleton.

[0175] 3. The particulate material according to disclosure 2, wherein the conductive porous particle skeleton is a conductive porous carbon particle skeleton.

[0176] 4. The particulate material according to disclosure 3, wherein the conductive porous carbon particle skeleton contains at least 80% by mass of carbon, at least 85% by mass of carbon, at least 90% by mass of carbon, or at least 95% by mass of carbon.

[0177] 5. The P 1 is in the range of 0.6 to 2.4, 0.7 to 2.4, 0.8 to 2.3, 0.9 to 2.2, 0.95 to 2.1, 1 to 2, 1.05 to 1.95, 1.1 to 1.9, 1.15 to 1.85, or 1.2 to 1.8, and is the particulate material according to any one of disclosures 1 to 4.

[0178] 6. The volume ratio of pores having a pore diameter in the range of 5 to 60 nm is at least 50 vol%, at least 55 vol%, at least 60 vol%, at least 65 vol%, at least 70 vol%, at least 75 vol%, at least 80 vol%, at least 85 vol%, or at least 90 vol% based on the total pore volume of pores having a pore diameter in the range of 3.5 to 100 nm in the porous particle skeleton, and is the particulate material according to any one of disclosures 1 to 5.

[0179] 7. The volume ratio of pores having a pore diameter in the range of 10 to 50 nm is The particulate material according to disclosure 6, wherein, based on the total pore volume of pores having a pore diameter in the range of 3.5 to 100 nm in the porous particle skeleton, it is at least 50 vol%, at least 55 vol%, at least 60 vol%, at least 65 vol%, at least 70 vol%, at least 75 vol%, at least 80 vol%, at least 85 vol%, or at least 90 vol%.

[0180] 8. The total pore volume of pores having a diameter of less than 3.5 nm in the porous particle skeleton determined by the nitrogen gas adsorption method is P 2 cm 3 / g, and the P 2 represents a number having a value of less than 0.5, less than 0.45, less than 0.4, less than 0.35, less than 0.3, less than 0.25, less than 0.2, less than 0.15, or less than 0.1, and is the particulate material according to any one of disclosures 1 to 7.

[0181] 9. The total volume of pores having a diameter of less than 3.5 nm in the porous particle skeleton determined by nitrogen gas adsorption is P 2 cm 3 / g, and the P 2 is less than or equal to [1 × P 1 , less than or equal to [0.8 × P 1 , less than or equal to [0.6 × P 1 , less than or equal to [0.5 × P 1 , less than or equal to [0.4 × P 1 , less than or equal to [0.3 × P 1 , less than or equal to [0.2 × P 1 , or less than or equal to [0.1 × P 1 , and is the particulate material according to any one of disclosures 1 to 8.

[0182] 10. The porous particle skeleton has a specific surface area of 250 m 2 / g to 2,500 m 2 / g, 500 m 2 / g to 2,500 m 2 / g, 750 m 2 / g to 2,000 m 2 / g, 750 m 2from 1,750 m to / g 2 750 m, / g 2 from 1,500 m to / g 2 1,000 to 2,000 m, / g 2 1,000 m, / g 2 from 1,750 m to / g 2 1,000 m, / g 2 from 1,500 m to / g 2 1,250 m, / g 2 from 2,000 m to / g 2 1,250 m, / g 2 from 1,750 m to / g 2 2,500 m, / g 2 from 2,000 m to / g 2 2,500 m, / g 2 from 1,750 m to / g 2 or 500 m, / g 2 from 1,500 m to / g 2 The particulate material according to any one of Disclosures 1 to 9, having a BET surface area in the range of / g.

[0183] 11. The particulate material according to any one of Disclosures 1 to 10, wherein the first electroactive material layer and the second electroactive material layer independently have an electroactive material selected from elemental silicon, elemental tin, elemental germanium, elemental aluminum, and mixtures and alloys thereof.

[0184] 12. The particulate material according to Disclosure 11, wherein the first electroactive material layer and the second electroactive material layer have elemental silicon or are composed of elemental silicon.

[0185] 13. The particulate material according to any one of Disclosures 1 to 11, wherein the first intermediate layer material contains carbon, nitrogen, oxygen, or a conductive metal element or alloy.

[0186] 14. The first intermediate layer material has a passivation layer formed on the surface of the first electroactive material layer or is composed of a passivation layer. The passivation layer is an oxide, nitride, oxynitride, or carbide of the first electroactive material. Preferably, the first intermediate layer material is an oxide selected from SiO x where 0 < x ≦ 2, or a nitride selected from SiN x where 0 < x ≦ 4 / 3, or a carbide selected from SiC x where 0 < x ≦ 1, the particulate material according to Disclosure 13.

[0187] 15. The first intermediate layer material has a passivation layer formed on the surface of the first electroactive material layer or is composed of a passivation layer, where the passivation layer contains a carbon-containing organic moiety covalently bonded to the surface of the first electroactive material layer, the particulate material according to Disclosure 13.

[0188] 16. The first intermediate layer material includes a conductive pyrolytic carbon material, the particulate material according to any one of Disclosures 1 to 15.

[0189] 17. The first intermediate layer material includes a conductive metal layer, the particulate material according to any one of Disclosures 1 to 15.

[0190] 18. The first intermediate layer material includes a lithium ion permeable solid electrolyte, the particulate material according to any one of Disclosures 1 to 15.

[0191] 19. The multilayer coating includes n electroactive material layers and (n - 1) intermediate layer materials disposed between each of the electroactive material layers, where n is an integer from 3 to 20, from 3 to 15, from 4 to 12, from 4 to 10, from 5 to 10, or from 5 to 8, the particulate material according to any one of Disclosures 1 to 18.

[0192] 20. Each of the n electroactive materials is independently defined as described in Disclosure 11. Preferably, each of the n electroactive materials is the same electroactive material. More preferably, each of the n electroactive materials is silicon, the particulate material according to Disclosure 19.

[0193] 21. Each of the (n - 1) intermediate layer materials is independently defined as described in any of Disclosures 13 to 18, and optionally, each of the (n - 1) intermediate layer materials is a particulate material as described in Disclosure 19 or 20, which is the same intermediate layer material.

[0194] 22. Further, (iv) a coating layer disposed on the outermost surface of the electroactive material layer and, if necessary, the coating layer is a particulate material as described in any of Disclosures 1 to 21, which is formed from an intermediate layer material as described in Disclosures 13 to 18.

[0195] 23. The amount of the electroactive material in the composite particles is at least 25% of the internal pore volume of the porous particle skeleton and is selected such that up to 80% is occupied by the electroactive material and the intermediate layer material, a particulate material as described in any of Disclosures 1 to 22.

[0196] 24. The composite particles contain 35 wt% to 75 wt% of silicon, 40 wt% to 70 wt% of silicon, or 45 wt% to 65 wt% of silicon, a particulate material as described in any of Disclosures 1 to 23.

[0197] 25. The composite particles contain at least 80 wt% or 80 to 98 wt% in total of silicon and carbon, a particulate material as described in any of Disclosures 1 to 24.

[0198] 26. At least 85 wt%, more preferably at least 90 wt%, more preferably at least 95 wt%, more preferably at least 98 wt% of the mass of the electroactive material within the composite particles is filled within the internal pore volume of the porous particle skeleton, a particulate material as described in any of Disclosures 1 to 25.

[0199] 27. The total oxygen content of the composite particles is less than 15% by weight, less than 10% by weight, less than 5% by weight, less than 2% by weight, less than 1% by weight, or less than 0.5% by weight, and the particulate material according to any one of Disclosures 1 to 26.

[0200] 28. The composite particles have a D 50 particle diameter in the range of 0.5 to 200 μm, 0.5 to 150 μm, 0.5 to 100 μm, 0.5 to 50 μm, 0.5 to 30 μm, 1 to 25 μm, 1 to 20 μm, 2 to 25 μm, 2 to 20 μm, 2 to 18 μm, 3 to 20 μm, 3 to 18 μm, 3 to 15 μm, 4 to 18 μm, 4 to 15 μm, 4 to 12 μm, 5 to 15 μm, 5 to 12 μm, or 5 to 10 μm, and the particulate material according to any one of Disclosures 1 to 27.

[0201] 29. The composite particles have a BET surface area in the range of 0.1 to 100 m 2 / g, or 0.1 to 80 m 2 / g, or 0.5 to 60 m 2 / g, or 0.5 to 40 m 2 / g, or 1 to 30 m 2 / g, or 1 to 25 m 2 / g, or 2 to 20 m 2 / g, and the particulate material according to any one of Disclosures 1 to 28.

[0202] 30. The particulate material according to any one of Disclosures 1 to 29 has a specific capacity during lithiation in the range of 1400 to 2340 mAh / g, preferably 1600 to 2340 mAh / g.

[0203] 31. A method for preparing composite particles, (a) providing a plurality of porous particles, wherein the total pore volume of pores having a pore diameter in the range of 3.5 to 100 nm determined by the nitrogen gas adsorption method is P 1 cm 3 per unit gram of the porous particles, where P 1 represents a number in the range of 0.3 to 2.4, and (b) depositing a first electroactive material layer on the internal pore surface of the porous particles; (c) forming a first intermediate layer material on the surface of the first electroactive material layer; (d) depositing a second electroactive material layer on the surface of the first intermediate layer material; A method comprising the steps above.

[0204] 32. The method according to disclosure 31, wherein the porous particles are conductive porous particles.

[0205] 33. The method according to disclosure 32, wherein the conductive porous particles are conductive porous carbon particles.

[0206] 34. The method according to disclosure 33, wherein the conductive porous carbon particles contain at least 80% by mass of carbon, at least 85% by mass of carbon, at least 90% by mass of carbon, or at least 95% by mass of carbon.

[0207] 35. The P 1 is in the range of 0.6 to 2.4, 0.7 to 2.4, 0.8 to 2.3, 0.9 to 2.2, 0.95 to 2.1, 1 to 2, 1.05 to 1.95, 1.1 to 1.9, 1.15 to 1.85, or 1.2 to 1.8, for the particulate material according to any one of disclosures 31 to 34.

[0208] 36. The volume ratio of pores having a pore diameter in the range of 5 to 60 nm is at least 50 vol%, at least 55 vol%, at least 60 vol%, at least 65 vol%, at least 70 vol%, at least 75 vol%, at least 80 vol%, at least 85 vol%, or at least 90 vol% based on the total pore volume of pores having a pore diameter in the range of 3.5 to 100 nm in the porous particle skeleton, for the particulate material according to any one of disclosures 31 to 35.

[0209] 37. The volume ratio of pores having a pore diameter in the range of 10 to 50 nm is at least 50 vol%, at least 55 vol%, at least 60 vol%, at least 65 vol%, at least 70 vol%, at least 75 vol%, at least 80 vol%, at least 85 vol%, or at least 90 vol% based on the total pore volume of pores having a pore diameter in the range of 3.5 to 100 nm in the porous particle skeleton. The particulate material according to Disclosure 36.

[0210] 38. The total pore volume of pores having a diameter of less than 3.5 nm in the porous particles determined by the nitrogen gas adsorption method is P 2 cm 3 / g, and the P 2 represents a number having a value of less than 0.5, less than 0.45, less than 0.4, less than 0.35, less than 0.3, less than 0.25, less than 0.2, less than 0.15, or less than 0.1. The particulate material according to any one of Disclosures 31 to 37.

[0211] 39. The total volume of pores having a diameter of less than 3.5 nm in the porous particles determined by nitrogen gas adsorption is P 2 cm 3 / g, and the P 2 is less than or equal to [1 × P 1 , less than or equal to [0.8 × P 1 , less than or equal to [0.6 × P 1 , less than or equal to [0.5 × P 1 , less than or equal to [0.4 × P 1 , less than or equal to [0.3 × P 1 , less than or equal to [0.2 × P 1 , or less than or equal to [0.1 × P 1 . The particulate material according to any one of Disclosures 31 to 38.

[0212] 40. The porous particles have a specific surface area of 250 m 2 / g to 2,500 m 2 / g, 500 m 2 / g to 2,500 m 2 / g, 750 m 2 / g to 2,000 m2 / g, 750 m 2 / g to 1,750 m 2 / g, 750 m 2 / g to 1,500 m 2 / g, 1,000 to 2,000 m 2 / g, 1,000 m 2 / g to 1,750 m 2 / g, 1,000 m 2 / g to 1,500 m 2 / g, 1,250 m 2 / g to 2,000 m 2 / g, 1,250 m 2 / g to 1,750 m 2 / g, 2500 m 2 / g to 2,000 m 2 / g, 2500 m 2 / g to 1,750 m 2 / g, or 500 m 2 / g to 1,500 m 2 The particulate material according to any one of Disclosures 31 to 39, having a BET surface area in the range of / g.

[0213] 41. The porous particles have a D particle diameter in the range of 0.5 to 200 μm, 0.5 to 150 μm, 0.5 to 100 μm, 0.5 to 50 μm, 0.5 to 30 μm, 1 to 25 μm, 1 to 20 μm, 2 to 25 μm, 2 to 20 μm, 2 to 18 μm, 3 to 20 μm, 3 to 18 μm, 3 to 15 μm, 4 to 18 μm, 4 to 15 μm, 4 to 12 μm, 5 to 15 μm, 5 to 12 μm, or 5 to 10 μm. 50 The particulate material according to any one of Disclosures 31 to 40, having the particle diameter.

[0214] 42. The first electroactive material and the second electroactive material are independently selected from elemental silicon, elemental tin, elemental germanium, elemental aluminum, and mixtures and alloys thereof, and are the particulate material according to any one of Disclosures 31 to 41.

[0215] 43. At least one of the first and / or second electroactive materials is deposited by a chemical vapor infiltration (CVI) process using a gaseous precursor of the first and / or second electroactive material, according to any of the methods described in Disclosures 31 to 42.

[0216] 44. The gaseous precursors of the first and second electroactive materials are, independently of each other, silane (SiH 4 ), disilane (Si 2 H 6 ), trisilane (Si 3 H 8 ), tetrasilane (Si 4 H 10 ), methyltrichlorosilane (CH 3 SiCl 3 ), or trichlorosilane (HSiCl 3 ) 2 SiCl 2 ) such as dimethyldichlorosilane ((CH 3 ) 3 ) 3 Si] 2 N] 2 Sn), tetraallyltin ((H 2 C=CHCH 2 ) 4 Sn), tetrakis(diethylamide)tin(IV) ([(C 2 H 5 ) 2 N] 4 Sn), tetrakis(dimethylamide)tin(IV) ([(CH 3 ) 2 N] 4 Sn), tetramethyltin (Sn(CH 3 ) 4 ), tetravinyltin (Sn(CH=CH 2 ) 4 ), tin(II) acetylacetonate (C 10 H 14 O 4 Sn), trimethyl(phenylethynyl)tin (C 6 H 5 C)≡CSn(CH 3 ) 3) Trimethyl(phenyl)tin (C 6 H 5 Sn(CH 3 ) 3 ) Aluminum tris(2,2,6,6 - tetramethyl - 3,5 - heptanedionate) (Al(OCC(CH 3 ) 3 CHCOC(CH 3 ) 3 ) 3 ) Trimethylaluminum ((CH 3 ) 3 Al), Tris(dimethylamide)aluminum(III) (Al(N(CH 3 ) 2 ) 3 ) Germanium (GeH 4 ), Hexamethyldigermane ((CH 3 ) 3 GeGe(CH 3 ) 3 ) Tetramethylgermane ((CH 3 ) 4 Ge), Tributylgermane hydride ([CH 3 (CH 2 ) 3 3 GeH), Triethylgermane hydride ((C 2 H 5 ) 3 GeH), and Triphenylgermane hydride ((C 6 H 5 ) 3 GeH)) selected from the method described in Disclosure 43.

[0217] 45. Both the first electroactive material and the second electroactive material are elemental silicon, If necessary, the gaseous precursors of the first and second electroactive materials are, independently of each other, silane (SiH 4 ), disilane (Si 2 H 6 ), trisilane (Si 3 H 8 ), tetrasilane (Si 4 H 10 ), trichlorosilane (HSiCl 3 ​) methyltrichlorosilane (CH 3 SiCl 3 ), and dimethyldichlorosilane ((CH 3 ) 2 SiCl 2 ), selected from, If necessary, the gaseous precursors of the first and second electroactive materials are silane (SiH 4 ), the method according to disclosure 42 or 44.

[0218] 46. Steps (b) and (d) are, independently of each other, contacting the plurality of porous particles with a gas comprising 1 to 100 vol%, 1 to 50 vol%, 2 to 40 vol%, 5 to 30 vol%, or 5 to 25 vol% of the respective gaseous precursor, the method according to any of disclosures 43 to 45.

[0219] 47. Steps (b) and (d) are carried out independently of each other at a temperature in the range of 300 to 700 °C, 350 to 700 °C, 400 to 700 °C, 400 to 650 °C, 400 to 600 °C, 400 to 550 °C, 400 to 500 °C, 400 to 450 °C, or 450 to 500 °C, the method according to any of disclosures 31 to 46.

[0220] 48. Step (c) has the step of passivating the surface of the first electroactive material layer with air or another oxygen-containing gas such that the first intermediate layer material becomes an oxide of the first electroactive material, the method according to any of disclosures 31 to 47.

[0221] 49. Step (c) has the step of passivating the surface of the first electroactive material layer with (i) ammonia, (ii) a gas containing ammonia and oxygen, or (iii) phosphine such that the first intermediate layer material contains a nitride, oxynitride or phosphide of the first electroactive material, the method according to any of disclosures 31 to 47.

[0222] 50. The step (c) is a passivating agent selected from one or more compounds of the following formulae: (i) R 1 -CH=CH-R 1 , (ii) R 1 -C≡C-R 1 , (iii) O=CR 1 R 1 , (iv) HX-R 2 , (v) HX-C(O)-R1, where X represents O, S, NR 1 or PR 1 , each R 1 independently of one another represents H, or an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having from 1 to 20 carbon atoms, or two R 1 groups form an unsubstituted or substituted ring structure containing from 3 to 8 carbon atoms in the ring, R 2 represents an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having from 1 to 20 carbon atoms, or R 1 and R 2 together form an unsubstituted or substituted ring structure containing from 3 to 8 carbon atoms in the ring; comprising the step of passivating the surface of the first electroactive material layer, The method according to any one of disclosures 31 to 47, wherein the first intermediate layer material comprises a carbon-containing organic moiety covalently bonded to the surface of the first electroactive material layer.

[0223] 51. The method according to any one of disclosures 31 to 50, wherein the step (c) comprises depositing a layer of a conductive pyrolytic carbon material on the surface of the optionally passivated first electroactive material layer.

[0224] 52. The step (c) comprises depositing a layer of a conductive metal on the surface of the optionally passivated first electroactive material layer, If necessary, the conductive metal is silver, according to the method described in any of Disclosures 31 to 50.

[0225] 53. Step (c) has the step of depositing a layer of a lithium-ion permeable solid electrolyte on the surface of the optionally passivated first electroactive material layer, according to the method described in any of Disclosures 31 to 50.

[0226] 54. Steps (c) and (d) are repeated one or more times to form a particulate material, The particulate material has n electroactive material layers and (n - 1) intermediate layer materials disposed between each of the electroactive material layers, where n is an integer from 3 to 20, from 3 to 15, from 3 to 12, from 3 to 10, from 4 to 10, or from 5 to 8, according to the method described in any of Disclosures 31 to 53.

[0227] 55. Each repetition of step (d) is independently defined as in any of Disclosures 42 to 47, and if necessary, each of the n electroactive materials is the same electroactive material, and if necessary, each of the n electroactive materials is silicon, according to the method described in Disclosure 54.

[0228] 56. Each repetition of step (c) is independently defined as in Disclosures 48 to 53, and if necessary, each of the (n - 1) intermediate layer materials is the same intermediate layer material, according to the method described in Disclosure 54 or 55.

[0229] 57. Further, (e) forming a coating layer on the surface of the last deposited electroactive material layer, Optionally, step (e) has any of the features of step (c) described in Disclosures 48 to 53, according to the method described in any of Disclosures 31 to 56.

[0230] 58. A composition comprising a particulate material according to any one of Disclosures 1 to 30 and at least one other component.

[0231] 59. A composition according to disclosure 58, comprising from 1 to 95% by weight, from 2 to 90% by weight, from 5 to 85% by weight, or from 10 to 80% by weight of the particulate material according to disclosures 1 to 27, based on the total dry weight of the composition.

[0232] 60. The composition according to disclosure 58 or 59, wherein the at least one other component is selected from (i) a binder, (ii) a conductive additive, and (iii) an additional particulate electroactive material.

[0233] 61. A composition according to disclosure 60, comprising at least one additional particulate electroactive material, which, if necessary, is selected from graphite, hard carbon, silicon, tin, germanium, aluminum, and lead.

[0234] 62. An electrode comprising the particulate material according to any one of disclosures 1 to 30 in electrical contact with a current collector, which, if necessary, is in the form of the composition according to disclosures 58 to 61.

[0235] 63. A rechargeable metal ion battery, (i) an anode comprising the electrode according to disclosure 62, (ii) a cathode comprising a cathode active material capable of releasing and reabsorbing metal ions, (iii) an electrolyte between the anode and the cathode, and having a metal ion battery.

[0236] 64. Use of the particulate material according to any one of disclosures 1 to 30 as an anode active material.

[0237] 65. The use according to disclosure 64, wherein the particulate material is in the form of the composition according to disclosures 58 to 61.

[0238] (Example - Preparation of Composite Particles in a Fluidized Bed Reactor) A stainless steel fluidized bed reactor with a gas inlet consisting of five nozzles each having an 8×0.8 mm hole was charged with 70 g of particulate porous carbon skeleton so that dispersed gas mixing was possible. The cross-sectional area of the fluidized bed was 0.058 m, and the superficial velocity could be calculated. The reactor was suspended from the frame, and a vertical tube furnace was arranged such that the high-temperature zone was 3 / 4 of the length from the conical section to the cylindrical section (a length of about 380 mm). The minimum fluidization velocity was determined by a cold flow pressure drop test using nitrogen as the inert gas. The ramping gas flow rate was between 1 and 5 L / min. Once the minimum fluidization velocity was determined, the inert gas flow rate was kept constant above the minimum fluidization velocity. The furnace was heated up to the desired reaction temperature under a constant inert gas flow rate. After the target temperature stabilized between 435 and 500 °C, the fluidizing gas was switched from pure nitrogen to a gas containing 4 vol% monosilane in nitrogen. The progress of the reaction was monitored by measuring the pressure drop between the top and bottom and the temperature difference of the furnace. To maintain a pressure drop consistent with continuous fluidization, the gas flow rate was adjusted throughout the run, and a minimum temperature difference of less than 100 °C was maintained between the top and bottom of the fluidized bed. The supply of monosilane was carried out over 6 hours or according to the thickness of the layer, after which the reactor was purged with nitrogen for 30 minutes to remove excess monosilane. Next, a pyrolytic carbon intermediate layer was formed by passing a 30% ethylene / nitrogen mixed gas at a temperature of 300 to 500 °C for 30 minutes, and then the reactor was purged with nitrogen for 30 minutes to remove any ethylene. The process of introducing the monosilane and ethylene reactants was repeated according to the number of layers required. At the end of the lamination technique, while maintaining fluidization, the fluidizing gas was switched to pure nitrogen, and this purge was continued for 30 minutes. Next, the furnace was cooled to ambient temperature over several hours. After reaching ambient temperature, the furnace atmosphere was gradually switched to air over several hours.

Claims

1. A particulate material composed of a plurality of composite particles, The composite particles include (a) a porous particulate scaffold, the total pore volume of pores having pore diameters in the range of 3.5 to 100 nm as determined by nitrogen gas adsorption is P per gram of said porous particulate scaffold; 1 cm 3 where P 1 represents a number ranging from 0.3 to 2.4; and (b) a multi-layer coating disposed on the interior pore surfaces of the porous particulate scaffold, the multi-layer coating comprising at least (i) a first electroactive material layer; (ii) a second electroactive material layer; and (iii) a first interlayer material disposed between the first and second electroactive material layers; and a multi-layer coating having 1. A particulate material having the following structure:

2. 2. The particulate material of claim 1, wherein the porous particle scaffold is an electrically conductive porous particle scaffold.

3. the conductive porous particle skeleton is a conductive porous carbon particle skeleton, 3. The particulate material of claim 2, wherein the electrically conductive porous carbon particle skeleton comprises at least 80% by weight carbon, at least 85% by weight carbon, at least 90% by weight carbon, or at least 95% by weight carbon.

4. P 1 4. The particulate material of claim 1 , wherein Mn is in the range of 0.6 to 2.4, 0.7 to 2.4, 0.8 to 2.3, 0.9 to 2.2, 0.95 to 2.1, 1 to 2, 1.05 to 1.95, 1.1 to 1.9, 1.15 to 1.85, or 1.2 to 1.

8.

5. 5. A particulate material according to any one of claims 1 to 4, wherein the volume fraction of pores having a pore diameter in the range of 5 to 60 nm is at least 50 vol%, at least 55 vol%, at least 60 vol%, at least 65 vol%, at least 70 vol%, at least 75 vol%, at least 80 vol%, at least 85 vol%, or at least 90 vol%, based on the total pore volume of pores having a pore diameter in the range of 3.5 to 100 nm in the porous particle skeleton.

6. The total pore volume of pores having a diameter of less than 3.5 nm in the porous particle skeleton as determined by nitrogen gas adsorption is P 2 cm 3 / g, The P 2 6. The particulate material of claim 1 , wherein m represents a number having a value less than 0.5, less than 0.45, less than 0.4, less than 0.35, less than 0.3, less than 0.25, less than 0.2, less than 0.15, or less than 0.

1.

7. The total volume of pores having a diameter of less than 3.5 nm in the porous particle skeleton as determined by nitrogen gas adsorption is P 2 cm 3 / g, The P 2 is [1×P 1 ] and below, [0.8×P 1 ]or below,[0.6×P 1 ]or below,[0.5×P 1 ]or below, [0.4×P 1 ]or below, [0.3×P 1 ]or below, [0.2×P 1 ]or less than [0.1×P 1 7. A particulate material according to any one of claims 1 to 6, wherein the molecular weight of the particulate material is equal to or less than 1.

8. The porous particle framework is 250 mm 2 / g to 2,500m 2 / g, 500m 2 / g to 2,500m 2 / g, 750m 2 / g to 2,000m 2 / g, 750m 2 / g to 1,750m 2 / g, 750m 2 / g to 1,500m 2 / g, 1,000 to 2,000m 2 / g, 1,000m 2 / g to 1,750m 2 / g, 1,000m 2 / g to 1,500m 2 / g, 1,250m 2 / g to 2,000m 2 / g, 1,250m 2 / g to 1,750m 2 / g, 2500m 2 / g to 2,000m 2 / g, 2500m 2 / g to 1,750m 2 / g, or 500m 2 / g to 1,500m 2 8. The particulate material of claim 1 , having a BET surface area in the range of 0.1% to 1.0% by mass.

9. 9. A particulate material according to any one of claims 1 to 8, wherein the first electroactive material layer and the second electroactive material layer, independently of each other, have an electroactive material selected from elemental silicon, elemental tin, elemental germanium, elemental aluminum, and mixtures and alloys thereof.

10. The particulate material of claim 9, wherein the first electroactive material layer and the second electroactive material layer comprise or are composed of elemental silicon.

11. the first interlayer material having or consisting of a passivation layer formed on a surface of the first electroactive material layer; 11. The particulate material of claim 1, wherein the passivation layer is an oxide, nitride, oxynitride, or carbide of the first electroactive material.

12. the first interlayer material having or consisting of a passivation layer formed on a surface of the first electroactive material layer; 11. A particulate material according to claim 1, wherein the passivation layer comprises a carbon-containing organic moiety covalently bonded to the surface of the first electroactive material layer.

13. 13. The particulate material of claim 1, wherein the first intermediate layer material comprises a conductive pyrolytic carbon material, a conductive metal layer, or a lithium ion permeable solid electrolyte.

14. 14. The particulate material of any one of claims 1 to 13, wherein the multilayer coating comprises n electroactive material layers and (n-1) intermediate layer materials disposed between each of the electroactive material layers, where n is an integer from 3 to 20, 3 to 15, 4 to 12, 4 to 10, 5 to 10, or 5 to 8.

15. (i) each of the n electroactive materials is independently defined as claimed in claim 9 or 10; and / or (ii) The particulate material of claim 14, wherein each of the (n-1) intermediate layer materials is independently defined as in any of claims 11 to 13.

16. moreover, (iv) a coating layer disposed on an outermost surface of the electroactive material layer; 16. The particulate material according to claim 1 , having the following structure:

17. 17. A particulate material according to any one of claims 1 to 16, wherein the amount of said electroactive material in said composite particles is selected such that at least 25% and up to 80% of the internal pore volume of said porous particle skeleton is occupied by said electroactive material and said intermediate layer material.

18. 18. A particulate material according to any one of claims 1 to 17, wherein the composite particles comprise from 35% to 75% by weight silicon, from 40% to 70% by weight silicon, or from 45% to 65% by weight silicon.

19. 19. A particulate material according to any one of claims 1 to 18, wherein at least 85% by mass of the electroactive material within the composite particles is filled within the internal pore volume of the porous particle skeleton.

20. The composite particles may have a D in the range of 0.5 to 200 μm, 0.5 to 150 μm, 0.5 to 100 μm, 0.5 to 50 μm, 0.5 to 30 μm, 1 to 25 μm, 1 to 20 μm, 2 to 25 μm, 2 to 20 μm, 2 to 18 μm, 3 to 20 μm, 3 to 18 μm, 3 to 15 μm, 4 to 18 μm, 4 to 15 μm, 4 to 12 μm, 5 to 15 μm, 5 to 12 μm, or 5 to 10 μm. 50 20. A particulate material according to any one of the preceding claims, having a particle diameter of 0.1 mm.

21. 1. A method for preparing a composite particle, comprising: (a) providing a plurality of porous particles, the total pore volume of pores having pore diameters in the range of 3.5 to 100 nm as determined by nitrogen gas adsorption is P per gram of said porous particles; 1 cm 3 where P 1 represents a number ranging from 0.3 to 2.4, and (b) depositing a first electroactive material layer on the interior pore surfaces of the porous particle; (c) forming a first interlayer material on a surface of the first electroactive material layer; (d) depositing a second electroactive material layer on a surface of the first interlayer material; The method comprising:

22. 22. The method of claim 21 , wherein the porous particles have any of the characteristics defined for a porous particle scaffold according to claims 2 to 8.

23. 23. The method of claim 21 or 22, wherein the first and second electroactive materials deposited in steps (b) and / or (d) are, independently of each other, selected from elemental silicon, elemental tin, elemental germanium, elemental aluminum, and mixtures and alloys thereof.

24. 24. The method of any one of claims 21 to 23, wherein at least one of the first and / or second electroactive materials is deposited in steps (b) and / or (d) by a chemical vapor infiltration (CVI) process using a gaseous precursor of the first and / or second electroactive material.

25. The gaseous precursors of the first and second electroactive materials may be, independently of one another, silane (SiH 4 ), disilane (Si 2 H 6 ), trisilane (Si 3 H 8 ), tetrasilane (Si 4 H 10 ), methyltrichlorosilane (CH 3 SiCl 3 ) or dimethyldichlorosilane ((CH 3 ) 2 SiCl 2 Trichlorosilane (HSiCl) 3 ), bis[bis(trimethylsilyl)amino]tin(II) ([[(CH 3 ) 3 Si] 2 N] 2 Sn), tetraaryltin ((H 2 C=CHCH 2 ) 4 Sn), tetrakis(diethylamido)tin(IV) ([(C 2 H 5 ) 2 N] 4 Sn), tetrakis(dimethylamido)tin(IV) ([(CH 3 ) 2 N] 4 Sn, tetramethyltin (Sn(CH 3 ) 4 ), tetravinyltin (Sn(CH=CH 2 ) 4 ), tin(II) acetylacetonate (C 10 H 14 O 4 Sn), trimethyl(phenylethynyl)tin (C 6 H 5 C)≡CSn(CH 3 ) 3 ), trimethyl(phenyl)tin (C 6 H 5 Sn(CH 3 ) 3 ), aluminum tris(2,2,6,6-tetramethyl-3,5-heptanedionate (Al(OCC(CH 3 ) 3 CHCOC (CH 3 ) 3 ) 3 ), trimethylaluminum ((CH 3 ) 3 Al), tris(dimethylamido)aluminum(III), (Al(N(CH 3 ) 2 ) 3 ), German (GeH 4 ), hexamethyldigermanium ((CH 3 ) 3 GeGe (CH 3 ) 3 ), tetramethylgermanium ((CH 3 ) 4 Ge), tributylgermanium hydride ([CH 3 (CH 2 ) 3 ] 3 GeH), triethylgermanium hydride ((C 2 H 5 ) 3 GeH), and triphenylgermanium hydride ((C 6 H 5 ) 3 25. The method of claim 24, wherein the at least one aryl group is selected from the group consisting of aryl, aryloxy ...

26. 26. The method of claim 24 or 25, wherein steps (b) and (d) independently of one another comprise contacting the plurality of porous particles with a gas comprising 1 to 100 vol%, 1 to 50 vol%, 2 to 40 vol%, 5 to 30 vol%, or 5 to 25 vol% of the respective gaseous precursor.

27. 27. The method of any one of claims 21 to 26, wherein steps (b) and (d) are carried out, independently of one another, at a temperature in the range of 300 to 700°C, 350 to 700°C, 400 to 700°C, 400 to 650°C, 400 to 600°C, 400 to 550°C, 400 to 500°C, 400 to 450°C, or 450 to 500°C.

28. The step (c) (a) air or other oxygen-containing gas such that the first interlayer material comprises an oxide of the first electroactive material; (b) a gas comprising ammonia or ammonia and oxygen, such that the first interlayer material comprises a nitride or oxynitride of the first electroactive material; (c) a phosphine, such that the first interlayer material comprises a phosphide of the first electroactive material; or (d) a passivating agent selected from one or more compounds of the following formula: (i)R 1 -CH=CH-R 1 、 (ii) R 1 -C≡C-R 1 、 (iii)O=CR 1 R 1 、 (iv)HX-R 2 、 (v) HX-C(O)-R1, where X is O, S, or NR 1 or PR 1 represents Each R 1 represent, independently of each other, 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 from 3 to 8 carbon atoms in the ring; R 2 represents an unsubstituted or substituted aliphatic or aromatic hydrocarbyl group having 1 to 20 carbon atoms, or R 1 and R 2 together form an unsubstituted or substituted ring structure containing from 3 to 8 carbon atoms in the ring; passivating the surface of the first electroactive material layer by 28. The method of claim 21, wherein the first interlayer material comprises a carbon-containing organic moiety covalently bonded to the surface of the first electroactive material layer.

29. Step (c) comprises depositing on a surface of the optionally passivated first electroactive material layer: (a) an electrically conductive pyrolytic carbon material; (b) A conductive metal; or (c) a lithium-ion permeable solid electrolyte; 29. A method according to any one of claims 21 to 28, comprising depositing a layer of:

30. Steps (c) and (d) are repeated one or more times to form a particulate material; the particulate material having n electroactive material layers and (n-1) interlayer materials disposed between each of the electroactive material layers; 30. The method of any one of claims 21 to 29, wherein n is an integer from 3 to 20, 3 to 15, 3 to 12, 3 to 10, 4 to 10, or 5 to 8.

31. (i) each repetition of step (d) is independently defined as in any one of claims 23 to 27; and / or (ii) the method of claim 30, wherein each repetition of step (c) is independently defined as in claim 28 or claim 29.

32. moreover, (e) forming a coating layer on the surface of the last deposited electroactive material layer; 32. The method of any one of claims 21 to 31, comprising:

33. 21. A composition comprising a particulate material according to any one of claims 1 to 20 and at least one other ingredient.

34. 21. An electrode comprising a particulate material according to any one of claims 1 to 20 in electrical contact with a current collector.

35. 1. A rechargeable metal ion battery, comprising: (i) an anode comprising the electrode of claim 34; and (ii) a cathode comprising a cathode active material capable of releasing and resorbing metal ions; (iii) an electrolyte between the anode and the cathode; A metal ion battery comprising:

36. 21. Use of a particulate material according to any one of claims 1 to 20 as an anode active material.

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