Patent Description:
Metals forming compounds or alloys with lithium exhibit very high specific charge in the negative electrode in lithium ion batteries. For example, the theoretical specific charge of silicon metal electrodes can be up to <NUM>'<NUM> mAh/g. However, silicon particles can crack owing to the large volume expansion of silicon when inserting lithium electrochemically (i.e., during lithium intercalation and de-intercalation). This cracking problem is known as silicon pulverization. Further, the creation of new surfaces during particle cracking can lead to excessive electrolyte decomposition and de-contacting of the silicon from the electrode. Silicon pulverization manifests as specific charge losses after several charge/discharge cycles as well as irreversible capacity during first cycle charge and discharge and, in general, poor cycle stability. These are significant limitations that have delayed the adoption of silicon-based active materials in commercial lithium-ion batteries.

Certain silicon / carbon particles have been described in the art. For example, <CIT> describes processes for making Stable-Porous-Silicon, wherein the silicon particles are subsequently coated with carbon. <CIT> describes the manufacture of a porous carbon material using silica as templating agent which is subsequently removed by chemical treatment. <CIT> discloses silicon / carbon composite particles having a size of between <NUM> and <NUM>. Finally, <CIT> describes processes for making certain silicon / carbon composite particles involving dry milling and wet milling steps.

Accordingly, there is an ongoing need to develop new silicon active materials for electrode materials which address the problem of silicon pulverization and the concomitant cycling stability problems.

A first aspect of the present invention is directed to a silicon-carbon particulate composite suitable for use as active material in a negative electrode of a Li-ion battery, characterized by:.

A second aspect of the present invention is directed to a precursor composition for a negative electrode of a Li-ion battery, the precursor composition comprising a silicon-carbon particulate composite according to first aspect, comprising a further carbonaceous particulate, optionally wherein the further carbonaceous particulate comprises at least two different types of carbonaceous particulate.

A third aspect of the present invention is directed to a negative electrode comprising a silicon-carbon particulate composite according to the first aspect.

A fourth aspect of the present invention is directed to a negative electrode comprising a precursor composition according to the second aspect.

A fifth aspect of the present invention is directed to a Li-ion battery comprising a negative electrode according to the third or fourth aspect.

A sixth aspect of the present invention is directed to a method of making a silicon-carbon particulate composite according to the first aspect of the present invention, comprising co-milling silicon and carbonaceous starting materials under wet conditions in the presence of solvent to produce a silicon-carbon particulate composite having a nanostructure which inhibits or prevents silicon pulverization when used as active material in a negative electrode of a Li-ion battery and/or which maintains electrochemical capacity of a negative electrode; wherein the silicon starting material is a micronized silicon particulate having a particle size of from <NUM> to <NUM>, for example, from <NUM> to <NUM>.

A seventh aspect of the present invention is directed to a method of preparing a precursor composition for a negative electrode of a Li-ion battery, comprising preparing, obtaining, providing or supplying a silicon-carbon particulate composite according to the first aspect or obtainable by a method according to the sixth aspect, and combining with a further carbonaceous particulate.

An eigth aspect of the present invention is directed to a method of preparing a precursor composition for a negative electrode of a Li-ion battery, comprising, preparing, obtaining, providing or supplying a carbonaceous particulate and combining with a silicon-carbon particulate composite according to the first aspect or obtainable by a method according to the sixth aspect.

A ninth aspect of the present invention is directed to the use of a silicon-carbon particulate composite according to the first aspect as active material in a negative electrode of a Li-ion battery to inhibit or prevent silicon pulverization during cycling, for example, during 1st cycle Li intercalation or de-intercalation and/or to maintain electrochemical capacity after100 cycles.

A tenth aspect of the present invention is directed to the use, as active material in a negative electrode of a Li-ion battery, of a silicon-carbon particulate composite according to the first aspect, for improving cycling stability of the Li-ion battery compared to a Li-ion battery which comprises an active material which is a mixture of silicon particulate and carbonaceous particulate which is not a composite and/or does not have a nanostructure which inhibits or prevents silicon pulverization during cycling, for example, during 1st cycle Li intercalation, and/or which is not prepared by co-milling and/or does not have a nanostructure which maintains electrochemical after <NUM> cycles.

An eleventh aspect of the present invention is directed to the use of a carbonaceous particulate material in a negative electrode of a Li-ion battery, wherein the negative electrode comprises a silicon-carbon particulate composite according to the first aspect.

A twelfth aspect of the present invention is directed to a device comprising the negative electrode according to the third and/or fourth aspect, or comprising a Li-ion battery according to the fifth aspect.

A thirteenth aspect of the present invention is directed to an energy storage cell comprising a silicon-carbon particulate composite according to the first aspect or a precursor composition according to the second aspect.

A fourteenth aspect of the present invention is directed to an energy storage and conversion system comprising a silicon-carbon particulate composite according to the first aspect or a precursor composition according to the second aspect.

It has surprisingly been found that by controlling the nanostructure and morphology of a silicon-carbon particulate, by co-milling silicon and carbonaceous starting materials under conditions which promote the formation of said nanostructure and morphology, produces a composite material that exhibits Si-nanodomains in close contact to conductive carbon in a three-dimensional network-like structures which are well suited to accommodate the large volume change that occurs with lithium-intercalation and de-intercalation in a negative electrodes of a Li-ion battery. More particularly, the silicon-carbon particulate inhibits or mitigates silicon pulverization during electrochemical lithium insertion/extraction and de-contacting effects which can occur with such large volume changes, by reducing the extent of the volume change and/or by providing sufficient pore void space to better accommodate said volume expansion during lithiation, thus improving cycling stability and/or reducing capacity losses during cycling of the Li-ion battery. Contact between nano-Si domains also remains favorable because of the three-dimensional network-like structure of these composites, as opposed to one-dimensional nano-Si morphologies (e.g. Si-nanotubes or nanowires) that upon breakage at a single point result in de-contacted nano-Si structures.

The silicon-carbon particulate composite suitable for use as active material in a negative electrode of a Li-ion battery is characterized by:.

By "silicon-carbon particulate composite" is meant a particulate composite in which individual particles have a morphology other than a one-dimensional morphology such as nanotubes or nanowires.

By "microporosity" is meant the % of external surface area of micropores in relation to the total BET specific surface area of the particulate. As used herein, a "micropore" means a pore width of less than <NUM>, a "mesopore" means a pore width of from <NUM> to <NUM>, and a "macropore" means a pore width of greater than <NUM>, in accordance with the IUPAC classification.

In certain embodiments (which may be referred to as Embodiment A), the silicon-carbon particulate has one or more of:.

In such embodiments, the microporosity may be from about <NUM>-<NUM> %, or from about <NUM>-<NUM> %, or from about <NUM>-<NUM> %, the BJH average pore width may be from about <NUM> to about <NUM>, or from about <NUM>-<NUM>, or from about <NUM>-<NUM>, and the BJH volume of pores may be at least about <NUM><NUM>/g, for example, from about <NUM>-<NUM><NUM>/g, or from about <NUM>-<NUM><NUM>/g.

In certain embodiments (which may be referred to as Embodiment B), the silicon-carbon particulate has one or more of:.

In certain embodiments, the silicon-carbon particulate composite may be further characterized in having a BET specific surface area (SSA) equal to or lower than about <NUM><NUM>/g.

In certain embodiments, the silicon-carbon particulate composite has an average particle size of from about <NUM>-<NUM>, or from about <NUM>-<NUM>, or from about <NUM>-<NUM>, or from about <NUM>-<NUM>, or from about <NUM>-<NUM>.

The BET SSA, pore volume and average particle size may vary depending on the amount of silicon in the silicon-carbon particulate. For example, at high silicon levels, e.g., a weight ratio of Si:C of at least about <NUM>:<NUM>, or at least about <NUM>:<NUM>, or at least about <NUM>:<NUM>, or at least about <NUM>:<NUM>, or at least about <NUM>:<NUM>, or at least about <NUM>:<NUM>, the BET SSA and pore volume will be higher, and the average particle size will be lower, compared to a silicon-carbon particulate in which the weight ratio of Si:C is at least about <NUM>:<NUM>, or at least about <NUM>:<NUM>, or at least about <NUM>:<NUM>, or at least about <NUM>:<NUM>, or at least about <NUM>:<NUM>, or at least about <NUM>:<NUM>.

Thus, in certain embodiments, such as Embodiment A, the silicon-carbon particulate composite may be further characterized in having:.

In such embodiments, the BET SSA may be from about <NUM>-<NUM><NUM>/g, the average particle size may be from about <NUM>-<NUM>, for example, from about <NUM>-<NUM> , or from about <NUM>-<NUM>, the BJH average pore width may be from about <NUM> to about <NUM>, the BJH volume of pores may be from about <NUM><NUM>/g, to about <NUM><NUM>/g, and the microporosity may be from about <NUM>-<NUM> %, for example, from about <NUM>-<NUM> % or from about <NUM>-<NUM> %.

In certain embodiments, such as Embodiment B, the silicon-carbon particulate composite may be further characterized in having:.

In such embodiments, the BET SSA may be from about <NUM>-<NUM><NUM>/g, the average particle size may be from about <NUM>-<NUM>, for example, from about <NUM>-<NUM>, or about <NUM>-<NUM>, the BJH average pore width may be from about <NUM> to about <NUM>, the BJH volume of pores may be from about <NUM><NUM>/g, to about <NUM><NUM>/g, and the microporosity may be from about <NUM>-<NUM> %, for example, from about <NUM>-<NUM> %.

In certain embodiments, such as Embodiment A, a majority of the silicon-carbon particulate composite is silicon, based on the total weight of the composite, for example, at least about <NUM> wt. %, or at least about <NUM> wt. %, or at least about <NUM> wt. %, or at least about <NUM> wt. % of the composite is silicon.

In certain embodiments, such as Embodiment B, a majority of the silicon-carbon particulate composite is carbon, based on the total weight of the composite, for example, at least about <NUM> wt. %, or at least about <NUM> wt. %, or at least about <NUM> wt. %, or at least about <NUM> wt. % of the composite is carbon.

In certain embodiments, the silicon-carbon particulate composition has a nanostructure which inhibits or prevents silicon pulverization when used as active material in a negative electrode of a Li-ion battery.

By "inhibiting or preventing silicon pulverization" is meant that Li is de-intercalated in a single amorphous phase in a continuous process, more particularly, that the nanostructure promotes the formation of amorphous LixSi with the gradual change of X in one continuous phase, and in the substantial absence of the formation of two phases containing crystalline Si and crystalline Li<NUM>S<NUM>. The formation of crystalline Li<NUM>S<NUM> is detectable in a <NUM>st cycle Li intercalation and de-intercalation curve by the presence of a characteristic plateau in the de-intercalation curve part way between full charge and full discharge. The plateau is characterized in that the Potential vs. Li/Li+ [V] (which is the Y-axis of the <NUM>st cycle Li intercalation and de-intercalation curve) changes by no more than about <NUM> V across a Specific Charge / <NUM> mAh/g (which is the X-axis of the <NUM>st cycle Li interaction and de-intercalation curve) of <NUM>. An example of this characteristic plateau is shown in <FIG>. Without wishing to be bound by theory, it is believed that the silicon-carbon particulate composite reduces the extent of volume expansion during lithium intercalation, by preventing or at least inhibiting the formation of Si-Li crystalline alloy phases, and promotes the formation of an amorphous LixSi phase, and moreover provides sufficient pore void space to better accommodate said volume expansion during lithiation, thus improving cycling stability and/or reducing capacity losses during cycling of the Li-ion battery. The result is improvement in cycle stability and reduction in specific charge loss.

Additionally or alternatively, therefore, in certain embodiments, the silicon particulate has a nanostructure which maintains electrochemical capacity of a negative electrode, of a Li-ion battery when used as active material. By "maintains electrochemical capacity", means that the specific charge of the negative electrode after <NUM> cycles is at least <NUM> % of the specific charge after <NUM> cycles, for example, at least <NUM> % of the specific charge after <NUM> cycles, or at least <NUM> % of the specific charge after <NUM> cycles. In other words, the negative electrode comprising the silicon particulate may have at least <NUM> % capacity retention after <NUM> cycles, for example, at least <NUM> % capacity retention after <NUM> cycles, or at least <NUM> % capacity retention after <NUM> cycles.

In certain embodiments, the silicon-carbon particulate composite is prepared by co-milling silicon and carbon starting materials under wet conditions, i.e., by wet-milling, in accordance with the methods described herein.

The silicon-carbon particulate composite may be manufactured by co-milling silicon particulate and carbonaceous particulate starting materials under wet conditions to produce a silicon-carbon particulate composite according to the first aspect and/or having a nanostructure which inhibits or prevents silicon pulverization and/or maintains electrochemical capacity when use as active material in a negative electrode of a Li-ion battery, wherein the silicon starting material is a micronized silicon particulate having particle sizes of from about <NUM> to about <NUM>. By "wet conditions" or "wet-milling" is meant milling in the presence of a liquid, which may be organic, aqueous or a combination thereof.

In certain embodiments, the silicon particulate starting material comprises silicon microparticles having particle sizes of from about <NUM> to about <NUM>, or from about <NUM> to about <NUM>, or from about <NUM> to about <NUM>, or from about <NUM> to about <NUM>. In certain embodiments, the silicon particulate starting material is a micronized silicon particulate having a particle size of from about <NUM> to about <NUM>. Carbonaceous particulate starting materials are described below.

In certain embodiments, the method comprises one or more of the following:.

In certain embodiments, the method comprises two or more of (i), (ii), (iii) and (iv) followed by drying, for example, three or more of (i), (ii), (iii) and (iv) followed by drying, or all of (i), (ii), (iii) and (iv) followed by drying.

In certain embodiments, the solvent is an aqueous alcohol-containing mixture which may comprise water and alcohol in a weight ratio of from about <NUM>:<NUM> to about <NUM>:<NUM>, for example, from about <NUM>:<NUM> to about <NUM>:<NUM>, or from about <NUM>:<NUM> to about <NUM>:<NUM>, or from about <NUM>:<NUM> to about <NUM>:<NUM>. The total amount of liquid may be such to produce a slurry of the silicon particulate starting material having a solids content of no greater than about <NUM> wt. %, for example, no greater than about <NUM> wt. %, or no greater than about <NUM> wt. %, or no greater than about <NUM> wt. %, or at least about <NUM> wt. %, or at least about <NUM> wt.

The liquid plus silicon particulate starting material and carbonaceous particulate starting material may be in the form of a slurry. In these embodiments, the alcohol could be replaced with an organic solvent other than an alcohol, or a mixture of organic solvents comprising alcohol and another organic solvents, or a mixture of organic solvents other than alcohol, with the weight ratios given above pertaining to the total amount of organic solvent.

The alcohol may be a low molecular weight alcohol having up to about <NUM> carbon atoms, for example, methanol, ethanol, propanol or butanol. In certain embodiments, the alcohol is propanol, for example, isopropanol.

In certain embodiments, the wet-milling is conducted in a rotor stator mill, a colloidal mill or a media mill. These mills are similar in that they can be used to generate high shear conditions and/or high power densities.

A rotor-stator mill comprises a rotating shaft (rotor) and an axially fixed concentric stator. Toothed varieties have one or more rows of intermeshing teeth on both the rotor and the stator with a small gap between the rotor and stator, which may be varied. The differential speed between the rotor and the stator imparts extremely high shear. Particle size is reduced by both the high shear in the annular region and by particle-particle collisions and/or particle-media collisions, if media is present.

A colloidal mill is another form of rotor-stator mill. It is composed of a conical rotor rotating in a conical stator. The surface of the rotor and stator can be smooth, rough or slotted. The spacing between the rotor and stator is adjustable by varying the axial location of the rotor to the stator. Varying the gap varies not only the shear imparted to the particles but also the mill residence time and the power density applied. Particle size reduction may be affected by adjusting the gap and the rotation rate, optionally in the presence of media.

Media mills are different in operation than a rotor-stator mill but likewise can be used to generate high shear conditions and power densities. The media mill may be a pearl mill or bead mill or sand mill. The mill comprises a milling chamber and milling shaft. The milling shaft typically extends the length of the chamber. The shaft may have either radial protrusions or pins extending into the milling chamber, a series of disks located along the length of the chamber, or a relatively thin annular gap between the shaft mill chamber. The typically spherical chamber is filled with the milling media. Media is retained in the mill by a mesh screen located at the exit of the mill. The rotation of the shaft causes the protrusions to move milling media, creating conditions of high shear and power density. The high energy and shear that result from the movement of the milling media is imparted to the particles as the material is circulated through the milling chamber.

The rotation speed within the mill may be at least about <NUM>/s, for example, at least about <NUM>/s or at least about <NUM>/s. The maximum rotation speed may vary from mill to mill, but typically is no greater than about <NUM>/s, for example, no greater than about <NUM>/s. Alternatively, the speed may be characterized in terms of rpm. In certain embodiments, the rpm of the rotor-stator or milling shaft in the case of a media mill may be at least about <NUM> rpm, for example, at least about <NUM> rpm, or at least about <NUM>,<NUM> rpm, or at least about <NUM>,<NUM> rpm. Again, maximum rpm may be vary from mill to mill, but typically is no greater than about <NUM>,<NUM> rpm. Power density may be at least about <NUM> kW/I (I = litre of slurry), for example, at least about <NUM> kW/l, or at least about <NUM> kW/l. In certain embodiments, the power density is no greater than about <NUM> kW/l, for example, no greater than about <NUM> kW/l.

In certain embodiments, the rpm of the rotor-stator or milling shaft in the case of a media mill may be at least about <NUM> rpm, for example, at least about <NUM> rpm, or at least about <NUM> rpm, or at least about <NUM> rpm. Again, maximum rpm may be vary from mill to mill, but typically is no greater than about <NUM> rpm.

Residence in time within the mill is less than <NUM> hours, for example, equal to or less than about <NUM> hours, or equal to or less than about <NUM> hours, or equal to or less than about <NUM> hours, or equal to or less than about <NUM> hours, or equal to or less than about <NUM> minutes, or equal to or less than about <NUM> minutes, or equal to or less than about <NUM> minutes, or equal to or less than about <NUM> minutes, or equal to or less than about <NUM> minutes, or equal to or less than about <NUM> minutes, or equal to or less than about <NUM> minutes, or equal to or less than about <NUM> minutes, or equal to or less than about <NUM> minutes, or equal to or less than about <NUM> minutes, or equal to or less than about <NUM> minutes.

In certain embodiments, the milling media is characterized by having a density of at least about <NUM>/cm<NUM>, for example, at least about <NUM>/cm<NUM>, or at least about <NUM>/cm<NUM>, or at least about <NUM>/cm<NUM>, or at least about <NUM>/cm<NUM>, or at least about <NUM>/cm<NUM>, or at least about <NUM>/cm<NUM>. In certain embodiments, the milling media is a ceramic milling media, for example, yttria-stabilized zirconia, ceria-stabilized zirconia, fused zirconia, alumina, alumina-silica, alumina-zirconia, alumina-silica-zirconia, and ytrria or ceria stabilized forms thereof. The milling media, for example, ceramic milling media, may be in the form of beads. The milling media, for example, ceramic milling media may have a size of less than about <NUM>, for example, equal to or less than about <NUM>, or equal to or less than about <NUM>, or equal to or less than about <NUM>, or equal to or less than about <NUM>, or equal to or less than about <NUM>, or equal to or less than about <NUM>, or equal or less than about <NUM>, or equal to or less than about <NUM>. In certain embodiments, the milling media has a size of at least <NUM>, mm, for example, at least about <NUM>, or at least about <NUM>, or at least about <NUM>, or at least about <NUM>.

In certain embodiments, wet milling is conducted in a planetary ball mill with milling media, for example, ceramic milling media, having a size of up to about <NUM>.

Drying may be affected by any suitable technique using any suitable drying equipment. Typically, the first step of the drying (or, alternatively, the last action of the milling step) is recovering the solid material from the dispersion, for example by filtration or centrifugation, which removes the bulk of the liquid before the actual drying takes place. In some embodiments, the drying step c) is carried out by a drying technique selected from subjecting to hot air/gas in an oven or furnace, spray drying, flash or fluid bed drying, fluidized bed drying and vacuum drying.

For example, the dispersion may be directly, or optionally after filtering the dispersion through a suitable filter (e.g. a <<NUM> metallic or quartz filter), introduced into an air oven at typically <NUM> to <NUM>, and maintained under these conditions, or the drying may be carried out at <NUM>, e.g., for <NUM> hours. In cases where a surfactant is present, the material may optionally be dried at higher temperatures to remove/destroy the surfactant, for example at <NUM> in a muffle furnace for <NUM> hours.

Alternatively, drying may also be accomplished by vacuum drying, where the processed dispersion is directly, or optionally after filtering the dispersion through a suitable filter (e.g. a <<NUM> metallic or quartz filter), introduced, continuously or batch-wise, into a closed vacuum drying oven. In the vacuum drying oven, the solvent is evaporated by creating a high vacuum at temperatures of typically below <NUM>, optionally using different agitators to move the particulate material. The dried powder is collected directly from the drying chamber after breaking the vacuum.

Drying may for example also be achieved with a spray dryer, where the processed dispersion is introduced, continuously or batch wise, into a spray dryer that rapidly pulverizes the dispersion using a small nozzle into small droplets using a hot gas stream. The dried powder is typically collected in a cyclone or a filter. Exemplary inlet gas temperatures range from <NUM> to <NUM>, while the outlet temperature is typically in the range of <NUM> to <NUM>.

Drying can also be accomplished by flash or fluid bed drying, where the processed expanded graphite dispersion is introduced, continuously or batch wise, into a flash dryer that rapidly disperses the wet material, using different rotors, into small particles which are subsequently dried by using a hot gas stream. The dried powder is typically collected in a cyclone or a filter. Exemplary inlet gas temperatures range from <NUM> to <NUM> while the outlet temperature is typically in the range of <NUM> to <NUM>.

Alternatively, the processed dispersion may be introduced, continuously or batch-wise, into a fluidized bed reactor/dryer that rapidly atomizes the dispersion by combining the injection of hot air and the movement of small media beads. The dried powder is typically collected in a cyclone or a filter. Exemplary inlet gas temperatures range from <NUM> to <NUM> while the outlet temperature is typically in the range of <NUM> to <NUM>.

Drying can also be accomplished by freeze drying, where the processed dispersion is introduced, continuously or batch wise, into a closed freeze dryer where the combination of freezing the solvent (typically water or water/alcohol mixtures) and applying a high vacuum sublimates the frozen solvent. The dried material is collected after all solvent has been removed and after the vacuum has been released.

The drying step may optionally be carried out multiple times. If carried out multiple times, different combinations of drying techniques may be employed. Multiple drying steps may for example be carried out by subjecting the material to hot air (or a flow of an inert gas such as nitrogen or argon) in an oven/furnace, by spray drying, flash or fluid bed drying, fluidized bed drying, vacuum drying or any combination thereof.

In some embodiments, the drying step is conducted at least twice, preferably wherein the drying step comprises at least two different drying techniques selected from the group consisting of subjecting to hot air in an oven/furnace, spray drying, flash or fluid bed drying, fluidized bed drying and vacuum drying.

In certain embodiments, drying is accomplished in an oven, for example, in air at a temperature of at least about <NUM>, for example, at least about <NUM>, or at least about <NUM>. In other embodiments, drying is done by spray drying, for example, at a temperature of at least about <NUM>, or at least about <NUM>, or at least about <NUM>.

In certain embodiments, the carbonaceous particulate starting material(s) is selected from natural graphite, synthetic graphite, coke, exfoliated graphite, graphene, few-layer graphene, graphite fibers, nano-graphite, non-graphitic carbon, carbon black, petroleum- or coal based coke, glass carbon, carbon nanotubes, fullerenes, carbon fibers, hard carbon, graphitized fined coke, or mixtures thereof. Specific carbonaceous particulate materials include, but are not limited to exfoliated graphites as described in <CIT> (highly oriented grain aggregate graphite, or HOGA graphite), or as described in co-pending <CIT>.

In certain embodiments, the carbonaceous particulate starting material is graphite, for example, natural or synthetic graphite, exfoliated graphite, or an expanded graphite, or combinations thereof, for example, a combination of expanded graphite and a synthetic graphite. In certain embodiments, the synthetic graphite is surface-modified, for example, coated, for example, with an amorphous coating. In certain embodiments, the synthetic graphite is not surface-modified.

The carbonaceous particulate starting material or materials may be selected such that following co-milling they provide a carbon matrix having a BET SSA which is suitable for use negative electrode of a Li-ion battery.

In certain embodiments, the silicon particulate starting material is initially milled in the absence of carbonaceous particulate starting material, for example, for a period of up to about <NUM> hour, up to about <NUM> mins, or up to about <NUM> mins, or up to about <NUM> mins, and then combined with carbonaceous particulate starting material and co-milled for a further period.

In certain embodiments, the carbonaceous particulate starting is added gradually or in batches during the co-milling process. In certain embodiments, the silicon particulate starting materials is added gradually or in batches during the co-milling process.

In other embodiments, the carbonaceous particulate starting material is initially milled in the absence of silicon particulate starting material, and then combined with silicon particulate starting material and co-milled for a further period.

The silicon-carbon particulate composite of the present invention may be used as active material in a negative electrode with or without additional carbonaceous particulate material and or Si-active material.

Sources of additional carbonaceous particulate materials may be selected from selected from natural graphite, synthetic graphite, coke, exfoliated graphite, graphene, few-layer graphene, graphite fibers, nano-graphite, non-graphitic carbon, carbon black, petroleum- or coal based coke, glass carbon, carbon nanotubes, fullerenes, carbon fibers, hard carbon, graphitized fined coke, or mixtures thereof. Specific carbonaceous particulate materials include, but are not limited to exfoliated graphites as described in <CIT> (highly oriented grain aggregate graphite, or HOGA graphite), or as described in co-pending <CIT>.

In certain embodiments, the additional carbonaceous particulate material is carbon black, for example conductive carbon black. In certain embodiments, the carbon black has a BET SSA of less than about <NUM><NUM>/g, for example, from about <NUM><NUM>/g to about <NUM><NUM>/g, or from about <NUM><NUM>/g to about <NUM><NUM>/g, or from about <NUM><NUM>/g to about <NUM><NUM>/g, or from about <NUM><NUM>/g to about <NUM><NUM>/g. In other embodiments, the carbon black, when present, may have a BET SSA of less than about <NUM><NUM>/g, for example, lower than about <NUM><NUM>/g or lower than about <NUM><NUM>/g, or lower than about <NUM><NUM>/g, or lower than about <NUM><NUM>/g, or lower than about <NUM><NUM>/g.

In certain embodiments, the additional carbonaceous particulate material comprises at least two different types of carbonaceous particulate material, for example, at least three different types of carbonaceous particulate material. The additional carbonaceous particulate serves as a carbon matrix for the silicon-carbon particulate composite.

The carbon matrix may have a BET SSA of less than about <NUM><NUM>/g, for example, less than about <NUM><NUM>/g, or less than about <NUM><NUM>/g, or less than about <NUM><NUM>/g, or less than about <NUM><NUM>/g, or less than about <NUM><NUM>/g, or less than about <NUM><NUM>/g, or less than about <NUM><NUM>/g, or less than about <NUM><NUM>/g. In certain embodiments, the carbon matrix has a BET SSA of at least about <NUM><NUM>/g, or at least about <NUM><NUM>/g, or at least about <NUM><NUM>/g.

In certain embodiments, the additional carbonaceous particulate material is or comprises a synthetic graphite, for example, a surface-modified synthetic graphite. In certain embodiments, the surface-modified synthetic graphite comprises core particles with a hydrophilic non-graphitic carbon coating, having a BET SSA of less than about <NUM><NUM>/g, for example, less than about <NUM><NUM>/g, or less than about <NUM><NUM>/g. In such embodiments, the core particles are synthetic graphite particles, or a mixture of synthetic graphite particles and silicon particles. Such a material and the preparation thereof is described in <CIT>. In certain embodiments, the at least one carbonaceous particulate is a surface modified carbonaceous particulate material according to any one of claims <NUM>-<NUM> of <CIT>, or that made by or obtainable by a process according to any one of claims <NUM>-<NUM> of <CIT>.

In certain embodiments, the additional carbonaceous particulate material is or comprises a surface-modified synthetic graphite, for example synthetic graphite which has been surface modified by either chemical vapor deposition ("CVD coating") or by controlled oxidation at elevated temperatures. In certain embodiments, the synthetic graphite prior to surface-modification is characterized by characterized by a BET SSA of from about <NUM> to about <NUM><NUM>/g, and by exhibiting a ratio of the perpendicular axis crystallite size Lc (measured by XRD) to the parallel axis crystallite size La (measured by Raman spectroscopy), i.e. Lc/La of greater than <NUM>. Following surface-modification, the synthetic is characterized by an increase of the ratio between the crystallite size Lc and the crystallite size La. In other words, the surface-modification process lowers the crystallite size La without substantially affecting the crystallite size Lc. In one embodiment, the surface-modification of the synthetic graphite is achieved by contacting the untreated synthetic graphite with oxygen at elevated temperatures for a sufficient time to achieve an increase of the ratio Lc/La, preferably to a ratio of ><NUM>, or even greater, such as ><NUM>, <NUM>, <NUM> or even <NUM>. Moreover, the process parameters such as temperature, amount of oxygen-containing process gas and treatment time are chosen to keep the burn-off rate relatively low, for example, below about <NUM>%, below <NUM> % or below <NUM>%. The process parameters are selected so as to produce a surface-modified synthetic graphite maintaining a BET surface area of below about <NUM><NUM>/g.

The process for modifying the surface of synthetic graphite may involve a controlled oxidation of the graphite particles at elevated temperatures, such as ranging from about <NUM> to about <NUM>. The oxidation is achieved by contacting the synthetic graphite particles with an oxygen-containing process gas for a relatively short time in a suitable furnace such as a rotary furnace. The process gas containing the oxygen may be selected from pure oxygen, (synthetic or natural) air, or other oxygen-containing gases such as CO2, CO, H2O (steam), O3, and NOx. It will be understood that the process gas can also be any combination of the aforementioned oxygen-containing gases, optionally in a mixture with an inert carrier gas such as nitrogen or argon. It will generally be appreciated that the oxidation process runs faster with increased oxygen concentration, i.e., a higher partial pressure of oxygen in the process gas. The process parameters such as treatment time (i.e. residence time in the furnace), oxygen content and flow rate of the process gas as well as treatment temperature are chosen to keep the burn off rate below about <NUM>% by weight, although it is in some embodiments desirable to keep the burn-off rate even lower, such as below <NUM>%, <NUM>%, <NUM>%, <NUM>% or <NUM>%. The burn-off rate is a commonly used parameter, particularly in the context of surface oxidation treatments, since it gives an indication on how much of the carbonaceous material is converted to carbon dioxide thereby reducing the weight of the remaining surface-treated material.

The treatment times during which the graphite particles are in contact with the oxygen-containing process gas (e.g. synthetic air) may be relatively short, thus in the range of <NUM> to <NUM> minutes. In many instances the time period may be even shorter such as <NUM> to <NUM> minutes, <NUM> to <NUM> minutes or <NUM> to <NUM> minutes. Of course, employing different starting materials, temperatures and oxygen partial pressure may require an adaptation of the treatment time in order to arrive at a surface-modified synthetic graphite having the desired structural parameters as defined herein. Oxidation may be achieved by contacting the synthetic graphite with air or another oxygen containing gas at a flow rate generally ranging from <NUM> to <NUM> I/min, for example, from <NUM> to <NUM> I/min, or from <NUM> to <NUM> I/min. The skilled person will be able to adapt the flow rate depending on the identity of the process gas, the treatment temperature and the residence time in the furnace in order to arrive at a surface-modified graphite.

Alternatively, the synthetic graphite starting material is subjected to a CVD coating treatment with hydrocarbon-containing process gas at elevated temperatures for a sufficient time to achieve an increase of the ratio Lc/La, preferably to a ratio of ><NUM>, or even greater, such as ><NUM>, <NUM>, <NUM> or even <NUM>. Suitable process and surface-modified synthetic graphite materials are described in <CIT>. The CVD process coats the surface of graphite particles with mostly disordered (i.e., amorphous) carbon-containing particles. CVD coating involves contacting the synthetic graphite starting material with a process gas containing hydrocarbons or a lower alcohol for a certain <NUM> time period at elevated temperatures (e.g. <NUM>° to <NUM>). The treatment time will in most embodiments vary from <NUM> to <NUM> minutes, although in many instances the time during which the graphite particles are in contact with the process gas will only range from <NUM> to <NUM> minutes, from <NUM> to <NUM> minutes, or from <NUM> to <NUM> minutes. Suitable gas flow rates can be determined by those of skill in the art. In some embodiments, the process gas contains <NUM> to <NUM>% of acetylene or propane in a nitrogen carrier gas, and a flow rate of around <NUM><NUM>/h.

In certain embodiments, the additional carbonaceous particulate is or comprises (e.g., in admixture with another carbonaceous particulate material) a synthetic graphite which has not been surface-modified, i.e., a non-surface-modified synthetic graphite. In addition to the BET SSA, particle size distribution and spring back described above, the non-surface modified synthetic particulate may have on or more of the following properties:.

In certain embodiments, the non-surface-modified synthetic graphite is prepared according to the methods described in <CIT>.

In certain embodiments, the additional carbonaceous particulate has a BET SSA higher than about <NUM><NUM>/g and lower than about <NUM><NUM>/g, for example, lower than about <NUM><NUM>/g, or lower than about <NUM><NUM>/g, or lower than about <NUM><NUM>/g. In such embodiments, carbonaceous particulate materials, may have a spring back of less than <NUM> %, for example, less than about <NUM> %, or less than about <NUM> %, or less than about <NUM> %, or equal to or less than about <NUM> %, or equal to or less than about <NUM> %. In such embodiments, the carbonaceous particulate material may have a particle size distribution as follows:.

In certain embodiments, the additional carbonaceous particulate material has a BET SSA higher than about <NUM><NUM>/g, for example, higher than about <NUM><NUM>/g, or higher than about <NUM><NUM>/g, optionally lower than about <NUM><NUM>/g, for example, lower than about <NUM><NUM>/g. In such embodiments, the second carbonaceous particulate material may have a spring back of less than <NUM> %, for example, less than about <NUM> %, or less than about <NUM> %, or less than about <NUM> %, or equal to or less than about <NUM> %, or equal to or less than about <NUM> %. In such embodiments, the carbonaceous particulate material may be graphite, for example, natural or synthetic graphite, for example, an exfoliated graphite (e.g. as described in <CIT> or <CIT>, or expanded graphite. In such embodiments, the additional carbonaceous particulate material may have a particle size distribution as follows:.

Based on the total weight of the precursor composition, the additional carbonaceous particulate material may be present in an amount of from about <NUM> wt. % to about <NUM> wt. %, for example, from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or less than about <NUM> wt. %, or less than about <NUM> wt.

In certain embodiments, any of the additional carbonaceous materials described herein may be used individually in the precursor composition along with the silicon-carbon particulate composite, or as a mixture of different additional carbonaceous materials.

In certain embodiments, the precursor composition comprises from about <NUM> wt. % to about <NUM> wt. % of silicon, based on the total weight of the precursor composition, for example, from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM>. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. The amount of silicon-carbon particulate composite may be varied according in order to produce a precursor composition having the required amount of silicon.

In certain embodiments, the precursor composition comprises from about <NUM> wt. % to about <NUM> wt. % of silicon, based on the total weight of the negative electrode, for example, from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. Again, the amount of silicon-carbon particulate composite may be varied according in order to produce a precursor composition or negative electrode having the required amount of silicon.

The precursor composition may be made by mixing the additional carbonaceous particulates in suitable amounts forming the carbon matrix optionally together with the silicon-carbon particulate composite. In certain embodiments, the carbon matrix is prepared, and then the silicon-carbon particulate composite is combined with the carbon matrix, again, using any suitable mixing technique. In certain embodiments, the carbon matrix is prepared at a first location and then combined with the silicon-carbon particulate composite in a second location. In certain embodiments, a carbon matrix is prepared in a first location and then transported to a second location (e.g., an electrode manufacturing site) where it is combined with silicon-carbon particulate composite and optionally additional carbonaceous particulate if desired, and then with any additional components to manufacture a negative electrode therefrom, as described below.

In certain embodiments, the method of preparing a precursor composition for a negative electrode of a Li-ion battery, comprises, preparing, obtaining, providing or supplying a carbonaceous particulate and combining with a silicon-carbon particulate composite as described herein.

In certain embodiments, the method of preparing a precursor composition for a negative electrode of a Li-ion battery, comprises combining a silicon-carbon particulate composite according to any one of claims <NUM>-<NUM> or obtainable by a method according to any one of claims <NUM>-<NUM> with a further carbonaceous particulate.

In certain embodiments, the further carbonaceous particulate is prepared at a first location and combined with the silicon-carbon particulate composite at a second location.

In certain embodiments, the further or additional carbonaceous particulate and silicon-carbon particulate composite are prepared and combined at the same location.

The silicon-carbon particulate composites and precursor compositions as defined herein can be used for manufacturing negative electrodes for Li-ion batteries, in particular Li-ion batteries empowering electric vehicles, or hybrid electric vehicles, or energy storage units.

Thus, another aspect is a negative electrode comprising a silicon-carbon particulate composite as described herein.

Another aspect is a negative electrode comprising or made from a precursor composition as described herein.

In certain embodiments, the negative electrode comprises a sufficient amount of the silicon-carbon particulate composite such that the negative electrode comprises at least <NUM> wt. % of silicon, based on the total weight of the electrode, for example, at least about <NUM> wt. %, or at least about <NUM> wt. %, or at least about <NUM> wt. %, and optionally up to about <NUM> wt. % of silicon, based on the total weight of the electrode, , for example, up to about <NUM> wt. %, or up to about <NUM> wt. %, or up to about <NUM> wt. %, or up to about <NUM> wt. %, or up to about <NUM> wt. In certain embodiments, the negative electrode comprises from about <NUM> wt. % to about <NUM> wt. silicon, based on the total weight of the electrode, for example, from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt.

The negative electrode may be manufactured using conventional methods. In certain embodiments, the precursor composition is combined with a suitable binder. Suitable binder materials are many and various and include, for example, cellulose, acrylic or styrene-butadiene based binder materials such as, for example, carboxymethyl cellulose and/or PAA (polyacrylic acid) and/or styrene-butadiene rubber. The amount of binder may vary. The amount of binder may be from about <NUM> wt. to about <NUM> wt. %, based on the total weight of the negative electrode, for example, from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt.

In certain embodiments, a method of manufacturing a negative electrode for a Li-ion battery, comprises forming the negative electrode from a precursor composition as described herein or obtainable by a method as described herein, optionally wherein the precursor composition comprises additional components or is combined with additional components during forming, optionally wherein the additional components include binder, as described in the preceding paragraph. The negative electrode may then be used in a Li-ion battery.

In certain aspects, therefore, there is provided a Li-ion battery comprising a negative electrode which comprises a silicon-carbon particulate composite, wherein silicon pulverization does not occur during <NUM>st cycle lithium intercalation and de-intercalation, and/or electrochemical capacity is maintained after <NUM> cycles. In certain embodiments, the Li-ion battery comprises silicon-carbon particulate composite as defined herein, optionally further comprising additional carbonaceous particulate material as described herein.

As described above, the Li-ion battery may be incorporated in a device requiring power. In certain embodiments, the device is an electric vehicle, for example, a hybrid electric vehicle or a plug-in electric vehicle.

In certain embodiments, the precursor composition is incorporated in an energy storage device.

In certain embodiments, the silicon particulate and/or precursor composition is incorporated in an energy storage and conversion system, for example, an energy storage and conversion system which is or comprises a capacitor, or a fuel cell.

In other embodiments, the carbon matrix is incorporated in a carbon brush or friction pad.

In other embodiments, the precursor composition is incorporated within a polymer composite material, for example, in an amount ranging from about <NUM>-<NUM> wt. %, or <NUM>-<NUM> %, based on the total weight of the polymer composite material.

In related aspects and embodiments, there is provided the use of a silicon-carbon particulate composite as defined herein as active material in a negative electrode of a Li-ion battery to inhibit or prevent silicon pulverization during cycling, for example, during <NUM>st cycle Li intercalation and de-intercalation, and/or to maintain electrochemical capacity after <NUM> cycles. In certain embodiments, Li is electrochemically extracted from an amorphous lithium silicon phase and in the substantial absence of two crystalline phases containing crystalline silicon metal and crystalline Li<NUM>Si<NUM> alloy.

In another embodiment, the silicon-carbon particulate composite of the first aspect is used as active material in a negative electrode of a Li-ion battery for improving cycling stability of the Li-ion battery compared to a Li-ion battery which comprises an active material which is a mixture of silicon particulate and carbonaceous particulate which is not a composite and/or is not produced by co-milling under wet conditions and/or does not have a nanostructure which inhibits or prevents silicon pulverization during cycling, for example, during <NUM>st cycle Li intercalation and/or does not have a nanostructure which maintains electrochemical capacity after <NUM> cycles.

The method is based on the registration of the absorption isotherm of liquid nitrogen in the range p/p<NUM>=<NUM>-<NUM>, at <NUM>. Following the procedure proposed by <NPL>), the monolayer adsorption capacity can be determined. On the basis of the cross-sectional area of the nitrogen molecule, the monolayer capacity and the weight of the sample, the specific surface area can then be calculated. Meso- and macro-porosity parameters, including average pore width and total volume of pores, were derived from the nitrogen adsorption data using the Barrett-Joyner-Halenda (BJH) theory and microporosity in relation to the total BET surface area was determined using the t-plot method. The average particle size was calculated from the BET surface area assuming nonporous spherical particles and the theoretical density of the carbon/silicon composite.

XRD data were collected using a PANalytical X'Pert PRO diffractometer coupled with a PANalytical X'Celerator detector. The diffractometer has the following characteristics shown in Table <NUM>:.

The data were analyzed using the PANalytical X'Pert HighScore Plus software.

The interlayer space c/<NUM> is determined by X-ray diffractometry. The angular position of the peak maximum of the [<NUM>] reflection profiles are determined and, by applying the Bragg equation, the interlayer spacing is calculated (<NPL>)). To avoid problems due to the low absorption coefficient of carbon, the instrument alignment and non-planarity of the sample, an internal standard, silicon powder, is added to the sample and the graphite peak position is recalculated on the basis of the position of the silicon peak. The graphite/silicon sample is mixed with the silicon standard powder by adding a mixture of polyglycol and ethanol. The obtained slurry is subsequently applied on a glass plate by means of a blade with <NUM> spacing and dried.

Crystallite size Lc is determined by analysis of the [<NUM>] X-ray diffraction profiles and determining the widths of the peak profiles at the half maximum. The broadening of the peak should be affected by crystallite size as proposed by Scherrer (<NPL>). However, the broadening is also affected by other factors such X-ray absorption, Lorentz polarization and the atomic scattering factor. Several methods have been proposed to take into account these effects by using an internal silicon standard and applying a correction function to the Scherrer equation. For the present disclosure, the method suggested by Iwashita (<NPL>) was used. The sample preparation was the same as for the c/<NUM> determination described above.

Crystallite size La is calculated from Raman measurements using equation: <MAT> where constant C has values <NUM>[nm] and <NUM>[nm] for lasers with wavelength of <NUM> and <NUM>, respectively.

The analysis is based on the principle of liquid exclusion as defined in DIN <NUM><NUM>. <NUM> (accuracy <NUM>) of powder is weighed in a <NUM> pycnometer. Xylene is added under vacuum (<NUM> mbar). After a few hours dwell time under normal pressure, the pycnometer is conditioned and weighed. The density represents the ratio of mass and volume. The mass is given by the weight of the sample and the volume is calculated from the difference in weight of the xylene filled pycnometer with and without sample powder.

The Scott density is determined by passing the dry powder through the Scott volumeter according to ASTM B <NUM>-<NUM> (<NUM>). The powder is collected in a <NUM> in <NUM> vessel (corresponding to <NUM><NUM>) and weighed to <NUM> accuracy. The ratio of weight and volume corresponds to the Scott density. It is necessary to measure three times and calculate the average value. The bulk density is calculated from the weight of a <NUM> sample in a calibrated glass cylinder.

Spring-back is a source of information regarding the resilience of compacted graphite/silicon powders. A defined amount of powder is poured into a die. After inserting the punch and sealing the die, air is evacuated from the die. A compression force of <NUM> tons/cm<NUM> is applied and the powder height is recorded. This height is recorded again after the pressure has been released. Spring-back is the height difference in percent relative to the height under pressure.

The presence of particles within a coherent light beam causes diffraction. The dimensions of the diffraction pattern are correlated with the particle size. A parallel beam from a low-power laser lights up a cell which contains the sample suspended in water. The beam leaving the cell is focused by an optical system. The distribution of the light energy in the focal plane of the system is then analyzed. The electrical signals provided by the optical detectors are transformed into particle size distribution by means of a calculator. A small sample of silicon/carbon dispersion or dried silicon/carbon is mixed with a few drops of wetting agent and a small amount of water. The sample is prepared in the described manner and measured after being introduced in the storage vessel of the apparatus filled with water that uses ultrasonic waves for improving dispersion.

The Particle Size Distribution is measured using a Sympatec HELOS BR Laser diffraction instrument equipped with RODOS/L dry dispersion unit and VIBRI/L dosing system. A small sample is placed on the dosing system and transported using <NUM> bars of compressed air through the light beam. The particle size distribution is calculated and reported in µm for the three quantiles: <NUM>%, <NUM>% and <NUM>%.

This test was used to quantify the specific charge of nano-Si/carbon-based negative electrodes.

Having described the various aspects of the present disclosure in general terms, it will be apparent to those of skill in the art that many modifications and slight variations are possible without departing from scope of the present invention as defined in the appended claims. The present disclosure is furthermore described by reference to the following, non-limiting working examples.

<NUM> of micronized silicon particles (<NUM>-<NUM>), <NUM> of an expanded graphite and <NUM> of polyacrylic acid (PAA) were dispersed with <NUM> of water and <NUM> of isopropanol and milled in a bead mill machine using <NUM>-<NUM> yttrium-stabilized zirconia at <NUM>. The slurry was collected after <NUM> and dried in a spray drier at <NUM> (producing Nano-composite <NUM>) or dried in an air oven at <NUM> (producing Nano-composite <NUM>).

<NUM> of micronized silicon particles (<NUM>-<NUM>), <NUM> of an expanded graphite were dispersed with <NUM> of water and <NUM> of isopropanol and milled in a bead mill machine using <NUM>-<NUM> yttrium-stabilized zirconia at <NUM>. 5kW/I for <NUM>, and afterwards <NUM> of synthetic graphite having a BET SSA of about <NUM><NUM>/g were added and further milled for <NUM>. The slurry was collected (producing Nano-composite <NUM>) or dried in an air oven at <NUM> (producing Nano-composite <NUM>).

SEM pictures of Nano-composite <NUM> and Nano-composite <NUM> are shown in <FIG>, respectively. The pore size distributions of Nano-composites <NUM>, <NUM> and <NUM> are shown in <FIG>, with this and additional data summarized in Table <NUM>.

Dispersion formulation A: <NUM>% Super C45 conductive carbon black, <NUM>% CMC (Na-carboxymethyl cellulose) binder, <NUM>% Nano-composite <NUM>.

Electrochemical capacity and cycling stability for each formulation were tested in accordance with the methods described herein.

Cycling performance of the negative electrodes made from Dispersion formulation A (black filled circles), Dispersion formulation B (grey filled circles) and Dispersion formulation C (open circles) is shown in <FIG>. <FIG>st cycle lithium intercalation (black curves) and de-intercalation (gray curves) of the negative electrodes are shown in <FIG> (Dispersion formulation A), <FIG> (Dispersion formulation B) and <FIG> (Dispersion formulation C including the commercial Si-particulate).

Claim 1:
A silicon-carbon particulate composite suitable for use as active material in a negative electrode of a Li-ion battery, characterized by:
(i) a microporosity of from about <NUM> % to about <NUM> %, wherein said microporosity in relation to the total BET surface area is determined using the t-plot method;
(ii) a BJH average pore width of from about <NUM> to about <NUM>,
(iii) a BJH volume of pores of at least about <NUM><NUM>/g; and
(iv) an average particle size of about <NUM>-<NUM>, wherein said average particle size is calculated from the BET specific surface area (SSA) assuming nonporous spherical particles and the theoretical density of the carbon/silicon composite;
optionally wherein the carbon comprises or is natural and/or synthetic graphite, or a mixture of natural and synthetic graphite, preferably wherein the natural or synthetic graphite is exfoliated graphite or expanded graphite.