HK1242845A1 - Silicon-silicon oxide-lithium composite material having nano silicon particles embedded in a silicon:silicon lithium silicate composite matrix, and a process for manufacture thereof - Google Patents

Description

With embedded silicon: silicon-silicon oxide-lithium composite material of nano-silicon particles in silicon-lithium silicate composite matrix and method for manufacturing same

Technical Field

Aspects of the present disclosure relate to a method of manufacturing a silicon wafer having embedded silicon: silicon-silicon oxide-lithium silicate composite (SSLC) -based materials of nano-silicon particles in a lithium silicate composite (Si: LSC) matrix, and methods for making the same. The SSLC-based material may be used as a negative active material for a non-aqueous electrolyte battery, such as a lithium ion battery (where the negative electrode conventionally corresponds to the negative terminal of the battery or cell during discharge of the battery).

Background

The rapid development and market growth of mobile devices and electric vehicles has resulted in a strong demand for low-cost, small-sized, lightweight, high-energy-density secondary batteries such as lithium ion batteries. In the development of high energy density secondary batteries, cathode material technology is a well-recognized bottleneck, as cathode materials exhibit lower capacity than anode materials. However, cathode material capacity increases continue to evolve, while anode capacity improvements can be many times increased by going from conventional graphite to non-carbon based anode materials. Accordingly, significant research and development efforts have been made to produce high capacity cathode materials because the higher capacity anodes can significantly increase the energy density of commercial secondary batteries, for example, by as much as 25%, when the batteries are manufactured using a given type of commercial cathode material technology.

Silicon (Si) has been used as a material for lithium ion (Li)⁺) The anode material of the battery was studied because it exhibited as high a theoretical capacity as the battery anode material (e.g., up to 3750-4200mAh/g), and silicon was an abundant and inexpensive element that was readily available as it is widely used in the semiconductor industry. Electrochemical lithiation and delithiation of silicon can be generally expressed as

This high theoretical capacity leads to a significant theoretical increase in the energy density and specific energy of the battery compared to graphite anode materials with respect to the use of silicon as anode material.

When a nano thin Si film is coated on conductive graphite/carbon, or nano Si is composited with a metal current collector of nano characteristics, the pure silicon anode shows excellent cycle performance. Silicon nanowires and silicon nanoparticles also exhibit good cycling performance, depending on the nature of the various polymeric binders with which they are used. However, these nanostructured silicon anodes only work well at very low packing densities. In order to increase the energy density of the battery, the packing density of the anode needs to be increased. This means that the anode is impregnated with a higher weight ratio of active material to render the components in the lithium ion battery inactive. However, as packing density increases, the electrode collapses after initial cycling and cycling performance deteriorates.

Unfortunately, silicon anodes also exhibit large first-cycle capacity losses, side reactions during cycling, and very large volume changes (e.g., up to 300% -400%) during battery charge-discharge or lithiation-delithiation cycles. For this volume change, the Si anode is lithiated by intercalating (e.g., reversibly intercalating) 4.4 Li atoms per Si atom during cycling of the lithium ion battery. Very large volume changes lead to mechanical failure and capacity fade.

For silicon oxide (SiO)_x) The use as anode material for lithium ion batteries has also been investigated, in particular because this material shows little volume change after the first cycle compared to pure silicon anode material. SiO 2_xConsidered to be in the original SiO_xNanosized Si and SiO formed after high energy processing of materials₂Homogeneous mixtures of phases, for example, by "TEM investigation of amorphous silicon monoxide structure" by K.Schulmeister and W.Mader, "amorphous solid Journal (non-Crystalline Solids), 320(2003), page 143-. When Si and SiO₂When the molar ratio of (3) is 1, the volume ratio is 0.5. This indicates that the nano-silicon particles are embedded in SiO_xSiO of material structure₂In the matrix of (a).

SiO_xIs less conductive and is SiO-free_xLithiated, its conductivity decreases. This poor conductivity helps to reduce the SiO dose during cycling_xThe utilization of (1). SiO can be mechanically milled with graphite by using high energy mechanical milling as described in U.S. Pat. No. 6,638,662(US 6638662)_x(x is more than 0.8 and less than 1.5); or SiO by thermal Chemical Vapor Deposition (CVD) as described in Japanese patent publication JP-A2002-042806_xParticles coated with a uniform carbon layer to enhance SiO_xIs used for the electrical conductivity of (1). These techniques successfully increase charge-discharge capacity, but fail to provide sufficient cycle performance, and thus fail to meet market demand for high energy density batteries. Such techniques have not been successfully used to produce commercial products in the marketplace, since additional improvements in cycle performance are necessary.

SiO, as described in U.S. Pat. No. 5,395,811(US 5395811)_xAnother problem with the electrochemical properties of the base anode is the high irreversible capacity loss below practical levels with respect to the first charge/discharge cycle. SiO can be prelithiated as shown in U.S. Pat. No. 7,776,473(US 7776472)_xMaterial reduction of SiO_xIrreversible capacity loss of the anode material.

US 7776473 and US patent 8,231,810(US 8231810) indicate the reaction between lithium and SiO as follows, respectively:

4Li+4SiO→Li₄SiO₄+3Si (2)

4Li+4SiO→3Si:Li₄SiO₄(3)

the chemical reaction forms primarily lithium silicate (Li)₄SiO₄) And silicon. In view of SiO_xInner nano-sized Si and SiO₂The aforementioned mixture of lithium and SiO_xThe reaction between can be represented as follows:

4Li+2SiO₂→Li₄SiO₄+Si→Si:Li₄SiO₄(Si:LSC) (4)

depending on the reaction conditions, some groups have indicated that lithium silicates are formed from Li₄SiO₄、Li₂O and Li₂SiO₃And (4) forming. The main component may be Li₄SiO₄. Li and SiO_xSiO in the structure₂Irreversible chemical reaction of the matrix also forms a certain amount of lithium silicide (Li)_ySi)。

During the first lithiation of SiO, when SiO₂Phase irreversibly changed to Li₄SiO₄With Li_yWith mixtures of Si, the volume increases by a factor of two. During delithiation, Li₄SiO₄Remain as Li₄SiO₄And Li_ySi becomes silicon. As a result, Si: LSC (Si: Li)₄SiO₄) Become porous and due to Li₄SiO₄Plastic deformation of, Li_ySi:Li₄SiO₄To Si Li₄SiO₄The volume change of (a) can be minimized. Thus, after the first cycle, the SiO_xThe volume change of the base anode particles is much smaller than that of pure silicon anode particles. Further, under both micron-sized conditions, the SiO was after the first cycle_xThe base anode generally shows much better cycling performance compared to pure Si based anodes.

US 7776472 teaches the milling of SiO with activated lithium powder by a high energy ball milling process_xPowder to SiO_xPre-lithiation is performed. This prelithiation successfully reduced the irreversible capacity loss from 35% to 15%. However, US 7776472 also states that due to this prelithiation treatment the irreversible capacity is only 800mAh/g to 900mAh/g, while most of the graphite coated SiO_xThe anode showed an irreversible capacity of 1400mAh/g to 1700 mAh/g. Unfortunately, the results obtained by the method of US 7776472 are insufficient to meet the characteristics required for a commercial anode material. There remains a need for lower irreversible capacity loss of the first cycle and improved cycle performance.

Also with respect to the foregoing, although pre-lithiation of the anode material can reduce irreversible capacity loss, the pre-lithiated anode material has undesirably high chemical reactivity due to the presence of highly reactive chemically unstable lithium in the pre-lithiated anode material. This high chemical reactivity can result in difficulty in handling and processing the prelithiated anode material during conventional battery manufacturing processes or render the prelithiated anode material incompatible with conventional battery manufacturing processes. For example, prelithiated anode materials are incompatible with solvents, binders, thermal processing conditions, and/or environments commonly encountered in battery manufacturing processes. There is also a need to overcome these problems.

BRIEF SUMMARY OF THE PRESENT DISCLOSURE

In the present disclosure, the description of a given element or the consideration or use of a particular element number in a particular figure or reference thereto in corresponding illustrative material may encompass the same, equivalent or similar element or element number identified in another figure or illustrative material related thereto.

Unless otherwise indicated, the use of "/" in the figures or related text is understood to mean "and/or". Recitation of a specific value or range of values herein is understood to include or refer to the recitation of approximate values or ranges of values, such as within +/-10%, +/-5%, +/-2.5%, or +/-1% of the specific value or range of values, as contemplated.

Further aspects of the technical problem

As described above, high capacity silica-based anodes provide superior cycling performance at higher packing densities compared to pure silica-based anodes, but silica-based anodes have low initial efficiencies. Although irreversible capacity loss can be reduced in the manner disclosed in US 7776473, the inventors of the present application have found that prelithiation according to the teachings of US 7776473, which is performed by ball milling solid materials (i.e., solid silicon oxide powder and metallic lithium powder), results in incomplete and non-uniform lithiation. That is, it is difficult to achieve SiO by ball milling a solid material in the manner disclosed in US 7776473_xIs completely and uniformly prelithiated.

US 7776473 discloses diffusion of metallic lithium into solid SiO_xThe rate of (5) is low, which makes it difficult for metallic lithium to uniformly penetrate into SiO_xIn (1). In addition, larger amounts of lithium metal powder were used during ball milling to potentially provide a useful diffusion into SiO_xThe larger concentration of lithium in (b) is not feasible in view of safety issues due to the highly reactive nature of lithium and the need to remove decomposition products during the ball milling process. US 7776473 teaches the use of smaller, controllable amounts of lithium powder such that the amount of lithium added provides an atomic ratio of lithium to oxygen of less than or equal to 2 (i.e., Li/O < 2). US 7776473 additionally teaches the use of SiO in the production of SiO by ball milling_xAfter reaction with the metallic lithium, an organolithium compound (e.g., an alkyllithium or aryllithium) may be added to compensate or supplement the lithium deficiency. Despite even with such addition of organolithium compounds (butyllithium), SiO coated with conventional carbon exhibiting irreversible capacities of 1400mAh/g to 1700mAh/g_xThe prelithiation treatment taught by US 7776473 resulted in a commercially unacceptable low reversible capacity of 800mAh/g to 900mAh/g compared to the anode.

The prelithiation process disclosed in US 7776473 does not avoid the formation of lithium silicide. The low reversible capacity of 800mAh/g to 900mAh/g obtained by the treatment of US 7776473 indicates that after performing this treatment, lithium silicide remains on the surface of the resulting particles and can be oxidized when the particles are exposed to air, thereby reducing conductivity. In addition, lithium silicide remaining on the particle surface will cause gelation of the electrode slurry mixture by reaction with the polymer binder or N-methyl-pyrrolidone (NMP).

Also as noted above, the prelithiated anode materials have undesirably high chemical reactivity due to the lithium contained therein, which can lead to handling difficulties or incompatibility problems when the prelithiated anode materials are used in conventional battery manufacturing processes.

Technical solution and summary of the invention

Embodiments according to the present disclosure relate to fully delithiated silicon-silica-lithium composite (SSLC) particulate materials or porous, plastically deformable silicon: SSLC-based particulate material with amorphous and/or crystalline nano-silicon particles embedded in a matrix of lithium silicate composite (Si: LSC). In various embodiments, the SSLC/SSLC-based material has an average particle size of about 1 μm to 10 μm; LSC matrix with particle or grain size of 10-200 nm; and the nano-silicon particles embedded therein have a particle or grain size of about 0.5nm to 150nm (e.g., 0.5nm to 80nm or 0.5nm to 50 nm).

Embodiments according to the present disclosure correspondingly relate to a method for producing or manufacturing an SSLC/SSLC-based material, wherein the method comprises a first method part and a subsequent second method part, the first method part relating to SiO_xAnd producing an SSLC/SSLC-based material having lithium silicide uniformly distributed therein; the second method involves, in part, complete or substantially complete delithiation of SSLC/SSLC-based materials. Due to the lack of lithium in the delithiated SSLC/SSLC-based material, it is suitable for use in battery manufacturing processes (e.g., conventional battery manufacturing processes). Embodiments according to the present disclosure are additionally directed to the use of delithiated SSLC/SSLC-based materials in the production or manufacture of batteries; and also to battery anodes made with delithiated SSLC/SSLC-based materials.

The SSLC/SSLC-based material has many advantages when used as a negative active material for a non-aqueous electrolyte battery, such as a lithium ion battery. During the charging and discharging processThe porous, already plastically deformed Si: LSC matrix greatly reduces or minimizes any volume change associated with lithiation/delithiation of SSLC/SSLC based materials. When used as an anode active material in a lithium ion battery, SSLC/SSLC-based materials according to embodiments of the present disclosure may exhibit a volume change between lithiation (charging) and delithiation (discharging) of about 7% to 35% (e.g., about 15% to 35%, or about 10% to 20% on average). This is in contrast to the earlier use of SiO₂Si in (a) is very advantageous compared to anodes in which unacceptable volume changes, e.g. up to 200%, are experienced during lithiation of the anode.

In view of the foregoing, when producing substantially fully or fully pre-lithiated SSLC/SSLC-based materials according to embodiments of the present disclosure, such pre-lithiated SSLC/SSLC-based materials will exhibit or occupy a maximized, substantially maximum or maximum volume (or, correspondingly, a maximum degree of volume expansion). When this substantially fully or fully pre-lithiated SSLC/SSLC-based material is subsequently substantially fully or fully delithiated (which occurs prior to its use in a lithium ion battery, cell or anode manufacturing process), it will exhibit or occupy a minimized, substantially minimum or minimal volume (or, correspondingly, a maximum degree of volume shrinkage). When such substantially fully or fully delithiated SSLC/SSLC-based materials are subsequently used as anode active materials in batteries (associated with (re) charging and discharging of the battery via lithiation and delithiation, respectively, of the anode active material), the change in volume of the SSLC/SSLC-based anode active material will be approximately in the range between or transition between the aforementioned volume extremes, such as the maximum volume of the prelithiated SSLC/SSLC-based material and the minimum volume of the delithiated SSLC/SSLC-based material.

Because the maximum degree of volume change, transformation, migration or swing of the SSLC/SSLC-based active anode material in a lithium-ion battery cell is limited to 10% to 35%, rather than a much larger or significantly larger volume change, such as 200%, this means that (a) for a given, targeted or predetermined size anode, the use of SSLC/SSLC-based materials in battery manufacture can produce a battery cell with a significantly larger or much larger energy density/capacity; or (b) a significantly smaller or very small amount of SSLC/SSLC-based material may be used in the cell fabrication process to create an anode for a given energy density/capacity, which results in a much smaller or much thinner anode and thus a significant or very small or very thin cell with a higher energy density/capacity. For example, SSLC/SSLC-based materials according to the present disclosure may exhibit an energy density of about 300% greater than conventional graphite materials. Thus, the use of an SSLC/SSLC-based material as an anode active material in a lithium ion battery means that (i) but for a given, target, or predetermined size battery anode, the battery can have a capacity that is approximately or about 300% greater than a battery using a conventional graphite material as its active anode material; or (ii) the size of the battery anode may be about or about 1/3 the size of a battery anode using conventional graphite materials as its active anode material for a given, target, or predetermined capacity of the battery.

With the foregoing in addition, those skilled in the relevant art will appreciate that the degree or extent of the overall volume change of the cell due to (re) charging and discharging will be less than the degree of volume change of the anode of the cell. More specifically, the overall degree to which the volume of the cell varies depends on the thickness of the anode of the cell relative to the thickness of the cathode of the cell; and the anode is often or generally significantly thinner or much thinner than the cathode (e.g., the anode may be only as thick as about 1/3 a of the cathode). In addition, cathode active materials often exhibit small or much smaller volume changes associated with (re) charging and discharging of the battery. Thus, the overall degree of volume change or volume expansion and contraction of a battery using an SSLC/SSLC-based material according to embodiments of the present disclosure as its active anode material may be about 3% to 10% (e.g., about 5% to 8%).

Additionally, lithium ion batteries including SSLC/SSLC-based anode materials according to embodiments of the present disclosure may exhibit reversible capacity loss of less than 15% (e.g., less than 12%, or less than 10%, or in the range of about 8% to 12%), which is significantly reduced compared to prior art irreversible capacity loss, and meet commercial demand. Further, such lithium ion batteries can exhibit a reversible capacity of greater than about 1100mAh/g (e.g., 1200mAh/g or higher). Finally, to facilitate its use in an anode or anode cell manufacturing process, the SSLC/SSLC-based material will be delithiated before it is used in the manufacturing process, and will not contain active lithium therein (i.e., the SSLC/SSLC-based material will be delithiated such that lithium from the active lithium silicide will be removed from the final product as the resulting SSLC/SSLC-based material) and thus will not cause handling or incompatibility issues associated with the cell manufacturing process.

In the disclosure herein, an SSLC-based material may be defined as where SiO is present_xAn SSLC-based material that has been pre-lithiated or combined with pre-lithiation to enhance conductivity. For example, the SSLC-based material may be a silicon-silicon oxide-carbon or silicon-silicon oxide-lithium-carbon-based composite (SSLCC) material, wherein the pre-lithiation, prior to or in conjunction with the pre-lithiation as described in further detail below, has been accomplished by treating the SiO with a carbon-based material, such as graphite_xOr combined with SiO_xEnhancement of SiO with carbon-based materials such as graphite_xIs used for the electrical conductivity of (1). For the sake of brevity and conciseness, in the following description, the term "SSLC material" encompasses or includes SSLC-based materials such as SSLCC materials.

According to one aspect of the disclosure, for producing silicon: silicon oxide: a method of lithium composite (SSLC) material includes performing a prelithiation process and a delithiation process. The pre-lithiation treatment produces a pre-lithiated material and includes producing a partially lithiated SSLC material by a mechanical mixing step including milling a silicon oxide powder and a lithium powder; and producing a further prelithiated SSLC material by a spontaneous lithiation step comprising: compressing the partially lithiated SSLC material matrix material; and exposing the compressed partially lithiated SSLC material to a lithium-based electrolyte, wherein the spontaneous lithiation step causes unreacted lithium to react with the SiO in the partially lithiated SSLC material_xUntil the unreacted lithium disappears and a uniform composition of lithium silicide is obtained in the SSLC material by lithium diffusion. The delithiation treatment follows the prelithiation treatment and results in a delithiated SSLC material. The delithiation treatment comprises dispersing the compressed further prelithiated SSLC material in a liquid carrier medium, thereby producing a dispersed prelithiated SSLC material; and exposing the dispersed prelithiated SSLC material to a volume of oneOne or more organic solvents to react and extract lithium from the lithium silicide within the dispersed pre-lithiated SSLC material with the one or more organic solvents until the reaction of the lithium silicide within the dispersed pre-lithiated SSLC material with the one or more organic solvents is complete, wherein a volume of the one or more organic solvents acts as a reservoir with respect to reacting with the lithium silicide within the dispersed pre-lithiated SSLC material, wherein the delithiated SSLC material comprises porous, plastically deformable Si: a lithium silicate composite (Si: LSC) matrix having nano-silicon particles embedded therein.

The delithiated SSLC material has a lithium silicide content of less than 0.5 wt%. The delithiated SSLC material may have a particle size of 1 to 10 μm, the Si: LSC matrix may exhibit a grain size of 10 to 200nm, and the nano-silicon particles may have a particle size of 5 to 150nm (e.g., 5 to 80nm or 5 to 50 nm). In various embodiments, the delithiated SSLC material has a silicon content of 30 wt.% to 60 wt.%, an oxygen content of 25 wt.% to 40 wt.%, and a lithium content of 10 wt.% to 20 wt.%. The composition of the delithiated SSLC material may be about 37 wt.% silicon, about 18 wt.% lithium, and about 43 wt.% oxygen.

The liquid carrier medium comprises an aprotic solvent, and the one or more organic solvents comprise an alcohol. For example, the liquid carrier medium may include hexane, and the one or more organic solvents may include ethanol, glycerol, and/or polyvinyl alcohol (PVA).

The silicon oxide powder can be characterized as SiO_x(0.8 < x < 1.6), and the mechanically mixing step may include ball milling the silica powder with the lithium powder, and the lithium powder may includeOr may be

The treating may include performing a first conductivity enhancement treatment prior to the prelithiation treatment, wherein the first conductivity enhancement treatment includes at least one of: ball milling the silicon oxide powder with a carbon-based material, and coating the silicon oxide powder with a carbon-based material. Additionally or alternatively, the processing may include performing a second conductivity enhancement processing after the delithiation processing, wherein the second conductivity enhancement processing includes at least one of: ball milling the silicon oxide powder with a carbon-based material, and coating the silicon oxide powder with a carbon-based material. The carbon-based material may include at least one of graphite, carbon black, buckyballs, carbon nanotubes, and carbon nanobuds.

According to aspects of the present disclosure, a delithiated SSLC material is produced by the method set forth above and has a lithium silicide content of less than 0.5 wt%.

According to aspects of the present disclosure, delithiated SSLC materials produced by the methods set forth above and having a lithium silicide content of less than 0.5 wt% are used in battery anode manufacturing methods.

According to one aspect of the present disclosure, a lithium ion battery has an SSLC material as its negative active material and exhibits an irreversible capacity loss of less than 15% (e.g., less than 12% or less than 10%). The SSLC active material may be produced by the methods set forth above. The anode of the lithium-ion battery cell may exhibit a volume change of 10% to 35% (e.g., an average volume change of 15% to 25% or an average volume change of 20%) associated with charging and discharging of the lithium-ion battery cell.

Specific advantageous effects

The SSLC material production method according to embodiments of the present disclosure provides a simple, robust, commercially scalable, cost-effective method by which SSLC materials can be produced that can be used as negative electrode materials to meet market needs. The SSLC materials can be used as anode materials to produce lithium ion battery anodes that exhibit more uniform or uniform and greatly reduced or minimal volume changes due to lithiation and delithiation, and that are comparable to existing SiO_xThe base anode has a significantly or greatly reduced irreversible capacity loss. To facilitate the use of SSLC materials in battery manufacturing processes, the SSLC materials are fully delithiated, and thusThe SSLC material is compatible with solvents, adhesives, thermal processing conditions, and/or the environment associated with typical cell manufacturing processes. In addition, electrode slurries containing SSLC materials produced in accordance with embodiments of the present disclosure form well-laminated electrode structures without forming detrimental gels, even when relatively large amounts of lithium have been used to prelithiate SiO_xThe same is true of the particles.

Drawings

Fig. 1 is a flow diagram of a representative method for producing or fabricating a silicon-silicon oxide-lithium composite (SSLC) material structure or composition in accordance with one embodiment of the present disclosure.

Fig. 2 is a schematic diagram of a representative delithiation reactor according to one embodiment of the present disclosure.

FIG. 3A to FIG. 3C are SiO_xA graphical representation of representative microstructural properties of (x ═ 1); a graphical representation of representative microstructure characteristics of a prelithiated SSLC produced according to one embodiment of the present disclosure; and a graphical representation of representative microstructure characteristics of a delithiated SSLC produced in accordance with an embodiment of the present disclosure.

Detailed description of representative example embodiments

Overview of representative SSLC Material Generation methods

Fig. 1 is a flow diagram of a representative method 100 for producing or fabricating an SSLC material, material structure or composition in accordance with one embodiment of the present disclosure. In various representative embodiments, the SSLC material production process 100 includes a first process portion 110 by which a pre-lithiated SSLC material is produced; a second process portion 120 by which the prelithiated SSLC material is delithiated; a third process portion 130 through which the delithiated SSLC material is filtered, washed and dried; a possible fourth process portion 140 by which the delithiated SSLC material is coated with one or more materials for the purpose of enhancing mechanical or structural integrity or stability; and a fifth method portion 150 by which the delithiated SSLC material or mechanically stabilized SSLC material is typically coated or combined with a carbon or carbon-based material to enhance conductivity. Aspects of the SSLC material generation method 100 are described in detail below.

The first method portion 110 produces a prelithiated SSLC material via a first or initial prelithiation step 112, followed by a second or subsequent prelithiation step 114. The first prelithiation step 112 produces a partially lithiated SSLC material, after which the second prelithiation step 114 produces a substantially fully or fully lithiated SSLC material that exhibits a significant enhancement over the prior art. More specifically, in the first prelithiation step, SiO_xAnd/or SiO in powder form with enhanced conductivity_xThe metal can be mixed with lithium metal, such as stabilized lithium powder (e.g.,from FMC corporation of Charlotte, south carolina, USA (FMC corporation, Charlotte, NC USA), www.fmclithium.com) to produce partially lithiated SSLC materials in powder form. The first or initial prelithiation step 112 may be similar, generally similar, analogous, substantially equivalent, or equivalent to the steps disclosed in US 7776473 (which is incorporated herein by reference). As will be readily understood by one of ordinary skill in the relevant art, the SiO may be coated in a conventional manner by treating, coating with one or more carbon or carbon-based materials (e.g., graphite, carbon black, graphene, buckyballs, carbon nanotubes, carbon mega-tubes, and/or carbon nanobuds)_xOr by reacting it with SiO_xThe combination produces SiO with enhanced conductivity_xEither for use in the first prelithiation step 112 or as part of the first prelithiation step 112. In some embodiments, the SiO is ball milled by using one or more carbon or carbon-based materials_xTo produce SiO with enhanced conductivity_xThe ball milling may cause carbon or carbon-based particles to enter agglomerated SiO generated during ball milling_xIn particles or as agglomerated SiO_xA portion of a particle. Such ball milling can be carried out by mixing with graphite on SiO as described in US 6638662 (which is also incorporated herein by reference)_xSubjecting the powder to ball milling in a similar, generally similar, analogous, substantially equivalent or equivalent stepThe process is carried out. Additionally or alternatively, the carbon or carbon-based material may be deposited on the SiO by another technique, such as thermal CVD, by which the carbon or carbon-based material is deposited on the SiO_xDeposited on the SiO before the powder reacts with the lithium powder_xOn the powder, SiO with enhanced conductivity is generated_xFor use in the first prelithiation step 112.

SiO can be produced using a temperature-controlled mixing/reaction apparatus_xAnd/or conductivity enhanced SiO_xThe powder is reacted with a stable lithium powder, and the temperature-controlled mixing/reaction device applies high shear stress in an inert atmosphere (e.g., an argon atmosphere or an atmosphere containing helium) and provides an effective dissipation effect on the heat generated during the reaction. The reaction apparatus may be a ball mill, for example a planetary ball mill as described in US 7776473, with SiO_xAnd/or conductivity enhanced SiO_xA thermally or thermally regulated reaction vessel, vessel or jar in which the powder is mixed with stabilized lithium powder. Mixing/reaction device-related parameters that may affect or determine the properties of the partially lithiated SSLC material include heat release, heat transfer, and shear stress during the reaction, and the properties of the partially lithiated SSLC material may vary with changes in charge, rotational speed, and/or milling time in a manner readily understood by one of ordinary skill in the art.

When conductivity is enhanced_xWhen used in the first method portion 110, the enhanced electrical conductivity may result in SiO having significantly improved thermal conductivity_x(e.g., when conductivity is enhanced SiO_xComprising or being SiO reacted with or coated with graphite_xWhen) as described in further detail below, which can aid in heat dissipation and thermal regulation during ball milling.

The first method portion 110 additionally includes subjecting the partially lithiated SSLC material to a second prelithiation step 114 in which the partially lithiated SSLC material is compressed (e.g., compressed into pellets or pelletized in a conventional manner, such as by conventional pelletizing equipment (i.e., a pelletizer) or pressing, or direct tableting equipment) and immersed in a lithium-based electrolyte solution (e.g., a lithium-salt-based electrolyte solution or direct tableting equipment) 114Its equivalent) to cause unreacted lithium to react with the SiO in the partially lithiated SSLC material_xUntil all unreacted lithium has disappeared and lithium silicide of enhanced uniformity or uniform composition is obtained by lithium diffusion in the SSLC material. The partially lithiated SSLC material may alternatively be immersed in another type of chemical solution, such as an ester, carbonate, or solvent used in Li-ion battery electrolyte solvents, in a manner understood by those of ordinary skill in the relevant art.

Due to the second prelithiation step 114, the SSLC material exhibits a more uniform or homogeneous lithiation, for example, over a shorter or greatly or significantly reduced time (e.g., as compared to ball milling alone), and a degree of prelithiation that is greater, significantly greater, or much greater than that achieved by the teachings of US 7776473. In various embodiments, the first method portion 110 (i.e., the first prelithiation step 112 in combination with the second prelithiation step 114) produces a substantially fully, or fully lithiated SSLC material that includes lithium silicide uniformly or generally uniformly distributed therein.

The second prelithiation step 114 further and possibly completely lithiates the SSLC material in a uniform or highly uniform manner, which enables the SSLC to achieve maximum volumetric plastic deformation of the SSLC material such that a majority of the free Si nanoparticles in the SSLC form lithium silicide. If the second prelithiation step 114 is not performed, the prelithiated SSLC material is likely to expand further or greatly when charged during actual use as an anode active material, which would result in undesirable volume expansion. Additionally, if the SSLC material is more completely or fully lithiated by the second prelithiation step 114, the energy density and capacity of the SSLC material can be enhanced or maximized/optimized such that the Si nanoparticles in the amorphous delithiated SSLC material have a greater capacity to receive lithium ions without an excessive increase in their volume. In various embodiments, the extent of prelithiation of the SSLC material during the first method portion 110 (i.e., after completion of the first prelithiation step 112 and the second prelithiation step 114) may range from about 25% to 75% or from about 25% to 100%.

After the first method portion 110 (i.e., after the first and second prelithiation steps 112, 114 have been performed), the SSLC material production method 100 in various embodiments additionally includes a second method portion 120 that involves delithiating the prelithiated SSLC material in a delithiation reactor to produce a delithiated SSLC material in which amorphous and/or crystalline silicon nanoparticles are intercalated in a Si: LSC matrix without retaining any unreacted lithium and active lithium silicide. The second method portion 120 involves dispersing a lithiated SSLC material in an organic solvent or organic solvent mixture, and controllably reacting this dispersed lithiated SSLC material with an alcohol that reacts with lithium silicide to cause the lithiated SSLC material to lose lithium and thereby become a substantially fully, completely, or completely delithiated SSLC material. For example, after the second method portion 120, the delithiated SSLC material may have a lithium silicide content of less than about 0.5 wt%.

Fig. 2 is a schematic diagram of a representative delithiation reactor 200 according to one embodiment of the present disclosure. In an embodiment, the delithiation reactor comprises a reaction vessel 210; an alcohol source or supply 212 having a conduit or feed line into reaction vessel 210; an inert gas supply (e.g., argon supply) 214 having a conduit or feed line into reaction vessel 210; a gas discharge 215 having a conduit or gas discharge line leading from the reaction vessel 210; and a first temperature probe 216 having a temperature sensing device (e.g., a thermocouple) disposed in the reaction vessel 210. The reaction vessel 210 is disposed in a cooling bath 220, the cooling bath 220 being associated with or including a second temperature probe 226 having a temperature sensing device (e.g., a thermocouple) disposed therein.

Fig. 3A to 3C are diagrams showing representative microstructure characteristics of SiOx (x ═ 1), respectively; a graphical representation of representative microstructure characteristics of a prelithiated SSLC produced according to one embodiment of the present disclosure; and a graphical representation of representative microstructure characteristics of a delithiated SSLC produced in accordance with an embodiment of the present disclosure. In view of fig. 1 and 3A through 3C, the first method portion 110 is SiO_xThe powder is reacted with lithium powder to formSiO_xThe powder reversibly transforms or plastically deforms into a substantially, substantially fully or fully lithiated SSLC material; the prelithiated SSLC material is then fully delithiated to produce a porous, plastically deformable Si: LSC matrix carrying amorphous and/or crystalline nano-silicon particles, which can be reversibly lithiated and delithiated in a manner readily understood by one of ordinary skill in the art. Thus, when delithiated SSLC materials are used as lithium ion battery anode materials, these nano-silicon particles carried by the Si: LSC matrix can act as lithium intercalation sites (or similarly, lithium "acceptor sites" and "donor sites", respectively) during lithiation and delithiation of the anode material.

In a delithiated SSLC material produced according to one embodiment of the present disclosure, the matrix of lithium silicate carrying silicon nanoparticles functions in a similar or analogous manner to a solid electrolyte that migrates lithium ions to the silicon nanoparticles. This is achieved by tightly controlling the uniform distribution of silicon nanoparticles and the porosity of the Si: LSC matrix during the anode material fabrication.

Referring again to fig. 1, the third method portion 130 involves filtering, washing, and the delithiated SSLC material can be dried in a conventional manner, e.g., in air and can be dried under negative pressure or vacuum, where such drying can be conducted at a temperature between 100 ℃ and 120 ℃ (e.g., in an oven). In the fourth method portion 140, the delithiated SSLC material may be formed by coating with one or more types of materials, such as LiAlO, in a conventional manner₃、Al₂O₃、TiO₂、AlF₃And LiF, while mechanically stable or structurally reinforced. Finally, in a fifth method portion 150, the delithiated SSLC material or mechanically stable delithiated SSLC material is treated, coated or combined in a conventional manner with one or more carbon and/or carbon-based materials, such as graphite, carbon black, graphene, buckyballs, carbon nanotubes, carbon mega-tubes and/or carbon nanobuds. In several embodiments, the fifth method portion 150 involves partially fusing the delithiated SSLC material with the delithiated SSLC material by CVD (which partially fuses the carbon-based material with the delithiated SSLC material)Or a mechanically stable delithiated SSLC material is coated with a carbon-based material (e.g., graphite).

Following the fifth method portion 150, the delithiated SSLC material can be used as a non-aqueous electrolyte secondary battery negative electrode (anode) material.

Additional aspects of representative SSLC material production methods

In view of the foregoing, a particulate delithiated SSLC material according to one embodiment of the present disclosure may be produced in powder form having a microstructure that: wherein amorphous and/or crystalline silicon at the atomic level is dispersed in its Si: LSC matrix in the form of nano-silicon grains. The size of the nano-silicon grains is typically in the range of 0.5nm to 80nm, and the Si: LSC matrix typically exhibits a grain size of 10nm to 200 nm. The average particle size of the SSLC material particles (i.e., SSLC powder particles) is typically 1 μm to 10 μm. In various embodiments, the delithiated SSLC material (i.e., wherein there is no unreacted lithium or lithium silicide) has a silicon content of 30 wt.% to 60 wt.%, and an oxygen content of 25 wt.% to 40 wt.%; and a lithium content of 10 to 20 wt%.

In many embodiments, the composition of the fully prelithiated SSLC material is about 31 wt.% silicon, about 32 wt.% lithium, and about 35 wt.% oxygen; and the composition of the fully delithiated SSLC material may be about 37 wt.% silicon, about 18 wt.% lithium, and about 43 wt.% oxygen.

Can be prepared by subjecting a mixture of compounds generally characterized as SiO at controlled temperatures_x(0.8 < x < 1.6) reacting the silicon oxide powder with lithium metal powder to produce a delithiated SSLC material. In the absence of conductivity enhancement, the SSLC material has a lower conductivity. Thus, it is proposed to use carbon or carbon-based materials for SiO_xAnd/or surface treatment of delithiated SSLC material or SiO_xAnd/or the surface of the delithiated SSLC material reacts with the carbon or carbon-based material to enhance its electrical conductivity. The carbon coating can be easily formed by thermal CVD (e.g., thermal CVD of graphite), which improves the conductivity to a high level. Additionally or alternatively, the SiO can be formed by pre-milling with a conductive material such as graphite powder or carbon black powder_xPowder ofA highly conductive surface is obtained. The amount of carbon present in or coated on the SSLC powder is typically from 3 wt% to 20 wt% based on the weight of the SSLC material powder. The carbon coating maintains chemical bonds with the surface of the SSLC material and may remain on the surface even after a large volume expansion.

Example 1

Silicon oxide powder (SiO) was dried in a high-energy ball mill under a protective argon atmosphere using hexane as the dispersing medium_x0.8 < x < 1.6, Sigma-Aldrich) and/or silica-based powder are milled with the lithium powder. The silica and/or silica-based powder is combined with the stabilized lithium powder in 5, 10, 15, and 20 weight percent increments in a closed container or vial under an inert gas (argon) atmosphere in a manner readily understood by one of ordinary skill in the relevant art(FMC Corp.) Pre-mixing (e.g., 6g SiO_xAnd 3.8gPremixed to prepare a solution having about 6g SiO_xAnd 0.6g of lithium, or about 10 wt% of the sample. Although metallic lithium is generally available in the form of powder, foil or block, stable lithium powder is used(FMC corporation) is generally preferred.

Transferring the silica and/or silica-based material pre-mixed with lithium metal into a ball mill container, vessel or jar (e.g., a 50ml or larger container); and then ball-milled, i.e., mechanically mixed for reaction with lithium in a ball mill having efficient heat dissipation capabilities. The reaction vessel was tightly sealed with a rubber band under an inert atmosphere designed for cooling control and capable of mixing under high shear stress. Planetary high energy ball mills are good examples of ball mills for use in such milling processes. For example, a planetary ball mill containing a predetermined number of stainless steel or zirconia milling balls, manufactured by Retsch GmbH, may be used. The mill has a tight closure to the balls, potential heat dissipation, and high shear stress. The temperature of the reaction vessel was controlled in the range of 40 ℃ to 150 ℃.

In one representative embodiment, the ball milling container is rotated in forward and backward directions, each for ten minutes while maintaining an internally controlled temperature (e.g., 40 ℃ to 150 ℃). After ball milling, the vessel is allowed to cool, e.g., to room temperature, after which the partially prelithiated silicon-silicon oxide-lithium complex (i.e., partially lithiated SSLC material) is removed from the vessel. To enhance or maximize the degree and uniformity of prelithiation, this partially lithiated SSLC material is then compressed into pellets in a conventional manner with the hexane removed by filtration or evaporation. The pellets are then placed in a vessel or container and immersed in an electrolyte or mixture of electrolytes to allow unreacted lithium and SiO_xThe powder reaction is complete, thereby producing a further substantially fully or fully prelithiated SSLC material that exhibits enhanced uniformity or uniform prelithiation. Temperature control to prevent unreacted lithium and SiO_xA violent reaction.

More particularly, in solid siliceous materials such as SiO_xIn a solid state reaction between the powder and metallic lithium, the rate of diffusion of lithium into the solid siliceous material is generally low. Lithium metal is difficult to be mixed with solid SiO_xThe powder is uniformly reacted, and thus, various chemical components such as unreacted lithium, unreacted SiO may be generated₂And various types of lithium silicide and lithium silicate. One effective method for remedying this lithium deficiency is to compress the prelithiated powder into pellets and submerge the compressed pellets in an electrolyte or mixture of electrolytes. To avoid a violent reaction, the temperature was controlled to start the reaction at a temperature between 5 ℃ and room temperature.

Pellets of enhanced, substantially fully or fully and homogeneously prelithiated SSLC material were subsequently ground in a mortar after filtration and re-dispersed in hexane. Slowly adding ethanol to the solutionIn the freshly prepared slurry. The lithium silicide reacts with the ethanol, so that the prelithiated SSLC material loses lithium. The alcohol was added until bubble formation ceased, indicating that a fully delithiated SSLC material had been produced. After filtration and washing, the powder can be coated with LiAlO₃、Al₂O₃、TiO₂、AlF₃LiF, and/or other material(s) (e.g., coating thickness about 20nm to 50nm or about 30nm) for mechanical stabilization, and/or dried and coated with carbon (e.g., graphite) by CVD.

Silicon oxide (SiO)_x0.8 < x < 1.6) and/or silica-based material until it reaches a predetermined or desired size distribution by high energy ball milling. Therefore, it is reacted with the metallic lithium powder in an inert atmosphere by a ball milling method. Since the reaction is strongly exothermic, it readily combusts and results in Si and SiO₂Significant particle growth and loss of electrochemical activity after disproportionation. In order to control unreacted SiO₂The phase growth is carried out by controlling the temperature of the reaction vessel to below 150 ℃.

SiO_xIs Si and SiO in the nanometer level₂A mixture of (a). Since the volume of crystalline Si therein is 33%, SiO_xHaving nanocrystalline Si particles embedded in SiO₂The substrate of (1).

When 2SiO₂When reacted with (4+ y) Li, it forms Li_ySi:Li₄SiO₄The compound is as follows:

4SiO+(4+3y)Li→2Li_ySi+Li_ySi:Li₄SiO₄during lithiation (5)

Wherein Li_ySi is in the form of nanoparticles, and Li_ySi:Li₄SiO₄In the form of a carrier carrying Li_yMatrix form of Si nanoparticles. When the delithiation is carried out,

2Li_ySi+Li_ySi:Li₄SiO₄→2Si+Si:Li₄SiO₄during delithiation (6)

Wherein Si is in the form of nanoparticles and Si Li₄SiO₄In the form of a matrix carrying Si nanoparticles.

During lithiation/delithiation, Li_ySi:Li₄SiO₄And Si Li₄SiO₄May be present in the form of a matrix with a certain level of lithiation (e.g., up to a limit of about 50%). Lithium silicide (Li) in the matrix if the reaction proceeds to an ignited state_ySi) can agglomerate into nano lithium silicide particles. Therefore, lithium silicide particles can grow, and due to Li_ySi:Li₄SiO₄The matrix of (a) loses lithium silicide to the lithium silicide particles, which become part of the matrix. This will result in large volume changes during lithiation and delithiation and degrade cycle performance. Thus, lithium and SiO are performed at a temperature not exceeding 150 deg.C_xThe reaction of (a) is important.

Used before ball millingMaterial pretreated or precoated SiO for enhancing its thermal conductivity_xHeat dissipation and temperature control can be improved within the ball milling vessel during ball milling. For example, SiO_xThe coating may be pre-treated or pre-coated (e.g., by ball milling and/or CVD as set forth above) with a carbon or carbon-based material that simultaneously increases electrical conductivity and SiO_xThermal conductivity of (2). Furthermore, due to the improved heat dissipation and better temperature control, larger amounts of lithium powder can be used with a given amount of this pre-treated/pre-coated SiO_xBall milling without the deleterious effects of uncontrolled heat and SiO powder agglomeration. For example, when SiO is pre-treated or pre-coated with a carbon or carbon-based material such as graphite_xWhen added, the additive may be added in about 25% incrementsRather than adding SLMP in 10% increments.

In SiO_xDuring lithiation of the anode, Li_yLi due to increase in volume of Si phase_ySi:Li₄SiO₄Li in matrix₄SiO₄Phase plastic deformation. Because of Li in the matrix_4.4Si and Li₄SiO₄Is 1, so Li is close to 4.4 when y is₄SiO₄The phases may not be present in the form of a matrix. During delithiation, Li_ySi loses lithium and its volume decreases rapidly. However, plastically deformed Li₄SiO₄Substantially or essentially remain unchanged or intact at some level and become very porous. This may explain passage of Li before and after delithiation₄SiO₄How plastic deformation of the phases minimizes volume changes. The foregoing reaction (4) showed that 2Li_yIntercalation of Si nanoparticles in Li_ySi:Li₄SiO₄In the matrix of (a). When y is close to 4.4, 2Li_ySi and Li_ySi:Li₄SiO₄Is 1, and 2Li_yThe increased volume of Si also contributes to Li_ySi:Li₄SiO₄Large plastic deformation of the phase and large permanent defects left in the matrix. This mechanism suggests that lithiation of SiO during lithiation/delithiation_xThe volume change of the anode is significantly minimized. Therefore, when SiO is in the micron order_xMicron SiO when both anodes and micron silicon anodes are well coated with conductive carbon_xThe anodes generally exhibit much better cycling performance than micron-sized silicon anodes.

Plastically deformed Li_ySi:Li₄SiO₄But brittle and collapsible due to lithiation/delithiation cycles between cycles. To enhance the mechanical properties of the matrix during cycling, nanofilms such as LiAlO are used after delithiation of LiySi₂、Al₂O₃、TiO₂、AlF₃、LiF、SiO₂And/or one or more other types of metal oxides may be coated with SiO_xAnd an anode. The coating can be filled with SiO_xDefects on the surface of the anode and support its mechanical stability. In addition, the coating may aid in shaping and may beThe stability of a Solid Electrode Interphase (SEI) layer formed at an anode-electrolyte interface in a lithium ion battery is enhanced. In addition, the coating may increase the likelihood that the Li-ion battery anode, made using the delithiated SSLC material according to one embodiment of the present disclosure, will maintain sufficient electrical conductivity over time between multiple charge/discharge or lithiation/delithiation cycles (or, correspondingly, expansion/contraction cycles).

To increase or further increase the electrical conductivity of the delithiated SSLC material, the carbon and/or carbon-based material may be applied to the delithiated SSLC material particles by thermal CVD, in particular by heating a CVD chamber in which the delithiated SSLC material is at a temperature of 600 ℃ to 900 ℃ and feeding an organic gas or vapour into the CVD chamber. The conductive carbon may not be sufficiently fused on the surface of the composite particle below 800 ℃. Above a certain temperature, however, it is embedded in SiO_xSiO in the structure₂The crystalline Si particles in the matrix may be associated with Si Li₄SiO₄The silicon phases in the matrix agglomerate and then crystalline silicon can grow. This increases the volume of the silicon particles to be larger than Li₄SiO₄And destroy nano-Si particle-embedded Li₄SiO₄Structure and ultimately cycle performance. The CVD chamber temperature should be maintained in the range of 800 c to 950 c.

The organic material used to coat the carbon via CVD may be selected from such materials: a material capable of forming carbon (graphite) by pyrolysis under an inert atmosphere at the above temperature range. Examples of hydrocarbons that can form such carbons include, but are not limited to, methane, ethane, ethylene, acetylene, propane, butane, butenes, pentane, isobutane, and hexane, alone or in mixtures thereof; and monocyclic to tricyclic aromatic hydrocarbons such as benzene, toluene, xylene, styrene, ethylbenzene, diphenylmethane, naphthalene, phenol, cresol, nitrobenzene, chlorobenzene, indene, coumarone, pyridine, anthracene, and phenanthrene, alone or in mixtures thereof. Organic polymers or polymeric or oligomeric siloxanes having larger hydrocarbon side chains may alternatively be used as the carbon source.

Delithiated SSLC material powder can be used as a negative electrode material for lithium ion batteriesA nonaqueous electrolyte secondary battery, particularly a lithium ion secondary battery, having a high capacity, good cycle performance, and a low irreversible capacity from the first cycle is constructed. The positive active material may be selected from commercially available cathodes, such as LiCoO₂Lithium nickel cobalt magnesium oxide (NCM), lithium rich NCM, aluminum doped lithium nickel cobalt oxide, and spinel lithium magnesium oxide. The electrolyte used herein may be a lithium salt such as lithium perchlorate, LiPF in a non-aqueous solution₆、LiBF₆And LITFSI (lithium bis (trifluoromethanesulfonyl) imide). The non-aqueous solvent includes propylene carbonate, ethylene carbonate, dimethoxyethane, gamma-butyrolactone, and 2-methyltetrahydrofuran, alone or in a mixture thereof.

Example 2

A second example is described below that, in view of the description herein, is performed in a manner similar or substantially identical to that described above for example 1, in a manner readily understood by a person of ordinary skill in the relevant art.

Ball milling of SiO in ethanol solvent_xPowder (SiO)_x0.8 < x < 1.6, sigma-aldrich) for 5 hours. In the presence of SiO_xAfter the particle size was reduced to 6um, ethanol was evaporated and graphite powder such as Mage3 graphite powder having an average size (D50) of 23 μm (Hitachi Chemical co. ltd., Tokyo, Japan) was added. Mixing SiO_xThe particles and graphite powder were ball milled for an additional 2 hours to produce SiO for prelithiation according to embodiments of the disclosure_xBase powders, i.e. SiO_xGraphite powder. Next, the following steps are carried outPowder (FMC Corp.) was added to the ball mill vessel and ball milled for an additional 30 minutes resulting in the initial SiO_xPartial prelithiation of graphite powder and produces a partially prelithiated SSLC material. Followed by partial prelithiation of the SiO with removal of the hexane by filtration or evaporation_xGraphite powder was compressed into pellets in a conventional manner. Then, the pellets were immersedIn an electrolyte or electrolyte mixture in a vessel or container, to react unreacted lithium with SiO_xThe reaction of the powder is complete, resulting in an enhanced substantially fully or fully prelithiated SSLC material having a uniform, substantially uniform, or substantially uniform distribution of lithium silicide therein.

Delithiation is performed in the delithiation reactor 200 in the manner described above to produce a fully delithiated SSLC material powder. The ethanol/powder slurry was initially dried using a centrifuge, followed by drying by a stream of ambient air. The dry delithiated SSLC material powder was mixed with carbon black and a binder in NMP solvent and cast on a Cu foil, followed by drying in a vacuum circuit at 250 ℃ for use as a negative electrode of a Li-ion battery.

Aspects of particular embodiments of the present disclosure address and match existing SiO_xAt least one aspect, problem, limitation, and/or disadvantage associated with the base anode material, composition, or structure; for preparing SiO_xMethods of anode materials, compositions or structures; and SiO_xAnd a base anode. Although features, aspects, and/or advantages associated with certain embodiments have been described in the present disclosure, other embodiments may also exhibit such features, aspects, and/or advantages that fall within the scope of the disclosure and the claims included herein. One of ordinary skill in the art will appreciate that several of the above-disclosed systems, components, methods, or alternative embodiments thereof, may be desirably combined into other different systems, components, methods, and/or applications. Furthermore, various modifications, alterations, and/or improvements to the various embodiments disclosed herein may be made by those having ordinary skill in the relevant art, and such modifications, alterations, and/or improvements are still within the scope of the disclosure and claims.

Claims (18)

1. A method for producing silicon: silicon oxide: a method of lithium composite (SSLC) material, comprising:

performing a prelithiation treatment to produce a prelithiated SSLC material, the prelithiation treatment comprising:

producing a partially lithiated SSLC material by a mechanical mixing step comprising milling a silica powder and a lithium powder; and

producing a further prelithiated SSLC material by a spontaneous lithiation step comprising:

compressing the partially lithiated SSLC material matrix material; and

exposing the compressed partially lithiated SSLC material to a lithium-based electrolyte, wherein the spontaneous lithiation step completes the reaction of unreacted lithium with SiOx in the partially lithiated SSLC material until the unreacted lithium disappears and a uniform composition of lithium silicide is achieved by lithium diffusion in the SSLC material;

performing a delithiation treatment after the prelithiation treatment to produce a delithiated SSLC material, the delithiation treatment comprising:

dispersing the compressed further prelithiated SSLC material in a liquid carrier medium, thereby producing a dispersed prelithiated SSLC material; and

exposing the dispersed pre-lithiated SSLC material to a volume of one or more organic solvents, thereby reacting and extracting lithium from the dispersed pre-lithiated SSLC material until the reaction of lithium silicide within the dispersed pre-lithiated SSLC material with the one or more organic solvents ceases, wherein the volume of one or more organic solvents acts as a reservoir with respect to reacting with lithium silicide within the dispersed pre-lithiated SSLC material,

wherein the delithiated SSLC material comprises a porous, plastically deformable matrix of Si: lithium silicate composite (Si: LSC) in which nano-silicon particles are embedded.

2. The method of claim 1, wherein the delithiated SSLC material exhibits a lithium silicide content of less than 0.5 wt.%.

3. The method of claim 1 or 2, wherein the delithiated SSLC material has a particle size of 1 to 10 μ ι η, the LSC matrix exhibits a grain size of 10 to 200nm and the nano-silicon particles have a particle size of 5 to 80 nm.

4. The method of any of claims 1-3, wherein the delithiated SSLC material has a silicon content of 30 to 60 wt.%, an oxygen content of 25 to 40 wt.%, and a lithium content of 10 to 20 wt.%.

5. The method of any one of claims 1-4, wherein the composition of the delithiated SSLC material is about 37 wt% silicon, about 18 wt% silicon, and about 43 wt% oxygen.

6. The method of any one of claims 1-5, wherein the liquid carrier medium comprises an aprotic solvent and the one or more organic solvents comprise an alcohol.

7. The method of any one of claims 1-6, wherein the liquid carrier medium comprises hexane and the one or more organic solvents comprise ethanol, glycerol, and/or polyvinyl alcohol (PVA).

8. The method of any one of claims 1-7, wherein the silicon oxide powder is characterized as SiO_x(0.8 < x < 1.6), wherein said mechanically mixing step comprises ball milling said silicon oxide powder with said lithium powder, and wherein said lithium powder comprises

9. The method of any of claims 1-8, further comprising performing a first conductivity enhancement treatment prior to the prelithiation treatment, wherein the first conductivity enhancement treatment comprises at least one of: ball milling the silicon oxide powder with a carbon-based material, and coating the silicon oxide powder with the carbon-based material.

10. The method of any of claims 1-9, further comprising performing a second conductivity enhancement treatment after the delithiation treatment, wherein the second conductivity enhancement treatment comprises at least one of: ball milling the silicon oxide powder with a carbon-based material, and coating the silicon oxide powder with the carbon-based material.

11. The method of claim 9 or 10, wherein the carbon-based material comprises at least one of: graphite, carbon black, buckyballs, carbon nanotubes, and carbon nanobuds.

12. A delithiated silicon: silicon oxide: a lithium composite (SSLC) material produced by the method of claim 1 and having a lithium silicide content of less than 0.5 wt%.

13. Delithiated silicon produced by the method of claim 1 and having a lithium silicide content of less than 0.5 wt%: silicon oxide: use of a lithium composite (SSLC) material in a method of manufacturing a secondary battery cell anode.

14. A silicon-containing alloy having: silicon oxide: a lithium ion battery of a lithium composite (SSLC) negative active material, wherein the lithium ion battery exhibits an irreversible capacity loss of less than 15%.

15. The lithium ion battery of claim 14, wherein the lithium ion battery exhibits an irreversible capacity loss of less than 12% or less than 10%.

16. The lithium ion battery of claim 14 or 15, wherein the anode thereof exhibits a volume change of 10 to 35% associated with charging and discharging of the lithium ion battery.

17. The lithium ion battery of claim 16, wherein the anode exhibits an average volume change of 20% associated with charging and discharging of a lithium ion battery.

18. The lithium ion battery of any of claims 14-17, wherein the SSLC material is produced by the method of claim 1.