Method for preparing pre-lithiated silicon oxide electroactive materials comprising silicide and silicate

Abstract

A method of preparing a negative electrode material for an electrochemical cell for recycling lithium ions is provided. The method may include centrifugally distributing a molten precursor comprising silicon, oxygen, and lithium by contacting the molten precursor with a rotating surface in a centrifugal atomization reactor. The molten precursor is formed by combining lithium, silicon, and oxygen. For example, the precursor may be formed from a mixture comprising silicon dioxide (SiO 2 ), lithium oxide (Li 2 O), and silicon (Si). The method may further include curing the molten precursor to form a plurality of substantially circular solid electroactive particles comprising lithium silicide (Li y Si, where 0 < y ≤ 4.4) and lithium silicate (Li 4 SiO 4 ) and having a D50 diameter less than or equal to about 20 microns.

Description

Technical Field

[0001] The present invention relates to a method for preparing a pre-lithiated silicon oxide electroactive material comprising silicide and silicate. Background Art

[0002] This section provides background information related to the present disclosure which is not necessarily prior art.

[0003] The present disclosure relates to a method for forming a pre-lithiated electroactive material for a negative electrode of a lithium ion electrochemical cell. The method comprises centrifugally distributing a molten precursor comprising silicon, lithium oxide, and optionally silicon oxide in a centrifugal atomization reactor to form a pre-lithiated silicon oxide material having a mixture of lithium silicide and lithium silicate.

[0004] Typical electrochemically active materials for forming negative electrode materials of anodes of lithium ion electrochemical cells or batteries include lithium-graphite intercalation compounds, lithium-silicon alloy compounds, lithium-tin alloy compounds, and lithium alloys. Although graphite compounds are the most common, there has been a growing interest in anode materials with high specific capacities (compared to conventional graphite) recently. For example, silicon has the highest known theoretical lithium loading capacity, which makes it one of the most promising materials for rechargeable lithium ion batteries. However, current silicon-containing anode materials can potentially have serious disadvantages.

[0005] For example, during the initial lithiation and delithiation cycles, silicon-based electroactive materials may undergo excessive volume expansion and contraction. In addition, additional volume changes may occur during successive charge and discharge cycles observed for silicon electroactive materials. Such volume changes can lead to fatigue cracking and bursting of electroactive materials. This may result in loss of electrical contact between the silicon-containing electroactive material and the rest of the battery cell and consumption of electrolyte for forming a new solid electrolyte interface (SEI), which results in attenuation of electrochemical cycling performance, reduced Coulombic charge capacity retention (capacity decay) and limited cycle life. This is especially true at the electrode loading levels required for the application of silicon-containing electrodes in high-energy lithium-ion batteries, such as those used in transportation applications.

[0006] Although pre-lithiation of certain silicon-based active materials prior to incorporation into electrochemical cells has been used to minimize some of these disadvantages, pure lithium and other expensive reactants are often the reactants used for pre-lithiation. Pure lithium is highly reactive and therefore makes handling during the preparation process more complicated. It would therefore be desirable to develop methods for pre-lithiation of silicon-containing electroactive materials that can employ more common and readily available reactants and can avoid some of the handling restrictions that may be required for lithium, while being able to obtain electroactive materials that can minimize capacity fade and maximize charge capacity in commercial lithium-ion batteries with long life, especially for transportation applications. Summary of the invention

[0007] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0008] The present disclosure relates to a method for preparing a negative electrode material for an electrochemical cell that circulates lithium ions. In certain aspects, the method comprises centrifugally distributing a molten precursor comprising silicon, oxygen, and lithium by contacting the molten precursor with a rotating surface in a centrifugal atomization reactor. The method further comprises solidifying the molten precursor to form a negative electrode material comprising lithium silicide (Li y Si, wherein 0<y≤4.4) and lithium silicate (Li4SiO4) and having a plurality of substantially round solid electroactive particles having a D50 diameter of less than or equal to about 20 microns.

[0009] In certain aspects, the molten precursor is formed by melting a precursor comprising silicon (Si) and lithium oxide (Li2O).

[0010] In certain further aspects, the precursor comprises a molar ratio of silicon (Si) to lithium oxide (Li2O) of greater than or equal to about 1:2 to less than or equal to about 2:1.

[0011] In certain further aspects, the precursor further comprises silicon dioxide (SiO2).

[0012] In certain aspects, the lithium silicide is further comprised of the formula Li 4.4x Si represents, wherein x is greater than 0 and less than or equal to about 0.85.

[0013] In certain aspects, the plurality of substantially round-shaped solid electroactive particles comprises a coating selected from the group consisting of a carbon-containing coating, an oxide-containing coating, and combinations thereof.

[0014] In certain aspects, the temperature in the centrifugal atomization reactor is greater than or equal to 400°C to less than or equal to about 800°C during centrifugal distribution.

[0015] In certain aspects, the environment in the centrifugal atomization reactor has less than or equal to about 0.5 wt % of any oxygenated species.

[0016] In certain aspects, the flow rate of the centrifugal atomization reactor is greater than or equal to 50 kg / hour to less than or equal to about 500 kg / hour.

[0017] In certain aspects, the D50 diameter is greater than or equal to about 1 μm to less than or equal to about 10 μm.

[0018] In certain aspects, the plurality of substantially round-shaped solid electroactive particles has a polydispersity index less than or equal to about 1.2.

[0019] The present disclosure further relates to a method for preparing a negative electrode material for an electrochemical cell that circulates lithium ions. The method includes centrifugally distributing a molten precursor by contacting the molten precursor with a rotating surface in a centrifugal atomization reactor. The molten precursor is formed from a mixture comprising silicon dioxide (SiO2), lithium oxide (Li2O) and silicon (Si). The method includes solidifying the molten precursor to form a molten precursor comprising lithium silicide (Li y Si, wherein 0 < y ≤ 4.4) and lithium silicate (Li4SiO4) and having a plurality of substantially round solid electroactive particles having a D50 diameter of less than or equal to about 20 microns.

[0020] In certain aspects, the precursor comprises a molar ratio of silicon (Si) to lithium oxide (Li2O) of greater than or equal to about 1:2 to less than or equal to about 2:1.

[0021] In certain aspects, the lithium silicide is further comprised of the formula Li 4.4x Si represents, wherein x is greater than 0 and less than or equal to about 0.85.

[0022] In certain aspects, the temperature in the centrifugal atomization reactor is greater than or equal to 400°C to less than or equal to about 800°C during centrifugal distribution.

[0023] In certain aspects, the flow rate of the centrifugal atomization reactor is greater than or equal to 50 kg / hour to less than or equal to about 500 kg / hour.

[0024] In certain aspects, the D50 diameter is greater than or equal to about 1 μm to less than or equal to about 10 μm.

[0025] In certain aspects, the plurality of substantially round-shaped solid electroactive particles has a polydispersity index less than or equal to about 1.2.

[0026] The present disclosure further relates to a method for preparing a negative electrode material for an electrochemical cell that cycles lithium ions. The method includes melting a precursor mixture comprising lithium oxide (Li2O) and silicon (Si) to form a molten precursor. The method also includes centrifugally distributing the molten precursor by contacting the molten precursor with a rotating surface in a centrifugal atomization reactor. The method further includes solidifying the molten precursor to form a molten precursor comprising lithium silicide (Li2O). y Si, wherein 0 < y ≤ 4.4) and lithium silicate (Li4SiO4) and having a plurality of substantially round solid electroactive particles having a D50 diameter of less than or equal to about 20 microns.

[0027] In certain aspects, the precursor further comprises silicon dioxide (SiO2).

[0028] The present invention discloses the following technical solutions:

[0029] 1. A method for preparing a negative electrode material for an electrochemical cell for cycling lithium ions, the method comprising:

[0030] The molten precursor comprising silicon, oxygen and lithium is centrifugally distributed by contacting the molten precursor with a rotating surface in a centrifugal atomization reactor, and the molten precursor is solidified to form a molten precursor comprising lithium silicide (Li y Si, wherein 0 < y ≤ 4.4) and lithium silicate (Li4SiO4) and having a plurality of substantially round solid electroactive particles having a D50 diameter of less than or equal to about 20 microns.

[0031] 2. The method according to technical solution 1, wherein the molten precursor is formed by melting a precursor containing silicon (Si) and lithium oxide (Li2O).

[0032] 3. A method according to technical solution 2, wherein the precursor comprises a molar ratio of silicon (Si) to lithium oxide (Li2O) greater than or equal to about 1:2 to less than or equal to about 2:1.

[0033] 4. The method according to Technical Solution 2, wherein the precursor further comprises silicon dioxide (SiO2).

[0034] 5. The method according to technical solution 1, wherein the lithium silicide is further composed of the formula Li 4.4x Si represents, wherein x is greater than 0 and less than or equal to about 0.85.

[0035] 6. A method according to technical solution 1, wherein the plurality of substantially circular solid electroactive particles comprises a coating selected from a carbon-containing coating, an oxide-containing coating and a combination thereof.

[0036] 7. The method according to technical solution 1, wherein the temperature in the centrifugal atomization reactor is greater than or equal to 400°C to less than or equal to about 800°C during the centrifugal distribution.

[0037] 8. A method according to Technical Solution 1, wherein the environment in the centrifugal atomization reactor has less than or equal to about 0.5 weight % of any oxygen-containing species.

[0038] 9. The method according to Technical Solution 1, wherein the flow rate of the centrifugal atomization reactor is greater than or equal to 50 kg / hour to less than or equal to about 500 kg / hour.

[0039] 10. The method according to technical solution 1, wherein the D50 diameter is greater than or equal to about 1 μm to less than or equal to about 10 μm.

[0040] 11. A method according to technical solution 1, wherein the plurality of substantially circular solid electroactive particles have a polydispersity index less than or equal to about 1.2.

[0041] 12. A method for preparing a negative electrode material for an electrochemical cell for cycling lithium ions, the method comprising:

[0042] centrifugally distributing the molten precursor by contacting the molten precursor with a rotating surface in a centrifugal atomization reactor, wherein the molten precursor is formed from a mixture comprising silicon dioxide (SiO2), lithium oxide (Li2O), and silicon (Si); and

[0043] Solidify the molten precursor to form a lithium silicide (Li y Si, wherein 0 < y ≤ 4.4) and lithium silicate (Li4SiO4) and having a plurality of substantially round solid electroactive particles having a D50 diameter of less than or equal to about 20 microns.

[0044] 13. A method according to technical solution 12, wherein the mixture comprises a molar ratio of silicon (Si) to lithium oxide (Li2O) greater than or equal to about 1:2 and less than or equal to about 2:1.

[0045] 14. The method according to technical solution 12, wherein the lithium silicide is further composed of the formula Li 4.4x Si represents, wherein x is greater than 0 and less than or equal to about 0.85.

[0046] 15. The method according to technical solution 12, wherein the temperature in the centrifugal atomization reactor is greater than or equal to 400°C to less than or equal to about 800°C during the centrifugal distribution process.

[0047] 16. A method according to technical solution 12, wherein the flow rate of the centrifugal atomization reactor is greater than or equal to 50 kg / hour to less than or equal to about 500 kg / hour.

[0048] 17. A method according to technical solution 12, wherein the D50 diameter is greater than or equal to about 1 μm to less than or equal to about 10 μm.

[0049] 18. A method according to technical solution 12, wherein the plurality of substantially circular solid electroactive particles have a polydispersity index less than or equal to about 1.2.

[0050] 19. A method for preparing a negative electrode material for an electrochemical cell for cycling lithium ions, the method comprising:

[0051] melting a precursor mixture comprising lithium oxide (Li2O) and silicon (Si) to form a molten precursor;

[0052] centrifugally distributing the molten precursor by contacting the molten precursor with a rotating surface in a centrifugal atomization reactor; and

[0053] Solidify the molten precursor to form a lithium silicide (Li y Si, wherein 0 < y ≤ 4.4) and lithium silicate (Li4SiO4) and having a plurality of substantially round solid electroactive particles having a D50 diameter of less than or equal to about 20 microns.

[0054] 20. A method according to technical solution 19, wherein the precursor mixture further contains silicon dioxide (SiO2).

[0055] Further areas of applicability will become apparent from the description provided herein.The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0057] Figure 1 is a schematic diagram of an exemplary electrochemical battery cell.

[0058] Figure 2 An exemplary centrifugal atomization reactor for forming ultrafine solid electroactive material particles according to the present disclosure is shown.

[0059] Figure 3 is an illustration of a cross-sectional view of a particle of a negative electroactive material formed according to certain aspects of the present disclosure, including a lithium-silicon oxide composition forming the negative electroactive particle, which may be processed to have a first coating and optionally further processed to have a second coating.

[0060] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0061] Exemplary embodiments are provided so that the present disclosure will be complete and the present disclosure will fully convey the scope to those skilled in the art. Many specific details, such as examples of specific compositions, components, devices and methods, are set forth to provide a full understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that the exemplary embodiments may be presented in many different forms, and that none of them should be construed as limiting the scope of the present disclosure. In some exemplary embodiments, known methods, known device structures and known techniques are not described in detail.

[0062] The terms used herein are only for describing specific exemplary embodiments, and are not intended to be limiting. Unless the context clearly indicates otherwise, as used herein, the singular forms "one", "an" and "the" may be intended to also include plural forms. The terms "comprise", "include", "cover" and "have" are compatible, and therefore specify the presence of the features, elements, compositions, steps, integers, operations and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or their groups. Although the open term "comprising" should be understood as a non-limiting term for describing and claiming the various embodiments described herein, in some aspects, the term may be understood as alternatively being a more restrictive and limited term, such as "consisting of..." or "consisting essentially of..." Thus, for any given embodiment of a narration composition, material, assembly, element, feature, integer, operation and / or method step, the present disclosure also specifically includes an embodiment consisting of or essentially consisting of such narrated compositions, materials, assemblies, elements, features, integers, operations and / or method steps. In the case of “consisting of,” alternative embodiments exclude any additional compositions, materials, components, elements, features, integers, operations, and / or method steps, while in the case of “consisting essentially of,” any additional compositions, materials, components, elements, features, integers, operations, and / or method steps that materially affect the basic and novel characteristics are excluded from such embodiments, but any compositions, materials, components, elements, features, integers, operations, and / or method steps that do not materially affect the basic and novel characteristics may be included in the embodiments.

[0063] Any method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless expressly identified as an order of performance. It is also to be understood that additional or alternative steps may be employed unless otherwise stated.

[0064] When a component, element, or layer is referred to as being "on," "engaged," "connected," or "coupled" to another element or layer, it may be directly on, engaged, connected, or coupled to another component, element, or layer, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on," "directly engaged," "directly connected," or "directly coupled" to another element or layer, there may be no intervening elements or layers. Other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0065] Although the terms first, second, third, etc. can be used to describe various steps, elements, components, regions, layers and / or sections in this article, unless otherwise specified, these steps, elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish a step, element, component, region, layer or section from another step, element, component, region, layer or section. Unless the context clearly indicates, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in this article. Therefore, the first step, element, component, region, layer or section discussed below can be referred to as the second step, element, component, region, layer or section without departing from the teaching of exemplary embodiments.

[0066] For ease of description, spatial or temporal relative terms may be used herein, such as "before", "after", "inside", "outside", "below", "beneath", "lower", "above", "upper", etc. to describe the relationship of one element or feature to other (one or more) elements or (one or more) features as shown in the drawings. Spatially or temporally relative terms may be intended to encompass different orientations of a device or system in use or operation in addition to the orientation shown in the drawings.

[0067] Throughout the present disclosure, numerical values ​​represent approximate measured values ​​or range limits to cover slight deviations from given values ​​and embodiments having approximately the values ​​mentioned and embodiments having exactly the values ​​mentioned. Except in the working examples provided at the end of the detailed description, all numerical values ​​of (such as amount or condition) parameters in this specification (including the appended claims) should be understood to be modified by the term "about" in all cases, regardless of whether "about" actually appears before the numerical value. "About" means that the numerical value allows a certain slight imprecision (close to the exact value of the value to a certain extent; approximately or reasonably approximate the value; almost). If the imprecision provided by "about" is not understood separately in this art with this common meaning, then "about" used herein refers to at least the deviation that can be caused by the common method of measuring and using such parameters. For example, "about" may include less than or equal to 5%, optionally less than or equal to 4%, optionally less than or equal to 3%, optionally less than or equal to 2%, optionally less than or equal to 1%, optionally less than or equal to 0.5%, and optionally less than or equal to 0.1% deviation in some aspects.

[0068] Furthermore, the disclosure of a range includes disclosure of all values ​​within the entire range and further subdivided ranges, including disclosure of endpoints and subranges given for that range.

[0069] As used herein, unless otherwise indicated, the terms "composition" and "material" are used interchangeably to refer broadly to a substance containing at least a preferred chemical constituent, element or compound, but which may also contain additional elements, compounds or substances (including trace amounts of impurities).

[0070] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0071] The present technology relates to improved electroactive materials for electrochemical cells, especially lithium ion batteries. In various cases, such batteries are used in vehicles or automotive transportation applications (e.g., motorcycles, boats, tractors, buses, motorcycles, mobile homes, campers, and tanks). However, the present technology can be used in a variety of other industries and applications, including aerospace components, consumer products, devices, buildings (e.g., residences, offices, sheds, and warehouses), office equipment and furniture, and industrial equipment machinery, agricultural or farm equipment, or heavy machinery, as non-limiting examples. In some aspects, lithium ion batteries can be used in various consumer products and vehicles, such as hybrid electric vehicles (HEVs) and electric vehicles (EVs).

[0072] An exemplary diagram of an electrochemical cell or battery for cycling lithium ions is shown in FIG. Figure 1 The battery 20 includes a negative electrode 22, a positive electrode 24, and a separator 26 (e.g., a microporous polymer separator) disposed between the two electrodes 22, 24. The separator 26 contains an electrolyte 30, which may also be present in the negative electrode 22 and the positive electrode 24. The negative electrode current collector 32 may be located at or near the negative electrode 22, and the positive electrode current collector 34 may be located at or near the positive electrode 24. An interruptible external circuit 40 and a load device 42 connect the negative electrode 22 (via its current collector 32) and the positive electrode 24 (via its current collector 34).

[0073] The battery 20 can generate current during discharge through a reversible electrochemical reaction that occurs when the external circuit 40 is closed (to connect the negative electrode 22 and the positive electrode 24) and the negative electrode 22 has a lower potential than the positive electrode. The chemical potential difference between the positive electrode 24 and the negative electrode 22 drives the electrons generated at the negative electrode 22 through the external circuit 40 to the positive electrode 24. The lithium ions also generated at the negative electrode 22 are simultaneously transferred to the positive electrode 24 through the electrolyte 30 contained in the separator 26. The electrons flow through the external circuit 40 and the lithium ions migrate through the separator 26 containing the electrolyte solution 30 to form intercalated lithium at the positive electrode 24. As described above, the electrolyte 30 is also generally present in the negative electrode 22 and the positive electrode 24. The current passing through the external circuit 40 can be utilized and directed through the load device 42 until the lithium in the negative electrode 22 is depleted and the capacity of the battery 20 is reduced.

[0074] The battery pack 20 can be charged or re-energized at any time by connecting an external power source to the lithium-ion battery pack 20 to reverse the electrochemical reactions that occur during the battery pack discharge process. The connection of the external power source to the battery pack 20 promotes reactions at the positive electrode 24, such as non-spontaneous oxidation of intercalated lithium to produce electrons and lithium ions. The lithium ions flow back to the negative electrode 22 through the separator 26 through the electrolyte 30 to replenish lithium (e.g., intercalate lithium) to the negative electrode 22 for use during the next battery pack discharge event. Therefore, a complete discharge event followed by a complete charging event is considered a cycle in which lithium ions circulate between the positive electrode 24 and the negative electrode 22. The external power source that can be used to charge the battery pack 20 may vary with the size, construction, and specific end use of the battery pack 20. Some notable and exemplary external power sources include, but are not limited to, AC-DC converters and automotive alternators connected to the AC power grid through a wall outlet.

[0075] In many lithium-ion battery configurations, each of the negative electrode current collector 32, the negative electrode 22, the separator 26, the positive electrode 24, and the positive electrode current collector 34 is prepared as a relatively thin layer (e.g., a few microns to a fraction of a millimeter or less in thickness) and assembled in layers connected in an electrically parallel arrangement to provide a suitable electrical energy and power stack. The negative electrode current collector 32 and the positive electrode current collector 34 collect free electrons from and move the free electrons to the external circuit 40, respectively.

[0076] In addition, the separator 26 operates as an electrical insulator by being sandwiched between the negative electrode 22 and the positive electrode 24 to prevent physical contact and thus prevent a short circuit from occurring. The separator 26 not only provides a physical barrier and an electrical barrier between the two electrodes 22, 24, but also contains the electrolyte solution in a network of open pores during the cycling of lithium ions to facilitate the function of the battery 20.

[0077] In addition, the battery pack 20 may include various other components known to those skilled in the art, although not depicted herein. For example, the battery pack 20 may include a housing, a gasket, an end cap, a tab, a battery terminal, and any other conventional components or materials that may be located within the battery pack 20, including between or near the negative electrode 22, the positive electrode 24, and / or the separator 26. The above-described battery pack 20 includes a liquid electrolyte and illustrates a representative concept of battery pack operation. However, as known to those skilled in the art, the battery pack 20 may also be a solid-state battery pack, which includes a solid electrolyte that may have a different design.

[0078] As described above, the size and shape of the battery pack 20 may vary with the specific application for which it is designed. Battery-driven vehicles and handheld consumer electronic devices, for example, are two examples in which the battery pack 20 is most likely to be designed to different sizes, capacities, and power output specifications. If the load device 42 requires, the battery pack 20 may also be connected in series or in parallel with other similar lithium-ion cells or battery packs to produce greater voltage output, energy, and power. Therefore, the battery pack 20 can generate current to the load device 42 as part of the external circuit 40. The load device 42 can be powered by the current passing through the external circuit 40 when the battery pack 20 is discharged. Although the electrical load device 42 can be any number of known electric devices, several specific examples include electric motors of electric vehicles, laptop computers, tablet computers, mobile phones, and cordless power tools or appliances. The load device 42 can also be a power generation device that charges the battery pack 20 for the purpose of storing electrical energy.

[0079] Re-reference Figure 1 , the positive electrode 24, the negative electrode 22, and the separator 26 can each include within their pores an electrolyte solution or system 30 capable of conducting lithium ions between the negative electrode 22 and the positive electrode 24. Any suitable electrolyte 30 capable of conducting lithium ions between the negative electrode 22 and the positive electrode 24 can be used in the lithium ion battery 20, whether in solid, liquid or gel form. In certain aspects, the electrolyte 30 can be a non-aqueous liquid electrolyte solution including a lithium salt dissolved in an organic solvent or an organic solvent mixture. A plurality of conventional non-aqueous liquid electrolyte 30 solutions can be employed in the lithium ion battery 20.

[0080] In certain aspects, the electrolyte 30 can be a non-aqueous liquid electrolyte solution comprising one or more lithium salts dissolved in an organic solvent or mixture of organic solvents. A variety of aprotic non-aqueous liquid electrolyte solutions can be used in the lithium-ion battery 20 . For example, a non-limiting list of lithium salts that can be dissolved in an organic solvent to form a non-aqueous liquid electrolyte solution includes lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium tetrachloroaluminate (LiAlCl4), lithium iodide (LiI), lithium bromide (LiBr), lithium thiocyanate (LiSCN), lithium tetrafluoroborate (LiBF4), lithium tetraphenylborate (LiB(C6H5)4), lithium bis(oxalato)borate (LiB(C2O4)2) (LiBOB), lithium difluorooxalatoborate (LiBF2(C2O4)), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethane)sulfonyl imide (LiN(CF3SO2)2), lithium bis(fluorosulfonyl)imide (LiN(FSO2)2) (LiSFI), and combinations thereof.

[0081] These and other similar lithium salts can be dissolved in various aprotic organic solvents, including, but not limited to, various alkyl carbonates, such as cyclic carbonates (e.g., ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), fluoroethylene carbonate (FEC)), linear carbonates (e.g., dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC)), aliphatic carboxylates (e.g., methyl formate, methyl acetate, methyl propionate), γ-lactones (e.g., γ-butyrolactone, γ-valerolactone), chain structure ethers (e.g., 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane), cyclic ethers (e.g., tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane), sulfur compounds (e.g., sulfolane), and combinations thereof.

[0082] The porous separator 26 may include a microporous polymer separator containing a polyolefin in some cases. The polyolefin may be a homopolymer (derived from a single monomer component) or a heteropolymer (derived from more than one monomer component), which may be linear or branched. If the heteropolymer is derived from two monomer components, the polyolefin may present any copolymer chain arrangement, including those of block copolymers or random copolymers. Similarly, if the polyolefin is a heteropolymer derived from more than two monomer components, it may also be a block copolymer or a random copolymer. In some aspects, the polyolefin may be a polyethylene (PE), a polypropylene (PP), or a blend of PE and PP, or a multilayer structured porous membrane of PE and / or PP. Commercially available polyolefin porous separators 26 include CELGARD® 2500 (single-layer polypropylene separator) and CELGARD® 2320 (three-layer polypropylene / polyethylene / polypropylene separator) available from Celgard LLC.

[0083] In some aspects, the spacer 26 may further include one or more ceramic coatings and heat-resistant material coatings. The ceramic coating and / or heat-resistant material coating may be disposed on one or more sides of the spacer 26. The material forming the ceramic layer may be selected from: alumina (Al2O3), silicon dioxide (SiO2) and combinations thereof. The heat-resistant material may be selected from: Nomex, Aramid and combinations thereof.

[0084] When the separator 26 is a microporous polymer separator, it can be a single layer or a multilayer laminate, which can be prepared by a dry process or a wet process. For example, in some cases, a polyolefin monolayer can form the entire separator 26. In other aspects, the separator 26 can be, for example, a fiber membrane having a large number of pores extending between the relative surfaces and can have an average thickness of, for example, less than 1 mm. However, as another example, multiple discrete layers of similar or different polyolefins can be assembled to form a microporous polymer separator 26. In addition to polyolefins, the separator 26 may also include other polymers, such as but not limited to polyethylene terephthalate (PET), polyvinylidene fluoride (PVdF), polyamide, polyimide, poly (amide-imide) copolymer, polyetherimide and / or cellulose or any other material suitable for establishing a desired porous structure. The polyolefin layer and any other optional polymer layer can be further included in the separator 26 as a fiber layer to help provide the separator 26 with appropriate structural and porosity characteristics. In certain aspects, the separator 26 may also be mixed with a ceramic material or its surface may be coated with a ceramic material. For example, the ceramic coating may include aluminum oxide (Al2O3), silicon dioxide (SiO2), titanium dioxide (TiO2), or a combination thereof. Various conventionally available polymers and commercial products are contemplated for forming the separator 26, as well as many preparation methods that can be used to prepare such a microporous polymer separator 26.

[0085] In various aspects, the porous separator 26 and the electrolyte 30 may be replaced with a solid electrolyte (SSE) (not shown) to act as both an electrolyte and a separator. The SSE may be disposed between the positive electrode 24 and the negative electrode 22. The SSE facilitates the transfer of lithium ions while mechanically separating the negative and positive electrodes 22, 24 and providing electrical insulation between the negative and positive electrodes 22, 24. As non-limiting examples, the SSE may include LiTi2(PO4)3, LiGe2(PO4)3, Li7La3Zr2O 12 , Li 3x La 2 / 3-x TiO3, Li3PO4, Li3N, Li4GeS4, Li 10 GeP2S 12 , Li2S-P2S5, Li6PS5Cl, Li6PS5Br, Li6PS5I, Li3OCl, Li 2.99 Ba 0.005 C10 or a combination thereof.

[0086] The positive electrode 24 can be formed of a lithium-based active material that can sufficiently perform lithium intercalation and deintercalation, or alloying and dealloying, while serving as the positive terminal of the battery pack 20. An exemplary common type of known material that can be used to form the positive electrode 24 is a layered lithium transition metal oxide. For example, in some aspects, the positive electrode 24 can include one or more materials having a spinel structure, such as lithium manganese oxide (Li (1+x) Mn2O4, where 0.1 ≤ x ≤ 1), lithium manganese nickel oxide (LiMn (2 x) Ni x O4, where 0 ≤ x ≤ 0.5) (e.g., LiMn 1.5 Ni 0.5 O4); one or more materials having a layered structure, such as lithium cobalt oxide (LiCoO2), lithium nickel manganese cobalt oxide (Li(Ni x Mn y Co z )O2, where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1 and x + y + z = 1) (e.g., LiMn 0.33 Ni 0.33 Co 0.33 O2) or lithium nickel cobalt metal oxide (LiNi (1-x y) Co x M y O2, where 0 < x < 0.2, y < 0.2 and M can be Al, Mg, Ti, etc.); or a lithium iron polyanion oxide having an olivine structure, such as lithium iron phosphate (LiFePO4), lithium manganese iron phosphate (LiMn 2-x Fe x PO4, where 0 < x < 0.3) or lithium iron fluorophosphate (Li2FePO4F).

[0087] In some variations, the positive electroactive material may be blended with an electronic conductive material that provides an electronic conductive path and / or at least one polymer binder material that improves the structural integrity of the electrode. For example, the electroactive material and the electronic conductive material or the conductive material may be slurried with the following binder, such as polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), ethylene propylene diene monomer (EPDM) rubber or carboxymethyl cellulose (CMC), nitrile rubber (NBR), styrene butadiene rubber (SBR), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate. The conductive material may include carbon-based materials, powdered nickel or other metal particles, or conductive polymers. The carbon-based material may include particles such as graphite, acetylene black (such as KETCHENTM black or DENKATM black), carbon fibers and nanotubes, graphene, etc. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, etc. In some aspects, a mixture of conductive materials may be used. The positive electrode current collector 34 may be formed of aluminum (Al) or any other suitable conductive material known to those skilled in the art.

[0088] The negative electrode 22 includes an electroactive material as a lithium host material capable of acting as a negative terminal of a lithium-ion battery. The negative electrode current collector 32 may include a metal containing copper, nickel, or an alloy thereof, or other suitable conductive materials known to those skilled in the art. In some aspects, the positive electrode current collector 34 and / or the negative electrode current collector 32 may be in the form of a foil, a slit mesh, and / or a woven mesh.

[0089] In certain aspects, the present disclosure provides methods for preparing a negative electrode 22 (e.g., an anode) comprising an improved electrochemically active negative electrode material. As described above, the negative electroactive material undergoes significant volume expansion during lithium cycling (e.g., is capable of accepting the insertion of lithium ions via lithiation or "intercalation" during the charging process of the electrochemical cell, and releasing lithium ions via delithiation or "deintercalation" or lithium alloying / dealloying during the discharge process of the electrochemical cell). Such an electrochemically active negative electrode material can be selected from: silicon, silicon-containing alloys, graphite, and combinations thereof. For example, silicon-containing electroactive material particles may include silicon or silicon-containing binary and ternary alloys. According to various aspects of the present teachings, the negative electroactive material can be incorporated into the negative electrode of the electrochemical cell.

[0090] In addition, in a typical preparation method, a negative electrode material that does not contain any lithium is incorporated into an electrochemical cell. The positive electrode has lithium and after the electrochemical cell is cycled, the lithium enters the negative electrode and lithiates the negative electrode. However, in a negative electroactive material containing silicon, for example, after the first lithiation cycle, a portion of the lithium may not be cycled back to the positive electrode through the electrolyte, but may remain in the negative electrode. This can be attributed to, for example, the formation of lithium silicates such as Li4SiO4 and / or solid electrolyte interface (SEI) layers on the negative electrode, and the continuous loss of lithium due to the rupture of the continuous solid electrolyte interface (SEI). The solid electrolyte interface (SEI) layer can be formed on the surface of the negative electrode (anode), which is usually generated by the reaction products of the anode material, electrolyte reduction and / or lithium ion reduction. This permanent loss of lithium ions can lead to a reduction in specific energy and power in the battery pack, which is caused by the increase of positive electrode materials that do not participate in the reversible operation of the battery pack. For example, an irreversible capacity loss of greater than or equal to about 5% to less than or equal to about 30% may occur in a lithium ion battery pack after the first cycle.

[0091] Lithiation, such as pre-lithiation of electroactive materials before incorporation into electrochemical cells, can compensate for this lithium loss during cycling. However, common lithiation methods, such as electrochemical methods, direct contact methods, and lamination methods, typically require half-cell manufacturing and disassembly and / or high-temperature chemical processes. In addition, it is difficult to control the degree of lithiation that occurs during these processes. In addition, these processes involve highly reactive chemicals and require additional manufacturing steps. These can be time-consuming and potentially expensive processes. In addition, these processes also often produce materials that are difficult to handle, such as anodes with undesirable thicknesses.

[0092] The present disclosure provides improved electroactive materials and electrode materials and methods for making the same that address these challenges. In various aspects, the present disclosure provides advantages, including reducing mechanical stress in the negative electrode, by forming a pre-lithiated negative electroactive material comprising silicon prior to forming the electrode. Significantly, the electroactive material is formed and pre-lithiated in a single process. In addition, the loss of active lithium during the formation cycle can be significantly reduced by the present technology. In addition, the cycle life performance of a lithium-ion battery pack comprising a negative electrode having a negative electroactive material comprising pre-lithiated silicon is improved according to certain aspects of the present disclosure.

[0093] Pre-lithiation of the reactant material via centrifugal atomization can be performed by lithiation of silicon via the reaction represented by: 4.4 x Li + Si → Li 4.4x Si, where 0 < x≤ 1. This pre-lithiation process can use relatively pure lithium (Li) metal and silicon (Si) as reactants. However, lithium metal is highly reactive and requires special handling and safety precautions. In addition, although the product of this reaction is lithium silicide (Li 4.4x Si, where 0 < x ≤ 1), which is a pre-lithiated electroactive material, but it may still undergo significant volume expansion during the lithium cycling process that occurs in battery operation.

[0094] Thus, according to certain aspects of the present disclosure, a method for preparing an electroactive material for a negative electrode of an electrochemical cell for cycling lithium ions as described above is provided. The method may be a method for producing pre-lithiated electroactive material particles, such as a lithiated silicon oxide alloy. Precursors for forming lithiated silicon-containing electroactive materials include lithium, silicon, and oxygen. In certain variations, the precursor may be formed by combining lithium oxide (Li2O) and silicon (Si). In certain other variations, the precursor may be formed by combining lithium oxide (Li2O), silicon (Si), and optionally silicon dioxide or silica (SiO2). These raw materials are more widely available than pure lithium (Li) metal, and are therefore cheaper. In addition, the preparation method requires fewer safety precautions in terms of avoiding handling highly reactive pure lithium metal as a reactant.

[0095] Typically, lithium silicide (Li y The preparation of lithium silicate (Li4SiO4) can be carried out by thermochemical reduction involving the following reactions in equations (1)–(3):

[0096] 2Li2O + Si = 4Li + SiO2(1)

[0097] yLi + Si = Li y Si (silicide), where 0 < y ≤ 4.4 (2)

[0098] 2Li2O + SiO2 = Li4SiO4 (silicate) (3)

[0099] The heat of formation of Li2O is about (-600 kJ / mol), and the heat of formation of SiO2 is (-910 KJ / mol).

[0100] Thus, starting with Li2O, Si and / or SiO2 reactant materials, a thermochemical reaction is performed to form an electroactive lithium silicide (e.g., Li y Si, where 0 < y ≤ 4.4, for example, in certain variations, Li 4.4x Si, where 0 < x≤ about 0.85) and pre-lithiated silicon oxide (SiOx) particles containing inactive lithium silicate. The lithium silicate may include Li4SiO4, Li8SiO6, Li2SiO3, and Li2Si2O5. In certain aspects, the lithium silicate (one or more) formed in the thermochemical reaction may be represented by Li4SiO4, which is considered to be the primary and most stable lithium silicate (having the highest melting point), although other lithium silicates may be included in the final product as will be appreciated by those skilled in the art. Significantly, as shown in equation (4), for the lithiated silicon oxide (SiO) product, part of the lithiation reaction of the silicon oxide is reversible (forming electroactive lithium silicide), while part of the situation reaction that occurs is irreversible (forming lithium silicate).

[0101] SiO + 4Li → 0.75Li4Si (reversible) + 0.25 Li4SiO4 (irreversible) (4).

[0102] Therefore, when silicon oxide-based electroactive materials are incorporated into electrochemical cells, lithium (Li) consumption may occur during cycling through the formation of lithium silicate (Li4SiO4) and / or the formation of an SEI layer on the surface of the electroactive material. However, in the case where the silicon oxide material is pre-lithiated according to certain aspects of the present teachings, it reduces lithium consumption during the first cycle of the battery by having an irreversible lithium silicate product already formed. Significantly, the silicon oxide-containing product formed according to certain aspects of the present disclosure can have a predetermined amount of electrochemically inert lithium silicate combined with the electroactive lithium silicide.

[0103] However, the presence of lithium silicate (mixed with lithium silicide) in the electroactive material particles can provide certain advantages to the electroactive material, such as enhancing mechanical strength and reducing volume expansion changes that may occur during lithiation and pre-lithiation to reduce stress on the electroactive material during cycling and thus reduce the likelihood of cracking, popping, etc. Thus, the silicon oxide-containing product comprising lithium silicide and lithium silicate is more robust than a comparative electroactive material comprising primarily only lithium silicide.

[0104] In certain aspects, the silicon oxide final product comprises lithium silicate, which can be represented by Li4SiO4, wherein the Li / Si ratio is about 4 (eg, 4:1), and lithium silicide, Li 4.4ySi, wherein the Li / Si ratio is greater than 0 to about 4.4. Thus, the total Li / Si ratio can be greater than 0 to about 4.4. For a precursor comprising Li2O and Si, the Li2O / Si ratio can be greater than 0 to about 2.2. In certain non-limiting aspects, when silicon (Si) is used to control the composition of the final product, the molar ratio of lithium oxide (Li2O) to silicon (Si) in the precursor can be about 2:1 to about 1:2 (6 moles of excess Si). In alternative aspects, lithium oxide (Li2O) and silicon oxide (SiO2) can be used to control the composition of the final product.

[0105] These pre-lithiated electroactive material particles may further have one or more coatings applied thereto, such as carbonaceous coatings and / or oxide-based coatings described in U.S. Patent Publication No. 2021 / 0175491, entitled “Methods of Forming Prelithiated Silicon Alloy Electroactive Materials,” the relevant portions of which are incorporated herein by reference. These oxide-based coatings may include aluminum oxide (Al2O3), titanium oxide coatings (TiO2), vanadium pentoxide coatings (V2O5), zirconium oxide coatings (ZrO2), hafnium oxide (HfO2), zinc oxide coatings (ZnO), silicon oxide (SiO2), and combinations thereof. The coating may include an electrically conductive and ionically conductive layer comprising a carbonaceous or carbonaceous material. In certain aspects, the electrically conductive and ionically conductive layer may include amorphous carbon or graphitic carbon that generally lacks any crystalline structure or order. As will be described herein, the method may be carried out via centrifugation / gas atomization to form pre-lithiated SiO having a favorable substantially spherical shape and a narrow size distribution range. x In addition, compared to other prelithiation methods, centrifugal / gas atomization is a high productivity process that provides a means to precisely control the level of prelithiation and the phases formed in the product. As a result, a unique spherical composite structure is formed that can make the prelithiation of silicon oxide (SiO x ) products are stabilized and achieve the desired mechanical and electrochemical properties when used as battery anode materials.

[0106] In various aspects, the present disclosure provides a controllable phase ratio in the final product. For example, the phase ratio can be controlled by controlling the relative amounts of the starting materials, such as the ratio of lithium oxide (Li2O) to silicon provided in silicon metal (Si) or silicon dioxide (SiO2). x ) contains silicides (e.g. Li y Si) and a silicate (e.g., Li4SiO4) as a first component. In certain aspects, the lithium silicide (e.g., Li yThe stoichiometric ratio of Si, wherein 0 < y ≤ 4.4) and inactive lithium silicate (eg, Li4SiO4) may be from about 1:1 to about 3:1.

[0107] Thus, the present disclosure contemplates improved battery pack cycle life performance. In addition, the present disclosure mitigates potential safety issues that would otherwise occur if lithium metal was used as a pre-lithiation reactant during the preparation process. In addition, the preparation process helps reduce raw material costs.

[0108] The present disclosure contemplates a method for preparing lithiated silicon electroactive materials from precursors comprising silicon, oxygen and lithium by a centrifugal / gas atomization method. During the centrifugal atomization process, the molten material is directed to at least one rotating disk or cup, where melt droplets are formed and fly off the rotating disk or cup to solidify and form spherical particles of silicon oxide. Therefore, in some aspects, a method for preparing a negative electrode material for an electrochemical cell that circulates lithium ions is provided. The method includes centrifugally distributing a molten precursor comprising silicon, lithium and oxygen by contacting the molten precursor with a rotating surface in a centrifugal atomization reactor, and solidifying the molten precursor to form a plurality of substantially circular solid electroactive particles comprising an alloy of lithium and silicon and having a D50 diameter of less than or equal to about 20 microns. In some variations, the centrifugal atomization method forms a plurality of particles having a relatively small particle size (e.g., ultrafine particles) and a smaller particle size distribution (e.g., monodisperse).

[0109] Figure 2 An exemplary centrifugal atomization reactor 50 is shown. It should be noted that the reactor 50 is a simplified version and may contain various other equipment. A suitable multi-stage centrifugal atomization reactor suitable for forming the plurality of electroactive particles is described in U.S. Patent Publication No. 2021 / 0138548 entitled "Article for Producing Ultra-Fine Powders and Method of Manufacture Thereof", the relevant parts of which are incorporated herein by reference. The molten precursor material 60 may be conveyed in batches or continuously from an upstream furnace and introduced into a distribution container or tundish 62. The tundish 62 has at least one outlet hole 64 having a suitable diameter to facilitate rapid discharge of the molten precursor material 60. As recognized by those skilled in the art, the number and diameter of the outlet holes 64 may be adjusted to control the particle size during and after the atomization process. In addition, the tundish 62 may be rotated or have a pressure source to enhance discharge via the outlet hole 64. A stream 66 of the molten precursor material 60 is discharged from the outlet 64.

[0110] The material stream 66 contacts the surface 76 of the rotating assembly 70, which can be in the form of a disk or cup. The rotating assembly 70 is in rotational communication with the shaft 72 and the motor 74. The rotational motion is transmitted from the motor 74 to the rotating assembly 70 via the shaft 72. The rotational motion of the rotating assembly 70 applies a centrifugal force to the molten precursor material 60, which distributes and crushes the precursor material outward from the central axis defined by the shaft 72 in the centrifugal direction 78 in the reactor 50. As shown, the molten precursor material 60 contacts the rotating surface 76 and forms droplets 80 as it is conveyed in the outward direction, and the droplets 80 solidify to form a plurality of substantially circular solid electroactive particles 82. Although not shown, ultrasonic or mechanical vibrations can be applied to the rotating assembly 70 to promote the crushing of the molten material and the deagglomeration of the particles. The droplets 80 are pushed outward. The solid particles 82 are pushed outward toward the wall 84 of the reactor 50 and then fall into the outlet zone 86 including the outlet 88. The ultrafine solid particles 82 are transported to the outlet 88 under the action of gravity. As shown, collection vessel 90 is coupled to outlet 88 and collects particles 82; however, as will be described in detail below, outlet 88 may alternatively be in fluid communication with an additional reactor chamber.

[0111] The solidified particles formed by this method can be relatively small (e.g., fine or ultrafine) and have a substantially circular shape. "Substantially circular shape" includes particles with a low aspect ratio and having a morphology or shape including spherical, circular, spheroidal, oval, elliptical, etc. In some variations, the particles have a spherical shape. In addition, the solid particles may have an average diameter (D). D50 refers to the diameter of the cumulative 50% points for a plurality of solid particles (or 50% through the particle size). In some aspects, the D50 of the plurality of electroactive solid particles formed by the centrifugal atomization method is less than or equal to about 20 microns, optionally less than or equal to about 15 microns, optionally less than or equal to about 10 microns, and optionally less than or equal to about 5 microns. In some variations, the D50 of the plurality of solid electroactive particles formed can be greater than or equal to about 1 μm to less than or equal to about 20 μm, optionally greater than or equal to about 1 μm to less than or equal to about 10 μm.

[0112] The plurality of electroactive solid particles formed by the centrifugal atomization process can be relatively monodisperse, for example having a narrow polydispersity index or particle size variation between the plurality of particles formed. In one aspect, the particle size distribution is narrow, for example having a polydispersity index of less than or equal to about 1.2.

[0113] In certain aspects, the centrifugal atomization method of forming the plurality of electroactive materials can provide a high yield for a target or predetermined particle size diameter range. For example, when the average particle size is selected to be greater than or equal to about 1 μm to less than or equal to about 20 μm, the method can have a total yield of solid particles having a predetermined particle size range of greater than or equal to about 10% to less than or equal to about 90%. These uniform diameter electroactive materials formed from alloys of lithium and silicon can be used in various electrochemical cells / batteries and energy storage devices.

[0114] In some variations, the environment in the centrifugal atomization reactor may be substantially free of gaseous oxygen-containing species to avoid reaction with lithium. Although lithium is not added as a precursor / reactant, it may be formed as an intermediate, and therefore as a precaution, the environment in which the reaction occurs may be relatively inert. For example, the environment may have less than or equal to about 0.5% by weight of any oxygen-containing species in the gas phase, such as oxygen, water, etc. The environment in the reactor optionally has a low water / moisture content, which is manifested as a relative humidity (RH) of less than 0.5% or 0.5% at the reaction condition temperature.

[0115] The centrifugal atomization reactor can achieve high throughput in the process of forming particles of electroactive material having a desired average particle size range, for example, having a mass flow rate of greater than or equal to 50 kg / hour to less than or equal to about 500 kg / hour. Higher flow rates are also feasible, as long as the particles formed have the desired D50. The flow rate has an effect on the particle size. For example, the higher the flow rate of the molten material, the larger the size of the particles produced. Therefore, the flow rate can be limited by the desired size of the particles.

[0116] In addition, the methods provided by certain aspects of the present disclosure advantageously provide a high level of control over the composition of the electroactive material formed. The methods of the present disclosure provide the ability to directly prepare pre-lithiated electroactive materials comprising silicon without requiring an initial formation step of particles and a subsequent pre-lithiation step in which lithium is introduced into the material. As described above, the alloy comprising lithium and silicon formed by the present method can be represented by the following formula: Lithium silicide (Li y Si, where 0 < y ≤ 4.4) or in certain variations, Li 4.4x Si, where 0 < x ≤ about 0.85. The precursor material used to form the electroactive material alloy can be selected to have a specific composition so that a specific phase can be formed according to the temperature conditions selected during the centrifugal atomization process in the reactor. Therefore, precise control of the phase present in the formed particles can be achieved through the composition of the melt.

[0117] In certain aspects, the precursor material has sufficient oxygen and lithium in combination with silicon to completely form a lithium silicate phase (Li4SiO4). The additional amount of lithium can be varied to form different variations of the Li-Si phase. As will be appreciated by those skilled in the art, it may be desirable to maximize the relative stoichiometric amount of lithium in the lithium-silicon alloy / electroactive material. In certain aspects, the precursor material is selected to have greater than 0 atomic % to less than or equal to about 82 atomic % lithium and correspondingly greater than or equal to about 18 atomic % to less than or equal to about 100 atomic % silicon, which generally corresponds to Li 4.4x Si, wherein x is greater than 0 to less than or equal to about 0.85. In other aspects, the precursor material optionally has greater than or equal to about 30 atomic % to less than or equal to about 70 atomic % lithium and correspondingly greater than or equal to about 30 atomic % to less than or equal to about 70 atomic % silicon, which generally corresponds to Li 4.4x Si, wherein x is greater than or equal to about 0.1 to less than or equal to about 0.5. In still other aspects, the precursor material optionally has about 50 atomic % lithium and correspondingly greater than or equal to about 50 atomic % silicon, which generally corresponds to Li 4.4x Si, wherein x is about 0.25.

[0118] In certain aspects, the lithium silicide alloy formed after the centrifugal atomization process may include Li y Si (where 0 < y ≤ 4.4) or, in some variations, Li 4.4x Si, where 0 < x ≤ about 0.85. For example, the lithium silicide alloy formed after the centrifugal atomization method may include one or more of the following phases: Li 22 Si5、Li 13 Si4、Li7Si3、Li 12 Si7 and LiSi. Notably, in certain variations where lower amounts of lithium are present in the alloy, a phase comprising only Si may be present. In certain variations, the alloy may comprise one or more of the following phases: Li 22 Si5、Li 13 Si4、Li7Si3、Li 12 Si7 and LiSi. In addition to the lithium silicide alloy formed in the centrifugal atomization process, the silicon oxide product may also include lithium silicates, for example including Li4SiO4, Li8SiO6, Li2SiO3 and / or Li2Si2O5.

[0119] In certain aspects, during the centrifugal distribution of the molten precursor, the temperature in the centrifugal atomization reactor may be greater than or equal to 400°C to less than or equal to about 1,000°C. In the case where the lithium, silicon, and oxygen precursors are miscible, higher temperatures may be used to promote the formation of the desired phase. In certain variations, during the centrifugal distribution of the molten precursor, the temperature in the centrifugal atomization reactor may be greater than or equal to 400°C to less than or equal to about 800°C. Compared to other pre-lithiation methods, the centrifugal / gas atomization provided by certain aspects of the present disclosure provides a means for precise control of the degree of pre-lithiation and the phases formed.

[0120] Thus, in various aspects, a centrifugal / gas atomization reactor is used to prepare particles comprising a pre-lithiated silicon alloy comprising lithium silicide and lithium silicon oxide. Such a centrifugal / gas atomization reactor provides high throughput production of lithium-silicon alloy electroactive particles having a relatively uniform size distribution, and thus provides a high yield for a predetermined average particle size diameter. 4.4x The presence of Si silicide alloys can reduce lithium consumption and initial stress during the formation cycle. The benefit is that the electroactive material containing silicon undergoes an initial volume expansion due to lithiation before being incorporated into the electrode to enhance the mechanical properties of the initially formed electrode. Conventionally, the electroactive material containing silicon is incorporated into the electrode (e.g., mixed with a polymer matrix and other electrode components) and then subjected to lithiation in which the initial expansion occurs. This expansion during lithiation can cause mechanical stress and potential damage not only to the electroactive particles, but also to the surrounding composite materials. For conventional silicon electroactive materials, the degree of volume expansion that occurs during the initial lithiation reaction can cause mechanical degradation and breakage of silicon particles into multiple smaller fragments or fragments. When the particles break into smaller fragments, additional lithium is consumed to form a new SEI and these fragments or smaller fragments can no longer maintain the performance of the electrochemical cell. When the electroactive materials are formed from lithium and silicon alloys according to the present disclosure, they have undergone an initial volume expansion, and therefore incorporating them into the electrode only causes minimal expansion and contraction stress during the lithium cycle.

[0121] In addition, the presence of lithium silicate (Li4SiO4) further enhances the mechanical properties of the lithium silicon oxide product containing lithium silicide alloys. As described above, it physically retains the lithium silicide(s) within the silicon oxide material and further reduces the overall volume expansion and contraction during lithiation cycles.

[0122] Furthermore, the lithium-silicon alloy powder produced by the centrifugal / gas atomization method can be subsequently coated with one or more coatings to protect the underlying electroactive material and / or to improve conductivity. In addition, prior to preparing the electrode, the lithium-silicon alloy particles can be exposed to a liquid electrolyte to form a surface solid electrolyte interface (SEI) layer.

[0123] like Figure 3 As shown in FIG. 1 , an optional first coating is disposed on the surface of negative electroactive material particles 100. In certain variations, the negative electroactive material particles 100 may be provided with a coating layer comprising lithium silicide (Li y In some embodiments, the negative electroactive particle 100 having a core region 110 and a first coating layer 120 of lithium silicate (Si, where 0 < y ≤ 4.4) and lithium silicate (Li4SiO4) is incorporated into a negative electrode. However, in some other variations, a multi-layer coating layer may be formed on the negative electroactive particle 100. Therefore, the second coating layer 130 may be disposed on the first coating layer 120 and the core region 110. Such a negative electroactive particle having a multi-layer coating layer including the first coating layer 120 and the second coating layer 130 may be incorporated into a negative electrode. It should be noted that more than two layers of coating layers may be applied or formed on the negative electroactive particle 100.

[0124] In some aspects, at least one of the first coating 120 or the second coating 130 can be an electrically conductive and ionically conductive layer comprising a carbonaceous or carbonaceous material. In some aspects, the electrically conductive and ionically conductive layer can comprise amorphous carbon, which generally lacks any crystalline structure or order. Amorphous carbon generally has excellent mechanical properties, such as tensile strength, to withstand volume changes of the electroactive material. In addition, the electrically conductive and ionically conductive layer can also comprise graphitic carbon, which is crystalline and has order. As will be further described below, graphitic carbon exhibits good electrical conductivity. Typically, graphitic carbon can have an sp2 / sp3 bond ratio of about 70:30 to about 100:1. In one example, the sp in the carbon coating can have a ratio of about 100:1 to about 200:1. 2 Carbon and sp 3 The ratio of carbon can be from about 74 to about 26. Such an electrically conductive and ionically conductive layer can be formed in a pyrolysis process. In certain variations, amorphous carbon can form a first layer within the first or second coating 120, 130, and graphitic carbon can form a second layer within the first or second coating 120, 130. However, there may not be a clear compositional boundary between the layers, but there is a gradient region between the respective compositions of the defined coatings. The outer region of the first or second coating 120, 130 can include graphitic carbon to provide good electrical conductivity, including good connectivity between adjacent electroactive particles.

[0125] The negative composite electrode may comprise greater than or equal to about 50% to less than or equal to about 90% of an electroactive material (e.g., a lithium-silicon oxide material comprising lithium silicide and lithium silicate particles optionally having one or more coatings prepared according to the present disclosure), optionally greater than or equal to about 5% to less than or equal to about 30% of a conductive material, and the balance a binder. Conductive materials are well known in the art and include graphite, carbon black, carbon nanotubes, powdered nickel, conductive metal particles, conductive polymers, and combinations thereof. Useful binders include any of those described above. For example, useful binders may include polymeric materials suitable for forming a bonded porous composite material and extractable plasticizers, such as halogenated hydrocarbon polymers (e.g., poly(vinylidene chloride) and poly((dichloro-1,4-phenylene)ethylene)), fluorinated urethanes, fluorinated epoxides, fluorinated acrylic resins, copolymers of halogenated hydrocarbon polymers, epoxides, ethylene propylene diamine terpolymers (EPDM), ethylene propylene diamine terpolymers (EPDM), polyvinylidene fluoride (PVDF), hexafluoropropylene (HFP), ethylene acrylic acid copolymers (EAA), ethylene vinyl acetate copolymers (EVA), EAA / EVA copolymers, PVDF / HFP copolymers, carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), and mixtures thereof.

[0126] The electrode can be prepared by mixing an electroactive material, such as a powder or particle containing a coated lithium-silicon oxide material, with a polymer binder compound, a non-aqueous solvent, an optional plasticizer, and, if necessary, optional conductive particles into a slurry. The slurry can be mixed or agitated and then thinly applied to a substrate with the aid of a doctor's blade. The substrate can be a removable substrate or an alternative functional substrate, such as a current collector (such as a metal grid or mesh layer) connected to one side of the electrode film. In one variation, heat or radiation can be applied to evaporate the solvent from the electrode film, leaving a solid residue. The electrode film can be further consolidated, wherein heat and pressure are applied to the film to sinter and calender it. In other variations, the film can be air-dried at a moderate temperature to form a self-supporting film. If the substrate is removable, it is subsequently removed from the electrode film, and the electrode film is then further laminated to the current collector. For either type of substrate, it may be necessary to extract or remove the residual plasticizer before incorporating it into the battery cell.

[0127] The battery pack can therefore be assembled in a laminated cell structure, which includes an anode layer, a cathode layer and an electrolyte / separator between the anode layer and the cathode layer. The anode layer and the cathode layer each include a current collector. The negative anode current collector can be a copper collector foil, which can be in the form of an open grid or a film. The current collector can be connected to an external current collector tab.

[0128] For example, in some variations, an electrode film, such as an anode film, comprises an electrode active material (e.g., particles containing coated lithium-silicon oxide) dispersed in a polymer binder matrix on a current collector. A separator can then be placed on the negative electrode element, which is covered with a positive electrode film comprising a composition of a finely divided lithium insertion compound in a polymer binder matrix. A positive electrode current collector, such as an aluminum current collector foil or mesh, completes the assembly. The tabs of the current collector element form the corresponding terminals of the battery pack. A protective bagging material covers the battery and prevents air and moisture from penetrating. Into the bag, a liquid electrolyte suitable for lithium ion transport can be injected into the separator (and can be absorbed into the positive electrode and / or the negative electrode). In some aspects, the laminated battery pack is further hermetically sealed before use.

[0129] A surface coating (e.g., an oxide-based coating) applied to a negative electroactive material comprising a lithium-silicon oxide composition according to certain aspects of the present technology can be formed on the entire exposed surface and thus act as an artificial solid electrolyte interface layer, which can prevent the electrode from reacting with a liquid electrolyte. In various aspects, the electroactive material comprising a lithium-silicon oxide composition can have a surface coating that provides certain advantages, such as a high cut-off voltage (e.g., a cut-off potential relative to a lithium metal reference potential), which desirably minimizes or avoids SEI formation. In certain aspects, a lithium-ion battery comprising a negative electroactive material of the present invention having a lithium-silicon oxide composition electroactive material and optional (one or more) coatings substantially maintains a charge capacity (e.g., within a preselected range or other targeted high-capacity use) for at least about 1,000 hours of battery operation, optionally greater than or equal to about 1,500 hours of battery operation, optionally greater than or equal to about 2,500 hours or more of battery operation, and in certain aspects, optionally greater than or equal to about 5,000 hours or more (active cycling).

[0130] In certain aspects, lithium ion batteries comprising negative electroactive / electrode materials of the invention having a lithium-silicon oxide composition electroactive material and optional coating(s) retain charge capacity and are therefore capable of operating within 20% of a target charge capacity for a duration of greater than or equal to about 2 years (including storage and active cycling time at ambient conditions), optionally greater than or equal to about 3 years, optionally greater than or equal to about 4 years, optionally greater than or equal to about 5 years, optionally greater than or equal to about 6 years, optionally greater than or equal to about 7 years, optionally greater than or equal to about 8 years, optionally greater than or equal to about 9 years, and in certain aspects, optionally greater than or equal to about 10 years.

[0131] In other aspects, lithium ion batteries comprising electroactive materials of the present invention are capable of operating for a duration of at least about 100 deep discharge cycles, optionally at least about 200 deep discharge cycles, optionally at least about 500 deep discharge cycles, optionally at least about 1,000 deep discharge cycles at a variation of less than or equal to about 30% of a preselected target charge capacity (thus having very low charge capacity fade), optionally at a variation of less than or equal to about 20%, optionally at less than or equal to about 15%, optionally at less than or equal to about 10%, and in certain variations optionally at less than or equal to about 5%.

[0132] In other words, in certain aspects, a lithium ion battery or electrochemical cell comprising a negative electroactive material of the invention having a lithium-silicon oxide electroactive material and optional coating(s) substantially retains charge capacity and is capable of operating for at least about 1,000 deep discharge cycles, optionally greater than or equal to about 2,000 deep discharge cycles, optionally greater than or equal to about 3,000 deep discharge cycles, optionally greater than or equal to about 4,000 deep discharge cycles, and in certain variations, optionally greater than or equal to about 5,000 deep discharge cycles.

[0133] The present disclosure therefore contemplates methods for forming a carbonaceous coating and / or an oxide-containing coating on a negative electroactive material comprising a lithium-silicon oxide material. The carbonaceous coating may be formed by a pyrolysis process, wherein a hydrocarbon is reduced to form a carbonaceous coating. The method of applying an oxide-based surface coating may be selected from atomic layer deposition (ALD), chemical vapor infiltration, chemical vapor deposition, physical vapor deposition, wet chemistry, and any combination thereof. In fact, in some aspects, the deposition method may first include applying a carbon material to one or more surfaces of an electrode material by a first process, and then applying a metal oxide material in a second process, or vice versa. In addition, in some variations, the first coating may include an oxide-based coating, the second coating may include a carbon-based coating, and the third coating may include an oxide-based coating.

[0134] In some aspects, the first and second processes may be performed in the same type of process or equipment, but the deposition or application steps are performed separately (e.g., sequentially), as described in U.S. Patent Publication No. 2021 / 0175491, entitled "Methods of Forming Prelithiated Silicon Alloy Electroactive Materials," the relevant portions of which are incorporated herein by reference. As will be further described herein, the first and second coating processes may be performed in a downstream reaction chamber that is fluidly connected to a centrifugal atomization reactor. In other aspects, the first and second processes may be completely different from each other and / or further performed separately after the negatively electroactive lithium-silicon oxide material particles are formed in a centrifugal atomization reactor.

[0135] The present disclosure therefore contemplates methods for forming a carbonaceous coating and / or an oxide-containing coating on a negative electroactive material comprising a lithium-silicon alloy. The carbonaceous coating may be formed by a pyrolysis process, wherein a hydrocarbon is reduced to form a carbonaceous coating. The method of applying an oxide-based surface coating may be selected from atomic layer deposition (ALD), chemical vapor infiltration, chemical vapor deposition, physical vapor deposition, wet chemistry, and any combination thereof. In fact, in some aspects, the deposition method may first include applying a carbon material to one or more surfaces of an electrode material by a first process, and then applying a metal oxide material in a second process, or vice versa. In addition, in some variations, the first coating may include an oxide-based coating, the second coating may include a carbon-based coating, and the third coating may include an oxide-based coating.

[0136] In some aspects, the first and second processes can be performed in the same type of process or equipment, but the deposition or application steps are performed separately (e.g., sequentially). As will be further described herein, the first and second coating processes can be performed in a downstream reaction chamber that is in fluid communication with the centrifugal atomization reactor. In other aspects, the first and second processes can be completely different from each other and / or further performed separately after the negatively electroactive lithium-silicon alloy particles are formed in the centrifugal atomization reactor.

[0137] The above description of the embodiments has been provided for the purpose of illustration and description. It is not intended to be exhaustive or to limit the present disclosure. The individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable and can be used in a selected embodiment if applicable, even if not explicitly shown or described. It can also be changed in many ways. Such variations should not be regarded as departing from the present disclosure, but all such modifications are intended to be included within the scope of the present disclosure.

Claims

1. A method for preparing a negative electrode material for an electrochemical cell for circulating lithium ions, the method comprising: Centrifugally distributing a molten precursor comprising silicon, oxygen, and lithium by contacting the molten precursor with a rotating surface in a centrifugal atomization reactor, and solidifying the molten precursor to form a plurality of substantially round solid electroactive particles comprising a mixture of lithium silicide and lithium silicate and having a D50 diameter of less than or equal to 20 microns, wherein the molten precursor is formed by melting a precursor comprising silicon and lithium oxide, wherein the lithium silicide is Li y Si, where 0 <y≤4.4。 2 . The method of claim 1 , wherein the precursor comprises a molar ratio of silicon to lithium oxide of greater than or equal to 1:2 to less than or equal to 2:

1. The method of claim 1 , wherein the precursor further comprises silicon dioxide.

4. The method according to claim 1, wherein the lithium silicide is further composed of the formula Li 4.4x Si represents, where x is greater than 0 and less than or equal to 0.

85.

5. The method of claim 1, wherein the plurality of substantially round solid electroactive particles comprises a coating selected from the group consisting of a carbon-containing coating, an oxide-containing coating, and combinations thereof.

6. The method according to claim 1, wherein the temperature in the centrifugal atomization reactor is greater than or equal to 400°C to less than or equal to 800°C during centrifugal distribution.

7. The method of claim 1, wherein the environment in the centrifugal atomization reactor has less than or equal to 0.5 wt% of any oxygen-containing species.

8. The method according to claim 1, wherein the flow rate of the centrifugal atomization reactor is greater than or equal to 50 kg / hour and less than or equal to 500 kg / hour. 9 . The method according to claim 1 , wherein the D50 diameter is greater than or equal to 1 μm to less than or equal to 10 μm.

10. The method of claim 1, wherein the plurality of substantially round solid electroactive particles have a polydispersity index less than or equal to 1.

2.

11. A method for preparing a negative electrode material for an electrochemical cell for cycling lithium ions, the method comprising: centrifugally distributing a molten precursor by contacting the molten precursor with a rotating surface in a centrifugal atomization reactor, wherein the molten precursor is formed from a mixture comprising silicon dioxide, lithium oxide, and silicon; and The molten precursor is solidified to form a plurality of substantially round solid electroactive particles comprising a mixture of lithium silicide and lithium silicate and having a D50 diameter of less than or equal to 20 microns, wherein the lithium silicide is Li y Si, where 0 <y≤4.4。 12 . The method of claim 11 , wherein the mixture comprises a molar ratio of silicon to lithium oxide of greater than or equal to 1:2 to less than or equal to 2:

1.

13. The method according to claim 11, wherein the lithium silicide is further composed of the formula Li 4.4x Si represents, where x is greater than 0 and less than or equal to 0.

85.

14. The method according to claim 11, wherein the temperature in the centrifugal atomization reactor is greater than or equal to 400°C to less than or equal to 800°C during centrifugal distribution.

15. The method according to claim 11, wherein the flow rate of the centrifugal atomization reactor is greater than or equal to 50 kg / hour and less than or equal to 500 kg / hour. The method according to claim 11 , wherein the D50 diameter is greater than or equal to 1 μm to less than or equal to 10 μm.

17. The method of claim 11, wherein the plurality of substantially round solid electroactive particles have a polydispersity index less than or equal to 1.2.

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