Coated and finished anode composition

Abstract

The present disclosure generally relates to coated anodes comprising coated microsilicon active material particles and / or anode compositions. The present disclosure also relates to anodes for lithium ion batteries and anode compositions thereof. The present disclosure also relates to methods of incorporating the anode compositions into electrochemical cells.

Description

[Technical field]

[0001] The present disclosure generally relates to coated anodes comprising coated microsilicon active material particles and / or anode compositions. The present disclosure also relates to anodes for lithium ion batteries and anode compositions thereof. The present disclosure also relates to methods of incorporating the anode compositions into electrochemical cells. [Background technology]

[0002] Conventional lithium-ion (Li-ion) batteries typically employ graphite-based anodes as the intercalation material for lithium. However, silicon-based anodes offer an improvement over graphite-based Li-ion batteries. 3.75 Si) has higher gravimetric (3579 mAh / g vs. 372 mAh / g for graphite) and volumetric capacity (in the fully lithiated state, about 750 mAh / cm for graphite). 3 Approximately 2194mAh / cm 3 In addition, silicon-based anodes exhibit both Li / Li + Silicon has a low lithiation / delithiation voltage plateau at about 0.3-0.4 V vs. , which allows for maintaining an open circuit potential that avoids undesirable Li plating and dendrite formation. Although silicon exhibits excellent electrochemical activity, it is difficult to achieve stable cycle life for silicon-based anodes due to the large volume change of silicon during lithiation and delithiation. Silicon active materials and regions can lose electrical contact from the anode, as the large volume change combined with its low electrical conductivity separates the silicon from the surrounding material in the anode.

[0003] In addition, the large silicon volume change aggravates the formation of the solid electrolyte interface (SEI), which may further lead to electrical insulation and therefore capacity loss. The expansion and contraction of silicon particles during charge-discharge cycling causes the pulverization of silicon particles, which increases their specific surface area. As the silicon surface area changes and increases during cycling, the SEI repeatedly decomposes and reforms. Thus, the SEI is continuously built up around the pulverized silicon regions during cycling, resulting in a thick electronically and ionically insulating layer. This accumulating SEI increases the impedance of the electrode, reduces the electrochemical reactivity of the electrode, and adversely affects the cycle life. Due to its high specific capacity, abundance, and low cost, silicon is a promising active material for Li-ion anodes. However, its large volume change during lithiation and delithiation (Li 3.75 The increase in the volume change (>280% for the Si1 phase) leads to mechanical degradation of the electrode and an unstable SEI, which leads to electrode swelling and poor cell cycle life.

[0004] Therefore, there is a need to provide new and alternative anode compositions for lithium ion batteries, especially anode compositions containing a majority of silicon active material, which can control the swelling effect of silicon and significantly extend the stability and / or cycle life of the anode. Summary of the Invention

[0005] The present disclosure provides a coated anode comprising the coated micro-silicon active material particles and / or the anode composition. The anode composition may comprise micro-silicon active material particles or coated micro-silicon active material particles, and the silicon content is at least 60% by weight, based on the total weight of the anode composition. The present disclosure also provides a method of incorporating an anode comprising the anode composition into an electrochemical cell and an electrochemical cell so formed, whereby the anode paired with the method of integration into an electrochemical cell can extend the stability and / or cycle life of the anode. The anode composition and / or the formed anode can be coated.

[0006] In one aspect, an anode composition is provided that includes microsilicon active material particles, the microsilicon active material particles having a particle size of less than about 0.1 m 2 / g~about 10m 2 / g, (ii) a measured BET surface area of ​​about 0.1 μm to about 10 μm 50 and (iii) a D of about 0.1 to about 10. 50 The anode composition has one or more of the following ratios of surface area to surface area:BET surface area, and the amount of microsilicon active material particles present in the anode composition is about 60% to about 95% by weight based on the total weight percent of the anode composition, and the anode composition includes a coating. In some embodiments, the coating can be a coating on the microsilicon active material particles. The coating can be selected from the group including carbon, graphene, graphite, metal oxides, polymers, and combinations thereof to form a coated microsilicon active material particle.

[0007] In some embodiments, the surface area of ​​the coated microsilicon active material particles is reduced compared to the surface area of ​​the uncoated microsilicon active material particles. It will be appreciated that in some instances the surface area may be reduced if the microsilicon active material particles have rough surfaces and the coating can actually fill these imperfections. In other embodiments, the surface area of ​​the coated microsilicon active material particles is increased compared to the surface area of ​​the uncoated microsilicon active material particles. In some embodiments, the measured BET surface area of ​​the coated microsilicon active material particles is greater than about 1 m 2 / g~about 100m 2 / g. In some embodiments, the amount of microsilicon active material particles or coated microsilicon active material particles present in the anode composition may be about 70 wt% to about 95 wt%, based on the total weight percent of the anode composition. In some embodiments, the purity of the microsilicon active material particles (oxygen free) may be at least 95 wt%, preferably 98 wt%. In some embodiments, the thickness of the coating may be about 0.1 nm to about 200 nm.

[0008] In some embodiments, the anode composition may further include one or more binders. The amount of binder present in the anode composition may be from about 2.5% by weight to about 15% by weight, based on the total weight of the anode composition.

[0009] In some embodiments, the anode composition can further include one or more conductive materials. The amount of conductive material present in the anode composition can be from about 2.5% by weight to about 40% by weight, based on the total weight of the anode composition.

[0010] In some embodiments, the micro-silicon active material particles or coated active material particles, and / or the anode composition may be prelithiated. The prelithiation level of the micro-silicon active material particles or coated active material particles, and / or the anode composition may be from about 1% to about 30% silicon lithiation.

[0011] In another aspect, an electrochemical cell is provided that includes an anode, a cathode, an electrolyte, and a separator, the anode comprising an anode composition defined in any one or more of the embodiments or examples described herein, and the lithium uptake capacity of the anode is greater than the lithium release capacity of the cathode. In some embodiments, the lithium uptake capacity of the anode may not be fully utilized during charging of the lithium ion battery. In one example, the anode may be only partially lithiated in a fully charged state. In some embodiments, the degree of silicon lithiation may be limited to about 20% to about 80% of the theoretical maximum. In some embodiments, the capacity ratio (N / P ratio) of the anode and the cathode may be about 1.05 to about 7. In other embodiments, the lower cutoff voltage may be about 2.0V to 3.5V.

[0012] In some embodiments, the pre-lithiation level of the anode can be from about 1% to about 30% silicon lithiation. The cathode can include an active material selected from the group including lithium nickel cobalt manganese oxide (NCM), lithium iron phosphate (LFP), lithium nickel manganese spinel (LNMO), lithium nickel cobalt aluminum oxide (NCA), lithium manganese oxide (LMO), lithium cobalt oxide (LCO), and sulfur or sulfur complexes. The electrolyte can be selected from non-aqueous electrolyte solutions including one or more lithium salts.

[0013] In some embodiments, the electrochemical cell can be an energy storage device. The energy storage device can be a battery, preferably a secondary battery. For example, the battery can be a lithium ion battery.

[0014] In another aspect, a method is provided for improving the cycling stability of a lithium-ion battery having an anode and a cathode, at least one electrolyte, and a separator, wherein the anode composition is defined according to any one or more of the embodiments or examples described herein. In some embodiments, the anode in the battery delivers a specific capacity of at least about 450 mAh / g, 500 mAh / g, 600 mAh / g, 800 mAh / g, 1000 mAh / g, 1200 mAh / g, or 1500 mAh / g and retains at least about 80% of its initial capacity after 100, 200, 400, 600, 800, 1000, or 1500 cycles of the battery.

[0015] In another aspect, there is provided a use of an anode composition in an electrochemical cell, wherein the anode composition is at least partially applied to a current collector material, and wherein the anode composition is as defined by any one or more of the embodiments or examples described herein.

[0016] In another aspect, there is provided a process for preparing an anode for an electrochemical cell comprising: (i) preparing an anode slurry comprising microsilicon active material particles or coated microsilicon active material particles, optionally one or more further active materials, optionally one or more binders, optionally one or more conductive materials, optionally one or more additives, and a solvent system; (ii) casting a layer of the anode slurry onto a current collector material to provide an anode composition layer on the current collector material; and (iii) optionally coating the anode composition, wherein the microsilicon active material particles are: (a) about 0.1 m 2 / g~about 10m 2 / g, (b) the measured BET surface area from about 0.1 μm to about 10 μm 50 particle size, and (c) D of about 0.1 to about 10 50 :BET surface area ratio.

[0017] In another aspect, there is provided an anode prepared as defined by the process in any one or more of the embodiments or examples described herein.

[0018] In another aspect, a process for assembling an electrochemical cell is provided, the process comprising the steps of: preparing an anode as defined by the process in any one or more of the embodiments or examples described herein, wherein the anode comprises an anode composition defined in any one or more of the embodiments or examples described herein, and assembling the anode into an electrochemical cell.

[0019] In any of the above aspects and embodiments, the anode comprising the micro-silicon active material particles and / or the anode composition comprises a coating. [Brief description of the drawings]

[0020] Preferred embodiments of the present disclosure will be further described and illustrated, by way of example only, with reference to the accompanying drawings, in which: [Figure 1a] FIG. 13 is a graph showing the specific coating capacity of a full cell (anode) (with Al2O3 coating vs. uncoated mSi) for limited capacity of 70 wt. % mSi at C / 2. [Figure 1b] FIG. 13 is a graph showing the discharge capacity retention of a full cell (anode) with limited capacity of 70 wt. % mSi (with Al2O3 coating vs. uncoated mSi) at C / 2. [Figure 2a] FIG. 13 is a graph showing the specific coating capacity of a full cell (anode) (with PR coating vs. uncoated mSi) for limited capacity of 70 wt % mSi at C / 2. [Figure 2b] FIG. 13 is a graph showing the discharge capacity retention of a full cell (anode) with limited capacity of 70 wt. % mSi (with PR coating vs. uncoated mSi) at C / 2. [Figure 3a]FIG. 13 is a graph showing the specific coating capacity of (PVP-SPD coated vs. uncoated) full cell (anode) with limited capacity of 70 wt. % mSi at C / 2. [Figure 3b] FIG. 13 is a graph showing the discharge capacity retention of 70 wt. % mSi limited capacity (PVP-SPD coated vs. uncoated) full cells (anodes) at C / 2. [Figure 4a] FIG. 13 is a graph showing the specific coating capacity of a full cell (anode) with limited capacity (PAN coating vs. uncoated mSi) of 70 wt % mSi at C / 2. [Figure 4b] FIG. 13 is a graph showing the discharge capacity retention of full cells (anodes) with limited capacity of 70 wt. % mSi (PAN coated vs. uncoated mSi) at C / 2. [Figure 5a] FIG. 13 is a graph showing the specific coating capacity (anode) at C / 2 of a pre-lithiated 70 wt % mSi anode (at 0 and 10% pre-lithiation). [Figure 5b] FIG. 13 shows the discharge capacity retention of a full cell of a pre-lithiated 70 wt % mSi anode (at 0 and 10% pre-lithiation) at a rate of C / 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] This disclosure describes the investigations conducted to identify alternative and improved anodes, including most microsilicon anode compositions for lithium ion batteries, optional methods of incorporating the anodes into electrochemical cells, electrochemical cells so formed, and the following various non-limiting examples of their uses.

[0022] General Definitions and Terminology In the following description, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration several embodiments, It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present disclosure.

[0023] With respect to the definitions provided herein, unless otherwise stated or implied from the context, the defined terms and phrases include the meanings provided. In addition, unless otherwise expressly stated or clear from the context, the following terms and phrases do not exclude the meaning that the term or phrase would have acquired by one of ordinary skill in the relevant art. The definitions are provided to aid in describing certain embodiments and are not intended to limit the claimed invention, as the scope of the invention is limited only by the claims. Further, unless otherwise required by context, singular terms shall include the plural and plural terms shall include the singular.

[0024] All publications discussed and / or referenced herein are incorporated herein in their entirety.

[0025] Throughout this disclosure, unless specifically stated otherwise or unless the context requires otherwise, reference to a single step, composition of matter, group of steps, or group of compositions of matter is intended to encompass one and more than one (i.e., one or more) of that step, composition of matter, group of steps, or group of compositions of matter. Thus, as used herein, the singular forms "a," "an," and "the" include plural aspects unless the context clearly indicates otherwise. For example, reference to "a" includes the singular and two or more, reference to "an" includes the singular and two or more, reference to "the" includes the singular and two or more, etc.

[0026] Those skilled in the art will appreciate that the disclosure herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the disclosure includes all such variations and modifications. The disclosure also includes, individually or collectively, all of the embodiments, steps, features, methods, compositions, and processes referred to or shown in this specification, and any and all combinations, or any two or more of such steps or features.

[0027] The term "and / or," e.g., "X and / or Y," shall be understood to mean either "X and Y" or "X or Y," and shall be interpreted as providing explicit support for both meanings or for either meaning.

[0028] Unless otherwise indicated, the terms "first," "second," and the like are used herein merely as labels, and are not intended to impose any sequential, positional, or hierarchical requirements on the items to which these terms refer. Moreover, a reference to a "second" item does not require or preclude the presence of a lower-numbered item (e.g., a "first" item) and / or a higher-numbered item (e.g., a "third" item).

[0029] As used herein, the phrase "at least one of," when used with a list of items, means that different combinations of one or more of the listed items may be used, and only one of the items in the list may be required. The items may be specific objects, things, or categories. In other words, "at least one of" means that any combination or number of items from the list may be used, but not all of the items in the list may be required. For example, "at least one of item A, item B, and item C" may mean item A; item A and item B; item B; item A, item B, and item C; or item B and item C. In some cases, "at least one of item A, item B, and item C" may mean, for example, but not limited to, two of item A, one of item B, and ten of item C, four of item B, and seven of item C, or some other suitable combination.

[0030] It should be understood that certain features that are, for clarity, described herein in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any subcombination.

[0031] Throughout this specification, various aspects and components of the invention can be presented in a range format. The range format is included for convenience and should not be construed as an inflexible limitation on the scope of the invention. Thus, the description of a range should be considered to have specifically disclosed all possible subranges and individual numerical values ​​within that range, unless specifically indicated otherwise. For example, the description of a range such as 1-5 should be considered to have specifically disclosed subranges such as 1-3, 1-4, 1-5, 2-4, 2-5, 3-5, etc., as well as individual and partial numbers within the recited range, such as 1, 2, 3, 4, 5, 5.5, and 6, unless an integer is required or is implied by context. This applies regardless of the breadth of the range disclosed. When specific values ​​are required, they are set forth herein.

[0032] Throughout this specification the word "comprise" or variations such as "comprises" or "comprising" will be understood to mean the inclusion of the specified elements, integers, or steps, or group of elements, integers, or steps, but not the exclusion of any other elements, integers, or steps, or group of elements, integers, or steps.

[0033] Throughout this specification, the term "consisting essentially of" is intended to exclude elements that would materially affect the properties of the claimed composition.

[0034] As used herein, the terms "comprising," "comprise," and "comprises" are intended to be optionally replaceable in all instances with the terms "consisting essentially of," "consist essentially of," "consist essentially of," "consisting of," "consist of," and "consists of," respectively.

[0035] As used herein, the term "about" encompasses a tolerance of 10% in any value or values ​​connected to the term.

[0036] As used herein, the term "weight percent" may be abbreviated as "wt.%."

[0037] Specific Terms As used herein, the term "lithiation" includes the lithiation of either the anode or the cathode and refers to the interaction of Li with the active material. + is intended to indicate the intercalation or alloying of

[0038] As used herein, the term "delithiation" includes the lithiation of either the anode or cathode and refers to the dissociation of Li from the active material. + is intended to indicate the extraction or dealloying of

[0039] The term "charging" can be used in the context of full cells and half cells. In full cells, the term "charging" refers to the charging of Li + The term "charging" refers to the involuntary process of forcing Li from the cathode to the anode (initial pairing of the anode and cathode) and indicates a rise in cell voltage. In a half cell, the term "charging" refers to the transfer of Li from the working electrode to the anode. + It involves an involuntary process of extraction and deposition on the reference electrode (lithium metal foil) and shows an increase in the cell voltage.

[0040] The term "discharge" can be used in the context of full cells and half cells. In a full cell, the term "discharge" refers to the removal of Li from the anode. + It encompasses the optional process of extracting ions and transferring them from the anode to the cathode when assembled, which indicates a decrease in cell voltage. In a half cell, the term "discharge" refers to the removal of Li from the reference electrode (lithium metal foil). + Optional process of dissolution, and Li + into the working electrode, showing a decrease in cell voltage.

[0041] As used herein, the term "half cell" describes a reference test system used for research and development purposes consisting of a working electrode (the electrode of interest) and a reference electrode (e.g., lithium metal foil).

[0042] As used herein, the term "full cell" describes a conventional electrochemical cell system that pairs a commercially relevant anode (graphite, silicon, LTO) with a commercially relevant cathode (LFP, LCO, NCM, NCA, LMO).

[0043] The term "prelithiated" refers to the process of prelithiating a lithium battery with Li prior to pairing with the cathode electrode in a full-cell format. + into the anode or anode active material.

[0044] The term "N / P ratio" or "negative to positive ratio" refers to the mass balance between the anode (negative electrode) and the cathode (positive electrode). The mass balance is the mass of each electrode cm 2 The available area capacity per

[0045] The term "areal capacity" refers to the available capacity of an electrode (anode or cathode) per area. The type and weight % of active material in the coating, as well as mg / cm 2 (or g / m 2 ) is determined by the amount of coating loading applied to the current collector substrate. 2The higher the load at cm 2 The capacity per unit area is increased.

[0046] Coated Micro Silicon Particles The present disclosure relates, at least in part, to a coated anode comprising the coated micro-silicon active particles and / or anode compositions described herein. It is believed that the coating applied to the micro-silicon active particles described herein can improve cycle stability and reduce electrolyte decomposition due to electrochemical protection of the anode surface. It will be understood that the coating can provide one or more of a number of properties to the micro-silicon active particles and / or anode, including, for example, structural strength, lower surface area, reduced powdering, electronic conductivity, Li-ion conductivity, passivation, and / or insulation, ultimately improving silicon anode capacity retention.

[0047] In some embodiments, the coating can protect the surface of the microsilicon particles from ongoing contact with the electrolyte, thus helping to reduce or eliminate the continuous reformation of the SEI layer and the associated loss of lithium with every charge and discharge cycle. To achieve this result, the coating should be thick enough to form an effective barrier and flexible enough to withstand the swelling behavior of the miro-silicon active material, but thin enough to avoid or minimize impeding the transfer of lithium ions or electrons from the electrolyte to the active material and vice versa. The coating is preferably electrochemically inert, thus forming a passivation layer on the microsilicon particle active material surface.

[0048] In another embodiment, the coating may be highly conductive, which may further reduce the interfacial resistance between the microsilicon particles and between those particles and the current collector.

[0049] In some embodiments, the coating may tailor the chemistry of the active material to provide greater affinity with the binder chemistry, for example, if the binder is more hydrophobic, the more hydrophobic active material surface will have greater affinity (and vice versa).

[0050] In some embodiments, the coating may reduce the charge transfer resistance between the phases and increase the electronic conductivity of the microsilicon particles.

[0051] In yet another embodiment, the coating may form a passivation layer that acts as a passivation layer to prevent oxidation of the micro-silicon active material once integrated into the aqueous anode slurry, thus preventing the formation of hydrogen gas during processing while keeping a maximum amount of the micro-silicon active material electrochemically active.

[0052] The coating may have different morphologies. The morphology of the resulting coating may depend on the coating method used to apply the coating and / or the chemical nature of the precursor or coating material used. In one embodiment, the coating may include loose aggregates or particulates, including nano- or micron-sized fibers, flakes, fine particles, etc., disposed on or embedded in the outer surface of the microsilicon particles. The particulates may include and include micro- or nano-sized powders, fibers, or flakes. In another embodiment, the coating may include a discontinuous layer. In another embodiment, the coating may include a continuous layer. In yet another embodiment, the coating may include a conformal layer. In other embodiments, the coating may present a pinhole-free quasi-pinhole-free coating.

[0053] The coating may be present in the anode layer from about 0.1% to about 20% by weight, or from about 0.1% to about 15% by weight, or from about 0.1% to about 10% by weight. It will be understood that the coating weight percentage will be minimized to the amount that provides the most beneficial performance to achieve the intended result.

[0054] In some embodiments, the coating may be selected from the group including carbon, graphene, graphite, metal oxides, polymers, and combinations thereof to form coated micro-silicon active material particles or coated anode compositions.

[0055] In some embodiments or examples, the coating thickness can be from about 0.1 nm to about 200 nm, or from about 0.2 nm to about 150 nm, or from about 0.3 nm to about 100 nm, or from about 0.3 nm to about 75 nm, or from about 0.3 nm to about 50 nm, or from about 0.3 nm to about 25 nm, or from about 0.3 nm to about 0.20 nm, or from about 0.3 nm to about 10 nm. The coating thickness (in nm) can be less than about 200, 175, 150, 125, 100, 90, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, 8, 6, 5, 4, 3, 2, 1, 0.8, 0.5, 0.2, or 0.1. The coating thickness (in nm) can be at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 100, 150, or 200. The coating thickness (in nm) can be in a range provided by any two of these upper and / or lower amounts.

[0056] In some embodiments, the ratio of coating thickness to uncoated silicon particle diameter (t / d as X:1) can be from about 0.0001:1 to about 0.2:1, or from about 0.0001:1 to about 0.15:1, or from about 0.0001:1 to about 0.12:1, or from about 0.0001:1 to about 0.1:1, or from about 0.0001:1 to about 0.09:1, or from about 0.0001:1 to about 0.085:1. Viewed another way, in some embodiments, the ratio of silicon particle diameter to coating thickness (d / t as 1:X) can be from about 1:100,000 to about 1:5, or from about 1:100,000 to about 1:8, or from about 1:100,000 to about 1:10, or from about 1:100,000 to about 1:12.

[0057] The silicon active material particles herein may be coated with a form of carbon. The carbon coating is primarily sp 2 Hybridized carbon or mainly sp 3 The carbon coating may also contain hybrid carbon with varying degrees of sp 2 and sp 3 Some embodiments of the coating may contain high levels of sp 2 Hybrid and low levels of sp 3 In some embodiments, the coating may include a sp 2 The level of hybridization can be from 1% to 100%. In another embodiment, the level of sp3 hybridization can be from 1% to 100%. Certain coating embodiments include 1-% sp 2 * 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80, 90%, 99%, or 100% sp3 hybridization levels may be combined with sp3 hybridization levels of 100. 2 In other words, mixed sp 2 / sp 3 In the hybrid coating, sp 2 Regardless of the level of hybridization, the remainder of the coating is composed of sp 3 Other coating embodiments include 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% sp 3It may contain levels of hybridization, but sp 2 The level of contamination was 1-% sp. 3 It is a mixture of *100.

[0058] Carbon-coated silicon active material particles can be provided by coating the microsilicon active material particles described herein with carbon using one or more carbon precursors. As used herein, the term "carbon" can refer to an amorphous or non-graphitizable carbon coating, a graphitic carbon coating, or graphene. A non-graphitizable material is a carbon material that remains substantially amorphous even when exposed to high temperatures. As discussed above, the carbon coating can be a mixture of sp 2 / sp 3 A range of hybrids may be exhibited. Carbon coatings may be applied using a variety of techniques known in the art, including but not limited to CVD, PVD, pyrolysis, and the like.

[0059] In an embodiment, the amorphous carbon coating may be a coating with soft or hard carbon, as known in the art. To achieve such an amorphous carbon coating, it will be understood that a wide range of precursor materials are commercially available, such as carbon black, petroleum pitch, coal tar pitch, acetylene gas, decomposable polymers, preferably decomposable polymers with low oxygen content, such as PVP (polyvinylpyrrolidone), polyacrylonitrile (PAN), polyaniline (PANi), polypyrrole (PPy), melamine resin, phenolic resin, polydopamine, resorcinol formaldehyde resin, citric acid, and glucose are just some non-limiting examples. Amorphous carbon layers can generally be obtained via a pyrolysis process, in which microsilicon particles are exposed to a decomposable gas, such as acetylene, and then deposited on the surface as a layer of carbon when heated to a sufficiently high temperature. Alternatively, they can be obtained by coating microsilicon particles in a precursor material, such as pitch or a combustible polymer, and pyrolyzing the pitch or polymer to form a carbon layer. Different carbon precursors can be selected to form carbon layers of different qualities. For example, aromatic compounds have a higher degree of sp 2 More linear organic compounds, such as acetylene or certain polymers, can form high quality coatings that may have a higher degree of sp 3 A more amorphous structure with hybridization may be formed.

[0060] In some embodiments, graphene-coated micro silicon active material particles may be provided by coating the micro silicon active material particles described herein with graphene. In some embodiments, the graphene may be selected from the group including graphene, graphene oxide, or reduced graphene oxide, and derivatives thereof. Graphite-coated micro silicon active material particles may be provided by coating the micro silicon active material particles described herein with graphite. In some embodiments, the graphite may be selected from the group including graphite, nano graphite, graphite oxide, and derivatives thereof.

[0061] Metal oxide coated micro silicon particles can be provided by coating the micro silicon active material particles described herein with a metal oxide. In some embodiments, the metal oxide can be selected from the group including aluminum oxide, aluminum oxide hydroxide (γ-AlO(OH)), aluminum hydroxide (Al(OH)3), aluminum nitrate (Al(NO3)3), or other equivalent aluminum-containing species. In some embodiments, the aluminum hydroxide or aluminum nitrate can form a precursor for subsequent conversion to aluminum oxide hydroxide or aluminum oxide. In some embodiments, the aluminum oxide can include alpha aluminum oxide. In another embodiment, the metal oxide can include titanium or niobium based metal oxide. The metal oxide coating can include titanium oxide (TiO2) or niobium oxide (Nb2O5). In yet another embodiment, the metal oxide coating can include a magnesium based oxide. The magnesium based oxide can be magnesium oxide (MgO).

[0062] In embodiments, metal oxides, such as, for example, α-aluminum oxide and other aluminum species, can be applied to the microsilicon particles either through a precipitation process followed by calcination at higher temperatures >400° C. or through processes such as atomic layer deposition (ALD). The precipitation process route typically involves dissolving the appropriate metal salt in water at the appropriate concentration and under controlled pH, and manipulating the pH so that the metal salt precipitates uniformly on the surface of the microsilicon active material. Typically, this involves raising the pH of the environment. The concentration of the metal salt in the solution determines the thickness of the final coating layer. The excess components and metal salts can be gently washed off, and the microsilicon active material can be transferred to a furnace. The precipitate can be heated under air or inert gas to temperatures up to 1200° C., which converts the metal salt precursor to the corresponding metal oxide.

[0063] Polymer-coated microsilicon active particles can be provided by coating the microsilicon active particles described herein with a polymer. In some embodiments, the polymer is selected from the group consisting of starch, lignin, cellulose, polyacrylamide, polymethacrylamide, polyamic acid, polystyrene-4-sulfonate (PSS), 3,4-ethylenedioxythiophene / polystyrene-4-sulfonate (PEDOT:PSS), polydiallyldimethylammonium chloride PDDA, polydiallyldimethylammonium / polystyrene-4-sulfonate (PDDA:PSS), urea-pyrimidinone (UPy), urea-oligo-amidoamine (UOAA), dopamine methacrylamide, dopamine methacrylate, dopamine acrylate, dopamine, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, polyethylene glycol methyl ether methacrylate and polyethylene glycol methyl ether acrylate, cis-1,4-polyisoprene natural rubber and trans-1,4-Natural polyisoprene including polyisoprene gum, synthetic polyisoprene, polybutadiene, chloroprene rubber, polychloroprene, butyl rubber including halogenated butyl rubber, styrene-butadiene rubber, nitrile rubber, ethylene propylene rubber, ethylene propylene diene rubber, epichlorohydrin rubber, polyacrylic rubber, silicone rubber, fluorosilicone rubber, fluoroelastomers, perfluoroelastomers, polyether block amides, chlorosulfonated polyethylene, ethylene-vinyl acetate, thermoplastic elastomers, protein resilin, protein elastin, ethylene oxide-epichlorohydrin copolymers, The polymer may be selected from the group including polyurethane, urethane-urea copolymer, polyaniline, polypyrrole, polythiophene, polyfuran, bicyclic polymer, poly(ethylene oxide) (PEO), polypropylene oxide (PPO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (PVdF), poly((bis-(methoxyethoxy)ethoxy)phosphazene), polyvinyl chloride, polydimethylsiloxane, poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP), any derivatives thereof (e.g., sulfonated derivatives), phenolic resins, or combinations thereof.

[0064] In some embodiments, the coated micro-silicon active material particles can be provided from precipitation, pyrolization of a precursor formulation coating, or by chemical vapor deposition, physical vapor deposition, atomic layer deposition sputtering, or mechanical deposition.

[0065] In some embodiments or examples, the coating may be in the form of a monolayer on the surface of the microsilicon active material particles. In another embodiment, the coating may be in the form of two or more layers, e.g., multiple layers, on the surface of the microsilicon active material particles. The coating may include about 1 to 5 layers. The coating may include less than 5 layers, 4 layers, 3 layers, or less than 2 layers. The coating may include at least about 1 layer, 2 layers, 3 layers, 4 layers, or at least about 5 layers. The coating may include layers in the range provided by any lower and / or upper limits previously described. It will be understood that each layer may be provided by a different coating. For example, the coated microsilicon active material particles may include a coating, where the coating layer includes graphene and a further coating layer includes a metal oxide (e.g., aluminum oxide) applied to the microsilicon in either order.

[0066] In one embodiment, the coated micro silicon active material particles may exhibit any morphology, for example, they may take the form of flakes, aggregates, granules, powders, spheres, powdered materials, etc., and combinations thereof. The coated micro silicon active material particles may have any desired shape, including, but not limited to, cubic, rod-like, plate-like, polyhedral, spherical or hemispherical, quasi-spherical, rounded or semi-rounded, angular, irregular, etc. In one embodiment, the coated micro silicon active material particles have an aspect ratio (i.e., the ratio of length to width, where length and width are measured perpendicular to each other and length refers to the longest linearly measured dimension) of 1.0 to 10.0, 1.0 to 5.0, or 1.0 to 4.0. In one embodiment, the coated micro silicon active material particles can have an aspect ratio of about 1.0 to 4.0, for example, about 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, or 4.0.

[0067] In some embodiments, the particle size (in μm) of the coated microsilicon active material particles may be at least about 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, or 50. In some embodiments, the particle size (in μm) of the coated microsilicon active material particles may be less than about 50, 45, 40, 35, 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, or 0.5. Combinations of any two or more of these upper and / or lower particle sizes are also possible, for example, the particle size (in μm) of the coated microsilicon active material particles may be about 1 to about 50, about 2 to about 40, or about 3 to about 30. The particle size is taken to be the longest cross-sectional diameter across the coated microsilicon active material particles. For non-spherical coated micro silicon active material particles, the particle size is taken to be the distance corresponding to the longest cross-sectional dimension across the particle.

[0068] The coated microsilicon active material particles may have a particle size distribution, with 90% of the microsilicon active material particles (D 90 ) may have a particle size of less than about 50, 45, 40, 35, 34, 32, 30, 28, 24, 20, 18, 16, 14, 12, 10, 8, 6, 5, or 4 μm, or 50% of the microsilicon active material particles (D 50 ) have a particle size (in μm) of less than about 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.8, 0.6, 0.4, 0.2, 0.1, or 10% of the microsilicon active material particles (D 10 ) has a particle size of less than about 4, 3, 2, or 1 μm. In some embodiments, the microsilicon active material particles have a (D 50 In some embodiments, the microsilicon active material particles have a particle size (in μm) of less than about 10, 9, 8, 7, 6, 5, 4, 3.5, 3, 2.5, 2, 1 (D 50) particle size (in μm). 0.9, 0.8, 0.7, 0.6, 0.5, 0.5, 0.4, 0.3, 0.2, or 0.1. Combinations of any two or more of these upper and / or lower particle sizes are also possible, for example, the microsilicon active material particles have a (D 50 ) particle size (in μm).

[0069] In some embodiments or examples, the coated micro silicon active material particles are about 0.1 mm 2 / g~about 100m 2 The coated micro silicon active material particles may have a BET surface area in the range of at least about 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, or 100 m 2 / g BET surface area (m 2 In other embodiments or examples, the coated micro silicon active material particles may have a molecular weight of about 100, 90, 80, 70, 60, 50, 45, 40, 35, 30, 25, 20, 10, 9, 8, 7, 6, 5, 4, 3, 21, 0.5, or 0.1 m 2 Surface area (m 2 / g). Combinations of these surface area values ​​to form various ranges are also possible.

[0070] In some embodiments or examples, the tap density of the coated micro silicon active material particles is about 0.5 g / cm 3 ~Approx. 1.5g / cm 3 The tap density of the coated micro silicon active material particles may be in the range of at least about 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, 1.2, 1.3, or 1.5 g / cm.3 In other embodiments or examples, the tap density of the coated micro silicon active material particles can be about 1.5, 1.4, 1.3, 1.2, 1.0, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, or 0.5 g / cm 3 Combinations of these density values ​​to form various ranges are also possible, for example, the coated micro silicon active material particles may be less than about 0.5 g / cm 3 ~Approx. 1.2g / cm 3 The density can be measured by any standard method, for example, according to ASTM D7481-18.

[0071] Advantageously, the microsilicon active material particles of the present disclosure can be provided with high purity. In some embodiments or examples, the purity of the microsilicon active material particles (oxygen free) can be in the range of about 95 to about 99.9 (by weight %). The purity of the microsilicon active material particles (oxygen free) can be at least about 95, 96, 97, 98, 99, 99.5, or 99.9 (by weight %). The purity of the microsilicon active material particles (oxygen free) can be less than about 99.9, 99.5, 99, 98, 97, 96, or 95 (by weight %). The purity of the microsilicon active material particles (oxygen free) can be in the range provided by any lower and / or upper limits as previously described.

[0072] In some embodiments or examples, the purity of the microsilicon active particles (with oxygen) may range from about 79 to about 99.5 (by weight %). The purity of the microsilicon active particles (with oxygen) may be at least about 75, 80, 85, 90, 95, 96, 97, 98, 99, or 99.5 (by weight %). The purity of the microsilicon active particles (with oxygen) may be less than about 99.5, 99, 98, 97, 96, 95, 90, 85, 80, or 75 (by weight %). The purity of the microsilicon active particles (with oxygen) may be in a range provided by any lower and / or upper limits as previously described.

[0073] The combination of the novel and inventive features of the coated microsilicon active material particles according to the present disclosure and their use in an anode composition for an anode in a lithium-ion battery can also surprisingly lead to improved battery cycling behavior. Unexpectedly, it has been shown that the lithium-ion battery described herein has a small irreversible capacity loss in the first charging cycle and a stable electrochemical behavior with minimal fading in subsequent cycles. Thus, the use of the coated microsilicon active material particles described herein can achieve a lower initial capacity loss and also a low continuous capacity loss in the lithium-ion battery. Overall, the lithium-ion battery described herein provides very good stability and cycle life. Thus, many cycles can be achieved with minimal fatigue as a result of, for example, mechanical destruction of the anode coating layer, the anode material, or the SEI formation.

[0074] Anode Composition The present disclosure is directed to providing improved anodes for lithium-ion batteries. The present disclosure spans various research and development efforts directed to identifying and better understanding the failure mechanisms of anodes, including most silicon anode compositions, and then optimizing their formulations so that solid electrolyte interface decomposition (e.g., cracking and delamination), silicon particle fracture, and instability can be controlled, reduced, or in some ways ameliorated, to improve the stability and cyclability of lithium-ion batteries.

[0075] Surprisingly, it has been found, at least according to some examples described herein, that most silicon anode compositions can exhibit significant anode stability and / or cycle life. Even more surprisingly, it has been found that most silicon anode compositions, paired with a method of integration into an electrochemical cell, can control the formation of the SEI, as well as the expansion and decomposition of the silicon, and thus significantly extend the anode stability and / or cycle life.

[0076] Also, according to at least some examples described herein, most silicon anode compositions for electrochemical cells (e.g., batteries) include: (a) Long-term cycling stability of lithium-ion (Li-ion) cells; (b) controlled expansion and contraction of silicon during charge and discharge cycling of Li-ion cells, minimizing silicon particle cracking, pulverization, and SEI growth; (c) reduced cell capacity fade during cycle life due to controlled silicon expansion / contraction and silicon anode voltage window; and / or (d) It has been found that the present invention may provide one or more additional advantages, such as high rate capability.

[0077] The anode compositions described herein may include microsilicon active material particles, which may be any of the following: (i) at least about 0.1 m 2 / g~about 10m 2 / g, (ii) a measured BET surface area of ​​about 0.1 μm to about 10 μm 50 particle size, and (iii) a D of about 0.1 to 10 50 :BET surface area ratios and the amount of silicon present in the anode composition is from about 60% by weight to about 95% by weight, based on the total weight percent of the anode composition.

[0078] In some embodiments, the anode compositions described herein may include microsilicon active material particles, the microsilicon active material particles having an average particle size of (i) about 0.1 m 2 / g~about 10m 2 / g, and (ii) a D of about 0.1 μm to about 10 μm. 50 particle size, or (iii) a D of about 0.1 to 10 50 :BET surface area ratio, and the amount of silicon present in the anode composition is from about 60% by weight to about 95% by weight, based on the total weight percent of the anode composition.

[0079] The anode compositions described herein may comprise or consist of the microsilicon active material particles described herein, optionally one or more additional active materials, optionally one or more binders, optionally one or more conductive materials, and optionally one or more additives. In one example, the anode compositions described herein comprise microsilicon active material particles, the microsilicon active material particles having a density of less than or equal to: (i) about 0.1 m 2 / g~about 10m 2 / g, (ii) a measured BET surface area of ​​about 0.1 μm to about 10 μm 50 particle size, and (iii) a D of about 0.1 to 10 50 % to about 95 wt %, based on the total weight % of the anode composition, and optionally one or more further active materials, optionally one or more binders, optionally one or more conductive materials, and optionally one or more additives.

[0080] In some embodiments, the anode compositions described herein comprise microsilicon active material particles, the microsilicon active material particles having a surface area of ​​(i) about 0.1 m 2 / g~about 10m 2 / g, and (ii) a D of about 0.1 μm to about 10 μm. 50 particle size, or (iii) a D of about 0.1 to 10 50 % to about 95 wt %, based on the total weight % of the anode composition, optionally one or more further active materials, optionally one or more binders, optionally one or more conductive materials, and optionally one or more additives.

[0081] In some embodiments or examples, the microsilicon active material particle content of the anode composition may be about 60% to about 95% by weight based on the total weight of the anode composition. It will be appreciated that further advantages may be exhibited when the microsilicon active material particle content of the anode composition is greater than 60% by weight, preferably greater than 70% by weight. The microsilicon active material particle content may be less than about 95% by weight, 90% by weight, 85% by weight, 80% by weight, 75% by weight, 70% by weight, 65% by weight, or 60% by weight. The microsilicon active material particle content may be at least about 60% by weight, 65% by weight, 70% by weight, 75% by weight, 80% by weight, 85% by weight, 90% by weight, or 95% by weight. The microsilicon active material particle content of the anode composition may be in a range provided by any two of these upper and / or lower amounts.

[0082] In some embodiments or examples, the thickness of the anode composition is substantially uniform and may be in the range of about 5 μm to about 70 μm. The thickness (μm) of the anode composition may be less than about 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, or 5. The thickness (μm) of the anode composition may be at least about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, or 65. The thickness of the anode composition may be in a range provided by any two of these upper and / or lower amounts.

[0083] In some embodiments or examples, the anode composition may be supported on a current collector material. In some embodiments or examples, the anode composition may be applied to the current collector material as a coating or film. It will be understood that the current collector may be at least partially coated with the anode composition. For example, the anode composition may be applied to only one side of the current collector material. The current collector material for the anode may be selected from the group including copper, aluminum, stainless steel, titanium, carbon, perforated metal foils, metal foams, and metal-coated polymer-based porous and non-porous films. It will be understood that the current collector material is of suitable dimensions, porosity, and pore size to include the above materials and act as a current collector. For example, the anode composition may be applied to a copper current collector material (e.g., copper foil). For example, an anode composition including or consisting of microsilicon active material particles, optionally one or more additional active materials, optionally one or more binders, optionally one or more conductive materials, and optionally one or more additives may be supported on a copper current collector material (e.g., copper foil). In some embodiments, the current collector material for the anode can have a thickness of about 4 μm to about 25 μm. The thickness (in μm) of the current collector can be less than about 25, 20, 15, 10, 8, 6, or 4. The thickness (in μm) of the current collector can be at least about 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, or 25. The thickness (in μm) of the current collector can be in a range provided by any two of these upper and / or lower amounts. In one example, the current collector material for the anode can be a copper foil having a thickness of about 6 μm to about 12 μm.

[0084] In some embodiments or examples, the anode composition can be an anode for a battery. For example, the anode composition can be an anode for a lithium ion battery.

[0085] The present disclosure may also be directed to an anode composition that includes a coating. In some embodiments or examples, the coating may be a coating of microsilicon active material particles that are then incorporated into the anode composition. In other embodiments or examples, the coating may be a coating of the anode composition or the anode itself. In other words, the coating may be present on at least a portion of the surface of the anode composition and the anode so formed. In some embodiments or examples, the portion (%) may be at least about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100.

[0086] In some embodiments, the coating may be selected from the group including carbon, graphene, graphite, metal oxides, polymers, and combinations thereof to form coated micro-silicon active material particles or coated anode compositions.

[0087] The silicon active material particles herein may be coated with a form of carbon. The carbon coating is primarily sp 2 Hybridized carbon or mainly sp 3 The carbon coating may also contain hybrid carbon with varying degrees of sp 2 and sp 3 Some embodiments of the coating may contain high levels of sp 2 Hybrid and low levels of sp 3 In some embodiments, the coating may include a sp 2 The level of hybridization can be from 1% to 100%. In another embodiment, the level of sp3 hybridization can be from 1% to 100%. Certain coating embodiments include 1-% sp 2 Hybrid*100 sp 3 Can be combined with a level of hybridization of 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80, 90%, 99%, or 100% sp. 2 In other words, mixed sp 2 / sp3 In the hybrid coating, sp 2 Regardless of the level of hybridization, the remainder of the coating is composed of sp 3 Other coating embodiments include 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% sp 3 It may contain levels of hybridization, but sp 2 The level of contamination was 1-% sp. 3 It is a mixture of *100.

[0088] Carbon-coated silicon active material particles can be provided by coating the microsilicon active material particles described herein with carbon using one or more carbon precursors. As used herein, the term "carbon" can refer to an amorphous or non-graphitizable carbon coating, a graphitic carbon coating, or graphene. A non-graphitizable material is a carbon material that remains substantially amorphous even when exposed to high temperatures. As discussed above, the carbon coating can be a mixture of sp 2 / sp 3 A range of hybrids may be exhibited. Carbon coatings may be applied using a variety of techniques known in the art, including but not limited to CVD, PVD, pyrolysis, and the like.

[0089] In an embodiment, the amorphous carbon coating may be a coating with soft or hard carbon, as known in the art. To achieve such an amorphous carbon coating, it will be understood that a wide range of precursor materials are commercially available, such as carbon black, petroleum pitch, coal tar pitch, acetylene gas, decomposable polymers, preferably decomposable polymers with low oxygen content, such as PVP (polyvinylpyrrolidone), polyacrylonitrile (PAN), polyaniline (PANi), polypyrrole (PPy), melamine resin, phenolic resin, polydopamine, resorcinol formaldehyde resin, citric acid, and glucose are just some non-limiting examples. Amorphous carbon layers can generally be obtained via a pyrolysis process, in which microsilicon particles are exposed to a decomposable gas, such as acetylene, and then deposited on a surface as a layer when heated to a sufficiently high temperature. Alternatively, they can be obtained by coating microsilicon particles in a precursor material, such as pitch or a combustible polymer, and pyrolyzing the pitch or polymer to form a carbon layer. Different carbon precursors can be selected to form carbon layers of different qualities. For example, aromatic compounds have a higher degree of sp 2 More linear organic compounds, such as acetylene or certain polymers, can form high quality coatings that may have a higher degree of sp 3 A more amorphous structure with hybridization may be formed.

[0090] In some embodiments, graphene-coated micro silicon active material particles may be provided by coating the micro silicon active material particles described herein with graphene. In some embodiments, the graphene may be selected from the group including graphene, graphene oxide, or reduced graphene oxide, and derivatives thereof. Graphite-coated micro silicon active material particles may be provided by coating the micro silicon active material particles described herein with graphite. In some embodiments, the graphite may be selected from the group including graphite, nano graphite, graphite oxide, and derivatives thereof.

[0091] Metal oxide coated micro silicon particles can be provided by coating the micro silicon active material particles described herein with a metal oxide. In some embodiments, the metal oxide can be selected from the group including aluminum oxide, aluminum oxide hydroxide (γ-AlO(OH)), aluminum hydroxide (Al(OH)3), aluminum nitrate (Al(NO3)3), or other equivalent aluminum-containing species. In some embodiments, the aluminum hydroxide or aluminum nitrate can form a precursor for subsequent conversion to aluminum oxide hydroxide or aluminum oxide. In some embodiments, the aluminum oxide can include alpha aluminum oxide. In another embodiment, the metal oxide can include titanium or niobium based metal oxide. The metal oxide coating can include titanium oxide (TiO2) or niobium oxide (Nb2O5). In yet another embodiment, the metal oxide coating can include a magnesium based oxide. The magnesium based oxide can be magnesium oxide (MgO).

[0092] In embodiments, metal oxides, such as, for example, α-aluminum oxide and other aluminum species, can be applied to the microsilicon particles either through a precipitation process followed by calcination at higher temperatures >400° C. or through processes such as atomic layer deposition (ALD). The precipitation process route typically involves dissolving the appropriate metal salt in water at the appropriate concentration and under controlled pH, and manipulating the pH so that the metal salt precipitates uniformly on the surface of the microsilicon active material. Typically, this involves raising the pH of the environment. The concentration of the metal salt in the solution determines the thickness of the final coating layer. The excess components and metal salts can be gently washed off, and the microsilicon active material can be transferred to a furnace. The precipitate can be heated under air or inert gas to temperatures up to 1200° C., which converts the metal salt precursor to the corresponding metal oxide.

[0093] Polymer-coated microsilicon active particles can be provided by coating the microsilicon active particles described herein with a polymer. In some embodiments, the polymer is selected from the group consisting of starch, lignin, cellulose, polyacrylamide, polymethacrylamide, polyamic acid, polystyrene-4-sulfonate (PSS), 3,4-ethylenedioxythiophene / polystyrene-4-sulfonate (PEDOT:PSS), polydiallyldimethylammonium chloride PDDA, polydiallyldimethylammonium / polystyrene-4-sulfonate (PDDA:PSS), urea-pyrimidinone (UPy), urea-oligo-amidoamine (UOAA), dopamine methacrylamide, dopamine methacrylate, dopamine acrylate, dopamine, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, polyethylene glycol methyl ether methacrylate and polyethylene glycol methyl ether acrylate, cis-1,4-polyisoprene natural rubber and trans-1,4-Natural polyisoprene including polyisoprene gum, synthetic polyisoprene, polybutadiene, chloroprene rubber, polychloroprene, butyl rubber including halogenated butyl rubber, styrene-butadiene rubber, nitrile rubber, ethylene propylene rubber, ethylene propylene diene rubber, epichlorohydrin rubber, polyacrylic rubber, silicone rubber, fluorosilicone rubber, fluoroelastomers, perfluoroelastomers, polyether block amides, chlorosulfonated polyethylene, ethylene-vinyl acetate, thermoplastic elastomers, protein resilin, protein elastin, ethylene oxide-epichlorohydrin copolymers, The polymer may be selected from the group including polyurethane, urethane-urea copolymer, polyaniline, polypyrrole, polythiophene, polyfuran, bicyclic polymer, poly(ethylene oxide) (PEO), polypropylene oxide (PPO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (PVdF), poly((bis-(methoxyethoxy)ethoxy)phosphazene), polyvinyl chloride, polydimethylsiloxane, poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP), any derivatives thereof (e.g., sulfonated derivatives), phenolic resins, or combinations thereof.

[0094] The coating on the micro silicon active material particles is derived from a silane coupling agent having the following formula (1): Y-(CH2) n -Si-X3, where Y represents a conductive polymer moiety, a conductive coating layer, a lithium ion conductive coating layer, a layer that favorably interacts with an electrode binder via physical attraction or bonding, a layer that favorably interacts with an electrode binder via forming a chemical bond, or a non-hydrolyzable group that can form a combination of any of the above upon polymerization on the active material surface; each X independently represents a hydroxyl group or a hydrolyzable group selected from the group consisting of halogen atoms, alkoxy groups, ether groups, and siloxy groups; The three X groups may be the same or different from each other; n represents an integer of 0 to 3.

[0095] In some examples, Y can include amino, epoxy, polyethylene glycol methyl ether, polyethylene glycol, acryloxy, methacryloxy functional groups, or any combination thereof.

[0096] Examples of silane coupling agents represented by formula (1) may include, but are not limited to, aminopropyltriethoxysilane, aminopropyltrimethoxysilane, bisgammatrimethoxysilypropylamine, aminoneohexyltrimethoxysilane.

[0097] In embodiments, the coated micro silicon active material particles or coated anode compositions may be provided in any manner or embodiment described above, including by pyrolization of the coating, or by chemical vapor deposition, physical vapor deposition, sputtering, or mechanical deposition.

[0098] In some embodiments or examples, the coating may be in the form of a single layer. In other embodiments, the coating may be in the form of two or more layers, e.g., a plurality of layers. The coating may include about 1 to 5 layers. The coating may include less than 5 layers, 4 layers, 3 layers, or less than 2 layers. The coating may include at least about 1 layer, 2 layers, 3 layers, 4 layers, or at least about 5 layers. The coating may include layers in the range provided by any lower and / or upper limits previously described. It will be understood that each layer may be provided by a different coating. For example, the coated microsilicon active material particles or coated anode composition may include a coating, one coating layer includes a carbon material, another coating layer includes a metal oxide (e.g., aluminum oxide), and another layer includes a polymer coating applied in any order to the microsilicon. Alternatively, the coating may be a carbon material coating and a metal oxide coating applied in any order to the microsilicon. Additionally, the coating may be a carbon material coating and a polymer coating applied in any order to the microsilicon.

[0099] It is believed that the coating on the microsilicon active particles or anode composition described herein can improve cycle stability and reduce electrolyte decomposition due to electrochemical protection of the anode surface.It will be understood that the coating can provide a number of properties to the microsilicon active particles or anode composition, including, for example, structural strength, lower surface area, reduced powdering, electronic conductivity, Li-ion conductivity, passivation, and / or insulation, ultimately improving silicon anode capacity retention.

[0100] Silicon particles The present invention relates to an anode composition comprising optionally coated micro-silicon active material particles.The present invention also relates to an anode composition comprising coated micro-silicon active material particles.

[0101] In some embodiments or examples, the microsilicon active material particles may include or be selected from the group consisting of metallurgical silicon, polycrystalline silicon, and single crystal silicon. In a preferred example, the microsilicon active material particles are metallurgical silicon.

[0102] It will be appreciated that the raw feedstock for elemental silicon of any kind is quartz sand (silicon dioxide (SiO2)). In conventional manufacturing processes, SiO2 is reacted with carbon in an arc furnace, which may be fed to the process in the form of coke, and high temperatures (about 1800°C) are applied to reduce the SiO2 to Si and CO according to the following reaction: SiO2+2C→Si+2CO………………………………………………………………(1)

[0103] This reaction produces metallurgical grade silicon, which may contain impurities such as Al, Ca, Fe, Ti, P, Cu, Cr, K, V, Ni, Na, and others at levels ranging from hundreds to thousands of parts per million (ppm). Metallurgical silicon can be used in a variety of industrial applications, including steel production. However, due to the impurities, it cannot be used for electronic applications. The crystal structure of metallurgical silicon is well defined, but it is not as pure as single crystal silicon, nor is it as efficient at conducting electricity. Metallurgical silicon has a metallic crystal structure, characterized by its metallic bonds between atoms. In a metallic crystal structure, the atoms are arranged in a repeating pattern, but lacking order.

[0104] Metallurgical silicon requires further purification to reduce impurities to parts per billion (ppb). This process can result in semiconductor or electronic grade Si (also called polycrystalline silicon). The reaction between metallurgical silicon and dry HCl forms trichlorosilane (SiHCl3), a liquid with a boiling point of 32°C. Si+3HCl→SiHCl3+H2……………………………………………………(2)

[0105] It will be appreciated that some chloride impurities may form, such as FeCl3, but due to the difference between the boiling points of these impurities and SiHCl3, the impurities can be separated using fractional distillation techniques. During this process, a mixture of SiHCl3 and chloride impurities is heated and the vapors are condensed in different distillation columns and held at the appropriate temperature. This allows the separation of pure SiHCl3 from the impurities. The reaction between SiHCl3 and H2 results in the formation of pure polycrystalline silicon. 2SiHCl3+2H2→2Si+6HCl…………………………………………(3)

[0106] The crystal structure of polycrystalline silicon is not well defined, and the small crystals (grains) that make up the material are randomly oriented and typically less than 100 micrometers in size. The grains are separated by grain boundaries and usually have a random crystallographic orientation. This results in a material that is weaker and less efficient at conducting electricity than single crystal silicon.

[0107] The Czochralski process is used to convert pure polycrystalline silicon to single crystal monocrystalline silicon. A seed crystal is required to grow a single crystal of material that acts as a template for the growth. The Czochralski process involves heating polycrystalline silicon in a quartz-lined graphite crucible by resistive heating to the melting point of Si (1412°C). The seed crystal is then lowered into the molten material and slowly raised, allowing a crystal to grow on the seed. During crystal growth, slow rotation is required to average out any temperature fluctuations that may result in uneven solidification.

[0108] The resulting single crystal silicon is often referred to as monocrystalline silicon. It is characterized by its regular and repeating arrangement of atoms in a three-dimensional lattice and consists of silicon that has no grain limits. Monocrystalline silicon can be treated as an intrinsic semiconductor consisting of only excessively pure silicon. Monocrystalline silicon is known for its high efficiency and high purity, making it ideal for use in electronic applications. Monocrystalline silicon can be p-type and n-type silicon by doping with other elements.

[0109] It is well known in the art that impurities may be present in any microsilicon active material particle. It is also well known that impurities may be selectively added to any microsilicon active material particle. In some embodiments, impurities selected from the group consisting of Al, Ca, Fe, Ti, P, Cu, Cr, K, V, Ni, and Na may be present in the microsilicon active material particle in a total or individual amount of, for example, less than about 5000 ppm, less than about 4500 ppm, less than about 4000 ppm, less than about 3500 ppm, or less than about 3000 ppm. In some embodiments, the total or individual impurities selected from the group consisting of Al, Ca, Fe, Ti, P, Cu, Cr, K, V, Ni, and Na may be present in the microsilicon active material particle in a range of about 0 ppm to about 5000 ppm, preferably about 0 ppm to about 4000 ppm, and more preferably about 0 ppm to about 3000 ppm.

[0110] In preferred embodiments or examples of the present disclosure, the microsilicon active material particles are coated microsilicon active material particles as described herein, and the anode composition comprising the coated microsilicon active material particles may or may not be additionally coated.

[0111] In some embodiments, the micro-silicon active material particle coating may be selected from the group including carbon, graphene, graphite, metal oxides, polymers, and combinations thereof to form a coated micro-silicon active material particle or coated anode composition.

[0112] In some embodiments or examples, the coating thickness can be from about 0.1 nm to about 200 nm, or from about 0.2 nm to about 150 nm, or from about 0.3 nm to about 100 nm, or from about 0.3 nm to about 75 nm, or from about 0.3 nm to about 50 nm, or from about 0.3 nm to about 25 nm, or from about 0.3 nm to about 20 nm, or from about 0.3 nm to about 10 nm. The coating thickness (in nm) can be less than about 200, 175, 150, 125, 100, 90, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, 8, 6, 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1.

[0113] In some embodiments, the ratio of coating thickness to uncoated silicon particle diameter (t / d as X:1) can be from about 0.0001:1 to about 0.2:1, or from about 0.0001:1 to about 0.15:1, or from about 0.0001:1 to about 0.12:1, or from about 0.0001:1 to about 0.1:1, or from about 0.0001:1 to about 0.09:1, or from about 0.0001:1 to about 0.085:1. Viewed another way, in some embodiments, the ratio of silicon particle diameter to coating thickness (d / t as 1:X) can be from about 1:100,000 to about 1:5, or from about 1:100,000 to about 1:8, or from about 1:100,000 to about 1:10, or from about 1:100,000 to about 1:12.

[0114] The silicon active material particles herein may be coated with a form of carbon. The carbon coating is primarily sp 2 Hybridized carbon or mainly sp 3 The carbon coating may also contain hybrid carbon with varying degrees of sp 2 and sp 3 Some embodiments of the coating may contain high levels of sp 2 Hybrid and low levels of sp 3 In some embodiments, the coating may include a sp 2The level of hybridization can be from 1% to 100%. In another embodiment, the level of sp3 hybridization can be from 1% to 100%. Certain coating embodiments include 1-% sp 2 Hybrid*100 sp 3 Can be combined with levels of hybridization: 10%, 20%, 30%, 50%, 60%, 70%, 80, 90%, 99%, or 100% sp 2 In other words, mixed sp 2 / sp 3 In the hybrid coating, sp 2 Regardless of the level of hybridization, the remainder of the coating is composed of sp 3 Other coating embodiments include 10%, 20%, 30%, 50%, 60%, 70%, 80, 90%, or 100% sp 3 It may contain levels of hybridization, but sp 2 The level of contamination was 1-% sp. 3 It is a mixture of *100.

[0115] Carbon-coated silicon active material particles can be provided by coating the microsilicon active material particles described herein with carbon using one or more carbon precursors. As used herein, the term "carbon" can refer to an amorphous or non-graphitizable carbon coating, a graphitic carbon coating, or graphene. A non-graphitizable material is a carbon material that remains substantially amorphous even when exposed to high temperatures. As discussed above, the carbon coating can be a mixture of sp 2 / sp 3 A range of hybrids may be exhibited. Carbon coatings may be applied using a variety of techniques known in the art, including but not limited to CVD, PVD, pyrolysis, and the like.

[0116] In an embodiment, the amorphous carbon coating may be a coating with soft or hard carbon, as known in the art. To achieve such an amorphous carbon coating, it will be understood that a wide range of precursor materials are commercially available, such as carbon black, petroleum pitch, coal tar pitch, acetylene gas, decomposable polymers, preferably decomposable polymers with low oxygen content, such as PVP (polyvinylpyrrolidone), polyacrylonitrile (PAN), polyaniline (PANi), polypyrrole (PPy), melamine resin, phenolic resin, polydopamine, resorcinol formaldehyde resin, citric acid, and glucose are just some non-limiting examples. Amorphous carbon layers can generally be obtained via a pyrolysis process, in which microsilicon particles are exposed to a decomposable gas, such as acetylene, and then deposited on a surface as a layer when heated to a sufficiently high temperature. Alternatively, they can be obtained by coating microsilicon particles in a precursor material, such as pitch or a combustible polymer, and pyrolyzing the pitch or polymer to form a carbon layer. Different carbon precursors can be selected to form carbon layers of different qualities. For example, aromatic compounds have a higher degree of sp 2 More linear organic compounds, such as acetylene or certain polymers, can form high quality coatings that may have a higher degree of sp 3 A more amorphous structure with hybridization may be formed.

[0117] In some embodiments, graphene-coated micro silicon active material particles may be provided by coating the micro silicon active material particles described herein with graphene. In some embodiments, the graphene may be selected from the group including graphene, graphene oxide, or reduced graphene oxide, and derivatives thereof. Graphite-coated micro silicon active material particles may be provided by coating the micro silicon active material particles described herein with graphite. In some embodiments, the graphite may be selected from the group including graphite, nano graphite, graphite oxide, and derivatives thereof.

[0118] Metal oxide coated micro silicon particles can be provided by coating the micro silicon active material particles described herein with a metal oxide. In some embodiments, the metal oxide can be selected from the group including aluminum oxide, aluminum oxide hydroxide (γ-AlO(OH)), aluminum hydroxide (Al(OH)3), aluminum nitrate (Al(NO3)3), or other equivalent aluminum-containing species. In some embodiments, the aluminum hydroxide or aluminum nitrate can form a precursor for subsequent conversion to aluminum oxide hydroxide or aluminum oxide. In some embodiments, the aluminum oxide can include alpha aluminum oxide. In another embodiment, the metal oxide can include titanium or niobium based metal oxide. The metal oxide coating can include titanium oxide (TiO2) or niobium oxide (Nb2O5). In yet another embodiment, the metal oxide coating can include a magnesium based oxide. The magnesium based oxide can be magnesium oxide (MgO).

[0119] In embodiments, metal oxides, such as, for example, α-aluminum oxide and other aluminum species, can be applied to the microsilicon particles either through a precipitation process followed by calcination at higher temperatures >400° C. or through processes such as atomic layer deposition (ALD). The precipitation process route typically involves dissolving the appropriate metal salt in water at the appropriate concentration and under controlled pH, and manipulating the pH so that the metal salt precipitates uniformly on the surface of the microsilicon active material. Typically, this involves raising the pH of the environment. The concentration of the metal salt in the solution determines the thickness of the final coating layer. The excess components and metal salts can be gently washed off, and the microsilicon active material can be transferred to a furnace. The precipitate can be heated under air or inert gas to temperatures up to 1200° C., which converts the metal salt precursor to the corresponding metal oxide.

[0120] Polymer-coated microsilicon active particles can be provided by coating the microsilicon active particles described herein with a polymer. In some embodiments, the polymer is selected from the group consisting of starch, lignin, cellulose, polyacrylamide, polymethacrylamide, polyamic acid, polystyrene-4-sulfonate (PSS), 3,4-ethylenedioxythiophene / polystyrene-4-sulfonate (PEDOT:PSS), polydiallyldimethylammonium chloride PDDA, polydiallyldimethylammonium / polystyrene-4-sulfonate (PDDA:PSS), urea-pyrimidinone (UPy), urea-oligo-amidoamine (UOAA), dopamine methacrylamide, dopamine methacrylate, dopamine acrylate, dopamine, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, polyethylene glycol methyl ether methacrylate and polyethylene glycol methyl ether acrylate, cis-1,4-polyisoprene natural rubber and trans-1,4-Natural polyisoprene including polyisoprene gum, synthetic polyisoprene, polybutadiene, chloroprene rubber, polychloroprene, butyl rubber including halogenated butyl rubber, styrene-butadiene rubber, nitrile rubber, ethylene propylene rubber, ethylene propylene diene rubber, epichlorohydrin rubber, polyacrylic rubber, silicone rubber, fluorosilicone rubber, fluoroelastomers, perfluoroelastomers, polyether block amides, chlorosulfonated polyethylene, ethylene-vinyl acetate, thermoplastic elastomers, protein resilin, protein elastin, ethylene oxide-epichlorohydrin copolymers, The polymer may be selected from the group including polyurethane, urethane-urea copolymer, polyaniline, polypyrrole, polythiophene, polyfuran, bicyclic polymer, poly(ethylene oxide) (PEO), polypropylene oxide (PPO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (PVdF), poly((bis-(methoxyethoxy)ethoxy)phosphazene), polyvinyl chloride, polydimethylsiloxane, poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP), any derivatives thereof (e.g., sulfonated derivatives), phenolic resins, or combinations thereof.

[0121] In some embodiments, the coated micro-silicon active material particles can be provided from precipitation, pyrolization of a precursor formulation coating, or by chemical vapor deposition, physical vapor deposition, atomic layer deposition sputtering, or mechanical deposition.

[0122] In some embodiments or examples, the coating may be in the form of a single layer. In other embodiments, the coating may be in the form of two or more layers, e.g., a plurality of layers. The coating may include about 1 to 5 layers. The coating may include less than 5 layers, 4 layers, 3 layers, or less than 2 layers. The coating may include at least about 1 layer, 2 layers, 3 layers, 4 layers, or at least about 5 layers. The coating may include layers in the range provided by any lower and / or upper limits previously described. It will be understood that each layer may be provided by a different coating. For example, the coated microsilicon active material particles or coated anode composition may include a coating, one coating layer includes a carbon material, another coating layer includes a metal oxide (e.g., aluminum oxide), and another layer includes a polymer coating applied in any order to the microsilicon. Alternatively, the coating may be a carbon material coating and a metal oxide coating applied in any order to the microsilicon. Additionally, the coating may be a carbon material coating and a polymer coating applied in any order to the microsilicon.

[0123] It is believed that the coating on the micro-silicon active material particles described herein can improve cycle stability and reduce electrolyte decomposition due to electrochemical protection of the anode surface.It will be understood that the coating can provide the micro-silicon active particles with a number of properties, including, for example, structural strength, lower surface area, reduced powdering, electronic conductivity, Li-ion conductivity, and / or insulation, ultimately improving silicon anode capacity retention.

[0124] In one embodiment, the microsilicon active material particles or coated microsilicon active material particles may exhibit any morphology, for example, they may take the form of flakes, aggregates, granules, powders, spheres, powdered materials, etc., and combinations thereof. The microsilicon active material particles or coated microsilicon active material particles may have any desired shape, including, but not limited to, cubic, rod-like, plate-like, polyhedral, spherical or hemispherical, quasi-spherical, rounded or semi-rounded, angular, irregular, etc. In one embodiment, the microsilicon active material particles or coated microsilicon active material particles have an aspect ratio (i.e., the ratio of length to width, where length and width are measured perpendicular to each other and length refers to the longest linearly measured dimension) of 1.0 to 10.0, 1.0 to 5.0, or 1.0 to 2.0. In one embodiment, the microsilicon active material particles or coated microsilicon active material particles may have an aspect ratio of about 1.0 to 5.0, or about 1.0 to 4.0, or about 1.0 to about 3.0, or about 1.0 to about 2.0, for example, about 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0.

[0125] In some embodiments, the particle size (in μm) of the microsilicon active material particles or the coated microsilicon active material particles may be at least about 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, or 30. In some embodiments, the particle size (in μm) of the microsilicon active material particles or the coated microsilicon active material particles may be less than about 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, or 0.5. Combinations of any two or more of these upper and / or lower particle sizes are also possible, for example, the particle size (in μm) of the microsilicon active material particles or the coated microsilicon active material particles may be about 1 to about 10, about 2 to about 8, about 3 to about 6, or about 2 to about 5. The particle size is taken to be the longest cross-sectional diameter across the microsilicon active material particles or the coated microsilicon active material particles. For non-spherical micro silicon active material particles or non-spherical coated micro silicon active material particles, the particle size is taken to be the distance corresponding to the longest cross-sectional dimension across the particle.

[0126] The microsilicon active material particles may have a particle size distribution, with 90% (D 90 ) may have a particle size of less than about 50, 45, 40, 35, 34, 32, 30, 28, 24, 20, 18, 16, 14, 12, 10, 8, 6, 5, or 4 μm, or 50% of the microsilicon active material particles (D 50 ) have a particle size (in μm) of less than about 10, 9, 8, 7, 6, 5, 4, 3, 2 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1, or 10% of the microsilicon active material particles (D 10 ) has a particle size of less than about 4, 3, 2, or 1. In some embodiments, the microsilicon active material particles have a particle size of at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 (D 50In some embodiments, the microsilicon active material particles have a particle size (in μm) of less than about 10, 9, 8, 7, 6, 5, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.9 (D 50 ) particle size (in μm). 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1. Combinations of any two or more of these upper and / or lower particle sizes are also possible, for example, the microsilicon active material particles have a (D 50 ) particle size (in μm).

[0127] In some embodiments or examples, the micro silicon active material particles are about 0.1 m 2 / g~about 10m 2 / g, for example, about 0.1m 2 / g ~ approx. 5m 2 The microsilicon active material particles may have a BET surface area in the range of at least about 0.1, 0.2 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 m / g. 2 / g BET surface area (m 2 In other embodiments or examples, the micro silicon active material particles may have a molecular weight of about 10, 9, 8, 7, 6, 5, 4, 3, 21, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 m 2 Surface area (m 2Combinations of these surface area values ​​to form various ranges are also possible, for example, the microsilicon active material particles may have a surface area of ​​about 0.1 to about 10, about 0.1 to about 9, about 0.1 to about 8, about 0.1 to about 7, about 0.1 to about 6, about 0.1 to about 5, about 0.5 to about 10, about 0.5 to about 9, about 0.5 to about 8, about 0.5 to about 7, about 0.5 to about 6, about 0.5 to about 5, about 1 to about 10, about 1 to about 9, about 1 to about 8, about 1 to about 7, about 1 to about 6, or about 1 to about 5.

[0128] In some embodiments or examples, the coated micro silicon active material particles are about 0.1 mm 2 / g~about 90m 2 The coated micro silicon active material particles may have a BET surface area in the range of at least about 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, or 90 m / g. 2 / g BET surface area (m 2 In other embodiments or examples, the coated micro silicon active material particles may have a molecular weight of about 90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5, or 0.1 m 2 Surface area (m 2 / g). Combinations of these surface area values ​​to form various ranges are also possible.

[0129] The inventors have surprisingly found that the D of uncoated micro silicon active material particles 50 Particle size (in μm) and BET surface area (m 2 / g) and the ratio of these parameters to the electrochemical performance of the anode. In some embodiments or examples, the D of the micro silicon active material particles 50 Particle size (in μm) and BET surface area (m 2 / g) may range from about 0.1 to about 10. In some embodiments or examples, the D 50 Particle size (in μm) and BET surface area (m 2 / g) may be at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. In some embodiments or examples, the D of the micro silicon active material particles 50 Particle size (in μm) and BET surface area (m 2 / g) can be less than about 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1. Combinations of these ratios to form various ranges are also possible, for example, the D of uncoated micro silicon active material particles. 50 Particle size (in μm) and BET surface area (m 2 The ratio of the particle diameter to the particle diameter (g) may be in the range of about 0.1 to about 10, about 0.1 to about 9, about 0.1 to about 8, about 0.1 to about 7, about 0.1 to about 6, about 0.1 to about 5, about 0.5 to about 10, about 0.5 to about 9, about 0.5 to about 8, about 0.5 to about 7, about 0.5 to about 6, about 0.5 to about 5, about 1 to about 10, about 1 to about 9, about 1 to about 8, about 1 to about 7, about 1 to about 6, or about 1 to about 5. For example, the ratio of the particle diameter to the particle diameter (g) may be in the range of about 0.1 to about 10, about 0.1 to about 9, about 0.1 to about 8, about 0.1 to about 7, about 0.1 to about 6, or about 1 to about 5. 2 / g ~ approx. 5m 2 / g D 50 and the D of the microsilicon active material particles in the range of about 0.1 to about 6 provided by the BET surface area range. 50 Particle size (in μm) and BET surface area (m 2 / g) improves the initial coulombic efficiency and capacity retention of the anode. 2 / g ~ approx. 3.5m 2 / g D 50 D of the microsilicon active material particles in the range of about 1.0 to about 3.5 provided by the particle size and BET surface area range50 Particle size (in μm) and BET surface area (m 2 / g) advantageously provided the most improved capacity retention in the full cell configuration for the micro-silicon anode design. 50 It will be appreciated that when the particle size / BET surface area ratio is greater than 3.5 and less than 1.0, a gradual decrease in electrochemical performance is found. 50 D with particle size / BET surface area ratio of 0.1 to 2.0 μm 50 Particle size range and >5m 2 A dramatic decrease in ICE and capacity retention is found when the r is 0.01-0.10 due to the BET surface area of ​​1000 μm / g. Without wishing to be bound by theory, this phenomenon is likely due to the low surface reactivity of the microsilicon active material particles with the electrolyte forming a thinner and less resistive SEI layer.

[0130] Surprisingly, when various microsilicon anode grades were cycled in half-cell and full-cell designs, an inverse relationship of cycling stability was found to exist, which correlated with the respective particle size, BET surface area, and d 50 It was governed by the ratio between particle size and BET surface area.

[0131] In a half-cell format, where the micro-silicon anode is tested under fully lithiated conditions, d 50 >2.0μm, BET surface area <5m 2 / g, and d of 0.01 to more than 0.1 50 A rapid capacity fade was evident for samples with particle size:BET surface area ratios. When microsilicon materials were tested in a limited capacity full cell design, the cycling stability observed from the half cell tests was reversed. High d 50 Particle size (preferably 2.0-8.0 μm), low BET surface area (preferably 1.0-5.0 m 2 / g), and high d 50Microsilicon materials with particle size:BET surface area ratio (preferably 0.1-6.0) provide stable cycling performance with higher ICE and capacity retention.

[0132] The expansion and contraction of silicon particles during charge-discharge cycling causes the silicon particles to pulverize, which increases their specific surface area. + With an unlimited supply of ions, the loss of Li from the SEI formation reaction with the newly formed surface can be easily compensated for, and the Si anode can continue to be cycled until the silicon electrode is completely depleted. Thus, a low d 50 , high BET surface area, and d 50 Micro silicon particles with a particle size:BET surface area ratio <0.1 take longer to reach complete depletion of the silicon electrode due to the presence of larger silicon surface area, lower average particle size, and therefore reduced stress on the particles, resulting in relatively stable cycling performance.

[0133] In a full-cell design with a limited Li reservoir, d 50 <2.0μm, BET surface area>5m 2 / g and d 50 The increased reactivity of microsilicon particles with larger surface area, with particle size:BET surface area ratio <0.1, was observed with Li + This leads to accelerated consumption of , resulting in poor capacity retention and cycle life. Low surface reactivity and therefore high d during cycling 50 Particle size (preferably 2.0-8.0 μm), low BET surface area (preferably 1.0-5.0 m 2 / g), and high d 50 Li in microsilicon material with particle size:BET surface area ratio (preferably 0.1-6.0) + The low irreversible consumption of ions extends the capacity retention and cycle life. 50 It has been found that a particular combination of and BET surface area can lead to exceptionally good performance in a full cell.

[0134] In some embodiments or examples, the tap density of the microsilicon active material particles or coated microsilicon active material particles is about 0.5 g / cm 3 ~Approx. 1.5g / cm 3 The tap density of the microsilicon active material particles or coated microsilicon active material particles may be in the range of at least about 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, 1.2, 1.3, or 1.5 g / cm. 3 In other embodiments or examples, the tap density of the microsilicon active material particles or coated microsilicon active material particles may be about 1.5, 1.4, 1.3, 1.2, 1.0, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, or 0.5 g / cm 3 Combinations of these density values ​​to form various ranges are also possible, for example, microsilicon active material particles or coated microsilicon active material particles may be less than about 0.5 g / cm 3 ~Approx. 1.2g / cm 3 The density can be measured by any standard method, for example, according to ASTM D7481-18.

[0135] Advantageously, the microsilicon active material particles of the present disclosure can be provided with high purity. In some embodiments or examples, the purity of the microsilicon active material particles (oxygen free) can be in the range of about 95 to about 99.9 (by weight %). The purity of the microsilicon active material particles (oxygen free) can be at least about 95, 96, 97, 98, 99, 99.5, or 99.9 (by weight %). The purity of the microsilicon active material particles (oxygen free) can be less than about 99.9, 99.5, 99, 98, 97, 96, or 95 (by weight %). The purity of the microsilicon active material particles (oxygen free) can be in the range provided by any lower and / or upper limits as previously described.

[0136] In some embodiments or examples, the purity of the microsilicon active particles (with oxygen) may range from about 79 to about 99.5 (by weight %). The purity of the microsilicon active particles (with oxygen) may be at least about 75, 80, 85, 90, 95, 96, 97, 98, 99, or 99.5 (by weight %). The purity of the microsilicon active particles (with oxygen) may be less than about 99.5, 99, 98, 97, 96, 95, 90, 85, 80, or 75 (by weight %). The purity of the microsilicon active particles (with oxygen) may be in a range provided by any lower and / or upper limits as previously described.

[0137] The combination of the novel and inventive features of the microsilicon active material particles according to the present disclosure, their optional coating, and their use in an optionally coated anode composition for an anode in a lithium-ion battery surprisingly leads to an improvement in the battery cycling behavior. Alternatively, the coated microsilicon active material particles according to the present disclosure and their use in an optionally coated anode composition for an anode in a lithium-ion battery also surprisingly leads to an improvement in the battery cycling behavior. Unexpectedly, it has been shown that the lithium-ion battery described herein has a small irreversible capacity loss in the first charging cycle and a stable electrochemical behavior with minimal fading in subsequent cycles. Thus, by using the microsilicon active material particles or coated microsilicon active material particles described herein, a lower initial capacity loss and also a low continuous capacity loss of the lithium-ion battery can be achieved. Overall, the lithium-ion battery described herein provides very good stability and cycle life. Thus, many cycles can be achieved with minimal fatigue as a result of, for example, mechanical destruction of the anode coating layer, the anode material, or the SEI formation.

[0138] Pre-lithiation The SEI layer is formed during the intercalation of lithium ions and the organic electrolyte is reduced on the surface of the anode when the anode potential is less than about 1 V vs. Li+ / Li. The SEI layer is important to prevent the co-intercalation of electrolyte ions into the bulk electrode material by creating an electrically insulating but ionically conductive film. This prevents excessive ongoing decomposition of the electrolyte. However, during the formation of the SEI layer film on the surface of the anode active material, some lithium ions may be irreversibly trapped in the electrode, which leads to the consumption of lithium ions.

[0139] The initial irreversible lithium loss of the anode can be compensated for by adding lithium to the anode via prelithiation. Prelithiation methods can be broadly grouped into electrochemical prelithiation and chemical prelithiation. Electrochemical prelithiation can be further grouped into half-cell prelithiation or short circuit prelithiation. Chemical prelithiation can be further grouped into chemical synthesis, solution soaking, and mechanical process methods. Additional methods for prelithiation that can be utilized at the anode coating level active material particles are represented by chemical vapor deposition (CVD) type methods and physical vapor deposition (PVD) methods. Preferred methods for prelithiating the anode coating also include methods that preform the SEI layer and can be performed in a roll-to-roll process, which is inherently cost-effective. It will be understood that the preferred prelithiation method for prelithiating the active material particles prior to incorporation into the anode coating may be different from the method used to prelithiate the anode composition. It will be understood that prelithiation at the particle level can be performed prior to applying a coating layer to the particles. It should be noted that the present disclosure is not limited to any particular method of prelithiation, and the most suitable method may be selected to achieve the intended results.

[0140] Prelithiation may be applied to the anode electrode. For example, prelithiation may be applied to compensate for lithium lost in the first cycle, which constitutes one full charge and one full discharge of the electrochemical cell. If the amount of prelithiation is selected such that an SEI layer forms but the lithium is not intercalated or alloyed with the active material prior to assembly into a full cell, it is expected that the first cycle loss of the anode will be minimized and any further loss of lithium will be contributed from other sources, such as the cathode electrode, once incorporated into the full cell. As a result, the electrochemical cell will now cycle at a higher cell capacity since more lithium is available for subsequent cycles to pass back and forth between the anode and cathode during repeated charge and discharge cycles.

[0141] Prelithiation can also provide a lithium reservoir to the anode before assembly into a cell assembly, in addition to compensating for any lithium loss that occurs during the first cycle and more generally the initialization formation cycle. The lithium reservoir can compensate for ongoing lithium loss over multiple cycles, thus reducing capacity fade and extending the useful life of the full cell. In other words, prelithiation can provide one or more advantages to silicon-containing anodes, particularly anodes that contain a high percentage of silicon. Providing a lithium reservoir to the anode using a method of applying an SEI layer to the active material can also maximize the first cycle efficiency of the cell.

[0142] Optionally, the anode composition may provide a prelithiated anode composition. Prelithiation may occur at the anode active material level prior to incorporation of the active material into the anode composition, or prelithiation may occur after the anode composition is prepared. One or more advantages of the present disclosure are provided by prelithiating anode compositions that can provide a lithium reservoir for the anode, thereby allowing ongoing Li ionization during charge / discharge cycling when incorporated into a full cell configuration. +By compensating for losses, its cycle life is extended.

[0143] In some embodiments, the microsilicon active material particles or coated microsilicon active material particles may be prelithiated microsilicon active material particles or coated microsilicon active material particles, where the prelithiation occurs prior to incorporating the active material into the anode composition. It will be appreciated that the microsilicon active material particles may be prelithiated prior to forming the coated microsilicon active material particles. In other embodiments, the microsilicon active material particles or coated microsilicon active material particles may be prelithiated microsilicon active material particles or coated microsilicon active material particles, where the prelithiation occurs after incorporating the active material into the anode composition. The degree of prelithiation can be determined by whether the phase produced is a mixture of Li0Si1 (0% prelithiation) and Li 4.40 LiSi1, Li 1.71 Si2, Li2Si1, Li 3.5 Si1, and Li 3.75 Any phase composition therebetween, including Si1, may be desirable. In some embodiments or examples, the amount of pre-lithiation of the microsilicon active material particles and / or anode composition may be about 1% to about 30%. The amount of pre-lithiation of the microsilicon active material particles or coated microsilicon active material particles and / or anode composition may be less than about 30%, 25%, 20%, 15%, 10%, 5%, or 1%. The amount of pre-lithiation of the microsilicon active material particles or coated microsilicon active material particles and / or anode composition may be at least about 1%, 5%, 10%, 15%, 20%, 25%, or 30%. The amount of pre-lithiation of the microsilicon active material particles or coated microsilicon active material particles and / or anode composition may be in a range provided by any two of these upper and / or lower amounts.

[0144] Pre-lithiation of the micro-silicon active material particles or coated micro-silicon active material particles may be carried out via physical vapor deposition (PVD) or chemical vapor deposition (CVD), or via mechanical alloying or chemical or electrochemical processes. It will be appreciated that a range of suitable methods may be applied to create a silicon-lithium alloy phase prior to incorporating the pre-lithiated micro-silicon active material particles into an anode composition.

[0145] Further active materials The anode compositions described herein may further comprise one or more additional active materials. In some embodiments, the additional active material may be graphite or silicon, such as flake graphite, natural graphite, artificial graphite, silicon oxides with x=0.8-2 (SiOx), silicon carbon composites, silicon alloys, or any combination thereof.

[0146] Binder The anode compositions disclosed herein may further include one or more binders. The binder may be a polymer. In some embodiments, the polymer may be selected from the group consisting of gum arabic, carboxymethylcellulose (CMC) / citric acid, CMC / styrene-butadiene rubber (SBR), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), poly(1-trimethylsilyl-1-propyne) (PTMSP), rubber binders such as gum arabic, xanthan gum, and guar gum, natural cellulosic binders, polysaccharides such as sodium carboxymethylcellulose, lithium carboxymethylcellulose, sodium alginate, polyacrylates, aliphatic polymers such as polyvinyl butyral, aromatic polymers such as styrene-butadiene rubber. For example, the polymer may be selected from the group consisting of polyvinylpyrrolidone, carboxymethylcellulose, polyacrylic acid (PAA), poly(methacrylic acid), maleic anhydride copolymers including poly(ethylene and maleic anhydride) copolymers, polyvinyl alcohol, carboxymethyl chitosan, natural polysaccharides, xanthan gum, alginates, polyimides, and PAA copolymers including one or several of the following polyvinyl alcohol (PVA), polyurethane (PU), polyimide (PI), or polyacrylonitrile (PAN), in one example, the binder is PAA. The binder may be dissolved in H2O or ethanol, or a mixture of H2O and ethanol or N,N' dimethylformamide, or any other solvent suitable for the intended purpose. Some binders may be in the form of a water-based emulsion.

[0147] In some embodiments or examples, the ratio of binder to microsilicon active material particles or coated microsilicon active material particles may be about 1:40, 1:35, 1:32, 1:30, 1:25, 1:23, 1:20, 1:15, 1:10, 1:9, 1:6, or 1:4. The ratio of binder to microsilicon active material particles or coated microsilicon active material particles may range from about 1:4 to about 1:32. The ratio of binder to microsilicon active material particles or coated microsilicon active material particles may range from about 1:8 to about 1:23. The ratio of binder to microsilicon active material particles or coated microsilicon active material particles may range from about 1:9 to about 1:15.

[0148] In some embodiments or examples, the binder (in weight %) may be present in the anode composition in a range of about 2.5 to 15. The binder (in weight %) may be present in the anode composition in an amount of less than about 15, 12, 10, 8, 5, or 2.5. The binder (in weight %) may be present in the anode composition in an amount of at least about 2.5%, 5%, 8%, 10%, 12%, or 15%. The binder (in weight %) may be present in the anode composition in a range provided by any two of these upper and / or lower amounts. For example, the binder (in weight %) may be present in the anode composition in a range of about 3 to about 8, or about 4 to about 8.

[0149] It has been found that the pH of the binder can affect the electrochemical performance of the anode composition. In some embodiments or examples, the pH of the binder can be less than 9, 8, 7, 6, 5, 4, 3, or 2. In some embodiments or examples, the pH of the binder can be at least 2, 3, 4, 5, 6, 7, 8, or 9. The pH of the binder can be in a range provided by any two of these upper and / or lower values. For example, the pH of the binder can be in the range of 4 to 8.

[0150] Conductive Materials The anode compositions described herein may further include one or more conductive materials. In some embodiments or examples, the conductive material may be a carbon-based material. In some embodiments or examples, the carbon-based material may be nano-sized or micro-sized carbon particles or flakes, or a combination thereof. In some embodiments or examples, the carbon-based material may be selected from the group consisting of activated carbon, carbon nanoparticles, graphite, single-walled (SWCNT) or multi-walled (MWCNT) carbon nanotubes, branched carbon nanotubes, carbon nanofibers, graphene, graphene oxide, MXene, nano- or micro-sized hard carbon, nano- or micro-sized porous carbon, and conductive polymers. The carbon-based material may be selected from the group consisting of graphene, graphene oxide, graphite, single-walled (SWCNT) or multi-walled (MWCNT) carbon nanotubes, branched carbon nanotubes, carbon nanofibers, MXene, nano- or micro-sized hard carbon, nano- or micro-sized porous carbon, and conductive polymers.

[0151] In some embodiments or examples, the ratio of conductive material to microsilicon active particles or coated microsilicon active particles may be about 1:50, 1:48, 1:45, 1:40, 1:35, 1:30, 1:25, 1:20, 1:18, 1:15, 1:10, 1:8, 1:6, 1:4, 1:3, 1:2, or 1:1.3. The ratio of conductive material to microsilicon active particles or coated microsilicon active particles may range from about 1:2 to about 1:30. The ratio of conductive material to microsilicon active particles or coated microsilicon active particles may range from about 1:2 to about 1:18. The ratio of conductive material to microsilicon active particles may range from about 1:2 to about 1:15.

[0152] In some embodiments or examples, the conductive material may be present in the anode composition in a range of about 2.5 to 40 weight percent (based on the total weight of the anode composition). The conductive material may be present in the anode composition in an amount of less than about 40 weight percent, 30 weight percent, 20 weight percent, 15 weight percent, 10 weight percent, 7 weight percent, 5 weight percent, or 2.5 weight percent (based on the total weight of the anode composition). The conductive material may be present in the anode composition in an amount of at least about 2.5 weight percent, 5 weight percent, 7 weight percent, 10 weight percent, 15 weight percent, 20 weight percent, 30 weight percent, or 40 weight percent (based on the total weight of the anode composition). The conductive material may be present in the anode composition in an amount provided by any two of these upper and / or lower amounts. For example, the conductive material may be present in the anode composition in an amount of about 7 weight percent to about 25 weight percent.

[0153] Electrochemical Cell The present disclosure is directed to providing an improved anode for an electrochemical cell. In some embodiments or examples, the present disclosure is directed to an anode for an electrochemical cell comprising an anode composition according to at least some embodiments or examples described herein.

[0154] In some embodiments or examples, an electrochemical cell can include a negative electrode, a positive electrode, at least one electrolyte, and a separator, where the anode comprises an anode composition defined herein. For example, an electrochemical cell can include or consist of an anode, a cathode, at least one electrolyte including one or more electrolyte solvents, and a separator, where the anode comprises an anode composition defined herein, and where the lithium uptake capacity of the anode is greater than the lithium release capacity of the cathode.

[0155] One or more advantages of the present disclosure are provided by the arrangement of the anode and cathode in the electrochemical cell, which has been found to be of significant importance for increasing the stability and cycle life of the anode compositions described herein.

[0156] In some embodiments, the capacity limit may be considered in terms of mass loading or areal capacity. Mass loading or areal capacity refers to an electrochemical cell assembly where the capacity of the anode may be significantly over-sized relative to the cathode. The capacity limit may have the effect of limiting the capacity of the over-sized electrode (anode) only by allowing partial lithiation to occur, since the amount of lithium contained in the electrochemical cell is limited by the lithium contained in the cathode at the time of cell assembly. For example, in an electrochemical cell assembly where the anode has an areal capacity of x and the cathode has an areal capacity of y, the resulting estimated percentage capacity limit is calculated by y / x*100. It will be appreciated that this approach to capacity limit may be particularly useful in situations where the anode contains a high percentage of elemental silicon as an active material providing a specific capacity in excess of 3500 mAh / g.

[0157] Specific area capacity (mAh / cm 2 (in mg / cm) is the specific loading weight (in mg / cm) provided by the amount of anode composition applied to the current collector. 2 It will be understood that the specific loading weight (mg / cm 2 The specific areal capacity (in mAh / cm) is based on the total weight of the anode composition including the microsilicon active material particles, one or more optional additional active materials, one or more optional binders, and one or more optional conductive materials. 2 (in) depends on the thickness of the anode composition coating on the current collector, the silicon content in the anode composition, and the availability of silicon.

[0158] In some embodiments, the specific areal capacity (mAh / cm) corresponding to full utilization of the active material contained within the anode composition of the anode. 2 at 2.5mAh / cm 2 ~20mAh / cm 2 It could be.

[0159] In some embodiments, the specific loading weight (mg / cm) of the anode composition 2at 0.95 mg / cm 2 ~7.5mg / cm 2 It could be.

[0160] In some embodiments, the anode and cathode have a capacity of about 0.5 mAh / cm 2 ~about 6mAh / cm 2 and the anode can deliver about 1500 mAh / g, 1200 mAh / g, 1000 mAh / g, 800 mAh / g, 600 mAh / g, 500 mAh / g, or 400 mAh / g. In another embodiment, the anode and cathode are arranged in such a way that the cathode can deliver about 0.5 mAh / cm 2 ~about 6mAh / cm 2 can be delivered and positioned in such a way that the anode can be utilized up to about 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, or 20%.

[0161] In other embodiments, the capacity limit may be considered in terms of the phase composition of the LiSi alloy. 3.75 Si1 or Li 4.4 Si1 corresponds to a maximum accessible capacity of 3590 mAh / g, or the highest theoretical state of lithiation of 4200 mAh / g. It will be appreciated that this may translate to a specific phase composition of the LiSi alloy when the availability of the anode is limited. The specific phase composition may also be translated to a specific capacity (mAh / g). For example, Li 1.71 Si1 can support a specific capacity of up to 1636 mAh / g, while Li 2.33 Si1 can support a specific capacity of up to 2227mAh / g, while Li 3.25 Si1 can support a specific capacity of up to 3101mAh / g, while Li 3.75 Si1 can support a specific capacity of up to 3579 mAh / g, while Li 4.4 Si1 can support a specific capacity of up to 4199 mAh / g.

[0162] In yet another embodiment, the capacity limit may be considered in terms of the voltage of the anode during charging and / or discharging. It will be appreciated that the amount of silicon lithiation after discharge may be accounted for by the discharge voltage of the anode.

[0163] For example, it will be understood that the N / P ratio balance between the anode and the cathode can be from about 1.05 to about 7, and / or the voltage range can be controlled with respect to the level of discharge of the electrochemical cell. In some embodiments or examples, the capacity of the lithium uptake capacity of the anode may not be fully utilized during charging of the lithium ion battery. In some embodiments or examples, the specific areal capacity of the anode may be greater than the specific areal capacity of the cathode. In other words, the anode is only partially lithiated at a fully charged state. Fully charged refers to the state of the electrochemical cell (e.g., Li-ion battery) in which the anode, specifically the microsilicon active material, has its highest degree of lithiation in accordance with the invention described herein. Partial lithiation of the anode means that the maximum lithium uptake capacity of the anode active material in the anode is not fully utilized. In some embodiments, the amount of lithium stored in the cathode (mAh / cm 2 ) is the lithium storage capacity of the anode (mAh / cm 2 ) may be at least 0.05 to 7.0 times smaller than the

[0164] In some embodiments, the Li / Si ratio of an electrochemical cell (e.g., a Li-ion battery) can be set by the anode to cathode ratio (N / P). In some embodiments, the N / P ratio between the anode and cathode can be about 1.05 to about 7, about 2 to about 5, or about 3 to about 4. The N / P ratio can be greater than about 7, 6, 5, 4, 3, 2, or 1.05. The N / P ratio can be at least about 1.05, 2, 3, 4, 5, 6, or 7. The N / P ratio can be in a range provided by any two of these upper and / or lower values. For example, the N / P ratio between the anode and cathode can be about 1.5 to about 4, or about 1.8 to about 3.5.

[0165] In some embodiments, the capacity limit (in %) can be at least about 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 0, 85, 90, 95, or 99. In some embodiments, the capacity limit (in %) can be less than about 99, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, or 20. The capacity limit (in %) can be in a range provided by any two of these upper and / or lower values. For example, the capacity limit (in %) can be from about 25 to about 90, or from about 30 to about 80.

[0166] The present disclosure advantageously provides an electrochemical cell designed such that the lithium uptake capacity of the anode is greater than the lithium release capacity of the cathode. This ensures that the lithium uptake capacity of the anode is not fully utilized, i.e., the silicon active material particles of the anode are only partially lithiated in the fully charged state, advantageously reducing or preventing the high volume change typically found in silicon anodes during lithiation / delithiation cycling, which degrades the structure of the silicon anode and shortens the life of the battery. In other words, a high N / P ratio can limit the degree of lithiation of the microsilicon, since the amount of Li ions is fixed by the cathode during cell assembly. For example, the anode can be significantly oversized relative to the amount of lithium contained in the cell and provided by the cathode. As the degree of lithiation is limited by the oversized anode, so too is the level of expansion of the microsilicon active material particles or coated microsilicon active material particles and their decomposition. In some embodiments or examples, the degree of silicon lithiation can be in the range of about 20% to about 80%. Unexpectedly, the degree of silicon lithium in this range can have a stabilizing effect on electrochemical cell performance.

[0167] In another embodiment, the capacity of the electrochemical cell can be limited by limiting the lower cutoff voltage. In some embodiments or examples, the lower cutoff voltage can be about 2.5V to about 3.0V. For example, the lower cutoff voltage can be 2.8V to about 3.0V. It will be understood that the voltage limit can be applied by limiting the lower cutoff voltage. This can prevent complete delithiation of the microsilicon active material particles or coated microsilicon active material particles at each cycle and reduce their expansion, which reduces decomposition and therefore leads to an extended cycle life.

[0168] In another embodiment, the capacity of the electrochemical cell can be limited by limiting the upper cutoff voltage. In some embodiments or examples, the upper cutoff voltage can be between about 3.6V and about 4.25V.

[0169] It will be appreciated that both capacitive and voltage limiting may be used simultaneously.

[0170] It will be understood that the anode composition may be pre-lithiated as described in any one of more of the embodiments or examples described herein. In some embodiments, the pre-lithiation may occur prior to incorporating the active material into the anode composition. In other embodiments, the pre-lithiation may occur after incorporating the active material into the anode composition. In some embodiments or examples, the amount of pre-lithiation of the anode composition may be from about 1% to about 30%. The amount of pre-lithiation of the anode composition may be less than about 30%, 25%, 20%, 15%, 10%, 5%, or 1%. The amount of pre-lithiation of the anode composition may be at least about 1%, 5%, 10%, 15%, 20%, 25%, or 30%. The amount of pre-lithiation of the anode composition may be in a range provided by any two of these upper and / or lower amounts.

[0171] In some embodiments, the amount of lithium contained in the anode may be about 30% of its maximum storage capacity, while the cathode may contain 100% of its maximum storage capacity. In some embodiments, the amount of lithium contained in the anode may be about 20% of its maximum storage capacity, while the cathode may contain 100% of its maximum storage capacity. In some embodiments, the amount of lithium contained in the anode may be about 10% of its maximum storage capacity, while the cathode may contain 100% of its maximum storage capacity.

[0172] In one embodiment, a half-cell method can be used to perform electrochemical prelithiation. A silicon-containing electrode is assembled in a half-cell setup using a lithium foil reference electrode, and the degree of prelithiation is controlled by setting appropriate parameters in a galvanostatic charge / discharge cycle program. The half-cell goes through a first cycle by partially or fully lithiating the silicon-containing electrode, followed by full delithiation, to create a lithium reservoir of up to 0% lithium in the SEI layer and anode.

[0173] On the other hand, creating a lithium reservoir in the anode requires partial lithiation to the desired degree of lithium reservoir. According to the composition of the silicon-containing anode and the associated material properties, the first cycle loss can be estimated by testing the corresponding composition in a half cell against a lithium metal foil reference electrode and determining the first cycle loss of the anode composition as such. If the first cycle loss is estimated to be x%, then the initial lithiation step during the prelithiation process required to achieve a lithiation level of the silicon anode composition of z% to create a lithium reservoir of y% should account for x%+y%. In one particular embodiment, if the anode composition exhibits a first cycle loss of 10%, this loss should be taken into account when calculating the desired degree of prelithiation to obtain the resulting lithium reservoir. For example, to achieve a 10% lithium reservoir, the anode may be lithiated to 20% of its expected design capacity (mAh / g), where the initial approximately 10% is intended to compensate for irreversible lithium loss during the first cycle, and additional lithium is stored in the anode or silicon material, thus forming the desired lithium reservoir. It will be understood that higher levels of pre-lithiation may be applied to achieve other desired levels of lithium reservoir. The maximum desired level of lithium reservoir may be 30%.

[0174] It is believed that the pairing of prelithiation and capacity limiting may provide one or more additional advantages to the electrochemical cells of the present disclosure. For example, the capacity of the anode occupied by lithium supplied by the cathode and stored in the anode in the first lithiation is the same with or without prelithiation, notwithstanding any loss of lithium in the first cycle, but the lithium reservoir in the anode can compensate for the gradual loss of lithium during repeated charge and discharge cycles over multiple cycles.

[0175] In some embodiments, the anode composition may be applied to a current collector material as a coating or film. The current collector material for the anode may be selected from the group including copper, aluminum, stainless steel, titanium, carbon, perforated metal foils, metal foams, and metal-coated polymeric porous and non-porous films. For example, the anode composition may be applied to a copper current collector material (e.g., copper foil).

[0176] In some embodiments, the current collector material for the anode can have a thickness of about 4 μm to about 25 μm. The thickness (in μm) of the current collector can be less than about 25, 20, 15, 10, 8, 6, or 4. The thickness (in μm) of the current collector can be at least about 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, or 25. The thickness (in μm) of the current collector can be in a range provided by any two of these upper and / or lower amounts. In one example, the current collector material for the anode can be a copper foil having a thickness of about 6 μm to about 12 μm.

[0177] In some embodiments or examples, the thickness of the anode composition is substantially uniform and may be in the range of about 5 μm to about 70 μm. The thickness (μm) of the anode composition may be less than about 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, or 5. The thickness (μm) of the anode composition may be at least about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, or 65. The thickness of the anode composition may be in a range provided by any two of these upper and / or lower amounts.

[0178] It will be understood that the cathode active material is also applied to the current collector material. The current collector material for the anode can be selected from the group including copper, aluminum, stainless steel, titanium, carbon, perforated metal foils, metal foams, and metal-coated polymer-based porous and non-porous membranes. For example, the cathode composition can be applied to an aluminum current collector material (e.g., aluminum foil).

[0179] In some embodiments, the current collector material for the cathode can have a thickness of about 10 μm to about 30 μm. The thickness (in μm) of the current collector can be less than about 30, 25, 20, 15, or 10. The thickness (in μm) of the current collector can be at least about 10, 12, 14, 16, 18, 20, 25, or 30. The thickness (in μm) of the current collector can be in a range provided by any two of these upper and / or lower amounts. In one example, the current collector material for the cathode can be an aluminum foil having a thickness of about 10 μm to about 30 μm.

[0180] In some embodiments, the cathode may be selected from the group consisting of lithium nickel cobalt manganese oxide (NCM), lithium iron phosphate (LFP), lithium nickel manganese spinel (LNMO), lithium nickel cobalt aluminum oxide (NCA), lithium manganese oxide (LMO), lithium cobalt oxide (LCO), and sulfur or a sulfur composite comprising a sulfur and carbon mixture.

[0181] In some embodiments or examples, the electrolyte may be selected from a non-aqueous solution of one or more lithium salts (eg, in a Li-ion cell). The one or more lithium salts may be selected from the group including lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium bis(trifluorosulfonylimide), lithium trifluoromethanesulfonate, lithium fluoroalkylsulfonimide, lithium fluoroarylsulfonimide, lithium bis(oxalatoborate), lithium tris(trifluoromethylsulfonylimide)methide, lithium difluoromethanesulfonate, lithium trifluoromethanesulfonate salt (lithium triflate), lithium bis(oxalato)borate, lithium tetrafluoroborate, lithium perchlorate, lithium tetrachloroaluminate, lithium hexafluoroarsenate, lithium hexafluoroantimonate, 4,5-dyano-2-(trifluoromethyl)imidazolide (LiTDI), LiPF3(CF5)3 (LiFAP), LiBF3(CF5), lithium chloride, and combinations thereof. For example, the electrolyte can include lithium hexafluorophosphate.

[0182] In some embodiments or examples, the lithium salt can be dissolved in an organic solvent. The lithium salt can be dissolved in an organic solvent selected from ethers, esters, carbonates, and acetals. In one example, the solvent can be selected from dimethoxyethane, diglyme, triglyme, tetraglyme, ethylene carbonate, propylene carbonate, dimethyl carbonate, tetrahydrofuran, and dioxolane. In some embodiments or examples, the lithium salt may be dissolved in an organic solvent selected from the group including ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, butyl methyl carbonate, ethyl propyl carbonate, dipropyl carbonate, cyclopentanone, sulfolane, dimethyl sulfoxide, 3-methyl-1,3-oxazolidin-2-one, γ-butyrolactone, 1,2-diethoxymethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 1,2-dimethoxyethane, methyl acetate, ethyl acetate, nitromethane, 1,3-propane sultone, γ-valerolactone, methyl isobutyryl acetate, 2-methoxyethyl acetate, 2-ethoxyethyl acetate, diethyl oxalate, ionic liquids, and any combination thereof. In some embodiments or examples, the lithium salt may be dissolved in an organic solvent selected from the group including ethylene carbonate, dimethyl carbonate, diethyl carbonate, and any combination thereof.

[0183] The electrolyte may include an additive selected from one or more alkali metal salts of LiPF6LiBF4, LiAsF6, LiSbF6, LiClO4, LiAlCl4, LiGaCl4, LiC(SO2CF3)3, LiN(SO2CF3)2, LiSCN, LiSO2CF2CF3, LiC6F5SO3, LiO2CCF3, LiSO3F, LiB(CH5)4, LiCF3SO3, LiNO3, and mixtures thereof. In other embodiments, the additive may be selected from one or more of fluoroethylene carbonate (FEC), vinyl ethylene carbonate (VEC), vinyl carbonate (VC), propylene carbonate (PC), ethyl methyl carbonate (EMC), propane sultone (PS), and mixtures thereof. The electrolyte additive may further improve certain characteristics of the cell. For example, an electrolyte (eg, lithium hexafluorophosphate) can include an additive (eg, fluoroethylene carbonate) dissolved in an organic solvent (eg, diethyl carbonate).

[0184] In some embodiments or examples, the lithium salt may be dissolved in one or more organic solvents described above, where the one or more organic solvents are present in a volume to volume ratio ranging from 10 to 1 to 1 to 10. For example, the lithium salt (e.g., 1M LiPF6) may be dissolved in FEC / DEC (2:8) vol%, FEC:EMC (3:7) w / w + 2 wt% VC, EC / EMC / DEC (3 / 5 / 2 vol%) + 1 wt% VC + 10 wt% FEC, or EC / EMC (3:7) wt% + 1 wt% VC.

[0185] In some embodiments or examples, the separator is used to electrically separate the anode from the cathode and allow free passage of lithium ions in the electrolyte. The separator may be selected from a variety of different porous polymer films. It will be understood that any porous polymer film may be selected for use as a separator having suitable porosity, tortuosity, and thickness. For example, a polymer film-based separator material may be selected. In some embodiments or examples, the separator may be selected from polyethylene (PE), polypropylene (PP), or polyethylene terephthalate (PET). In another embodiment, a nonwoven fibrous material is selected as the separator, comprising fibers selected from nylon, polyethylene terephthalate (PET), cellulose, aramid, or polyacrylonitrile.

[0186] In some embodiments or examples, the electrochemical cell can be an energy storage device. The energy storage device can be a battery. For example, the battery can be a secondary battery. In one particular example, the battery can be a lithium ion battery (Li-ion battery).

[0187] Anode Compositions for Lithium-Ion Batteries In some embodiments or examples, the present disclosure also provides a method for improving the cycling stability of a battery having an anode and a cathode, at least one electrolyte, and optionally a separator, the anode comprising the anode composition described herein. It has been found that the anode comprising the anode composition provides a particularly effective anode for use in a battery (e.g., a Li-ion battery) that can maintain long-term capacity retention. In some embodiments or examples, the anode within the battery can have a discharge capacity of at least about 800 mAh / g for at least 100 cycles of the battery. In some embodiments or examples, the specific capacity (mAh / g) can be at least about 500, 600, 800, 1000, 1200, 1400, 1600, 1800, 2000, 2200, 2400, 2600, 2800, 3000, or 3500. In some embodiments or examples, the specific capacity (mAh / g) may be less than about 3500, 3400, 3200, 3000, 2800, 2600, 2400, 2200, 2000, 1800, 1600, 1400, 1200, 1000, 800, 600, or 500. The specific capacity (mAh / g) may be in a range provided by any two of these upper and / or lower values. In some embodiments or examples, the number of cycles may be at least 80, 100, 120, 140, 160, 180, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380, 400, 420, 440, 460, 480, 500, 1000, or 1500.

[0188] The long-term cycling performance of electrochemical cells (e.g., Li-ion batteries) including the anode compositions can be tested for high silicon content anodes (i.e., about 70% silicon content) with various capacity limits. The initial discharge capacity of an anode including the anode compositions according to at least some embodiments or examples described herein can be at least about 600, 800, 1100, 1200, 1300, 1400, 1500, or 1600 (in mAh / g). According to at least some embodiments or examples, 80% of the discharge capacity can be retained after 100, 200, 300, 400, 500, 800, 1000, or 1500 cycles.

[0189] It will be appreciated that galvanostatic charge-discharge cycling experiments can typically be used to evaluate the performance metrics of a battery: capacity, rate capability, coulombic efficiency, and capacity retention upon cycling.

[0190] In some embodiments or examples, the present disclosure is also directed to the use of an anode comprising the anode composition described herein in an electrochemical cell. For example, the electrochemical cell can be an energy storage device such as a battery, preferably a secondary battery. More specifically, the battery can be a lithium ion battery.

[0191] In some embodiments or examples, the present disclosure is also directed to an anode comprising the anode composition, which can be a battery anode. More particularly, a lithium ion battery anode.

[0192] It has been found that the optionally coated anode composition, which may comprise or consist of the optionally coated microsilicon active material particles, optionally one or more binders, optionally one or more conductive materials, and optionally one or more additives, significantly reduces the effects exhibited by SEI formation and silicon expansion and decomposition, thus providing improved performance of Li-ion batteries. The anode composition provides high first cycle efficiency and provides the additional advantage of providing controlled silicon utilization, thereby improving the high current response and performance of the battery. For example, an electrochemical cell (e.g., Li-ion battery) comprising the anode composition described herein allows for partial silicon utilization / lithiation, and the specific capacity of the anode is reduced and controlled by the amount of lithium the cathode can supply, providing an improved average coulombic efficiency (CE) of at least about 75, 80, 85, 90, 95, 98%, 99%, 99.5%, 99.8%, 99.9% or more, or less than 100%, over at least 200 cycles. In another example, the use of the anode composition as an anode provides improved performance of a Li-ion battery that exhibits cycling stability after at least 200 cycles at C / 2.

[0193] Moreover, it has been surprisingly found that when the N / P ratio for an anode containing a majority of microsilicon (e.g., >70%) is operated to a value greater than 3 (e.g., 3.3), it is possible to provide stable cycling of the anode, achieving more than 200 cycles with greater than 80% capacity retention. In other words, Li +The high N / P ratio limits the degree of lithiation of the microsilicon since the amount of N is fixed by the cathode during cell assembly. This leads to a degree of silicon lithiation of about 20% to about 80%, instead of 80% to 90% as found in conventional cell assemblies where the anode contains mostly graphite, which has a stabilizing effect on cell performance. It will be appreciated that the anode is significantly oversized relative to the amount of lithium contained in the cell and provided by the cathode. Advantageously, since the degree of lithiation is limited by the oversized anode, so too is the level of expansion of the silicon and its decomposition.

[0194] Preparation process In some embodiments or examples, the present disclosure is directed to a process for preparing an anode for an electrochemical cell. The process includes at least one of incorporating coated microsilicon active material particles into the anode or coating the anode itself either during or after its formation. The process may be for preparing an anode according to any embodiment or example described herein. It will be understood that the anode prepared by the process may include an anode composition including microsilicon active material particles or coated microsilicon active material particles. It will be understood that the anode prepared by the process may include or consist of an anode composition including microsilicon active material particles, optionally one or more additional active materials, optionally one or more binders, optionally one or more conductive materials, optionally one or more additives, and optionally a solvent. It will also be understood that the anode prepared by the process may comprise or consist of an anode composition comprising the coated microsilicon active material particles, optionally one or more additional active materials, optionally one or more binders, optionally one or more conductive materials, optionally one or more additives, and optionally a solvent. The microsilicon active material particles, the coated microsilicon active material particles, the one or more additional active materials, the one or more optional binders, the one or more optional conductive materials, the one or more optional additives, and the one or more optional solvents may be selected from any one or more of the embodiments or examples described herein.

[0195] In some embodiments or examples, (i) a plurality of micro silicon active material particles is provided, the micro silicon active material particles being less than or equal to: (i) about 0.1 m 2 / g~about 10m 2 / g, (ii) a measured BET surface area of ​​about 0.1 μm to about 10 μm 50 and (iii) a D of about 0.1 to about 10. 50In one embodiment, a process is provided for preparing coated micro silicon active material particles comprising (i) providing a coating having one or more of a ratio of a surface area of ​​the coating to a surface of the micro silicon active material particles; and (ii) applying a coating onto the surface of the micro silicon active material particles.

[0196] In some embodiments or examples, the method includes providing a plurality of micro silicon active material particles, the micro silicon active material particles being (i) about 0.1 m 2 / g~about 10m 2 / g, and (ii) a D of about 0.1 μm to about 10 μm. 50 particle size, or (iii) D of about 0.1 to about 10 50 In one embodiment, a process for preparing coated micro silicon active material particles is provided, the process comprising: (i) providing a coating having a ratio of 0.1 to 0.25 μm of surface area to 0. ...

[0197] In some embodiments or examples, there is provided a process for preparing an anode for an electrochemical cell comprising: (i) preparing an anode slurry comprising microsilicon active material particles or coated microsilicon active material particles, optionally one or more further active materials, optionally one or more binders, optionally one or more conductive materials, optionally one or more additives, and a solvent system; (ii) casting a layer of the anode slurry onto a current collector material to provide an anode composition layer on the current collector material; and (iii) optionally coating the anode composition, wherein the microsilicon active material particles are: (a) about 0.1 m 2 / g~about 10m 2 / g, (b) the measured BET surface area from about 0.1 μm to about 10 μm 50 particle size, and (c) D of about 0.1 to about 10 50 :BET surface area ratio.

[0198] In some embodiments or examples, there is provided a process for preparing an anode for an electrochemical cell comprising: (i) preparing an anode slurry comprising microsilicon active material particles or coated microsilicon active material particles, optionally one or more further active materials, optionally one or more binders, optionally one or more conductive materials, optionally one or more additives, and a solvent system; (ii) casting a layer of the anode slurry onto a current collector material to provide an anode composition layer on the current collector material; and (iii) optionally coating the anode composition, wherein the microsilicon active material particles are (a) about 0.1 m 2 / g~about 10m 2 / g, and (b) a measured BET surface area of ​​about 0.1 μm to about 10 μm. 50 particle size, or (c) D of about 0.1 to about 10 50 :BET surface area ratio.

[0199] In some embodiments or examples, the process may further include step (iii) solidifying the wet anode layer by solvent evaporation to provide a dry anode composition layer on the current collector material.

[0200] In some embodiments or examples, the coating may be selected from the group including carbon, graphene, graphite, metal oxides, polymers, and combinations thereof to form coated micro-silicon active material particles or coated anode compositions.

[0201] In some embodiments or examples, the coating may be a coating of the microsilicon active material particles. In other embodiments or examples, the coating may be a coating of the anode composition. In other words, the coating may be present on at least a portion of a surface of the anode composition.

[0202] In some embodiments, the coating may be selected from the group including carbon, graphene, graphite, metal oxides, polymers, and combinations thereof to form coated micro-silicon active material particles or coated anode compositions.

[0203] The coating may be from the materials and made by the approaches as described in any of the preceding embodiments relating to the coatings of the present disclosure and / or the silicon particles of the present disclosure to which the coatings have been so applied.

[0204] In some embodiments or examples, the solvent may be an organic solvent selected from aromatics, halogenated aromatics, halogenated aliphatic hydrocarbons, aliphatic hydrocarbons, glycols, ethers, glycol ethers, esters, alcohols, ketones, or combinations thereof. In some embodiments or examples, the solvent may be present in an amount of about 40% to 90% by weight, about 40% to 70% by weight, or about 40% to 60% by weight (by weight % of the total anode composition). The solvent may be a low boiling organic solvent, or a mixture of one or more of such solvents. In some embodiments or examples, the solvent may be selected from the group including water, methanol, ethanol, n-propanol, isopropanol, tetrahydrofuran, methylene chloride, chloroform, diethyl ether, room temperature ionic liquids, ethylene glycol, glycerol, formamide, N-methylformamide, dimethylformamide, N-methylsydnone, aqueous solutions thereof, and any mixtures thereof. For example, the solvent may be water, ethanol, N,N' dimethylformamide, or a combination thereof.

[0205] In some embodiments or examples, the ratio of binder to microsilicon active material particles may be about 1:40, 1:35, 1:32, 1:30, 1:25, 1:23, 1:20, 1:15, 1:10, 1:9, 1:6, or 1:4. The ratio of binder to microsilicon active material particles or coated microsilicon active material particles may range from about 1:4 to about 1:32. The ratio of binder to microsilicon active material particles or coated microsilicon active material particles may range from about 1:8 to about 1:23. The ratio of binder to microsilicon active material particles or coated microsilicon active material particles may range from about 1:9 to about 1:15.

[0206] In some embodiments or examples, the binder (in weight %) may be present in the anode composition in a range of about 2.5 to 15. The binder (in weight %) may be present in the anode composition in an amount of less than about 15, 12, 10, 8, 5, or 2.5. The binder (in weight %) may be present in the anode composition in an amount of at least about 2.5%, 5%, 8%, 10%, 12%, or 15%. The binder (in weight %) may be present in the anode composition in a range provided by any two of these upper and / or lower amounts. For example, the binder (in weight %) may be present in the anode composition in a range of about 3 to about 8, or about 4 to about 8.

[0207] In some embodiments or examples, the viscosity of the anode slurry may be in the range of about 10 mPas to 100,000 mPas. The viscosity (mPas) may be less than about 100,000, 90,000, 80,000, 70,000, 60,000, 50,000, 40,000, 30,000, 20,000, 10,000, 8000, 6000, 4000, 2000, 1000, 800, 600, 400, 200, 100, 50, or 10 at a given shear rate. The viscosity may be at least about 10, 20, 40, 60, 80, 100, 300, 500, 700, 900, 1000, 3000, 5000, 7000, 9000, 10,000, 20,000, 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, 90,000, or 100,000 at a given shear rate. The viscosity (mPas) of the anode slurry may be in a range provided by any two of these upper and / or lower amounts. For example, the viscosity (mPas) of the anode slurry may be in a range of about 2500 mPas to about 8000 mPas at a given shear rate. All viscosity values ​​listed herein may be at a given shear rate. In embodiments, the shear rate may be that used in any art accepted standard testing approach.

[0208] In some embodiments or examples, the thickness of the dry anode composition is substantially uniform and may be in the range of about 5 μm to about 70 μm. The thickness (μm) of the dry anode composition may be less than about 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, or 5. The thickness (μm) of the dry anode composition may be at least about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, or 65. The thickness of the dry anode composition may be in a range provided by any two of these upper and / or lower amounts.

[0209] In some embodiments or examples, the wet anode composition layer may be maintained at a temperature of about 40° C. to about 60° C. for about 30 seconds to about 5 minutes in step (iii)(a). The wet anode composition may be maintained at a temperature (° C.) less than about 60, 55, 50, 45, or 40. The wet anode composition may be maintained at a temperature (° C.) of at least about 40, 45, 50, 55, or 60. The wet anode composition may be maintained at a temperature (° C.) in the range provided by any two of these upper and / or lower amounts. The wet anode composition may be maintained at a temperature described herein for less than about 24 hours, 12 hours, 8 hours, 4 hours, 2 hours, 1 hour, 30 minutes, 5 minutes, 4 minutes, 3 minutes, 2 minutes, 1 minute, or 30 seconds. The wet anode composition can be maintained at a temperature described herein for at least about 30 seconds, 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 30 minutes, 1 hour, 2 hours, 4 hours, 10 hours, 12 hours, or 24 hours. The wet anode composition can be maintained at a temperature described herein for a time range provided by any two of these upper and / or lower amounts.

[0210] In some embodiments or examples, the wet anode composition may be maintained in step (iii)(b) at a temperature of about 90° C. to about 180° C. for about 30 seconds to about 5 minutes. The wet anode composition may be maintained at a temperature (° C.) of less than about 180, 170, 160, 150, 140, 130, 120, 115, 110, 105, 100, 95, or 90. The wet anode composition may be maintained at a temperature (° C.) of at least about 90, 95, 100, 105, 110, 115, 120, 130, 140, 150, 160, or 170. The wet anode composition may be maintained at a temperature (° C.) in the range provided by any two of these upper and / or lower amounts. The wet anode composition may be maintained at a temperature described herein for less than about 24 hours, 12 hours, 8 hours, 4 hours, 2 hours, 1 hour, 30 minutes, 5 minutes, 4 minutes, 3 minutes, 2 minutes, 1 minute, or 30 seconds. The wet anode composition may be maintained at a temperature described herein for at least about 30 seconds, 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 30 minutes, 1 hour, 2 hours, 4 hours, 10 hours, 12 hours, or 24 hours. The wet anode composition may be maintained at a temperature described herein for a time range provided by any two of these upper and / or lower amounts.

[0211] In some embodiments or examples, the anode slurry may be homogenized to provide further advantages / improvements.

[0212] In some embodiments or examples, the present disclosure is directed to a process for assembling an electrochemical cell, which may include preparing an anode as defined by at least one of the processes described herein, where the anode may include an anode composition comprising microsilicon active material particles, and assembling the anode into an electrochemical cell. In some other embodiments or examples, the present disclosure is directed to a process for assembling an electrochemical cell, which may include preparing an anode as defined by at least one of the processes described herein, where the anode may include or consist of an anode composition comprising microsilicon active material particles or coated microsilicon active material particles, optionally one or more additional active materials, optionally one or more binders, and optionally one or more conductive materials, at least one of the processes described herein, where the anode may include or consist of an anode composition comprising microsilicon active material particles or coated microsilicon active material particles, optionally one or more additional active materials, optionally one or more binders, and optionally one or more conductive materials, at least one of the processes described herein, and assembling the anode into an electrochemical cell.

[0213] Upon formation of the anode slurry, some or all of the solvent may be removed (e.g., by natural evaporation, forced evaporation, or under vacuum) to produce a solid or viscous anode slurry. The anode slurry may be formed or shaped into any desired shape, such as an anode.

[0214] In some embodiments or examples, the anode slurry may also be deposited onto a current collector material as defined herein to produce an anode. It will be understood that the anode is a combination of the current collector material and the anode composition, also referred to as the anode composition applied to the current collector material. The current collector material may be selected from any of the current collector materials mentioned herein.

[0215] During preparation of the anode, the anode composition may be applied to only a portion of the surface of the current collector material. In some embodiments or examples, the portion (%) may be less than about 100, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, or 5. In some embodiments or examples, the anode composition may be applied by casting onto the current collector material (e.g., roll-to-roll processing).

[0216] The coatings can be prepared by dissolving or dispersing the coating in a suitable solvent and then mixing them, optionally together with one or more agents, or by dissolving the coating in a suitable solvent under suitable processing conditions.

[0217] The coating may be applied in different physical forms such as a solution, dispersion, suspension, mixture, aerosol, emulsion, paste, or combinations thereof.

[0218] In one example, a process for preparing a coated anode includes: a. applying a coating as described herein to an anode composition; b. optionally, applying one or more post-coating layers to the coating present on the anode composition.

[0219] In some embodiments, the coated anode composition can be provided from pyrolization of the coating or by chemical vapor deposition, physical vapor deposition, sputtering, or mechanical deposition.

[0220] In some embodiments or examples, the coating may be in the form of a single layer. In other embodiments, the coating may be in the form of two or more layers, e.g., a plurality of layers. The coating may include about 1 to 5 layers. The coating may include less than 5 layers, 4 layers, 3 layers, or less than 2 layers. The coating may include at least about 1 layer, 2 layers, 3 layers, 4 layers, or at least about 5 layers. The coating may include layers in the range provided by any lower and / or upper limits previously described. It will be understood that each layer may be provided by a different coating. For example, the coated microsilicon active material particles or coated anode composition may include a coating, one coating layer includes a carbon material, another coating layer includes a metal oxide (e.g., aluminum oxide), and another layer includes a polymer coating applied in any order to the microsilicon. Alternatively, the coating may be a carbon material coating and a metal oxide coating applied in any order to the microsilicon. Additionally, the coating may be a carbon material coating and a polymer coating applied in any order to the microsilicon.

[0221] In some embodiments or examples, the coating thickness can be from about 0.1 nm to about 200 nm, or from about 0.2 nm to about 150 nm, or from about 0.3 nm to about 100 nm, or from about 0.3 nm to about 75 nm, or from about 0.3 nm to about 50 nm, or from about 0.3 nm to about 25 nm, or from about 0.3 nm to about 20 nm, or from about 0.3 nm to about 10 nm. The coating thickness (in nm) can be less than about 200, 175, 150, 125, 100, 90, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, 8, 6, 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1. The coating thickness (in nm) can be at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80. The coating thickness (in nm) can be in a range provided by any two of these upper and / or lower amounts.

[0222] In some embodiments, the ratio of coating thickness to uncoated silicon particle diameter (t / d as X:1) can be from about 0.0001:1 to about 0.2:1, or from about 0.0001:1 to about 0.15:1, or from about 0.0001:1 to about 0.12:1, or from about 0.0001:1 to about 0.1:1, or from about 0.0001:1 to about 0.09:1, or from about 0.0001:1 to about 0.085:1. Viewed another way, in some embodiments, the ratio of silicon particle diameter to coating thickness (d / t as 1:X) can be from about 1:100,000 to about 1:5, or from about 1:100,000 to about 1:8, or from about 1:100,000 to about 1:10, or from about 1:100,000 to about 1:12.

[0223] It is believed that the coating on the microsilicon active particles or anode composition described herein can improve cycle stability and reduce electrolyte decomposition due to electrochemical protection of the anode surface.It will be understood that the coating can provide a number of properties to the microsilicon active particles or anode composition, including, for example, structural strength, lower surface area, reduced powdering, electronic conductivity, Li-ion conductivity, passivation, and / or insulation, ultimately improving silicon anode capacity retention.

[0224] It will be understood by those skilled in the art that numerous variations and / or modifications may be made to the above-described embodiments without departing from the broad general scope of the present disclosure, and the present embodiments are therefore considered in all respects to be illustrative and not restrictive. EXAMPLES

[0225] The present invention is further described by the following examples. It should be understood that the following descriptions are only for the purpose of describing specific embodiments, and are not intended to be limiting with respect to the above descriptions.

[0226] Example 1: General procedure for preparing the anode To prepare the anode slurry, the binder solution and conductive material are combined using a planetary centrifugal mixer. The mixture is then incorporated at 2000 rpm for 2 minutes, mixed manually with a spatula, and then mixed for an additional 2 minutes. Microsilicon active material particles and the required amount of additional water are added and the mixing step is repeated. Activated graphite is added and the mixing step is repeated. Unless otherwise stated, a predetermined amount of the anode slurry is transferred to a Dispermat compatible container and mixed for 5 minutes at 6000 rpm using an overhead mixer (e.g., VMA-Getzmann Dispermat).

[0227] For full cell assembly, the slurry was cast on copper foil and dried at 60 °C before being cut for coin cell assembly. The electrodes (coated anode and commercial NCM523 cathode) were further dried at 110 °C for 12 h under vacuum. 150 μL of 1 M LiPF6 in FEC / DEC (2:8) vol% was used as electrolyte and Whatman glass fiber was used as separator for coin cell (CR20232 type) assembly. For charge / discharge cycle test, the coin cell was activated at 0.05 C for one cycle and then cycled at 0.5 C for long-term stability test. The C rate was based on the mass of active materials (Si particles, graphite) in the electrode. The voltage range for charge / discharge cycle test was 4.2-2.5 V during formation and 4.2-3 V during cycling. Charge / discharge test was performed on a Neware multichannel battery tester controlled by a computer. Four replicate cells were fabricated and tested for each condition. [Table 1]

[0228] It should be noted that the current densities used in the cycling tests were based on the electrode capacity achieved at the final delithiation step of the formation program. [Table 2]

[0229] It will be understood that the thickness of the coating applied to the microsilicon particles can be estimated if the surface area of ​​the particles before coating, the weight that the coating contributes to the microsilicon particle powder, and the density of each coating material are known. The following general formula is used to estimate the coating thickness of the coating applied to the microsilicon particles disclosed in any of the examples below, and is used in all discussions of coating thickness within this disclosure, where the true density of the coating material is used as an approximation for the resulting coating density.

[0230] Calculated coating thickness on a microsilicon particle = (weight added to the microsilicon particle by the coating material / true density of the coating material) / surface of the uncoated microsilicon particle.

[0231] It will be appreciated that the actual coating thickness on the microsilicon particles may be slightly higher or lower depending on the properties and actual density of the coating, which varies depending on the coating material and application method.

[0232] Example 2: Al2O3 coated microsilicon D for uncoated and Al2O3-coated microsilicon 50 The particle sizes and BET surface area values ​​are as follows: [Table 3]

[0233] Example 2(a) Electrode Composition Anode compositions were prepared containing uncoated microsilicon or Al2O3 coated microsilicon. The specific electrodes and slurry compositions used for all experiments are shown in Table 4 below. [Table 4]

[0234] Slurries were prepared using the compositions in Table 4. The procedure described in Example 1 was used for the preparation process.

[0235] Example 2(b) Slurry Preparation Slurries were prepared using the compositions in Table 4. The procedure described in Example 1 was used for the preparation process.

[0236] Example 2(c) Electrochemical Test Program The full cell was assembled using the procedure described in Example 1. See Tables 1 and 2 for the cycle program. Example 2(d) Cyclic Study - Summary of Key Findings [Table 5]

[0237] Coatings of Al2O3 with different ratios showed equal increase in ICE (0.8%) and equal starting capacity when compared to uncoated (Table 5). At cycle 90, there was no clear difference in capacity retention (about 96%) between 0.2 wt% Al2O3 coated samples and 0.3 wt% Al2O3 coated samples (Fig. 1b), with only 1% difference in capacity retention when compared to uncoated. Meanwhile, higher amounts of Al2O3 (0.6 wt%) showed a rapid decrease in capacity retention at cycle 90, with the tested cells losing 6% of their capacity.

[0238] Example 3: Phenolic resin precursor carbon coated microsilicon Example 3(a) Microsilicon Particle Coating Example 3.1: 6.6 wt% carbon coated microsilicon 30 g of phenolic resin was added to 150 g of absolute ethanol, and the solution was mixed at room temperature using a magnetic stirrer until the resin was completely dissolved. Next, 104 g of microsilicon was added to the ethanol resin solution, and the suspension was kept stirring for 1 hour. The mixture was then heated at 70° C. for 12 hours until the ethanol was completely evaporated. 61.5 g of resin-coated microsilicon was transferred to a ceramic crucible and placed in a furnace tube. The furnace was purged with high purity nitrogen gas at a flow rate of 2 L / min at room temperature for 30 minutes before starting the firing process and maintained throughout. The sample was heated to 900° C. at a heating rate of 4° C. / min and fired for 1 hour. The furnace was then allowed to cool to room temperature while maintaining the flow of nitrogen gas until the furnace temperature reached at least 100° C. The fired microsilicon sample was crushed using a mortar and pestle for approximately 5 minutes to break up any larger silicon chunks. The product was then ball milled at 520 rpm using a milling ratio of 30 wt. % silicon and 70 wt. % grinding media (i.e., 1 cm diameter ceramic balls) for a total of 3 hours with 6 minutes of milling and 3 minutes rest intervals.

[0239] Example 3.2: 7.93 wt% carbon coated microsilicon The coating procedure of Example 3.1 was repeated using 40 g of phenolic resin and 104 g of microsilicon. 65 g of resin-coated microsilicon was transferred to a ceramic crucible and placed in a furnace tube. The furnace was purged with high purity nitrogen gas at a flow rate of 2 L / min at room temperature for 30 minutes before starting the firing process and maintained throughout. The sample was heated to 900°C at a heating rate of 4°C / min and fired for 2 hours. The furnace was then allowed to cool to room temperature while maintaining the flow of nitrogen gas until the furnace temperature reached at least 100°C. The fired microsilicon sample was ground using a mortar and pestle for approximately 5 minutes to break up any larger silicon chunks. The product was then ball milled at 520 rpm using a milling ratio of 30 wt% silicon and 70 wt% grinding media (i.e., 1 cm diameter ceramic balls) for a total of 3 hours with 6 minutes of milling and 3 minutes of rest intervals.

[0240] D for carbon-coated microsilicon 50 The particle sizes and BET surface area values ​​are as follows: [Table 6]

[0241] Example 3(b) Electrode Composition An anode composition consisting of carbon coated microsilicon was prepared. The specific slurry and electrode compositions used for all experiments are shown in Table 7 below. [Table 7]

[0242] Example 3(c) Slurry Preparation The amounts of materials specified in Table 7 were used in the slurry preparation process. The same procedure as in Example 1 was followed.

[0243] Example 3(d) Electrochemical Test Program The full cell was assembled using the procedure described in Example 1. See Tables 1 and 2 for the cycle program. Example 3(e) Cyclic Study - Summary of Key Findings [Table 8]

[0244] Table 8 shows that increasing the content of phenolic resin (PR) in the coating affected the ICE. When compared to the control, the 8 wt% PR coating showed a 3.7% decrease in ICE and the 6.6 wt% PR coating showed a 2.4% decrease. At cycle 50, the capacity retention for the uncoated was 99.4%, whereas the capacity retention for the 8 wt% PR coated cells was 96.2% and for the 6.6 wt% PR coated cells was 97% (Figure 2b).

[0245] Example 4: PVP precursor carbon coated microsilicon Example 4(a) Microsilicon Particle Coating Examples 4.1 - 6.03 wt% carbon coated microsilicon 22.5 g of PVP (55,000 MW) was added to 250 ml of absolute ethanol and the solution was mixed at 40° C. using a magnetic stirrer until the polymer was completely dissolved. Then, 22.5 g of microsilicon was added to the ethanol-PVP solution and the suspension was kept stirred. An additional 30 ml of absolute ethanol was added to the mixture to promote uniform dispersion of the components. The mixture was then dried at 40° C. for 12 hours under ambient conditions, followed by a further drying step at 40° C. for 3 hours under vacuum. 31.6 g of PVP-coated microsilicon was transferred to a ceramic crucible and placed in a furnace tube. The furnace was purged with high purity nitrogen gas at a flow rate of 2 L / min at room temperature for 30 minutes before starting the firing process and maintained throughout. The sample was heated to 700° C. at a heating rate of 4° C. / min and fired for 2 hours. The furnace was then allowed to cool to room temperature while maintaining the flow of nitrogen gas until the furnace temperature reached at least 100° C. The calcined microsilicon samples were ground using a mortar and pestle to break up any larger chunks of silicon. The products were then ball milled at 520 rpm using a milling ratio of 30% silicon and 70% grinding media (i.e., 0.7 cm diameter ceramic balls) by weight, with 6 minutes of milling and 3 minutes of rest intervals, for a total of 3 hours.

[0246] Examples 4.2-3.12 wt% carbon coated microsilicon 45 g of PVP (55,000 MW) was added to a mixture of 3 L of deionized water and 5 ml of absolute ethanol. The solution was mixed at room temperature using a magnetic stirrer until the polymer was completely dissolved. Then, 90.0 g of microsilicon was added to the PVP solution and the suspension was kept stirred. To promote uniform dispersion of the microsilicon powder, the suspension was ultrasonicated for another 30 minutes. The prepared 5 wt. % suspension was then spray dried using a Mini Spray Dryer B-290 (BUCHI) at an inlet temperature of 220° C., an air flow of 30 L / min, 100% suction, and 40% solution feed rate. 37.0 g of PVP-coated microsilicon was transferred to a ceramic crucible and placed in the furnace tube. The furnace was purged with high purity nitrogen gas at a flow rate of 2 L / min for 30 minutes at room temperature before starting the firing process and maintained throughout. The samples were heated to 700° C. at a heating rate of 4° C. / min and fired for 1 h. The furnace was then allowed to cool to room temperature while maintaining the flow of nitrogen gas until the furnace temperature reached at least 100° C. The coated microsilicon samples were first crushed using a mortar and pestle to break up larger silicon chunks, followed by a laboratory sample mill for 30 min.

[0247] Examples 4.3-6.92 wt% Carbon Coated Microsilicon 90 g of PVP (55,000 MW) was added to 6 L of deionized water and the solution was mixed using a magnetic stirrer at 30° C. until the polymer was completely dissolved. Then, 91.0 g of microsilicon was added to the PVP solution cooled to room temperature and stirring was continued. The suspension was ultrasonicated for another 30 minutes to promote uniform dispersion of the microsilicon powder. The prepared 3 wt. % suspension was then spray dried using a Mini Spray Dryer B-290 (BUCHI) at an inlet temperature of 220° C., an air flow of 30 L / min, 100% suction, and 40% solution feed rate. 27.0 g of PVP-coated microsilicon was transferred to a ceramic crucible and placed in a furnace tube. The furnace was purged with high purity nitrogen gas at a flow rate of 2 L / min at room temperature for 30 minutes before starting the firing process and maintained throughout. The sample was heated to 700° C. at a heating rate of 4° C. / min and fired for 2 hours. The furnace was then allowed to cool to room temperature while maintaining the flow of nitrogen gas until the furnace temperature reached at least 100° C. The calcined microsilicon sample was ground using a mortar and pestle to break up any larger chunks of silicon. The product was then ball milled at 520 rpm using a milling ratio of 30% silicon and 70% grinding media (i.e., 0.7 cm diameter ceramic balls) by weight, with 6 minutes of milling and 3 minutes of rest intervals, for a total of 3 hours.

[0248] The D50 particle size and BET surface area values ​​for the carbon coated microsilicon are as follows: [Table 9]

[0249] Example 4(b) Electrode Composition An anode composition consisting of carbon coated microsilicon was prepared. The specific electrode composition used for all experiments is shown in Table 10 below. [Table 10]

[0250] Example 4(c) Slurry Preparation The amounts of materials specified in Table 10 were used in the slurry preparation process. The same procedure as in Example 1 was followed.

[0251] Example 4(d) Electrochemical Test Program The full cell was assembled using the procedure described in Example 1. See Tables 1 and 2 for the cycle program. Example 4(e) Cycling Study - Summary of Key Findings [Table 11]

[0252] Table 11 showed that increasing the content of PVP coating adversely affected the ICE. The 3.12 wt% PVP sample showed a slight decrease of 0.6% in ICE when compared to the control, while the 6.92 wt% PVP sample lost about 3% of its ICE. At cycle 100, the uncoated sample lost about 3% of its capacity, while the 3.1 wt% PVP lost 5% at the same cycle.

[0253] Example 5: PAN precursor carbon coated microsilicon Example 5(a) - 14.5 wt% Carbon Coated Microsilicon 45 g of PAN (150,000 MW) was added to 500 ml of DMF while stirring at 70° C. using a shear mixer. After complete dissolution of the polymer, 90.0 g of microsilicon was added to the polymer solution and the suspension was kept mixed using a shear mixer. During this process, the solution temperature increased to 120° C., which promoted the evaporation of the DMF solvent. After the solution consistency became difficult to mix mechanically, the resulting product was transferred to three ceramic crucibles and further dried at either: (i) 200° C. for 2 hours under N2 gas flow, (ii) 200° C. for 2 hours at atmospheric conditions, or (iii) 110° C. for 2 hours under vacuum. 60 g of the resulting dried product was placed in a furnace tube and the furnace was purged with high purity nitrogen gas at a flow rate of 2 L / min for 30 minutes at room temperature before starting the calcination process. The sample was heated to 900° C. with a heating rate of 4° C. / min and calcined for 2 hours. The furnace was then allowed to cool to room temperature while maintaining the flow of nitrogen gas until the furnace temperature reached at least 100° C. The calcined microsilicon sample was ground using a mortar and pestle for approximately 5 minutes to break up any larger chunks of silicon. The product was then ball milled at 520 rpm using a milling ratio of 30% silicon and 70% grinding media (i.e., 0.7 cm diameter ceramic balls) by weight, with 6 minutes of milling and 3 minutes of rest intervals, for a total of 3 hours.

[0254] D for carbon-coated microsilicon 50 The particle sizes and BET surface area values ​​are as follows: [Table 12]

[0255] Example 5(b) Electrode Composition An anode composition consisting of carbon coated microsilicon was prepared. The specific electrode composition used for all experiments is shown in Table 13 below. [Table 13]

[0256] Example 5(c) Slurry Preparation The amounts of materials specified in Table 13 were used in the slurry preparation process. The same procedure as in Example 1 was followed.

[0257] Example 5(d) Electrochemical Test Program The full cell was assembled using the procedure described in Example 1. See Tables 1 and 2 for the cycle program. Example 5(e) Cycling Study - Summary of Key Findings [Table 14]

[0258] The 14.5 wt % PAN-coated micro-Si had an ICE of 82.1%, whereas the uncoated mSi had an ICE of 89% (Table 14). After 50 cycles (Fig. 4b), the PAN-coated sample lost 4.4% of its capacity.

[0259] Example 6: Prelithiation of Coated Microsilicon Example 6(a) Electrode Composition All silicon material samples were incorporated into electrodes using the specific electrode compositions shown in Table 15 below. [Table 15]

[0260] Example 6(b) Slurry Preparation The amounts of materials specified in Table 15 were used in the slurry preparation process. The same procedure as in Example 1 was followed. Example 6(c) Electrochemical Test Program [Table 16]

[0261] Example 6(d) Prelithiation Step The slurry was cast onto copper foil and dried at 60°C before being cut for coin cell assembly. The electrodes were further dried at 110°C under vacuum for 12 hours. Lithium (Li) metal was used as the counter electrode and a Celgard separator was used. 150 μL of 1M LiPF6 in FEC / DEC (2:8) vol% was used as the electrolyte for coin cell assembly. The coin cells underwent partial formation cycling from 0.05C to some degree of lithiation based on the expected capacity of the anode (Table 16).

[0262] C-rates were based on the mass of active material (Si particles, graphite) in the electrode. The first lithiation is limited by a capacity (mAh / g) of ∼20% of the expected capacity of the anode, accounting for the ∼10% lithium loss in the first cycle.

[0263] Example 6(e) Post-Prelithiation Steps The coin cell was removed, introduced into a glove box (under Ar atmosphere) and disassembled for full cell preparation. The anode was washed with DMC and dried before assembly. The full cell was assembled using the procedure described in Example 1. See Tables 1 and 2 for the cycle program. Example 6(f) Cycling Study - Summary of Key Findings. [Table 17]

[0264] Data for non-lithiated samples were taken from Example 2 for 0.6 wt% Al2O3 and Example 4 for 3.12 wt% PVP. Electrochemical prelithiation of the coated samples significantly improved the ICE (about 1%) when compared to non-lithiation, which led to cycles at higher capacity (Table 17). The cycle capacity and average coulombic efficiency increased substantially. Negligible capacity loss was observed over the first 50 cycles for both prelithiated (3.12 wt% PVP and 0.6 wt% Al2O3) cells (Figure 5).

Claims

1. 1. An anode composition comprising micro-silicon active material particles, The micro silicon active material particles have a size of: (i) about 0.1 m 2 / g ~ approx. 10m 2 / g, (ii) a measured BET surface area of ​​about 0.1 μm to about 10 μm 50 particle size, and (iii) a D of about 0.1 to about 10 50 :BET surface area ratios, the amount of the microsilicon active material particles present in the anode composition is about 60 wt % to about 95 wt %, based on the total weight percent of the anode composition; The anode composition, wherein the anode composition comprises a coating.

2. 10. The anode composition of claim 1, wherein the coating is a coating of the micro-silicon active material particles.

3. The anode composition of claim 2, wherein the measured BET surface area of ​​the coated micro-silicon active material particles is from about 1 μm to about 100 μm.

4. The anode composition of claim 1 , wherein the coating is a coating of the anode composition.

5. D of the micro silicon active material particles 50 the ratio of :BET surface area is from about 0.1 to about 6; and / or the measured BET surface area of ​​the microsilicon active material particles is from about 1 m 2 / g to about 5 m 2 / g; and / or 10. The anode composition of claim 1, wherein the D 50 particle size of the micro-silicon active material particles is from about 2 μm to about 8 μm.

6. 10. The anode composition of claim 1, wherein the coating is selected from the group comprising carbon, graphene, graphite, metal oxides, polymers, and combinations thereof to form coated micro-silicon active material particles.

7. 10. The anode composition of claim 1, wherein the coating has a thickness of about 0.1 nm to about 200 nm.

8. 10. The anode composition of claim 1, wherein the ratio of coating thickness to uncoated silicon particle diameter (t / d as X:1) is from about 0.0001:1 to about 0.2:

1.

9. The anode composition of claim 1 , further comprising one or more binders and / or one or more conductive materials.

10. 10. The anode composition of claim 1, wherein the micro-silicon active material particles or coated micro-silicon active material particles are prelithiated.

11. 11. The anode composition of claim 10, wherein the microsilicon active material particles or coated microsilicon active material particles have a pre-lithiation level of about 1% to about 30%.

12. 10. The anode composition of claim 1, wherein the anode composition is a coating or film applied to a surface of a current collector material.

13. 10. The anode composition of claim 1, wherein the microsilicon active material particles or anode composition comprises one or more layers of the coating.

14. An electrochemical cell comprising an anode, a cathode, an electrolyte, and a separator, An electrochemical cell, wherein the anode comprises the anode composition of any one of claims 1 to 13.

15. The electrochemical cell of claim 14, wherein the lithium uptake capacity of the anode is greater than the lithium release capacity of the cathode.

16. 15. The electrochemical cell of claim 14, wherein the lithium uptake capacity of the anode is not fully utilized during charging of the lithium ion battery.

17. 15. The electrochemical cell of claim 14, wherein the anode is only partially lithiated in a fully charged state.

18. 15. The full cell assembly of claim 14, wherein the volume ratio of the anode to the cathode (N / P ratio) is from about 1.05 to about 7.

19. 15. The electrochemical cell of claim 14, wherein the lower cutoff voltage is between about 2.5V and 3.0V.

20. 15. The electrochemical cell of claim 14, wherein the anode is pre-lithiated.

21. 15. The electrochemical cell of claim 14, wherein the cathode is selected from the group comprising lithium nickel cobalt manganese oxide (NCM), lithium iron phosphate (LFP), lithium nickel manganese spinel (LNMO), lithium nickel cobalt aluminum oxide (NCA), lithium manganese oxide (LMO), lithium cobalt oxide (LCO), and sulfur or sulfur composites.

22. 1. A process for preparing an anode for an electrochemical cell, comprising: (i) preparing an anode slurry comprising micro-silicon active material particles or coated micro-silicon active material particles, optionally one or more further active materials, optionally one or more binders, optionally one or more conductive materials, optionally one or more additives, and a solvent system; (ii) casting a layer of the anode slurry onto a current collector material to provide an anode composition layer on the current collector material; (iii) optionally coating the anode composition; The micro silicon active material particles are: (a) about 0.1 m 2 / g ~ approx. 10m 2 / g, (b) a measured BET surface area of ​​about 0.1 μm to about 10 μm 50 particle size, and (c) a D of about 0.1 to about 10 50 :BET surface area ratio.

23. 23. The process of claim 22, further comprising the step (iii) solidifying the anode layer by (a) solvent evaporation and / or (b) heat treatment to provide a dry anode composition layer coated on the current collector material.

24. 23. The process of claim 22, wherein the coating is selected from the group comprising carbon, graphene, graphite, metal oxides, polymers, and combinations thereof.

25. the binder content in the anode slurry is from about 2.5 wt % to about 15 wt %, based on the total weight of the anode composition; and / or 23. The process of claim 22, wherein the content of the conductive material in the anode slurry is from about 2.5 wt % to about 40 wt %, based on the total weight of the anode composition.

26. 23. The process of claim 22, wherein the dried anode composition layer has a thickness in the range of about 5 μm to about 70 μm.

27. 23. The process of claim 22, wherein the temperature for step (iii)(a) is from about 40°C to 60°C, and / or the temperature for step (iii)(b) is from about 90°C to 180°C.

28. 23. The process of claim 22, wherein the coating is applied to at least a portion of a surface of the anode composition.

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