Fast-charging prelithiated silicon anode

Abstract

To provide a battery having lithiated or prelithiated components that are capable of rapid charging and have improved safety and efficiency, and further to provide a battery having a silicon anode that reduces volume expansion and irreversible capacity loss when lithium is alloyed with silicon.SOLUTION: A battery includes a cathode and an anode having a three-dimensional porous skeleton. The anode includes an anode active material lithiated with a lithium source. Lithium particles from the lithium source are alloyed or intercalated with the anode active material during diffusion to form a three-dimensional porous skeleton. The porous skeleton reduces electrode degradation due to volume expansion.SELECTED DRAWING: None

Description

[Technical Field]

[0001] Related Applications The following application claims priority to U.S. Patent Application No. 17 / 178,439, filed February 18, 2021, and U.S. Provisional Patent Application No. 62 / 978,475, filed February 19, 2020, the disclosures of which are incorporated by reference in their entireties.

[0002] The present invention relates to a battery having a cathode and a porous anode with improved lithium diffusion rates and surface conductivity. [Background technology]

[0003] Lithium and lithium-ion secondary or rechargeable batteries are found in certain applications such as mobile phones, camcorders, and laptop computers, and more recently in higher power applications such as electric and hybrid electric vehicles. In these applications, it is desirable for the secondary battery to have the highest possible specific capacity, while still providing safe operating conditions and good cyclability so that high specific capacity is maintained over subsequent recharge and discharge cycles.

[0004] Although various secondary battery configurations exist, each configuration includes a positive electrode (or cathode), a negative electrode (or anode), a separator separating the cathode and anode, and an electrolyte in electrochemical communication with the cathode and anode. In secondary lithium batteries, lithium ions migrate from the anode to the cathode through the electrolyte when the secondary battery is being discharged, i.e., used in its specific application. During the discharge process, electrons are withdrawn from the anode and travel through an external circuit to the cathode. When the secondary battery is being charged or recharged, lithium ions migrate from the cathode to the anode through the electrolyte.

[0005] A new lithium-ion cell or battery is initially in a discharged state. During the first charge of a lithium-ion cell, lithium migrates from the cathode material to the anode active material. The lithium migrated from the cathode to the anode reacts with the electrolyte material on the surface of the graphite anode, forming a passivation film on the anode. The passivation film formed on the graphite anode is also called the solid electrolyte interface (SEI). During subsequent discharges, the lithium consumed by the formation of the SEI is not returned to the cathode. This results in a lithium-ion cell with a lower capacity compared to its initial charge capacity because some of the lithium was consumed by the formation of the SEI. The partial consumption of available lithium during the first cycle reduces the capacity of the lithium-ion cell. This phenomenon, called irreversible capacity, is known to consume approximately 10% to 20% or more of the capacity of a lithium-ion cell. Therefore, after the first charge of a lithium-ion cell, the lithium-ion cell loses approximately 10% to 20% or more of its capacity.

[0006] One solution has been to prelithiate the anode using stabilized lithium metal powder. For example, lithium powder can be stabilized by passivating the metal powder surface with carbon dioxide, as described, for example, in U.S. Patent Nos. 5,567,474, 5,776,369, and 5,976,403, the disclosures of which are incorporated herein by reference in their entireties. CO₂-passivated lithium metal powder can only be used in air with low moisture levels for a limited period of time before the lithium metal content disappears due to reaction between the lithium metal and the air. Another solution is to apply a coating, such as fluorine, wax, phosphorus, or polymer, to the lithium metal powder, as described, for example, in U.S. Patent Nos. 7,588,623, 8,021,496, 8,377,236, and U.S. Patent Application Publication No. 2017 / 0149052. These coatings provide the lithium powder with high stability in a dry room environment.

[0007] When lithium foil is used for prelithiation and laminated directly to the surface of the electrode, significant heat can potentially be generated as a result of "short-circuit" lithiation due to the applied lamination pressure. If this prelithiation technique is performed in a roll-to-roll process, heat can accumulate in the center of the roll and can be difficult to dissipate. This heat accumulation can lead, for example, to mechanical damage to the electrode and, more importantly, to potential thermal runaway.

[0008] Another known battery problem is lithium plating, which commonly occurs during fast charging when lithium deposits called dendrites build up on the electrode surface and can lead to short circuiting and failure of the battery.

[0009] Silicon and silicon-containing anodes have been developed for decades due to their high theoretical charge capacity (4200 mAh / g). However, current silicon anodes can be hindered by various issues, such as high irreversible capacity and short cycle life due to volume expansion problems. For example, as silicon particles alloy with lithium, the particle volume can expand by up to 400%.

[0010] Thus, there remains a need for batteries with lithiated or pre-lithiated components that are capable of fast charging with improved safety and increased efficiency, as well as batteries with silicon anodes that experience reduced volume expansion and irreversible capacity loss upon lithium alloying with silicon. Summary of the Invention

[0011] To this end, the present invention provides a battery having a cathode and a porous anode lithiated with lithium powder, lithium particulate, or a printable lithium formulation. The pores are formed by lithium diffusing into the anode active material from, for example, the printable lithium composition. Batteries having the porous anodes described herein have improved lithium diffusion rates and / or gradient porosity, resulting in increased fast-charge capability and improved low-temperature performance.

[0012] In one embodiment, the anode active material is a silicon-containing active material. The silicon active material is alloyed with lithium particles to form a three-dimensional porous framework in the anode, increasing electrode porosity and reducing electrode degradation from volume expansion due to the buffering effect of the pores. A highly conductive porous layer may be formed on the surface of the anode. The porous conductive surface layer and gradient porosity effectively reduce areal current density, increase conductivity, and enable faster diffusion of lithium at the electrode surface and in the electrode bulk, thereby enabling higher charge rates and allowing for thicker electrodes while reducing the possibility of lithium plating on the anode surface.

[0013] In one embodiment, the anode active material is selected from the group consisting of graphite, hard carbon, graphite-SiOx composites, SiOx, SiO, SiO2, Si powder, Si film, SiC, Si / C composites, Si-based alloys, graphite-SnO, Sn / C composites, and other lithium-ion battery and lithium-ion capacitor anode materials, singly or in combination.

[0014] The printable lithium formulation may comprise lithium metal powder, a polymer binder compatible with the lithium metal powder, a rheology modifier compatible with the lithium metal powder, and a solvent compatible with the lithium metal powder and the polymer material. The polymer material may form a polymer film on the surface of the electrode that acts as a lithiation control layer. The lithiation control layer may regulate lithium diffusion and slow the rate of dry-state prelithiation that may occur during the deposition of lithium onto the surface of the negative electrode, and subsequently allow for the dissipation of heat during storage of the electrode material. Sulfide (Li 10 GeP2S 12 , Li3PS4, Li2GeS3, Li4GeS4, Li2ZnGeS4), oxides (Li7La3Zr2O 12 , Li x La y TiO3), phosphate (Na3Zr2PSi2O 12 , LiZr2(PO4)3, Li 1.3 Al 0.3 Ti 1.7 (PO4)3, Li 1.5 Al 0.5 Ge 1.5 By adding lithium ion conductive additives such as solid electrolyte salts including (PO4)3, LiGe2(PO4)3, and argyrodite-type electrolytes (Li6PS5Cl, Li6PS5Br, and Li6PS5I), the formed layer can also function as an artificial solid electrolyte interface. The polymer can form a flexible electronically insulating layer with the silicon anode that can expand and contract, maintaining its integrity while allowing lithium ions to migrate across the layer.

[0015] By depositing printable lithium as thin stripes in the Y plane, alternating between silicon anode stripes, the silicon anode material can expand in the X plane, mitigating electrochemical grinding and loss of particle electrical contact. Therefore, the printing method can provide a buffer for expansion. In another example, where a printable lithium formulation is used to form an anode, it can be coextruded in layers with a cathode and separator, resulting in an all-solid-state battery. [Brief explanation of the drawings]

[0016] [Figure 1A] 1 is an SEM backscattered image of a graphite electrode containing 10% SiO treated with a printable lithium composition.

[0017] [Figure 1B] 1 is an SEM backscattered image of a graphite electrode containing 10% SiO after lithium diffusion is complete.

[0018] [Figure 2A] 10 is a plot comparing gassing of a baseline cell with gassing of a cell treated with a printable lithium composition at 60° C. for 24 hours at rest. [Figure 2B] 10 is a plot comparing gassing of a baseline cell to gassing of a cell treated with a printable lithium composition at 45° C. [Figure 2C] 10 is a plot comparing gassing of a baseline cell with gassing of a cell treated with a printable lithium composition upon cycling at room temperature.

[0019] [Figure 3A] 1 is a reflected illumination microscope image of a SiO electrode surface on which an SLMP has first been deposited.

[0020] [Figure 3B] 1 is a reflected illumination microscope image of a SiO electrode surface 5 minutes after SLMP was deposited on the surface.

[0021] [Figure 3C] 1 is a reflected illumination microscope image of a SiO electrode surface 15 minutes after SLMP was deposited on the surface.

[0022] [Figure 3D] 1 is a reflected illumination microscope image of a SiO electrode surface 20 minutes after SLMP was deposited on the surface.

[0023] [Figure 3E] 1 is a reflected illumination microscope image of a SiO electrode surface on which a printable lithium composition has first been deposited.

[0024] [Figure 3F] 1 is a reflected illumination microscope image of a SiO electrode surface 5 hours after a printable lithium composition was deposited on the surface.

[0025] [Figure 3G] 12 is a reflected illumination microscope image of a SiO electrode surface 15 hours after the printable lithium composition was deposited on the surface.

[0026] [Figure 3H] 12 is a reflected illumination microscope image of a SiO electrode surface 20 hours after the printable lithium composition was deposited on the surface.

[0027] [Figure 4] 10 is a plot comparing differential capacity (dQ / dV) versus potential (V) during the first charge between baseline and cells treated with printable lithium compositions.

[0028] [Figure 5A] 1 is a plot showing the AC impedance of a baseline cell and a cell treated with a printable lithium composition, measured after a formation cycle.

[0029] [Figure 5B] 10 is a plot showing the AC impedance of a baseline cell and a cell treated with a printable lithium composition after cycling at the end of cycle life (20% capacity loss). DETAILED DESCRIPTION OF THE INVENTION

[0030] These and other aspects of the present invention will now be described in more detail with reference to the descriptions and methodologies provided herein. It is understood that the present invention may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0031] The terms used in the description of the present invention herein are intended to describe particular embodiments only and are not intended to limit the present invention. As used in describing the embodiments of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. Also, as used herein, "and / or" refers to and includes any and all possible combinations of one or more of the associated listed items.

[0032] The term "about" as used herein when referring to a measurable value such as the amount of a compound, dosage, time, temperature, etc. is meant to encompass a variation of 20%, 10%, 5%, 1%, 0.5%, or even 0.1% of the specified amount. Unless otherwise defined, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0033] As used herein, the terms "comprise, comprise, comprising, include, includes and including" specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0034] As used herein, the term "consists essentially of" (and grammatical variations thereof) as applied to the compositions and methods of the present invention means that the composition / method may contain additional components as long as the additional components do not substantially alter the composition / method. The term "substantially alter" as applied to a composition / method refers to an increase or decrease in the effectiveness of the composition / method by at least about 20% or more.

[0035] All patents, patent applications, and publications mentioned herein are incorporated by reference in their entirety. In the event of a conflict of terminology, the present specification will control.

[0036] According to the present invention, a battery is provided that includes a cathode and a porous silicon anode lithiated with a lithium source. In one embodiment, the anode comprises a silicon active material including carbon nanotubes. Examples of suitable lithium sources include lithium powder, lithium particulates, lithium mesh, or a printable lithium composition. As disclosed in U.S. Patent Application Nos. 16 / 359,707 and 16 / 573,587, which are incorporated herein by reference in their entireties, the printable lithium composition includes lithium metal powder, a polymer binder, a rheology modifier, and optionally a solvent. The polymer binder may be compatible with the lithium metal powder. The rheology modifier may be compatible with the lithium metal powder and the polymer binder. The solvent may be compatible with the lithium metal powder and the polymer binder.

[0037] The silicon active material is lithiated with lithium powder, lithium particulate, or a printable lithium composition to provide a silicon anode with pores throughout the electrode, generated, for example, by lithium diffusing from the printable lithium formulation. In one embodiment, a porous silicon anode is formed by mixing lithium powder, lithium particulate, or a printable lithium composition with the silicon active material in a slurry. The slurry may be coated onto a foil, mesh, or foam. The solvent is removed from the slurry to form a dry anode, which can then be pressed. Upon addition of electrolyte, the lithium intercalates or alloys with the negative electrode active material, forming a porous silicon or silicon-containing anode. The porous structure formed within the silicon anode mitigates volume expansion by providing a buffer to accommodate volume changes during subsequent electrochemical processing.

[0038] Silicon anodes formed with silicon active materials and printable lithium compositions have porosities that can range from about 25% to 60%. In one embodiment, the porosity of the silicon anode is about 30% to 50%. Prelithiating the electrode active material with a lithium source can increase the porosity of the electrode by about 5 to 15%.

[0039] For example, the porosity of a non-prelithiated electrode can be determined by first subtracting the actual electrode density from its theoretical density and then dividing by the theoretical density. The theoretical density of an electrode is the true density of a complete monolithic layer, but the actual density of an electrode will be lower than its theoretical density due to the ratio of void volume to total volume. Therefore, subtracting the actual electrode density from its theoretical density indicates the amount of void space between the electrode's particles, and dividing the electrode's void space by its theoretical density provides the electrode's % porosity. Prelithiation of an electrode can affect the electrode's actual density and therefore its porosity. The actual density of a prelithiated electrode can be determined by first subtracting the lithium contribution from the true density of each component to determine the electrode active material ratio, and then multiplying the electrode active material ratio by the actual density of the non-prelithiated electrode. This is based on the assumption that all lithium is intercalated into the host active material, leaving pores where the lithium particles once resided after diffusion. The porosity of the prelithiated electrode is then calculated by subtracting its actual density from the theoretical density of the non-prelithiated electrode and then dividing by the theoretical density.

[0040] A porous conductive layer may also be formed on the surface of the anode during lithium diffusion. In one embodiment, a printable lithium formulation can be applied to a prefabricated silicon anode to create a porosity gradient electrode. The porosity of the lithium layer when the printable lithium composition is first applied to the surface of the prefabricated surface can be expressed as follows:

number

[0041] The theoretical density of a printable lithium composition is the sum of the true densities of each component multiplied by their respective mass percentages, where the total mass percentage equals 1. The porosity of the lithium layer after diffusion onto a prefabricated surface can be expressed as:

number

[0042] The theoretical density of a lithium-free printable lithium composition can be determined by dividing the sum of the mass percentages of all components excluding lithium by the total volume of the printable lithium composition initially applied to the electrode surface. This assumes that all lithium from the printable lithium composition has diffused into the electrode. Therefore, the surface treated with the printable lithium composition after lithium diffusion will have a higher porosity than the bulk electrode. Furthermore, the porosity of the electrode surface can depend on the amount of lithium deposition and diffusion.

[0043] The additives in the printable lithium formulation also increase the surface and bulk conductivity of the electrode. The resulting porous conductive gradient structure reduces the effective areal current density, enabling faster charging by increasing surface and bulk conductivity, and allows for faster diffusion of lithium ions at the electrode surface and in the electrode bulk, thereby reducing the possibility of lithium plating on the anode surface. Faster diffusion kinetics results in lower charge transfer impedance and provides better charge rate capability. For example, silicon anodes formed with silicon active material and printable lithium compositions can have an improvement in rate capability of approximately 5% to 30% at a 1C charge rate and approximately 20% to 50% at a 2C charge rate compared to unlithiated silicon anodes.

[0044] Standard rechargeable lithium-ion batteries typically require a multi-day formation process to form a robust solid electrolyte interface (SEI) layer on the surface anode material. As described by An et al. (“Fast formation cycling for lithium ion batteries,” J Power Sources, 2017, 342, 846), the entire contents of which are incorporated herein by reference, the formation process slows the production rate of Li-ion batteries and requires a larger facility footprint and significant investment in formation equipment. However, the formation cycle time can be significantly reduced by prelithiating the electrode with a printable lithium composition. Typically, gas is evolved during a standard SEI formation cycle due to solvent reduction during SEI layer formation. Electrolyte solvents such as ethylene carbonate react at 2.7 V (approximately 0.9 V vs. Li / Li) on a graphite surface. +), which is much lower than the open-circuit voltage of cells prelithiated with printable lithium compositions, typically 2.9–3 V. As a result, cells with electrodes prelithiated with printable lithium compositions may generate very little gas during a typical SEI formation charge-discharge cycle. This is because an SEI layer forms on electrodes prelithiated with printable lithium compositions during the rest period before the formation cycle. Therefore, simplified and shortened formation cycles can be used. For example, a simplified formation process can consist of only a rest period of a few hours up to 24 hours at room temperature or an elevated temperature, followed by a degassing process. Figure 2A shows that a pouch cell with electrodes prelithiated with printable lithium compositions generates gas during the 24-hour rest period. This gas can be removed by a degassing step before the formation cycle. In contrast, a baseline cell that was not prelithiated does not generate gas during the 24-hour rest period. Figure 2B shows that the baseline cell generated gas during the formation charge-discharge cycle, while the pouch cell with prelithiated electrodes did not. Figure 2C shows that both the baseline cell and the cell containing the printable lithiated electrode produce similar gas during extended cycling. Figure 3 shows that the cell with the electrode prelithiated with the printable lithium composition does not have any solvent reduction peaks during the formation cycle before 2.9 V. This is because the prelithiation treatment results in partial charging of the cell above 2.9 V, which is above the voltage for solvent reduction. This is a further indication that the prelithiation process initiates SEI formation.

[0045] In some embodiments, the lithium source for lithiating a silicon or silicon-containing anode is lithium metal powder. The lithium metal powder may be in the form of a finely divided powder. The lithium metal powder typically has an average particle size of less than about 80 μm, often less than about 40 μm, and sometimes less than about 20 μm. The lithium metal powder may be non-pyrophoric stabilized lithium metal powder (SLMP®) available from FMC USA Lithium Corp. The lithium metal powder may also include a substantially continuous layer or coating of fluorine, wax, phosphorus, or a polymer, or a combination thereof (as disclosed in U.S. Pat. Nos. 5,567,474, 5,776,369, and 5,976,403, which are incorporated herein by reference in their entireties). Lithium metal powder has an extremely low reactivity with moisture and air.

[0046] Lithium metal powder may also be alloyed with metals. For example, lithium metal powder may be alloyed with a Group I-VIII element. Suitable elements from Group IB may include, for example, silver or gold. Suitable elements from Group IIB may include, for example, zinc, cadmium, or mercury. Suitable elements from Group IIA of the periodic table may include, for example, beryllium, magnesium, calcium, strontium, barium, and radium. Suitable elements from Group IIIA that can be used in the present invention may include, for example, boron, aluminum, gallium, indium, or thallium. Suitable elements from Group IVA that can be used in the present invention may include, for example, carbon, silicon, germanium, tin, or lead. Suitable elements from Group VA that can be used in the present invention may include, for example, nitrogen, phosphorus, or bismuth. Suitable elements from Group VIIIB may include, for example, palladium or platinum.

[0047] In some embodiments, the lithium source is a printable lithium composition such as those described in U.S. Patent Application Nos. 16 / 359,707 and 16 / 573,587, which are incorporated by reference herein in their entireties. The printable lithium composition includes lithium metal powder, a polymer binder, a rheology modifier, and may further include a solvent.

[0048] The polymer binder is selected to be compatible with the lithium metal powder. "Compatible with" or "compatibility" is intended to convey that the polymer binder will not react violently with the lithium metal powder to pose a safety hazard. The lithium metal powder and the polymer binder may react to form a lithium-polymer composite, but such a composite should be stable at various temperatures. It is recognized that the amount (concentration) of lithium and polymer binder contributes to stability and reactivity. The polymer binder may have a molecular weight of about 1,000 to about 8,000,000, and often has a molecular weight of 2,000,000 to 5,000,000. Suitable polymeric binders may include one or more of poly(ethylene oxide), polystyrene, polyisobutylene, natural rubber, butadiene rubber, styrene-butadiene rubber, polyisoprene rubber, butyl rubber, hydrogenated nitrile butadiene rubber, epichlorohydrin rubber, acrylate rubber, silicone rubber, nitrile rubber, polyacrylic acid, polyvinylidene chloride, polyvinyl acetate, ethylene propylene diene termonomer, ethylene vinyl acetate copolymer, ethylene-propylene copolymer, ethylene-propylene terpolymer, polybutene. The binder may also be a wax.

[0049] In some embodiments, the battery may further include a lithiation control layer. For example, a polymer binder can form a film on the surface of the electrode to regulate the activation and lithiation rate of the electrode. The film formed by the polymer binder thus acts as a prelithiation control layer because lithium does not directly contact the electrode surface and lithiation is unlikely to occur until an electrolyte is added to the cell. The lithiation control layer can regulate lithium diffusion and slow the rate of dry-state prelithiation that can occur during lithium buildup on the surface of the negative electrode, subsequently allowing heat dissipation during storage of the electrode material. An example of a lithium control layer is described in U.S. Patent Application Publication No. 2019 / 0229380, which is incorporated herein by reference in its entirety. Having a controlled lithium diffusion rate increases the safety of the prelithiation process due to controlled heat dissipation.

[0050] The rheology modifier is selected to be compatible with the lithium metal powder and polymer binder and dispersible in the composition. In one embodiment, the rheology modifier is carbon-based. For example, the rheology modifier may comprise carbon nanotubes to provide structure for the coated electrode. In another embodiment, carbon black may be added as a rheology modifier.

[0051] A preferred embodiment of the printable lithium composition includes a carbon-based rheology modifier such as carbon nanotubes. The use of carbon nanotubes can also provide a three-dimensional support structure and conductive network for the lithium anode when coated with the printable lithium composition, increasing its surface area. Another support structure may be as described by Cui et al. [Science Advances, Vol. 4, no. 7, page 5168, DOI: 10.1126 / sciadv.aat5168], which uses hollow carbon spheres as stable hosts to prevent parasitic reactions and result in improved cycling behavior. Yet another support structure may be nanowires, as described in U.S. Pat. No. 10,090,512, which is incorporated herein by reference in its entirety. Other suitable carbon-based rheology modifiers include carbon black, graphene, graphite, hard carbon, and mixtures or blends thereof.

[0052] Other examples of suitable rheology modifiers include non-carbon-based materials, including titanium oxide and silicon oxide. For example, silicon nanostructures, such as nanotubes or nanoparticles, can be added as rheology modifiers to provide three-dimensional structure and / or additional capacity. Rheology modifiers can also enhance the durability of layers (i.e., coatings, foils, or films) formed from printable lithium compositions by preventing mechanical degradation, which may enable faster charging.

[0053] Additional rheology modifiers can be added to the composition to adjust properties such as viscosity and flow under shear conditions. The rheology modifier can also provide improved conductivity, capacity, and / or improved stability / safety, depending on the selection of the rheology modifier. To this end, the rheology modifier may be a combination of two or more compounds to provide different or additional properties. Exemplary rheology modifiers may include one or more of silicon nanotubes, fumed silica, titanium dioxide, zirconium dioxide, and other Group IIA, IIIA, IVB, VB, and VIA elements / compounds, as well as mixtures or blends thereof. Other additives designed to enhance lithium ion conductivity can be used in electrochemical electrolyte salts, such as lithium perchlorate (LiClO), lithium hexafluorophosphate (LiPF), lithium difluoro(oxalato)borate (LiDFOB), lithium tetrafluoroborate (LiBF), lithium nitrate (LiNO), lithium bis(oxalato)borate (LiBOB), lithium trifluoromethanesulfonimide (LiTFSI), and lithium bis(fluorosulfonyl)imide (LiFSI). The additives included in the printable lithium formulations can also be selected to modify the porosity and overall three-dimensional support structure as needed. Examples include carbon nanotubes (CNTs), graphene, or polyacrylates, as described in Electrochemical and Solid-State Letters, 12, 5, A107-A110, 2009.

[0054] Solvents compatible with lithium can include acyclic hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons, symmetrical ethers, asymmetrical ethers, cyclic ethers, alkanes, sulfones, mineral oils, and mixtures, blends, or cosolvents thereof. Examples of suitable acyclic and cyclic hydrocarbons include n-hexane, n-heptane, cyclohexane, and the like. Examples of suitable aromatic hydrocarbons include toluene, ethylbenzene, xylene, isopropylbenzene (cumene), and the like. Examples of suitable symmetrical, asymmetrical, and cyclic ethers include di-n-butyl ether, methyl t-butyl ether, tetrahydrofuran, glyme, and the like. Commercially available isoparaffinic synthetic hydrocarbon solvents with tailored boiling ranges, such as Shell Sol® (Shell Chemicals) or Isopar® (Exxon), are also suitable.

[0055] The polymer binder and solvent are selected to be compatible with each other and with the lithium metal powder. Generally, the binder or solvent should be non-reactive with the lithium metal powder, or in an amount such that any reaction is kept to a minimum and violent reactions are avoided. The binder and solvent must be compatible with each other at the temperatures at which the printable lithium composition will be made and used. Preferably, the solvent (or co-solvent) is sufficiently volatile to readily evaporate from the printable lithium composition (e.g., in slurry form) and dry the printable lithium composition (slurry) after application.

[0056] In another embodiment, a mixture of polymer binders, rheology modifiers, coating agents, and other potential additives for the lithium metal powder can be formed and introduced into contact with the lithium droplets during dispersion at a temperature above the melting point of lithium or at a lower temperature after the lithium dispersion has cooled, as described in U.S. Patent No. 7,588,623, the disclosure of which is incorporated by reference in its entirety. The lithium metal thus modified can be introduced in dry powder form or in solution in a selected solvent. It is understood that different combinations of process parameters can be used to achieve specific coating and lithium powder properties for specific applications.

[0057] The components of the printable lithium composition may be mixed together as a slurry or paste to have a high concentration of solids. Thus, the slurry / paste may be in the form of a concentrate, to which not all of the solvent is necessarily added prior to the time of deposition or application. In one embodiment, the lithium metal powder, when applied or deposited, should be uniformly suspended in the solvent so that a substantially uniform distribution of lithium metal powder is deposited or applied. The dry lithium powder can be dispersed by vigorously mixing or stirring, applying high shear forces, etc.

[0058] In another embodiment, a mixture of polymer binders, rheology modifiers, coating agents, and other potential additives for the lithium metal powder can be formed and introduced into contact with the lithium droplets during dispersion at a temperature above the melting point of lithium or at a lower temperature after the lithium dispersion has cooled, as described in U.S. Patent No. 7,588,623, the disclosure of which is incorporated by reference in its entirety. The lithium metal thus modified can be introduced in dry powder form or in solution in a selected solvent. It is understood that different combinations of process parameters can be used to achieve specific coating and lithium powder properties for specific applications.

[0059] Conventional prelithiation surface treatments require compositions with very low binder content and very high lithium content; see, for example, U.S. Pat. No. 9,649,688, the disclosure of which is incorporated by reference in its entirety. However, embodiments of printable lithium compositions according to the present invention can accommodate high binder ratios, such as up to 20% on a dry basis. Various properties of printable lithium compositions, such as viscosity and flow, can be adjusted by increasing the binder and modifier content up to 50% dry basis without losing the electrochemical activity of lithium. Increasing the binder content facilitates the flow of the printable lithium composition during filling and printing. The printable lithium composition may comprise, on a dry weight basis, about 50% to about 98% lithium metal powder and about 2% to about 50% polymer binder and rheology modifier. In one embodiment, the printable lithium composition comprises about 60% to about 90% lithium metal powder and about 10% to about 40% polymer binder and rheology modifier. In another embodiment, the printable lithium composition comprises about 75% to about 85% by weight of lithium metal powder and about 15% to about 30% by weight of a polymer binder and a rheology modifier.

[0060] An important aspect of printable lithium compositions is the rheological stability of the suspension. Because lithium metal has a low density of 0.534 g / cc, it is difficult to prevent the lithium powder from separating from the solvent suspension. By selecting the lithium metal powder loading, the type and amount of polymer binder and conventional modifier, viscosity, and rheology can be tailored to create a stable suspension of the present invention. Preferred embodiments show no separation for more than 90 days. This is consistent with a 1×10 4 cps~1×10 7 This can be achieved by designing a composition with a zero shear viscosity in the cps range, which keeps the lithium in suspension, especially during storage. When shear is applied, the suspension viscosity decreases to a level suitable for use in printing or coating applications.

[0061] The resulting printable lithium composition is preferably 10 s -1 The printable lithium composition may have a viscosity of about 20 to about 20,000 cps, sometimes about 100 to about 2,000 cps, and often about 700 to about 1,100 cps. At such viscosities, the printable lithium composition is a fluid suspension or gel. The printable lithium composition preferably has a long shelf life at room temperature and is stable against metallic lithium loss at temperatures up to 60°C, often up to 120°C, and sometimes up to 180°C. The printable lithium composition may separate somewhat over time, but can be returned to suspension by gentle agitation and / or the application of heat.

[0062] In one embodiment, the printable lithium composition is solution-based and includes about 5-50% lithium metal powder, about 0.1-20% polymer binder, about 0.1-30% rheology modifier, and about 50-95% solvent. In one embodiment, the printable lithium composition is solution-based and includes about 15-25% lithium metal powder, about 0.3-0.6% polymer binder having a molecular weight of 4,700,000, about 0.5-0.9% rheology modifier, and about 75-85% solvent.

[0063] In some embodiments, a lithium source is applied to the surface of the anode to form a porous conductive layer on the surface during lithium diffusion. In some embodiments, the lithium source can be lithium metal powder or a printable lithium composition. The printable lithium composition can have a slower lithium diffusion rate than other lithium sources during prelithiation due to the polymer layer applied to the surface during application of the printable lithium composition. In some embodiments, the diffusion rate can be reduced by about half for lithium deposited as a printable lithium composition. The high heat generation caused by rapid diffusion in the dry state can damage the electrode or cause fires while the electrode roll is stored before slitting and final cell assembly. Therefore, a slower diffusion rate can provide a safer prelithiation process because the rate of heat generated during the diffusion process is slower, thereby providing more time to dissipate the heat.

[0064] Another aspect of the present invention relates to an all-solid-state battery having a porous silicon anode lithiated with a printable lithium composition. The current collector, electrode, and / or solid electrolyte of the all-solid-state battery can comprise a substrate coated with a printable lithium composition as described in U.S. Patent Application Nos. 16 / 573,556, 16 / 359,733, and 16 / 573,587, all of which are incorporated by reference in their entireties.

[0065] In one embodiment, a battery can include a cathode, an electrolyte, and a porous anode lithiated with a printable lithium composition. The electrolyte can have a concentration greater than 1 M, often about 3 M or greater, and sometimes greater than 5 M. Examples of suitable electrolytes include lithium perchlorate (LiClO), lithium hexafluorophosphate (LiPF), lithium difluoro(oxalato)borate (LiDFOB), lithium tetrafluoroborate (LiBF), lithium nitrate (LiNO), lithium bis(oxalato)borate (LiBOB), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium trifluoromethanesulfonimide (LiTFSI), as well as mixtures or blends thereof. One illustrative example is a battery having a cathode, a porous anode lithiated with a printable lithium composition, and a high-concentration electrolyte, where LiFSI is the primary salt in the high-concentration electrolyte. Another example is a battery having a cathode, a porous anode lithiated with a printable lithium composition, and a two-salt liquid electrolyte, as described in Weber et al. [Nature Energy, Vol. 4, pgs. 683-689 (2019), DOI: 10.1038 / s41560-019-0428-9] and U.S. Patent Application Publication No. 2019 / 0036171, both of which are incorporated herein by reference. The two-salt liquid electrolyte may comprise lithium difluoro(oxalato)borate (LiDFOB) and LiBF4 and may have a concentration of about 1 M. The two-salt electrolyte may provide increased initial capacity retention and improved cycling performance.

[0066] The current collector material can be foil, mesh, or foam. For example, anode materials can include graphite, hard carbon, graphite-SiOx composites, SiOx, SiO, SiO2, SiC, Si, Si / C composites, Si-based alloys, graphite-SnO, Sn / C composites, and other lithium-ion battery and lithium-ion capacitor anode materials. Because of the holes that run through the substrate, meshes are used to improve the energy density of the battery by reducing the weight of the current collector. Foams can also be used as current collectors. A continuous 3D morphology allows for more Li + It can provide a special porous structure that helps to accommodate Li, thus hindering the growth of Li dendrites, improving rate capability and extending cycle life.

[0067] In one embodiment, the anode active material and the printable lithium composition are provided together and extruded onto a current collector (e.g., copper, nickel, etc.). For example, the anode active material and the printable lithium composition can be mixed and coextruded together. Examples of anode active materials include graphite, graphite-SiO, graphite-SnO, SiO, hard carbon, and other lithium-ion battery and lithium-ion capacitor anode materials. In another embodiment, the anode active material and the printable lithium composition are coextruded to form a layer of the printable lithium composition on the current collector. Deposition of the printable lithium composition, including the extrusion techniques described above, may include deposition in a variety of patterns (e.g., dots, stripes), thicknesses, widths, etc. For example, the printable lithium composition and the anode active material may be deposited as a series of stripes, as described in U.S. Patent Application Publication No. 2014 / 0186519, which is incorporated herein by reference in its entirety. The stripes form a 3D structure that accounts for the expansion of the anode active material during lithiation. For example, silicon can expand 300-400% during lithiation. Such swelling can adversely affect the anode and its performance. By depositing printable lithium as thin stripes in the Y plane, alternating between silicon anode stripes, the silicon anode material can expand in the X plane, mitigating electrochemical grinding and loss of particle electrical contact. Therefore, the printing method can provide a buffer for expansion. In another example, where a printable lithium formulation is used to form an anode, it can be coextruded in layers with a cathode and separator, resulting in an all-solid-state battery.

[0068] In additional embodiments, at least a portion of the printable lithium composition can be applied to the anode active material prior to the battery formation process. For example, the anode may include a partially lithium-loaded silicon-based active material, such as described in U.S. Patent Application Publication No. 2018 / 0269471, which is incorporated herein by reference in its entirety, where the partially loaded active material has a selected degree of lithium loading, such as by intercalation / alloying. In some embodiments, the anode active material may be mechanically lithiated with the printable lithium composition. For example, once the printable lithium composition has been applied to its surface, the anode active material can be pressed with a force selected to induce mechanical lithiation.

[0069] In one embodiment, the printable lithium composition can be incorporated into a three-dimensional electrode structure, such as that described in U.S. Patent Application Publication No. 2018 / 0013126, which is incorporated herein by reference in its entirety. For example, the printable lithium composition can be incorporated into a three-dimensional porous anode, a porous current collector, or a porous polymer or ceramic membrane, and the printable lithium composition can be deposited therein. The printable lithium composition can also be incorporated into a solid electrolyte, which can be combined with or applied to a lithium metal anode to form a composite anode. The solid electrolyte can also be applied as one or more interfacial ion-conducting electrolyte layers or interfaces to the lithium metal anode. An example is described in U.S. Patent No. 8,182,943, which is incorporated herein by reference in its entirety.

[0070] In another embodiment, the printable lithium composition can be incorporated into a three-dimensional electrode structure, such as that described in U.S. Patent Application Publication No. 2018 / 0013126, which is incorporated herein by reference in its entirety. The three-dimensional electrode can be a permeable composite material comprising a support defining pores and an alkali metal deposit on the support, where the alkali metal is deposited using the printable lithium composition. The three-dimensional electrode can have a porosity of about 1% to about 95% by volume and a mean flow pore size ranging from about 1 nm to about 300 μm.

[0071] Another embodiment of the battery may include a composite anode formed using a pulsed electron beam, as described in U.S. Patent No. 10,047,432, the entirety of which is incorporated herein by reference. For example, a pulsed electron beam can be used as a virtual cathode deposition (VCD) process applied to the anode material, using the electron beam to create a three-dimensional porous anode structure. The three-dimensional structure formed from the pulsed electron beam can be a carbon allotrope for lithium ion batteries (CALIB). The CALIB structure can be co-deposited with lithium using a printable lithium composition to form a carbon polymorph.

[0072] In some embodiments, electrodes prelithiated with the printable lithium composition can be assembled into a cell with electrodes preloaded with lithium. A separator can be placed between each electrode. A current can be passed between the electrodes. For example, an anode prelithiated with the printable lithium composition of the present invention can be formed into a second battery as described in U.S. Pat. No. 6,706,447, which is incorporated herein by reference in its entirety.

[0073] The cathode is formed from an active material, typically combined with a carbonaceous material and a binder polymer. The active material used in the cathode is preferably a lithiated material. Preferably, non-lithiated materials such as MnO2, V2O5, MoS2, metal fluorides or mixtures thereof, sulfur, and sulfur composites can be used as the active material. However, lithiated materials such as LiMn2O4 and LiMO2 (where M is Ni, Co, or Mn) that can be further lithiated can also be used. Non-lithiated active materials are generally preferred because they have higher specific capacity, lower cost, and a wider selection of cathode materials in this configuration, which can provide higher energy and power than conventional secondary batteries containing lithiated active materials.

[0074] For example, the printable lithium compositions can be used to form monolithic lithium metal anodes of various thicknesses and widths for use in all-solid-state batteries, including those described in U.S. Patent Nos. 8,252,438 and 9,893,379, which are incorporated herein by reference in their entireties. In yet another embodiment, the printable lithium compositions can be applied or deposited to form solid electrolytes for all-solid-state batteries, including combining the printable lithium compositions with polymeric or ceramic materials to form the solid electrolyte.

[0075] The surface of a typical solid electrolyte can be rough, depending on the solid electrolyte selection, and therefore may not form good contact between the solid electrolyte and the lithium (foil) anode, resulting in a suboptimal interface and reduced battery performance. In one embodiment, a printable lithium composition can be used to prelithiate the solid electrolyte, improving the solid electrolyte surface and thus forming an interfacial layer that provides improved adhesion with the lithium anode. In another embodiment, the interfacial layer may comprise a foil or film formed from the printable lithium composition. The printable lithium composition that forms the interfacial layer can be applied to various types of solid electrolytes, including polymer, glass, and ceramic electrolytes. Having a tailored solid electrolyte surface optimizes contact between the solid electrolyte and the lithium anode, improving the interface between the solid electrolyte and the lithium anode, and resulting in better battery performance by reducing the increase in impedance caused by loss of contact between the lithium and the electrolyte due to the volumetric expansion of lithium during cycling.

[0076] Other examples of all-solid-state secondary batteries include a cathode capable of electrochemically absorbing and desorbing lithium, an anode capable of electrochemically absorbing and desorbing lithium, the anode including an active material layer comprising an active material, the active material layer being supported on a current collector, and a non-aqueous electrolyte, as described in U.S. Patent No. 7,914,930, the entire contents of which are incorporated herein by reference. The method includes contacting a printable lithium composition with a surface of the active material layer of the anode, thereby reacting lithium with the active material of the anode, and then combining the anode with the cathode to form an electrode assembly.

[0077] example Example 1 17g of artificial graphite, 2g of SiO, and 12.5g of 8% styrene butadiene rubber in toluene were combined with 8.5g of toluene in a 250ml polypropylene cup. The mixture was blended in a THINKY ARE250 planetary centrifugal mixer at 1000 rpm for 3 minutes to create a uniform anode slurry. 0.85g of stabilized lithium metal powder (SLMP®, FMC USA Lithium Corp.) or PLF with equivalent lithium metal content was added to the slurry and blended in the THINKY at 1000 rpm for 30 seconds. The resulting slurry was coated onto copper foil using a 6 mil doctor blade. The solvent was dried using a forced hot air dryer at 110°C until all solvent was removed. The dried electrode was pressed using a roll press with a 30µm gap. A 4 cm x 4 cm piece of pressed electrode is placed in a sealed pouch containing 1 g of 1 M LiPF6 in EC / DEC 1:1 electrolyte and observed under a digital microscope. After lithium diffusion, there is an increase in porosity of 33.6% to 35.2% (an increase of approximately 5%). This is estimated based on the thickness and true density of the material. The theoretical density is calculated by subtracting the lithium contribution from the true density of each component, based on the assumption that all lithium is intercalated into the host anode material, leaving pores where the lithium particles once were after diffusion.

[0078] Example 2 Anode electrodes manufactured by LiFun Technologies are used to test the effectiveness of printable lithium formulations for enhancing first cycle efficiency (FCE). Electrodes containing 10% SiO are used for testing. The formulation for the 10% SiO anode electrode contains 85.32% artificial graphite + 9.48% SiO, 3.8% binder (CMC + SBR), and 1.4% carbon black. The loading of the anode material is 8.2 mg / cm. 2 The press density is approximately 1.5 g / cm 3 The electrode dimensions are 7 cm x 7 cm. This anode electrode has an FCE of 85% when tested in a half cell with a lithium metal counter electrode.

[0079] Printable Lithium Formulation (PLF) containing 6 mg of stabilized lithium metal powder (SLMP®, FMC USA Lithium Corp.) was applied to the surface of a 10% SiO2 electrode. After drying and pressing, the electrode was assembled into a half-cell in a pouch cell format with a lithium metal counter electrode using 1 M LiPF6 in a 1:1:2:6 (volume ratio) EC:FEC:EMC:DMC electrolyte. The cell was tested on a Maccor Series 4000 cycler using the following protocol: 24 h at 45 °C, followed by one cycle: 1) discharge at 0.1 C to 0.005 V, 2) constant voltage step until the current decreased to 0.05 C, and 3) charge at 0.1 C to 1.5 V. The first cycle efficiency increased from 85.59% to 97.32% (Table 1). 1A and 1B show the as-printed, dried, and pressed formulation on the surface of a 10% SiO-containing graphite electrode and the resulting increase in surface porosity after lithium diffusion. [Table 1]

[0080] Example 3 Cells, including baseline (BL) and PLF-integrated electrode monolayer pouch cells, were fabricated using graphite-10% SiO2 with an NMC811 cathode and a Celgard 3501 separator. 1 g of 1 M LiPF6 in a 1:1:2:6 Vol EC:FEC:EMC:DMC electrolyte was used. The cells were cycled using a formation protocol at 45 °C with a 24-hour rest period, followed by a constant current charge of 10 mA to 4.2 V, and then a constant current discharge of 10 mA to 2.8 V with a 5 mA current cutoff. After the formation step for impedance measurements, the cells were charged to 3.8 V. Following the initial impedance test, the cells were tested for rate capability. [Table 2] The surface porosity of the PLF cell is approximately 50% before lithium diffusion. Lithium accounts for approximately 84% of the volume of the PLF treatment solution. After lithium diffusion, the surface porosity is approximately 88.5%, and the bulk porosity is 34%. The increased surface porosity provides increased surface area for electrolyte absorption and therefore faster lithium ion diffusion kinetics. Faster diffusion kinetics results in lower charge transfer impedance and better charge rate capability. Comparing the total impedance of graphite-10% SiO2 complete cells, there is a 14% decrease in the PLF-treated cells compared to the baseline cells. Furthermore, at the end of cycle life, there is an approximately 16% decrease in total impedance for cells with PLF-treated electrodes compared to the baseline cells. There is an approximately 9% improvement in rate capability at a 1C charge rate and an approximately 36% improvement at a 2C charge rate.

[0081] Standard batteries require several days to form a good SEI layer on the surface anode material. However, treating the electrode with a printable lithium composition significantly reduces the SEI formation time. Figures 2A–C are plots comparing gas evolution between a baseline and PLF-treated NMC811 / graphite-5% SiO pouch cell during a 24-hour rest at 60 °C, b) the first two formation cycles, and c) cycling at room temperature. Gas evolution indicates SEI formation. As seen in Figures 2A–C, the PLF-incorporated cell produced the most gas during a 24-hour rest at 60 °C. In contrast, the baseline cell produced no gas during the same rest period. Figures 2A–C demonstrate that the PLF-incorporated cell can form an SEI layer within a shorter period compared to the baseline cell.

[0082] Figure 2B shows the difference in gas generation between the baseline and PLF-incorporated NMC811 / graphite-5% SiO pouch cells during the first two cycles. The PLF-incorporated cell produced very little gas, while the baseline cell produced gas during the formation cycle. This is because SEI formation in the baseline cell occurs below 3 V, where most of the solvent is reduced at the anode surface. In contrast, the PLF-incorporated cell formed an SEI layer during the 24-hour rest period; therefore, no formation cycle is required for the SEI layer to form in the PLF-treated cell.

[0083] Figure 2C shows a comparison of gas production between the baseline and PLF-integrated NMC811 / graphite-5%SiO pouch cells during 1C rate cycling at room temperature (RT), measured at the end of cycle life (20% capacity loss). Both the baseline and PLF-integrated cells produced similar volumes of gas.

[0084] Solvent reduction during the formation of the SEI layer results in gas generation during the SEI formation cycle. Cells incorporating PLFs produce gas during the rest step and minimal gas generation during formation.

[0085] Comparing the rate at which lithium diffuses into silicon-containing anode materials during the prelithiation process, the PLF diffusion rate is 30% slower than when using SLMP alone. The diffusion rate is slowed by the polymer layer applied to the anode surface during PLF application. This slower diffusion rate can result in controlled heat dissipation during the diffusion process, resulting in a safer prelithiation process. Furthermore, PLF diffusion has been observed to be minimal during the dry-state diffusion stage before electrolyte addition compared to the use of dry SLMP. This results in less heat generated by lithium diffusion after laminating the PLF to the electrode surface. Heat generated by dry-state lithium diffusion within electrode rolls during storage has been observed to generate enough heat to damage the electrode film or even cause thermal events while the electrode rolls are stored before being used in the cell assembly process.

[0086] Figure 3 shows a comparison of the diffusion rate of lithium deposited as a printable lithium composition into a dry SiO anode material compared to that deposited as an SLMP, approximately 0.7 mg / cm, sufficient to compensate for irreversible capacity. 2 The electrodes are treated with either SLMP or PLF at a loading equal to 1000 W of lithium. The electrodes are then pressed with a force selected to induce mechanical lithiation. Test results show that the diffusion rate of lithium deposited using PLF is significantly slower than that of SLMP.

[0087] Figure 4 shows the differential capacity (dQ / dV) versus potential (V) curves for the baseline cell and the PLF-incorporated cell. As can be seen in Figure 4, the baseline cell has a prominent peak at 2.7 V due to the reduction of fluoroethylene carbonate on the graphite surface and a peak at 2.9 V due to the well-known reduction of ethylene carbonate on the anode surface. For further discussion of the solvent reduction peaks, see Wang et al. [Journal of The Electrochemical Society. 161 (2014) 467-472 DOI: 10.1149 / 2.001404jes] and Xia et al. [Journal of Power Sources. 328 (2016) 124-135. DOI: 10.1016 / j.jpowsour.2016.08.015], both of which are incorporated herein by reference in their entireties.

[0088] In contrast, Figure 4 shows that the PLF-treated cell does not have any solvent reduction peak during the formation cycle before 2.9 V, as the prelithiation treatment results in partial charging of the cell above 2.9 V. This voltage exceeds the voltage for solvent reduction, indicating that direct anodic contact with Li metal initiates SEI layer formation during the prelithiation process.

[0089] Figures 5A and 5B compare the AC impedance between baseline and PLF-incorporated NMC811 / graphite-5% SiO pouch cells measured after two formation cycles and after cycling. AC impedance spectra were collected using Gamry Potentiostats (Reference 3000™) with 10 points per decade from 100 kHz to 100 mHz and a signal amplitude of 10 mV. Figures 5A and 5B show that the PLF-incorporated cells have significantly lower impedance after formation and during cycling, indicating that treating the cells with printable lithium compositions can improve their rate capabilities. As reported in Table 1, the PLF-incorporated cells can have improved cycling efficiency compared to baseline lithium-ion cells. [Table 3]

[0090] Table 4 compares various characteristics between the baseline cell and the printable lithium-incorporated cell. Compared to the baseline cell, the PLF-incorporated cell, NMC811 / graphite-5%SiO, exhibits a thickness increase of approximately 5% after cell assembly. Each double-sided treated anode electrode exhibits a thickness increase of approximately 10 μm, and thus the 10-layer cell exhibits a total thickness increase of approximately 100 μm when assembled. However, during formation, all of the deposited lithium intercalates into the bulk of the anode, resulting in no appreciable thickness change between the treated pouch cell and the baseline pouch cell. Cell volume measurements show no increase after formation. There is an increase in first-cycle discharge capacity, resulting in a 7% higher first-cycle efficiency for the cell incorporating the anode treated with the printable lithium composition. Volumetric energy density and gravimetric energy density increased by approximately 11% and 10%, respectively, for the PLF-incorporated cell.

[0091] The gas generation data in Figures 2A-2C and the voltage data in Figure 4 show that the SEI layer of the PLF-incorporated cells is formed during the resting step. An advantage is that the formation cycle of the PLF-incorporated cells can be eliminated or dramatically reduced.

[0092] While the present approach has been illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those skilled in the art that other embodiments and examples may perform similar functions and / or achieve similar results, and all such equivalent embodiments and examples are within the spirit and scope of the present approach.

Claims

1. a cathode; an anode comprising an anode active material and lithiated with a lithium source; A battery comprising: the anode active material alloys or intercalates with lithium particles diffused from the lithium source to form a three-dimensional porous framework within the anode that reduces electrode degradation due to volume expansion.

2. 10. The battery of claim 1, wherein the anode active material has a porosity of about 25% to about 60%.

3. 3. The battery of claim 2, wherein the porosity of the anode active material increases by about 1% to about 10% upon alloying or intercalating with lithium particles diffused from the lithium source to form the three-dimensional porous framework within the anode.

4. 10. The battery of claim 1, further comprising a lithiation control layer on a surface of the anode adapted to control the activation and prelithiation rates of the anode.

5. 5. The battery of claim 4, wherein the lithiation control layer is a film on the surface of the anode formed from the polymer binder and adapted to slow the diffusion of lithium onto the surface.

6. 10. The battery of claim 1, wherein the surface of the anode is porous and the bulk of the electrode has a gradient porosity to enhance lithium conductivity, mitigate lithium plating, and enable rapid charging of the battery.

7. 7. The battery of claim 6, wherein the surface of the anode has a porosity greater than about 40%.

8. 7. The battery of claim 6, wherein the gradient porosity has increased surface area for lower charge transfer impedance and high charge rate capability.

9. 10. The battery of claim 1, wherein the anode has a first cycle efficiency of greater than about 90%.

10. 10. The battery of claim 1, wherein the lithium source is a stabilized lithium metal powder.

11. 10. The battery of claim 1, wherein the lithium source comprises a printable lithium formulation comprising lithium metal powder, a polymer binder compatible with the lithium metal powder, a rheology modifier compatible with the lithium metal powder, and a solvent compatible with the lithium metal powder and the polymer binder.

12. 12. The battery of claim 11, wherein the rheology modifier is selected from the group consisting of carbonaceous materials, silicon-containing materials, tin-containing materials, Group IIA oxides, Group IIIA oxides, Group IVB oxides, Group VB oxides, and Group VIA oxides.

13. 13. The battery of claim 12, wherein the carbonaceous material is selected from the group consisting of carbon black, carbon nanotubes, graphite, hard carbon, and graphene.

14. 13. The battery of claim 12, wherein the silicon-containing material is selected from the group consisting of silicon nanotubes and fumed silica.

15. 12. The battery of claim 11, wherein the polymer binder has a molecular weight of 1,000 to 8,000,000 and is selected from the group consisting of unsaturated elastomers, saturated elastomers, thermoplastics, polyacrylic acid, polyvinylidene chloride, and polyvinyl acetate, poly(ethylene oxide), polystyrene, polyisobutylene, natural rubber, butadiene rubber, styrene-butadiene rubber, polyisoprene rubber, butyl rubber, hydrogenated nitrile butadiene rubber, epichlorohydrin rubber, acrylate rubber, silicone rubber, nitrile rubber, polyacrylic acid, polyvinylidene chloride, polyvinyl acetate, ethylene propylene diene termonomer, ethylene vinyl acetate copolymer, ethylene-propylene copolymer, ethylene-propylene terpolymer, polybutene, and wax.

16. 12. The battery of claim 11, wherein the solvent is selected from the group consisting of alkanes, toluene, ethylbenzene, cumene, xylene, sulfones, mineral oil, glyme, and isoparaffinic synthetic hydrocarbon solvents.

17. 17. The battery of claim 16, further comprising an artificial solid electrolyte interfacial layer on a surface of the anode.

18. 18. The battery of claim 17, wherein the artificial solid electrolyte interface is formed from the polymer binder and a lithium ion conductive additive.

19. 20. The battery of claim 18, wherein the lithium ion conductive additive comprises one or more solid electrolyte salts selected from the group comprising sulfides, oxides, phosphates, and argyrodite-type electrolytes.

20. The anode active material is selected from the group consisting of graphite, hard carbon, graphite-SiOx composite, SiOx, SiO, and SiO ２ , SiC, Si, Si / C composites, Si-based alloys, graphite-SnO, Sn / C composites, and other lithium ion battery and lithium ion capacitor anode materials.

21. a cathode; a silicon-containing anode lithiated with a printable lithium composition comprising lithium metal powder, a polymer binder compatible with the lithium metal powder, a rheology modifier compatible with the lithium metal powder, and a solvent compatible with the lithium metal powder and the polymer binder; A battery comprising: a battery wherein a surface of the silicon anode alloys with lithium particles diffused from the printable lithium composition to form a porous layer on the surface, enhancing lithium conductivity and preventing lithium plating, thereby enabling fast charging of the battery.

22. 1. A method of forming an anode, comprising: providing a slurry comprising a silicon active material; adding a printable lithium composition comprising lithium metal powder, a polymer binder compatible with the lithium metal powder, a rheology modifier compatible with the lithium metal powder, and a solvent compatible with the lithium metal powder and the polymer binder to an anode slurry to form an anode slurry; A method of forming an anode comprising:

23. 23. The method of claim 22, further comprising coating the anode slurry onto a current collector.

24. 24. The method of claim 23, further comprising drying the solvent from the anode slurry to form an anode.

25. 25. The method of claim 24, further comprising forming a solid electrolyte interfacial layer within an initial 24 hour rest period.

26. 26. The method of claim 25, wherein the solid electrolyte layer is formed without a formation cycle.

27. 10. The battery of claim 1, wherein the printable lithium composition significantly reduces the formation time by forming a solid electrolyte interfacial layer during the resting step.

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