Compositions and methods for silicon-containing dry anode films

Abstract

To provide an electrode film capable of improving the performance of an energy storage device.SOLUTION: The invention provides dry-processed films including a silicon active material. and energy storage devices incorporating the same. The films may be free-standing anode electrode films. Also provided are methods for fabricating such anode electrode films.SELECTED DRAWING: None

Description

Technical Field

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 62 / 666,037, filed May 2, 2018, entitled "Compositions and Methods for Dry Anode Films Containing Silicon", the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to energy storage devices, and more particularly to materials and methods for dry electrode films containing silicon-based active materials.

Background Art

[0003] Electrical energy storage cells are widely used to power electronics, electromechanical, electrochemical, and other useful devices. Such cells include various types of capacitors, including batteries such as primary chemical and secondary (rechargeable) batteries, fuel cells, and ultracapacitors. Increasing the operating power and energy of energy storage devices, including capacitors and batteries, is desirable to improve energy storage performance, increase power capabilities, and expand practical use cases.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Energy storage devices that include electrode films that combine complementary attributes can improve the performance of energy storage devices in practical applications. Additionally, existing dry and solvent-free manufacturing methods can impose practical limitations on the composition of the electrodes. Accordingly, new electrode film formulations, and methods for their manufacture, can expand the possibilities of electrode film formulations and, as a result, improve performance.

Means for Solving the Problems

[0005] For the purpose of summarizing the present invention achieved beyond the prior art and its advantages, the specific objects and their advantages of the present invention will be described in this specification. Not all such objects or advantages are achieved in a specific embodiment of the present invention. Thus, for example, those skilled in the art will not necessarily achieve other objects or advantages taught or suggested in this specification, and will recognize that the present invention can be embodied or practiced by a method of achieving or optimizing one or a group of advantages taught in this specification.

[0006] One embodiment is a silicon-based lithium battery anode that includes two different graphite particle sizes and is fabricated by a non-solvent-based dry process. In the anode, the primary graphite can have an average (i.e., D 50 ) particle size of about 20 - 30 μm, and the secondary graphite can have an average particle size of about 4 - 7 μm. The silicon component of the anode can include pure silicon, silicon oxide, prelithiated silicon, and silicon-carbon composites. In one embodiment, the silicon component constitutes about 10 wt% - 30 wt% of the total mass of the electrode formulation. The dry binder in the anode can include carboxymethyl cellulose, polyethylene oxide, polyacrylic acid, polyvinylidene fluoride, polytetrafluoroethylene, and combinations thereof. In one embodiment, the dry binder is included at about 4 wt% - 10 wt% of the total mass of the anode formulation.

[0007] In a first aspect, a self-supporting dry anode film including a silicon active material is provided.

[0008] In a second aspect, a dry electrode film for an energy storage device is provided. The dry electrode fil m includes a dry active material including a Group 14 active material and a graphite active material, and a dry binder for which the dry electrode film is self-supporting.

[0009] In a third aspect, a method for manufacturing a dry electrode film of an energy storage device is provided. The method includes the steps of mixing a dry Group 14 active material with a dry graphite material to form a dry active material mixture, mixing the dry active material mixture with a dry binder to form a dry electrode film mixture, and calendering the dry electrode film mixture to form a self-supporting dry electrode film.

[0010] All of these embodiments are intended to be within the scope of the invention disclosed herein. These and other embodiments of the invention will be readily apparent to those skilled in the art from the following detailed description of the preferred embodiments with reference to the accompanying drawings, but the invention is not limited to any particular preferred embodiment disclosed.

Brief Description of the Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0012] Various embodiments of electrode films for use in energy storage devices are described. In particular, in certain embodiments, the energy storage devices disclosed herein include an anode electrode film containing a silicon material. The electrode film exhibits improved mechanical and processing properties compared to typical silicon-containing electrode films. Also provided is a method of manufacturing such an electrode film. The present invention reveals that when the particle size of specific components is within the range provided herein, the material of the electrode film can be realized.

[0013] Lithium-ion batteries, for example, have long been trusted as numerous commercial and industrial power sources in consumer devices, productivity devices, and battery-powered vehicles. However, the requirements for energy storage devices are continuously and rapidly increasing. For example, the automotive industry is developing vehicles that rely on small and efficient energy storage, such as plug-in hybrid vehicles and pure electric vehicles.

[0014] Group 14 semimetals and metals, such as tin and silicon, are the anodes of energy storage devices is known as a high-energy active material that is desirably included in the anode. One silicon atom is considered capable of accommodating 4.4 equivalents of lithium ions. Theoretically, the material formed could be Li 4.4 4.4 Si. Thus, in principle, silicon anode materials have the potential to store approximately 11 times the capacity of graphite (372 mAh / g) (4200 mAh / g and 97 82 mAh / L). Silicon has been described as a high-capacity anode material. Tin is another Group 14 element described herein as an anode active material.

[0015] However, some properties of Group 14 semimetals and metals, particularly silicon, present challenges in the implementation in actual devices. In particular, silicon is thought to undergo a relatively large volume change during lithiation and delithiation. Such changes can lead to a loss of cohesion and / or adhesion of the electrode film during cycling, which results in high contact resistance within the electrode and can ultimately contribute to cell failure. Further, silicon is typically incorporated into the electrode as nanoparticles. Such nanoparticles require a larger amount of binder, up to 30% by mass, to maintain film integrity. Additionally, in a wet manufacturing process, a larger amount of solvent is required to suspend the nanoparticles. Therefore, when formulating silicon, where improvement in electrode film capacity is desired, there is a risk of degradation in the stability and processability of the electrode film. Accordingly, there is a need for an electrode film containing silicon that maintains cyclability and is compatible with industrial processing techniques.

[0016] The silicon material may include nanoparticles, nanowires, and silicon / graphene composite materials. Anodes of silicon nanoparticles and nanowires are expected to benefit from a fairly high binder load (~30 wt%) and solvents in the wet electrode coating process due to the large surface area of these materials. One approach to using silicon in anodes is to combine silicon and graphite to form a silicon / graphite composite. However, the silicon content in the silicon / graphite composite can be limited by the properties of the material, which are expected to affect the electrochemical performance of the silicon / graphite composite electrode, such as achieving volume expansion and uniform dispersion of silicon.

[0017] One embodiment includes an electrode film manufactured including various electrode materials such as graphite, silicon, silicon oxide, silicon-graphene, silicon-aluminum alloy, tin / graphene, and various polymer binders. Group 14 active materials including silicon active materials have been found to provide an anode electrode film that is processable while increasing the energy storage capacity, together with graphite in the anode. One embodiment is a silicon-containing anode electrode film including a first graphite material having a particle size greater than about 10 μm and a second graphite material having a particle size less than about 10 μm.

[0018] The materials and methods described herein may result in a higher Si content in the synthetic anode electrode film being advantageous and may provide a high energy density electrode. A dry anode electrode film including the silicon / graphite composite anode active material described herein can provide an electrochemical charge capacity comparable to its theoretical charge capacity. Thus, the silicon active material in the dry silicon / graphite composite anode electrode film is electrochemically active and may be accessible over charge / discharge cycles.

[0019] The terms "battery" and "capacitor" are given their ordinary and customary meaning to those of ordinary skill in the art. The terms "battery" and "capacitor" are not mutually exclusive. A capacitor or battery is a single electrochemical cell that may operate alone or as a component of a multi-cell system.

[0020] The voltage of the energy storage device is the operating voltage of a single battery or capacitor cell. The voltage may exceed or be below the rated voltage under load or according to manufacturing tolerances.

[0021] The term "self-supporting" electrode film is an electrode film that incorporates a binder matrix structure sufficient to support the film or layer and maintain its shape so that the electrode film or layer can be self-standing. When incorporated into an energy storage device, the self-supporting electrode membrane or active layer incorporates such a binder matrix structure. Generally, and depending on the method of use, such an electrode film has sufficient strength to be employed in the manufacturing process of an energy storage device without the use of external support elements such as current collectors or other films. For example, a "self-supporting" electrode film can have sufficient strength to be wound, handled, and unwound during the electrode manufacturing process without other support elements. Dry electrode films such as cathode electrode films or anode electrode films may be self-supporting.

[0022] A "solvent-free" electrode film is an electrode film that does not contain detectable processing solvents, processing solvent residues, or processing solvent impurities. Dry electrode membranes such as cathode electrode membranes or anode electrode membranes can be solvent-free.

[0023] A "wet" electrode, "wet process" electrode, or slurry electrode is an electrode prepared by at least one step involving a slurry of active material, binder, and optionally additives. A wet electrode may contain a processing solvent, processing solvent residues, and / or processing solvent impurities.

[0024] A "non-destructive" process is a process in which the electrode active material, including the surface of the electrode active material, is not substantially modified during the process. Thus, the analytical characteristics and / or performance in applications such as incorporation of the active material into an energy storage device are the same or substantially the same as those that have not undergone the process. For example, a coating on the active material may not be disturbed or may be substantially undisturbed during the process. Non-limiting examples of non-destructive processes are "non-destructive mixing or blending", where under reduced pressure, an increase in feed rate, a decrease in speed (e.g., blender speed), and / or shear applied to the active material are varied such that other process parameters remain below a threshold at which the analytical characteristics and / or performance of the active material are adversely affected when implemented in an energy storage device, such as jet milling. A "non-destructive" process can be distinguished from a high-shear process that substantially modifies the electrode active material, such as the surface of the electrode active material, and substantially affects the analytical characteristics and / or performance of the active material. For example, high-shear blending or high-shear jet milling can have an adverse effect on the surface of the electrode active material. High-shear processes can be carried out to provide other advantages, such as fibrillation of the binder material or formation of a binder / active material matrix to assist in the formation of a self-supporting electrode film, without impairing the surface properties of the active material. Embodiments herein can provide similar benefits while avoiding the detrimental effects of excessive use of high-shear processes. Generally, the non-destructive processes herein are carried out at one or more of a higher feed rate, a lower speed, and / or a lower pressure, resulting in a lower shear process than a destructive process that substantially modifies the electrode active material and affects its performance.

[0025] Silicon-containing self-supporting anode electrode film By optimizing the shape and size of the electrode material and changing the material composition in the electrode formulation, silicon- and / or tin-containing electrodes with high energy density can be manufactured by dry processing methods. The graphite material can include artificial graphite such as synthetic graphite, natural graphite, and mixtures of graphite. Generally, the graphite material may have different properties such as mass ratio, particle size, particle shape, and raw material.

[0026] One embodiment is a free-standing and / or self-supporting silicon / graphite composite dry film having a high silicon content. The dry film can be manufactured by using two different sizes of graphite. The primary graphite may have a particle size of about 20 - 30 μm, and the secondary graphite material has a smaller particle size, for example, having a particle size of 4 - 7 microns. It has been found that using different sizes of graphite enables the use of a relatively high silicon content up to 10 - 30% by mass and allows the production of a strong and thin dry film with roll-to-roll electrode processability.

[0027] In some embodiments, the anode electrode film provided herein includes at least one active material and at least one binder. The at least one active material generally includes a Group 14 active material, such as a silicon active material and / or a tin active material, and at least one carbon-based material, such as a graphite material.

[0028] One embodiment is a method for manufacturing a self-supporting anode electrode film containing silicon produced when including a plurality of graphite materials with different particle sizes. The graphite materials can be distinguishable by, for example, raw materials such as natural or artificial graphite, surface properties, particle size, surface area, and / or particle shape. In some embodiments, at least one primary graphite (PG) and at least one secondary graphite (SG) are included in the anode electrode film.

[0029] At least one primary graphite and at least one secondary graphite can be distinguished as having two different particle sizes. In some embodiments, at least one primary graphite having a first average particle size (i.e., D 50 ) and at least one secondary graphite having a smaller second average particle size are included in the silicon-containing electrode film. The at least one primary graphite may be artificial graphite or natural graphite having a particle size greater than about 10 μm. The at least one secondary graphite may be artificial graphite or natural graphite having a particle size less than 10 μm. In some embodiments, the at least one primary graphite has an average particle size of about 10 μm, about 15 μm, about 20 μm, about 25 μm, about 30 μm, about 35 μm, or about 40 μm, or any value therebetween. In further embodiments, the at least one secondary graphite has an average particle size of about 1 μm, about 2 μm, about 3 μm, about 4 μm, about 5 μm, about 6 μm, about 7 μm, about 8 μm, about 9 μm, or about 10 μm, or any value therebetween. In certain embodiments, the at least one primary graphite has an average particle size of about 22 - 30 μm and the at least one secondary graphite has an average particle size of about 4 - 7 μm. In further embodiments, the anode electrode film includes a first primary graphite and a second primary graphite in combination with the secondary graphite as described above. In further embodiments, the anode electrode film includes a first secondary graphite and a second secondary graphite in combination with the primary graphite as described above. In further embodiments, the anode electrode film further includes a third primary graphite and / or a third secondary graphite.

[0030] The anode electrode film can include primary graphite (PG) and secondary graphite (SG) in various mass ratios, for example, PG:SG can be from 10:1 to 1:10. In various embodiments, the PG:SG mass ratio can be, for example, about 10:1, about 8:1, about 6:1, about 5:1, about 4:1, about 3:1, about 2:1, about 1:1, about 1:2, about 1:3, about 1:4, about 1:5, about 1:6, about 1:8, or about 1:10, or any value within the range therebetween.

[0031] Each of at least one primary graphite and / or at least one secondary graphite may be natural graphite or artificial graphite. Each of at least one primary graphite and / or at least one secondary graphite may be characterized by a particle shape such as, for example, spherical, flaky, elliptical, or irregular shape. Each of the primary graphite and / or secondary graphite may include a surface coating. In some embodiments, at least one primary graphite includes natural graphite or synthetic graphite. In further embodiments, at least one secondary graphite includes natural graphite or synthetic graphite.

[0032] The anode electrode film generally includes an anode active material. The anode active material can include at least one primary graphite, at least one secondary graphite, and a Group 14 active material, for example, a silicon active material or a tin active material. The silicon active material in the anode electrode film can include pure silicon, silicon oxide, pre-lithiated silicon, or a silicon-carbon composite. The silicon active material can be selected from pure silicon (Si), silicon oxide (SiO), a silicon alloy, for example, Si-Al or Si-Sn. The silicon active material can include a silicon-carbon composite. The silicon-carbon composite can be, for example, Silicon carbide (SiC), silicon graphite (Si / C), silicon oxide carbide (SiOC), silicon oxide graphite (SiO / C), prelithiated silicon graphite, and prelithiated silicon carbide. In some embodiments, the prelithiated silicon graphite may be a prelithiated silicon oxide graphite composite. The silicon active material may be SiH. The silicon active material may be prelithiated silicon. The prelithiated silicon is Li x SiO y or Li x Si y may be incorporated into the electrode film as. The particle size of the silicon active material may be on the nanoscale, i.e., about 1 nm to about 1000 nm, or on the microscale, i.e., about 1 μm to about 1000 μm. The silicon active material can include particles having a primary particle size of about 30 nm to about 10 μm. The silicon active material may include particles having a primary particle size of about 100 nm, about 250 nm, about 500 nm, about 1 μm, about 2 μm, about 4 μm, about 6 μm, about 8 μm, or about 10 μm, or any value therebetween. In some embodiments, the silicon active material is a commercially available material used without further treatment.

[0033] In some embodiments, the anode electrode film comprises, or occupies, about 1 wt%, about 2 wt%, about 3 wt%, about 5 wt%, about 7.5 wt%, about 10 wt%, about 15 wt%, about 20 wt%, about 25 wt%, about 30 wt%, about 40 wt%, or about 50 wt% of silicon, or any value therebetween. In further embodiments, the anode electrode film or anode electrode film mixture comprises, or occupies, about 1 - 30 wt% of silicon, or 10 - 30 wt% of silicon. In still further embodiments, the anode electrode film or anode electrode film mixture comprises, or occupies, about 1 - 5 wt% of silicon, or 5 - 15 wt% of silicon. In some embodiments, the anode electrode film comprises, or occupies, about 1%, about 2%, about 3%, about 5%, about 7.5%, about 10%, about 15%, about 20%, about 25%, about 30%, about 40%, or about 50 wt%, or any value therebetween of a Group 14 active material. In further embodiments, the anode electrode film or anode electrode film mixture comprises, or occupies, about 1 - 30 wt% of the Group 14 active material, or 10 - 30 wt% of the Group 14 active material. In still further embodiments, the anode electrode film or anode electrode film mixture comprises, or occupies, about 1 - 5 wt% of the Group 14 active material, or 5 - 15 wt% of the Group 14 active material. Typically, an anode electrode film containing a Group 14 active material, such as a silicon active material, in a specified amount (such as a percentage) contains the specified amount of the Group 14 active material, and the remainder of the active material is graphite. Unless otherwise specified, the wt% of the Group 14 active material is relative to the total mass of the electrode film material including the active material, binder, and any other additives.

[0034] Anode active materials containing silicon active materials and graphite can be classified, for example, as insertion materials (such as carbon, graphite, and / or graphene), alloying / dealloying materials (such as silicon, silicon oxide (SiOx), aluminum, tin, and / or tin oxide (SnOx)), metal alloys or compounds (such as Si-Al and / or Si-Sn), and / or conversion materials (transition metal oxides, for example, manganese oxide (MnOx), molybdenum oxide (MoO2), nickel oxide (NiOx), and / or copper oxide (CuOx)). The anode active materials can be used alone or mixed together to form multiphase materials (such as Si-C, Sn-C, SiOx-C, SnOx-C, Si-Sn, Si-SiOx, Sn-SnOx, Si-SnOx-C, Sn-SnOx-C, Si-Sn-C, SiOx-Sn, or Sn-SiOx-SnOx). The silicon active materials can include nanoparticles. In some embodiments, the anode active material includes a single Group 14 active material. In further embodiments, the anode active material includes a single Group 14 element. In yet another embodiment, the anode active material includes a plurality of Group 14 elements. In still further embodiments, the anode active material includes silicon and tin.

[0035] As shown in Table 1, Table 2, and Table 3, the anode active material can include various combinations of silicon and graphite active materials. As shown in each formulation example of Table 1, Table 2, and Table 3, the ratios of primary graphite, secondary graphite, and silicon active materials can be varied.

[0036] [Table 1]

[0037] [Table 2]

[0038] [Table 3]

[0039] The anode electrode film described in this specification can have a film thickness of at least 50 μm, for example, about 50 μm, about 100 μm, about 150 μm, about 200 μm, about 225 μm, about 250 μm, about 275 μm, about 300 μm, or about 400 μm, or any value therebetween.

[0040] The anode electrode film described herein has an active material loading of at least about 10 mg / cm 2 , for example, about 10 mg / cm 2 , about 15 mg / cm 2 , about 20 mg / cm 2 , about 25 mg / cm 2 , about 30 mg / cm 2 , about 35 mg / cm 2 , about 40 mg / cm 2 , or can have an active material loading of any value therebetween (which can be expressed as the mass per unit area of the electrode film or current collector).

[0041] In some embodiments, the silicon-containing anode electrode film can provide a Coulombic efficiency of about 75%, about 78%, about 80%, about 82%, about 84%, about 86%, about 88%, about 90%, about 92%, about 94%, or any value therebetween.

[0042] In some embodiments, the silicon-containing anode electrode film can provide an energy density (which can be expressed as the energy per mass of the electrode film) of about 1000 Wh / kg, about 1200 Wh / kg, about 1400 Wh / kg, about 1600 Wh / kg, about 1800 Wh / kg, about 2000 Wh / kg, or any value within any range therebetween.

[0043] In some embodiments, the silicon-containing anode electrode film can provide a specific energy storage (which can be expressed as the energy per unit volume of the final or in-situ electrode film) of about 2000 Wh / L, about 3000 Wh / L, about 4000 Wh / L, about 5000 Wh / L, or any value in between.

[0044] In some embodiments, the silicon-containing anode electrode film can provide a specific capacity during charging or discharging of about 400 mAh / g, about 500 mAh / g, about 600 mAh / g, about 700 mAh / g, about 800 mAh / g, about 1000 mAh / g, about 1500 mAh / g, about 2000 mAh / g, about 3000 mAh / g, or any value in between.

[0045] In some embodiments, the silicon-containing anode electrode film can provide a measured specific capacity of at least 95% of its theoretical capacity, such as about 95%, about 96%, about 97%, about 98%, about 99%, about 99.9%, or any value in between.

[0046] One or more binders are polytetrafluoroethylene (PTFE), polyolefin, polyalkylene, polyether, styrene butadiene rubber (SBR), polysiloxane and copolymers of polysiloxane, branched polyether, polyvinyl ether, polyacrylic acid, polyvinyl carbonate, copolymers thereof, and / or mixtures thereof It can include. One or more binders can further include guar, alginic acid, poly[(isobutylene-alt-maleic acid, ammonium salt)-co-isobutylene-alt-maleic anhydride], poly(ethylene-alt-maleic anhydride), poly(methyl vinyl ether-alt-maleic anhydride), polyacrylonitrile (PAN), poly(methyl methacrylate) (PMMA), poly(vinyl chloride) (PVC), and polyvinyl ether. The binder can include cellulose. In some embodiments, the polyolefin can include polyethylene (PE), polypropylene (PP), polyvinylidene fluoride (PVDF), their copolymers, and / or their mixtures. For example, the binder can be polyvinylidene chloride, poly(phenylene oxide) (PPO), polyethylene -block-poly(ethylene glycol), poly(ethylene oxide) (PEO), poly( phenylene oxide) (PPO), polyethylene-block-poly(ethylene glycol) , polydimethylsiloxane (PDMS), polydimethylsiloxane-coal alkyl methylsiloxane, their copolymers, and / or their mixtures. In certain embodiments, the fibrillatable binder is PTFE. The dry self-supporting electrode film can include the interpenetrating network of the aforementioned binders.

[0047] The binder may contain cellulose or a derivative of cellulose. Examples of cellulose derivatives include cellulose esters such as cellulose acetate; cellulose ethers such as methyl cellulose, ethyl cellulose, hydroxypropyl cellulose (HPC), hydroxypropyl methyl cellulose, or hydroxyethyl cellulose (HEC); cellulose nitrate; cellulose chitosan such as carboxymethyl cellulose chitosan; or carboxyalkyl cellulose such as carboxymethyl cellulose (CMC), carboxyethyl cellulose, carboxypropyl cellulose, or carboxyisopropyl cellulose. In a further embodiment, the cellulose or cellulose derivative may contain a cellulose salt. In yet a further embodiment, the cation of the cellulose salt may be selected from sodium, ammonium, calcium, or lithium. For example, the cellulose or cellulose derivative may contain a sodium cellulose or sodium cellulose derivative selected from sodium cellulose ester, sodium cellulose ether, sodium cellulose nitrate, or sodium carboxyalkyl cellulose. CMC may include sodium carboxymethyl cellulose. In some embodiments, one or more binders include CMC, PVDF, and / or PTFE.

[0048] In some embodiments, the silicon-containing anode electrode film provided herein includes a graphite material selected for such a film. In some embodiments, a graphite-containing formulation is provided to enable a dry electrode process for the silicon-containing anode electrode film provided herein. In a further embodiment, the anode electrode film is a self-supporting film. In some embodiments, the silicon-containing anode electrode film provided herein includes a silicon mass loading of greater than 10% by mass. In some embodiments, the silicon-containing anode electrode film provided herein includes a non-aqueous carbonate-based electrolyte to improve performance.

[0049] The electrode film described herein, or an energy storage device incorporating the electrode film described herein, can advantageously be characterized by an improved specific capacity (which may be measured in mAh / g). Further improvements that can be realized in various embodiments include a reduction in the decrease in the ability of the device over its lifetime, as compared to a typical silicon-containing electrode film.

[0050] The self-supporting anode electrode film described herein has an improved maximum tensile strength (which can be measured in Newtons (N) from a film having a width of 20 millimeters). In some embodiments, the maximum tensile strength of the anode electrode film is at least about 2 N, such as about 2 N, about 2.5 N, about 3 N, about 3.5 N, about 4 N, or any value therebetween.

[0051] Some embodiments relate to dry electrode processing techniques. The dry electrode manufacturing process can be assumed to be disclosed in one or more of U.S. Patent Application Publication No. 2006 / 0114643, U.S. Patent Application Publication No. 2006 / 0133013, U.S. Patent No. 9,525,168, or U.S. Patent No. 7,935,155, each of which is hereby incorporated by reference in its entirety.

[0052] In some embodiments, a method of manufacturing a self-supporting electrode film is provided. With reference to FIG. 2, method 200 can include a step of selecting a Group 14 active material (205), a step of combining (e.g., mixing) the Group 14 active material with one or more graphite materials such as a first and a second graphite material to form an active material mixture (210), a step of mixing the active material mixture with a binder to form an electrode film mixture (215), and a step of calendaring the electrode film mixture to form a self-supporting and / or self-standing electrode film (220). Step 210 may include blending or milling the Group 14 active material and the graphite to disperse the particles. In some embodiments, each step is dry and solvent-free. In further embodiments, the Group 14 active material is a silicon active material. In still further embodiments, the binder is a fibrillatable binder such as PTFE. Some embodiments can include a premixing step prior to step 210, including premixing the dry Group 14 active material with a dry binder. The dry binder used in such a premixing step may be the same or a different substance than the binder used in step 215.

[0053] In various embodiments, a dry powder, e.g., a mixture comprising binder particles and / or active material particles, can be formed by gentle steps using, e.g., a tumbler, paddle mixer, blade blender, or acoustic mixer, with and without a mixing medium (e.g., glass beads, ceramic balls), such as a convection, pneumatic, or diffusive mixer (e.g., in step 210, 215, or the aforementioned premixing step of method 200). The gentle mixing process can be non-destructive with respect to any active material in the mixture. Without limitation, graphite particles and / or silicon active material particles may retain their size after the gentle mixing process. In further embodiments, the sequence and conditions of powder mixing can be varied to improve the uniform distribution of the active material, binder, and any additives. Gentle premixing can also enhance the structural stability of group 14 active materials, such as silicon, during the cycles of an energy storage device.

[0054] In various embodiments, a dry powder, e.g., a mixture comprising binder particles and / or active material particles, can be formed by high shear steps, such as high shear blending or high shear jet milling (e.g., in step 210, 215, or the aforementioned premixing step of method 200). High shear premixing can enhance the contact between a group 14 active material, such as silicon, and one or more binders. In further embodiments, the sequence and conditions of powder mixing can be varied to improve the uniform distribution of the active material, binder, and any additives.

[0055] The materials and methods provided herein can be implemented in various energy storage devices. As provided herein, the energy storage device can be a capacitor, lithium-ion capacitor (LIC), ultracapacitor, lithium-ion battery, etc. battery, or a hybrid energy storage device combining two or more of the aforementioned aspects. In a preferred embodiment, the device is a lithium-ion battery.

[0056] The energy storage device provided herein may be of any suitable shape, such as planar, helically wound, button-shaped, or a pouch. The energy storage device provided herein may be a component of a system, such as a power generation system, an uninterruptible power supply (UPS) system, a solar power generation system, or an energy recovery system used, for example, in industrial machinery and / or transportation. The energy storage device provided herein may be used to power various electronic devices and / or vehicles, including hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and / or electric vehicles (EVs).

[0057] FIG. 1 shows a schematic side cross-sectional view of an example of an energy storage device 100 having an electrode film including a silicon-containing anode electrode film provided herein. The energy storage device 100 can be classified, for example, as a capacitor, a battery, a capacitor-battery hybrid, or a fuel cell. In a preferred embodiment, the device 100 is a lithium-ion battery.

[0058] This device has a silicon-based anode 102, a cathode 104, and a separator 106 disposed between the anode 102 and the cathode 104. The anode 102 and the cathode 104 are adjacent to respective opposing surfaces of the separator 106. The energy storage device 100 includes an electrolyte 118 for facilitating ionic communication between the anode 102 and the cathode 104 of the energy storage device 100. The electrolyte 118, the anode 102, the cathode 104, and the separator 106 are housed within an energy storage device housing 120.

[0059] The energy storage device housing 120 may be sealed around the first electrode 102, the second electrode 104, and the separator 106 and may be physically sealed from the surrounding environment.

[0060] Separator 106 is configured to electrically insulate the anode 102 from the cathode 104 while enabling ionic communication between two adjacent electrodes. The separator 106 can include a suitable porous electrical insulating material. In some embodiments, the separator 106 can include a polymer material. For example, the separator 106 can include a cellulose material (e.g., paper), a polyethylene (PE) material, a polypropylene (PP) material, and / or a polyethylene and polypropylene material.

[0061] Generally, the anode 102 and the cathode 104 each include a current collector and an electrode film. For example, the anode 102 includes an electrode film 112, and the cathode 104 includes an electrode film 114, respectively. The electrode films 112 and 114 can have any suitable shape, size, and thickness. For example, the electrode film can have a thickness of about 30 microns (μm) to about 250 microns, such as about 50 microns, about 100 microns, about 150 microns, about 200 microns, about 250 microns, about 300 microns, about 400 microns, about 500 microns, about 750 microns, about 1000 microns, about 2000 microns, or a value therebetween. The electrode film generally includes one or more active materials, such as the anode active material or the cathode active material provided herein. The electrode films 112 and / or 114 can be dry and / or self-supporting electrode films as provided herein and can have beneficial properties such as tensile strength or capacitance as provided herein. The first electrode film 112 and / or the second electrode film 114 can include a Group 14 active material, such as a silicon active material, as described herein. This is also possible. As shown, the first electrode film 112 includes silicon active material particles 122 and graphite active material particles 124. The electrode films 112 and / or 114 can be prepared by methods as described herein. The electrode films 112 and / or 114 can be wet electrodes or self-supporting dry electrodes as described herein.

[0062] The first current collector 108 and the second current collector 110 facilitate the electrical coupling between their respective corresponding electrode films and an external electrical circuit (not shown). The first current collector 108 and / or the second current collector 110 can include one or more conductive materials and can have any suitable shape and size selected to facilitate the movement of charge between the corresponding electrode and the external circuit. For example, the current collector can include a metal material such as aluminum, nickel, copper, rhenium, niobium, tantalum, and precious metals such as silver, gold, platinum, palladium, rhodium, osmium, iridium, as well as alloys and combinations of these materials. For example, the first current collector 108 and / or the second current collector 110 can include, for example, aluminum foil or copper foil. The first current collector 108 and / or the second current collector 110 can have a rectangular or substantially rectangular shape sized to provide for the movement of charge between the corresponding electrode and the external circuit.

[0063] In some embodiments, the energy storage device 100 can be a lithium-ion battery. In some embodiments, the electrode film of the lithium-ion battery electrode can include a silicon active material.

[0064] In a further embodiment, the energy storage device 100 is charged with a suitable lithium-containing electrolyte. For example, the device 100 can include a lithium salt and a solvent such as a non-aqueous or organic solvent. Generally, the lithium salt includes an anion with redox stability. In some embodiments, the anion can be monovalent. In some embodiments, the lithium salt can be selected from lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium bis(trifluoromethanesulfonyl)imide (LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (F2NO4S2Li), lithium trifluoromethanesulfonate (LiSO3CF3), lithium bis(oxalato)borate (LiBC2O4)2, and combinations thereof. In some embodiments, the electrolyte can include a quaternary ammonium cation and an anion selected from the group consisting of hexafluorophosphate, tetrafluoroborate, and iodide. In some embodiments, the salt concentration is from about 0.1 mol / L (M) to about 5 M, from about 0.2 M to about 3 M, or from about 0.3 M to about 2 M. This may also be the case. In a further embodiment, the salt concentration of the electrolyte may be from about 0.7 M to about 1 M. In certain embodiments, the salt concentration of the electrolyte may be about 0.2 M, about 0.3 M, about 0.4 M, about 0.5 M, about 0.6 M, about 0.7 M, about 0.8 M, about 0.9 M, about 1 M, about 1.1 M, about 1.2 M, or a value therebetween.

[0065] In some embodiments, the energy storage device electrolytes provided herein can include a liquid solvent. The solvent provided herein need not dissolve all components of the electrolyte, nor does any component need to be completely dissolved. In further embodiments, the solvent can be an organic solvent. In some embodiments, the solvent can include one or more functional groups selected from carbonates, ethers, and / or esters. In some embodiments, the solvent can include a carbonate. In further embodiments, the carbonate can be selected from cyclic carbonates such as, for example, ethylene carbonate (EC), propylene carbonate (PC), vinyl ethylene carbonate (VEC), vinylene carbonate (VC), fluoroethylene carbonate (FEC), and combinations thereof, or non-cyclic carbonates such as, for example, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and combinations thereof. In certain embodiments, the electrolyte can include LiPF6 and one or more carbonates.

[0066] In some embodiments, the electrolyte solvent includes ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and propylene carbonate (PC). In further embodiments, the electrolyte solvent includes ethylene carbonate (EC) and dimethyl carbonate (DMC). In still further embodiments, the electrolyte solvent includes ethylene carbonate (EC) and ethyl methyl carbonate (EMC). In further embodiments, the electrolyte solvent includes ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC). The electrolyte solvent may include an EMC-rich solvent formulation. The electrolyte may further include an additive. The electrolyte additive may be a carbonate, such as fluoroethylene carbonate (FEC) or diallyl pyrophosphate (DAPC). The electrolyte additive may be cyclohexane (CH). The electrolyte solvent can include the additive in an amount of about 1 wt% to about 30 wt%, such as about 1 wt% to about 20 wt% or about 1 wt% to about 10 wt%.

[0067] Table 4 provides embodiments of electrolyte formulations that include a carbonate solvent, a lithium salt, and one or more additives, where the one or more additives were FEC, CH, and / or DAPC. Certain embodiments provide each of Electrolytes 1-4 having a volume ratio of EC:EMC of about 3:7. Further embodiments provide each of Electrolytes 1-4 having a LiPF6 salt concentration of about 1.2 M. In Table 4, the wt% of each additive is relative to the total weight of the electrolyte including the solvent, salt, and additive.

[0068] [Table 4]

[0069] The materials and methods provided herein can be implemented in various energy storage devices. As provided herein, the energy storage device can be a capacitor, a lithium-ion capacitor (LIC), an ultracapacitor, a battery, or a hybrid energy storage device and / or a hybrid cell, and two or more of these aspects can be combined. In a preferred embodiment, the device is a battery. The energy storage device can be characterized by an operating voltage. In some embodiments, the energy storage device described herein can have an operating voltage of about 0V to about 5V. In further embodiments, the operating voltage can be about 2.7V to about 4.2V, about 3.0V to about 4.2V, or a value therebetween.

[0070] In some embodiments, the lithium-ion battery is configured to operate at about 2.5 - 5V, i.e., 3.0 - 4.2V. In further embodiments, the lithium-ion battery is configured to have a minimum operating voltage of about 2.5V to about 3V, respectively. In yet another embodiment, the lithium-ion battery is configured to have a maximum operating voltage of about 4.1V to about 4.4V, respectively.

[0071] In some embodiments, the electrode film provided herein includes at least one active material and at least one binder. The at least one active material can be any active material known in the art. The at least one active material can be a material suitable for use in the anode or cathode of a battery. The cathode active material can be, for example, a metal oxide, a metal sulfide, a sulfur-carbon composite, or a lithium metal oxide. ​The lithium metal oxide can be, for example, lithium nickel manganese cobalt oxide (NMC), lithium manganese oxide (LMO), lithium iron phosphate (LFP), lithium cobalt oxide (LCO), lithium titanate (LTO), lithium nickel manganese oxide (LNMO) and / or lithium nickel cobalt aluminum oxide (NCA). In some embodiments, the cathode active material is, for example, a layered transition metal oxide (such as LiCoO2 (LCO), Li(NiMnCo)O2 (NMC) and / or LiNi 0.8 Co 0.15 Al 0.05 O2 (NCA), etc.), spinel manganese oxide (such as LiMn2O4 (LMO) and / or LiMn 1.5 Ni 0.5 O4 (LMNO), etc.) or olivine (such as LiFePO4). The cathode active material can include sulfur, or a material containing sulfur such as lithium sulfide (Li2S), or other sulfur-based materials, or a mixture thereof. In some embodiments, the cathode film includes sulfur, or a material containing at least 50% by mass of a sulfur active material. In some embodiments, the cathode film containing sulfur or a material containing a sulfur active material has a specific capacity normalized by area (i.e., areal capacity) of at least 10 mAh / cm 2 . In some embodiments, the cathode film containing sulfur or a material containing a sulfur active material has an electrode film concentration of 1 g / cm 3 . In some embodiments, the cathode film containing sulfur or a material containing a sulfur active material further includes a binder.

[0072] At least one active material may include one or more carbon materials. The carbon material may be selected, for example, from graphite materials, graphite, graphene-containing materials, hard carbon, soft carbon, carbon nanotubes, porous carbon, conductive carbon, or combinations thereof. Graphite may be synthetic or of natural origin. Activated carbon can be obtained from a steam process or an acid / etching process. In some embodiments, the graphite material may be a surface-treated material. In some embodiments, the porous carbon can include activated carbon. In some embodiments, the porous carbon can include hierarchically structured carbon. In some embodiments, the porous carbon can include structured carbon nanotubes, structured carbon nanowires, and / or structured carbon nanosheets. In some embodiments, the porous carbon can include graphene sheets. In some embodiments, the porous carbon may be surface-treated carbon.

[0073] In some embodiments, the cathode electrode film of a lithium ion battery or a hybrid energy storage device can include at least one active material in an amount of from about 70 wt% to about 98 wt%, from about 70 wt% to about 92 wt%, or from about 70 wt% to about 96 wt%. In some embodiments, the cathode electrode film can include a porous carbon material in an amount of up to about 10 wt%, or from about 1 wt% to about 5 wt%. In some embodiments, the cathode electrode film includes a conductive additive in an amount of up to about 5 wt% including from about 1 wt% to about 3 wt%. In some embodiments, the cathode electrode film includes a binder in an amount of up to about 20 wt%, such as from about 1.5 wt% to 10 wt%, from about 4 wt% to 10 wt%, from about 1.5 wt% to 5 wt%, or from about 1.5 wt% to 3 wt%. In some embodiments, the cathode electrode film includes a binder in an amount of from about 1.5 wt% to about 3 wt%.

[0074] In some embodiments, the anode electrode film can include at least one active material, a binder, and optionally a conductive additive. In some embodiments, the conductive additive can include a conductive carbon additive such as carbon black. In some embodiments, at least one active material of the anode can include synthetic graphite, natural graphite, hard carbon, soft carbon, graphene, mesoporous carbon, silicon, silicon oxide, tin, tin oxide, germanium, lithium titanate, a mixture of the foregoing materials, or a composite. In some embodiments, the anode electrode film can include from about 80 wt% to about 98 wt%, or from about 94 wt% to about 97 wt%, of at least one active material, including from about 80 wt% to about 98 wt%. In some embodiments, the anode electrode film includes a conductive additive of up to about 5 wt% including from about 1 wt% to about 3 wt%. In some embodiments, the anode electrode film includes a binder of up to about 20 wt% including from about 1.5 wt% to 10 wt%, from about 4 wt% to 10 wt%, from about 1.5 wt% to 5 wt%, or from about 3 wt% to 5 wt%. In some embodiments, the anode electrode film includes about 4 wt% of the binder. In some embodiments, the anode film may not include a conductive additive.

[0075] One or more binders can include polytetrafluoroethylene (PTFE), polyolefin, polyalkylene, polyether, styrene-butadiene, polysiloxane and co polymers of polysiloxane, branched polyether, polyvinyl ether, polyacrylic acid, copolymers thereof, and / or mixtures thereof. The binder can include cellulose. In some embodiments, the polyolefin can include polyethylene (PE), polypropylene (PP), polyvinylidene fluoride (PVDF), copolymers thereof, and / or mixtures thereof. For example, the binder can be polyvinyl chloride, poly(phenylene oxide) (PPO), polyethylene-block-poly( (ethylene glycol), poly(ethylene oxide) (PEO), poly(phenylene oxide) (PPO), polyethylene-block-poly(ethylene glycol), polydimethylsiloxane (PDMS), polydimethylsiloxane-core alkylmethylsiloxane, copolymers thereof, and / or mixtures thereof. In certain embodiments, the fibrillatable binder is PTFE. The dry self-supporting electrode film can include an interpenetrating network of the aforementioned binders.

[0076] The binder can include cellulose or a derivative of cellulose. Derivatives of cellulose can include, for example, cellulose esters such as cellulose acetate; cellulose ethers such as methylcellulose, ethylcellulose, hydroxypropylcellulose (HPC), or hydroxyethylcellulose (HEC); cellulose nitrate; or carboxyalkylcelluloses such as carboxymethylcellulose (CMC), carboxyethylcellulose, carboxypropylcellulose, or carboxyisopropylcellulose. In further embodiments, the cellulose or cellulose derivative can include a cellulose salt. In still further embodiments, the cation of the cellulose salt can be selected from sodium, ammonium, or lithium. For example, the cellulose or cellulose derivative can include a sodium cellulose or sodium cellulose derivative selected from sodium cellulose ester, sodium cellulose ether, sodium cellulose nitrate, or sodium carboxyalkylcellulose. CMC can include sodium carboxymethylcellulose. In some embodiments, one or more binders include CMC, PVDF, and / or PTFE.

[0077] The electrode film mixture can include binder particles having a selected size, such as polytetrafluoroethylene binder particles. In some embodiments, the binder particles can be about 50 nm, about 100 nm, about 150 nm, about 200 nm, about 250 nm, about 300 nm, about 350 nm, about 400 nm, about 450 nm, about 500 nm, about 1 μm, about 2 μm, about 3 μm, about 4 μm, about 5 μm, about 10 μm, about 50 μm, about 100 μm, or values therebetween.

[0078] A dry manufacturing process can refer to a process that does not use or substantially does not use a solvent in forming the electrode film. For example, the components of the electrode film including the active material and the binder can include dry particles. Dry particles for forming the electrode film can be combined to provide a dry particle electrode film mixture. In some embodiments, the electrode film can be formed from the dry particle electrode film mixture such that the mass percentage of the components of the electrode film and the mass percentage of the components of the dry particle electrode film mixture are substantially the same. In some embodiments, the electrode film formed from the dry particle electrode film mixture using a dry manufacturing process can be free or substantially free of processing additives such as solvents and solvent residues resulting therefrom. In some embodiments, the resulting electrode film is a self-supporting film formed from the dry particle mixture using a dry method. In some embodiments, the resulting electrode film is a self-standing film formed from the dry particle electrode film mixture using a dry method. A method for forming the active layer or the electrode film can include fibrillating a fibrillatable binder component such that the film includes a fibrillated binder matrix. In a further embodiment, the self-standing electrode film can be formed in the absence of a current collector. In yet a further embodiment, the electrode film can include a fibrillated polymer matrix such that the film is self-supporting. It is believed that a matrix, lattice, or web of fibrils can be formed to provide a mechanical structure to the electrode film.

[0079] The electrode film can have a selected thickness suitable for a particular application. The thickness of the electrode film provided herein may be thicker than the thickness of the electrode film prepared by conventional processes. In some embodiments, the electrode film can have a thickness of about 250 microns, about 300 microns, about 350 microns, about 400 microns, about 450 microns, about 500 microns, about 750 microns, about 1 mm, or about 2 mm, or any value therebetween. In some embodiments, the thickness of the electrode film can be varied to correspond to a selected volumetric energy density.

[0080] In the following specific examples, an anode electrode film was fabricated and tested.

[0081] Example Preparation of Composite Dry Electrodes: The silicon / graphite composite dry electrodes of the embodiments were prepared by dry powder mixing of graphite and silicon together with electrode components, calendaring to form a self-standing film, and then laminating onto a current collector. The dry powder mixing was performed in the order of graphite / polymer binder / silicon. Specifically, the dry powder mixing was carried out as follows using a resonant acoustic mixer at 50% acceleration: primary and secondary graphite, and any group 14 active material were mixed for 5 minutes, and then CMC, PVDF, and PTFE were added while continuously mixing into the graphite mixture. The dry mixed powder was processed through a micronizing jet mill at a feed of 40 psi and a grinding pressure of 40 psi, and then calendared at 100 °C to 185 °C to form a self-standing film.

[0082] Electrochemical Property Evaluation: To perform electrochemical measurements, a single-layer anode / lithium foil half-cell was assembled into a pouch cell configuration. The electrochemical measurements were performed by applying a constant current and / or a constant potential to the anode half-cell at ambient temperature.

[0083] Example 1 Figure 3 is a graph showing the specific capacity of an exemplary silicon and graphite composite anode node electrode film compared to the theoretical specific capacity of the film. The theoretical specific capacity was determined assuming capacities of 370 mAh / g for graphite and 4200 mAh / g for silicon.

[0084] Example 2 In the embodiments of FIGS. 4A - 4C, a silicon / graphite composite electrode prepared by a dry manufacturing process was fabricated using commercially available artificial graphite (AG) and natural graphite (NG). Surprisingly, in the embodiments of FIGS. 4A - 4C, artificial graphite provided a higher electrochemical capacity in the silicon / graphite composite half - cell with a slightly lower Coulombic efficiency than natural graphite in a half - cell configuration. A more uniform distribution of silicon powder and the interconnection between artificial graphite powder and silicon nanoparticles may play a role. In the embodiments in FIGS. 4A - 4C, natural graphite provided a higher Coulombic efficiency than artificial graphite. Regarding surface - modified artificial graphite / 10 mass% Si ("AG") and natural graphite / 10 mass% Si ("NG") composite anode electrode half - cells, FIG. 4A shows the electrochemical capacity, FIG. 4B shows the Coulombic efficiency, and FIG. 4C shows the energy density. The active material load was as follows. AG: 23.5 m g / cm 2 , NG: 25 mg / cm 2 .

[0085] Example 3 Figure 5 provides a comparison of the electrochemical specific capacity and Coulombic efficiency of a graphite dry electrode ("0 wt% Si") with two embodiments of silicon / graphite dry electrodes containing 5 wt% ("5 wt% Si") and 10 wt% Si ("10 wt% Si"), respectively. In both cases, the graphite was artificial graphite. As expected, the silicon / graphite dry electrode containing 10 mass% silicon (as Si) had the highest specific capacity and energy density. The increase in the specific capacity of the 10 wt% silicon graphite composite relative to the 5 wt% silicon-containing graphite composite electrode was also proportional to the silicon content of each electrode, suggesting that the silicon active material powder was well dispersed and active under the conditions of the dry electrode processing method described herein. The active material load was 0 wt% Si: 24.5 mg / cm 2 , 5 wt% Si: 24.6 mg / cm 2 , 10 wt% Si: 23.5 mg / cm 2 .

[0086] Example 4 Figures 6A - 6C are embodiments according to Formulations 2, 3, and 4 of Table 1, and show the electrochemical performance of an Si / PG / SG composite dry electrode half-cell containing 10 mass% silicon (Si). Corresponding to each embodiment, Figure 6A provides the capacity, Figure 6B provides the efficiency, and Figure 6C provides the electrode energy density. The results showed that the choice of primary graphite affected the electrochemical capacity and Coulombic efficiency of the composite electrode. In this embodiment, natural graphite improved the electrochemical performance and energy density. The active substance load was as follows. Formulation 2: 22.5 mg / cm 2 , Formulation 3: 24.6 mg / cm 2 , Formulation 4: 22.5 mg / cm 2 .

[0087] Example 5 Figures 7A - 7C show the electrochemical performance of silicon / graphene (SiC) including a SiC / PG / SG composite dry electrode half - cell according to formulation 1 containing 15 mass% silicon active material. The electrode films were prepared with PG:SG ratios of 1:1, 1:2, 1:3, and 1:4. Both PG and SG contained artificial graphite in their respective films. Corresponding to each embodiment, Figure 7A provides the capacity, Figure 7B provides the efficiency, and Figure 7C provides the electrode energy density. As a result, it was shown that the change in the mass ratio of PG:SG has little effect on the specific capacity and effectiveness of this series of composite dry electrodes. The volume energy density is governed by the overall electrode thickness. Thus, the thickness can be changed in the electrode manufacturing step for a better arrangement of the volume energy density. The active material loadings were as follows. 1:1 film: 12.7 mg / cm 2 , 1:2 film: 12.5 mg / cm 2 , 1:3 film: 11 mg / cm 2 , 1:4 film: 11.6 mg / cm 2 .

[0088] Example 6 Figures 8A - 8C show the electrochemical performance of a PG(AG) / SG(AG) composite dry electrode half - cell containing silicon (“Si”), silicon / graphene (“SiC”), and silicon oxide (“SiO”) according to formulation 1. The electrode films were prepared with a PG:SG ratio of 3:1. Both PG and SG contained artificial graphite. The Si film contained 10% Si, the SiC film contained 15% SiC, and the SiO film contained 10% SiO. Corresponding to each embodiment, Figure 8A provides the capacity, Figure 8B provides the efficiency, and Figure 8C provides the electrode energy density. The active material loadings were Si film: 22.5 mg / cm 2 , SiC film: 12.5 mg / cm 2 , SiO film: 17 mg / cm 2 .

[0089] Example 7 Figure 9 shows the maximum tensile strength of various silicon / graphite composite dry films compared to a standard graphite dry film. The films tested were self-supporting dry electrode films and contained various anode active materials. The films tested included a natural graphite film ("NG"), an artificial graphite film ("AG"), an artificial graphite film containing 10% by mass silicon ("Si as"), a natural graphite film containing 10% by mass silicon ("10% by mass Si / NG"), and a film containing artificial graphite and natural graphite and 10% by mass silicon ("Si as") ("10% by mass Si / AG / NG"). The thickness of the films was as follows. NG film: 264 μm, AG film: 260 μm, 10 wt% Si / AG film: 248 μm, 10 wt% Si / NG film: 311 μm, 10 wt% Si / AG / NG film: 292 μm. The results showed that the silicon / graphite composite dry film exhibited an improvement in tensile strength compared to a simple graphite film. Furthermore, the anode film containing PG and SG improved the elasticity and flexibility of the self-supporting dry silicon-containing composite film with an observed increase in tensile strength.

[0090] Example 8 Figures 10A - 10C provide the electrochemical performance and energy density of four synthetic dry electrode films of SiO / PG / SG containing 10% by mass silicon active material as a half-cell and using the electrolyte formulations listed in Table 4. Corresponding to each example, Figure 10A provides the capacity, Figure 10B provides the efficiency, and Figure 10C provides the electrode energy density. As a result, it was found that the electrolyte composition affects the electrochemical ability and Coulombic efficiency, leading to a high energy density of the silicon / graphite composite dry electrode. The active material load was as follows. Electrolyte 1 film: 19.2 mg / cm 2 , Electrolyte 2 film: 17.5 mg / cm 2 , Electrolyte 3 film: 21 mg / cm 2 , Electrolyte 4 film: 19.2 mg / cm 2 .

[0091] Example 9 Figures 11A and 11B provide additional performance data regarding silicon-containing anode electrode films. The films tested were free-standing dry electrode films and contained a silicon-containing anode active material. The films tested included a typical graphite anode electrode film ("0 wt.% Si"), a 4.7 wt% silicon / graphite film ("4.7 wt.% Si"), and a 10 wt% silicon / graphite film ("10 wt.% Si"). Figures 11A and 11B demonstrate that the silicon-containing films provide a greater energy density than a typical graphite anode electrode film.

[0092] Example 10 Figure 12 provides a SEM image of the surface of a silicon-containing anode electrode film containing 4.7 mass% of nanoparticle silicon.

[0093] Example 11 Figures 13A and 13B are graphs showing the theoretical increase in capacity corresponding to various fractions of Group 14 elements as components of a graphite anode film. Theoretically, as little as 3% silicon can increase the capacity by approximately 33% compared to a typical graphite anode.

[0094] Example 12 Figures 14A and 14B provide graphs of the charge and discharge capacities of silicon- and tin-containing anode electrode films versus voltage, respectively, compared to a typical graphite film ("control"). The Group 14 elements including the films tested included graphite with 4.7 mass% silicon ("4.7 mass% Si-C") or 4.7 mass% tin ("4.7% Sn-C"). Both the silicon-containing and tin-containing films had improved capacity compared to the typical graphite control film. In the case of silicon, this increase correlates with an extended flat region around 0.4 V to 0.5 V in the graph of the charge cycle shown in Figure 14A.

[0095] Example 13 Figure 15 provides the maximum tensile strength of a dry free-standing anode electrode film containing a Group 14 active material, compared to a typical free-standing graphite film ("control"). The films tested included a first graphite film containing nanoparticle silicon ("Si-C") and a second graphite film containing nanoparticle tin ("Sn-C"). The film containing silicon had the highest tensile strength measured.

[0096] Example 14 A prelithiated silicon oxide graphite (SiO / C) half-cell was prepared and tested. Table 5 shows commercially available prelithiated SiO / C of purchased types A to C. Type C has similar physical properties to type B without a surface coating, and types A and B have surface coatings.

[0097]

Table 5

[0098] Each type of prelithiated SiO / C was used to fabricate electrodes according to the formulations detailed in Table 6. Dry powder mixing was carried out following resonant acoustic mixing at 60% strength for 5 minutes. The dry mixed powder was jet milled with a 40 psi feed and 40 psi milling. The final formulation was calendared at room temperature 50 °C to form a free-standing film, which was subsequently laminated onto a current collector at 185 °C. All calendaring and lamination steps were carried out in a drying chamber.

[0099]

Table 6

[0100] For the prelithiated Li - SiO / C composite anodes of Formulations 1 - 3 tested at a voltage of 5 mV to 2 V at a 0.05C rate, Figure 16A provides a bar graph showing the charge - discharge capacity, and Figure 16B provides a bar graph showing the efficiency. The B - type prelithiated SiO / C anode of Formulation 2 showed slightly higher efficiency, which is thought to be due to its slightly lower surface area, indicating that the uncoated prelithiated SiO / C may be processed through a dry - coating process. The load of the active material was as follows. Formulation 1: 20.4 mg / cm 2 , Formulation 2: 18.9 mg / cm 2 , Formulation 3: 17.8 mg / cm 2 .

[0101] Although specific embodiments of the present invention have been described, these embodiments are presented only as examples and are not intended to limit the scope of the present disclosure. In fact, the novel methods and systems described herein may be embodied in various other forms. Furthermore, various omissions, substitutions, and changes in the systems and methods described herein may be made without departing from the spirit of the present disclosure. The appended claims and their equivalents are intended to cover such forms or modifications as fall within the scope and spirit of the present disclosure. Accordingly, the scope of the present invention is defined only by reference to the appended claims.

[0102] Features, materials, characteristics, or groups described in connection with a particular aspect, embodiment, or example are to be understood as applicable to any other aspect, embodiment, or example described in this section of the specification or elsewhere herein, unless they are incompatible with those. All features (including the appended claims, abstract, and drawings) disclosed herein, and / or all steps of any method or process so disclosed, can be combined in any combination, except where at least some of such features and / or steps are mutually exclusive. The protection is not limited to the details of the foregoing embodiments. The protection extends to any novel one, or any novel combination, of the features disclosed herein (including the appended claims, abstract, and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0103] Furthermore, certain features described in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment can also be implemented separately in multiple embodiments, or in any suitable sub-combination. Additionally, although features may be described as acting in a particular combination, one or more features from the claimed combination may, in some cases, be excluded from the combination, and the combination may be claimed as a sub-combination of sub-combinations or variations.

[0104] Furthermore, the operations may be shown in the drawings or described herein in a particular order, but such operations need not be performed in the particular order shown, or in a sequential order, or all operations need to be performed to achieve the desired result. Other operations not shown or described may be incorporated into the exemplary methods and processes. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the described operations. Further, the operations may be rearranged or reordered in other implementations. Those skilled in the art will understand that in some embodiments, the actual steps taken in the illustrated and / or disclosed processes may differ from those shown in the drawings. Depending on the embodiment, some of the steps described above may be removed and other steps may be added. Additionally, the features and attributes of the specific embodiments disclosed above may be combined in different ways to form additional embodiments, all of which are within the scope of the present disclosure. Also, the separation of the various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the components and systems described may generally be integrated into a single product or packaged into multiple products. For example, any of the components for the energy storage system described herein may be provided separately or integrated (e.g., packaged together or attached together) to form an energy storage system.

[0105] For purposes of the present disclosure, specific aspects, advantages, and novel features are described herein. Not necessarily all such advantages can be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the present disclosure may be implemented or carried out in a manner that achieves one advantage or group of advantages as taught herein without necessarily achieving other advantages that may be taught or suggested herein.

[0106] Conditional language such as "may", "is capable of", "can", "may be", etc., unless otherwise specified or understood differently within the context in which it is used, generally conveys that while other embodiments do not include a particular feature, element, and / or step, a particular embodiment is intended to include it. Thus, such conditional language generally does not imply that a feature, element, and / or step is required in any way in one or more embodiments, or that one or more embodiments necessarily include logic for determining whether these features, elements, and / or steps are included in, or are to be performed in, any particular embodiment, regardless of user input or instructions.

[0107] Unless otherwise specified, connectives such as the phrase "at least one of X, Y, and Z" are understood separately from the context in which they are generally used to convey that an item, term, etc. can be any of X, Y, or Z, and thus such connectives are not generally intended to imply that a particular embodiment requires the presence of at least one of X and Y and at least one of Z.

[0108] Degree language such as "substantially", "about", "generally", and "substantially" as terms represent values, amounts, or characteristics that are close to the recited values, amounts, or characteristics that still perform the desired function or achieve the desired result.

[0109] The scope of the present disclosure is not intended to be limited by the specific disclosure of the preferred embodiments in this section or elsewhere in this specification, and may be defined by the claims, as presented in this section or elsewhere in this specification, or as may be presented in the future. The words of the claims should be construed broadly based on the words used in the claims, and not limited to the examples described in this specification or during the implementation of this application, and these examples should be construed as non-exclusive. Subsequent to this, it should be construed broadly and not limited to the examples described in this specification or during the implementation of this application, and these examples should be construed as non-exclusive.

[0110] Embodiment Various exemplary embodiments are provided below.

[0111] 1. A dry electrode film for an energy storage device, comprising a dry active material containing a Group 14 active material and a graphite active material, and a dry binder, wherein the dry electrode film is self-supporting.

[0112] 2. The electrode film according to Embodiment 1, wherein the dry electrode film contains about 1 mass% to 30 mass% of the Group 14 active material.

[0113] 3. The electrode film according to Embodiment 2, wherein the dry electrode film contains about 10 mass% to 30 mass% of the Group 14 active material.

[0114] 4. The electrode film according to any one of Embodiments 1 to 3, wherein the Group 14 active material contains at least one of silicon and tin.

[0115] 5. The electrode film according to any one of Embodiments 1 to 4, wherein the Group 14 active material is selected from at least one of pure silicon, silicon oxide (SiO), silicon-carbon composite material, silicon alloy, and SiH.

[0116] 6. The electrode film according to Embodiment 5, wherein the silicon-carbon composite is selected from at least one of silicon graphene (SiC), tin graphene, silicon graphite (Si / C), tin graphite, silicon oxide graphene (SiOC), and silicon oxide graphite (SiO / C).

[0117] 7. The electrode film according to Embodiment 5, wherein the silicon alloy is selected from at least one of Si-Al and Si-Sn.

[0118] 8. The electrode film according to any one of Embodiments 1 to 7, wherein the Group 14 active material is prelithiated.

[0119] 9. The Group 14 active material comprises particles having a primary particle size of about 1 μm to about 10 μm, the electrode film according to any one of Embodiments 1 to 8. 50

[0120] 10. The graphite active material is selected from at least one of artificial graphite and natural graphite, the electrode film according to any one of Embodiments 1 to 9.

[0121] 11. The graphite active material comprises primary graphite (PG) particles and secondary graphite (SG) particles, the electrode film according to any one of Embodiments 1 to 10.

[0122] 12. The PG particles have a primary particle size of about 15 μm to about 30 μm, the electrode film according to Embodiment 11. 50

[0123] 13. The SG particles have a secondary particle size of about 2 μm to about 10 μm, the electrode film according to Embodiment 11 or 12. 50

[0124] 14. The mass ratio of the PG particles to the SG particles is from 10:1 to 1:10, the electrode film according to any one of Embodiments 11 to 13.

[0125] 15. The dry binder comprises at least one of carboxymethyl cellulose (CMC), poly(ethylene oxide) (PEO), polyacrylic acid, polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE), the electrode film according to any one of Embodiments 1 to 14.

[0126] 16. The dry binder comprises a dry fibrillated binder, the electrode film according to any one of Embodiments 1 to 15.

[0127] 17. The dry fibrillated binder comprises polytetrafluoroethylene, the dry electrode film according to Embodiment 16.

[0128] 18. An electrode comprising the dry electrode film according to any one of Embodiments 1 to 17 in contact with a current collector.

[0129] 19. A lithium-ion battery comprising the electrode of Embodiment 18.

[0130] 20. A method for manufacturing a dry electrode film of an energy storage device, the method comprising mixing a dry Group 14 active material with a dry graphite material to form a dry active material mixture, mixing the dry active material mixture with a dry binder to form a dry electrode film mixture, and calendering the dry electrode film mixture to form a self-supporting dry electrode film.

[0131] 21. The method according to Embodiment 20, further comprising pre-mixing the dry Group 14 active material with a first dry binder before mixing the dry Group 14 active material with the dry graphite material, and mixing the dry active material mixture with a dry binder includes mixing the dry active material mixture with a second dry binder.

[0132] 22. The method according to Embodiment 21, wherein the first dry binder and the second dry binder are different binder materials.

[0133] 23. The method according to any one of Embodiments 20 to 22, wherein at least one of the pre-mixing process, the first mixing process, and the second mixing process includes a non-destructive mixing process.

[0134] 24. The method according to Embodiment 23, wherein the non-destructive mixing process includes a resonant acoustic mixing process.

[0135] 25. The method according to any one of Embodiments 20 to 24, wherein at least one of the pre-mixing process, the first mixing process, and the second mixing process includes a high-shear process.

[0136] 26. The high-shear process is the method according to embodiment 25, including jet mill pulverization treatment.

[0137] 27. The method according to any one of embodiments 20 to 26, wherein the dry graphite material includes primary graphite (PG) particles and secondary graphite (SG) particles.

[0138] 28. The method according to embodiment 27, wherein the PG particles have a primary particle size of about 15 μm to about 30 μm. 50

[0139] 29. The method according to embodiment 27 or 28, wherein the SG particles have a secondary particle size of about 2 μm to about 10 μm. 50 ​

Claims

1. A dry electrode film for an energy storage device, comprising a dry active material containing a Group 14 active material and a graphite active material, and a dry binder, wherein the dry electrode film is self-supporting.

2. The electrode film according to claim 1, wherein the dry electrode film contains about 1% to 30% by mass of the Group 14 active material.

3. The electrode film according to claim 2, wherein the dry electrode film contains about 10% to 30% by mass of the Group 14 active material.

4. The electrode film according to any one of claims 1 to 3, wherein the Group 14 active material contains at least one of silicon and tin.

5. The electrode film according to any one of claims 1 to 4, wherein the Group 14 active material is selected from at least one of pure silicon, silicon oxide (SiO), silicon-carbon composite material, silicon alloy, and SiH.

6. The electrode film according to claim 5, wherein the silicon-carbon composite material is selected from at least one of silicon graphene (SiC), tin graphene, silicon graphite (Si / C), tin graphite, silicon oxide graphene (SiO C), and silicon oxide graphite (SiO / C).

7. The electrode film according to claim 5, wherein the silicon alloy is selected from at least one of Si-Al and Si-Sn.

8. The electrode film according to any one of claims 1 to 7, wherein the Group 14 active material is pre-lithiated.

9. The Group 14 active material has a D of from about 1 μm to about 10 μm ５０ The electrode film according to any one of claims 1 to 8, comprising particles having a primary particle diameter

10. The electrode film according to any one of claims 1 to 9, wherein the graphite active material is selected from at least one of artificial graphite and natural graphite.

11. The electrode film according to any one of claims 1 to 10, wherein the graphite active material contains primary graphite particles (PG particles) and secondary graphite particles (SG particles).

12. The PG particles have a primary particle size of about 15 μm to about 30 μm ５０ The electrode film according to claim 11

13. The SG particles have a secondary particle size of about 2 μm to about 10 μm ５０ The electrode film according to claim 11 or 12, having a secondary particle size of about 2 μm to about 10 μm

14. The electrode film according to any one of claims 11 to 13, wherein the mass ratio of the PG particles to the SG particles is 10:1 to 1:

10.

15. The dry binder contains at least one of carboxymethyl cellulose (CMC), poly(ethylene oxide) (PEO), polyacrylic acid, polyvinylidene fluoride (PVDF), and polytetra fluoroethylene (PTFE), according to any one of claims 1 to 14 The electrode film according to item 1.

16. The electrode film according to any one of claims 1 to 15, wherein the dry binder includes a dry fibrillated binder.

17. The electrode film according to claim 16, wherein the dry fibrillated binder includes polytetrafluoroethylene.

18. An electrode comprising the dry electrode film according to any one of claims 1 to 17 in contact with a current collector.

19. A lithium-ion battery comprising the electrode according to claim 18.

20. A method for manufacturing a dry electrode film of an energy storage device, mixing a dry Group 14 active material with a dry graphite material to form a dry active material mixture, mixing the dry active material mixture with a dry binder to form a dry electrode film mixture, The method for manufacturing a dry electrode film of an energy storage device, wherein the dry electrode film mixture is calendered to form a self-supporting dry electrode film.

21. The method according to claim 20, further comprising premixing the dry Group 14 active material with a first dry binder before mixing the dry Group 14 active material with the dry graphite material, and mixing the dry active material mixture with the dry binder includes mixing the dry active material mixture with a second dry binder.

22. The method according to claim 21, wherein the first dry binder and the second dry binder are different binder materials.

23. The method according to any one of claims 20 to 22, wherein at least one of the premixing step, the first mixing step, and the second mixing step includes a non-destructive mixing process.

24. The method according to claim 23, wherein the non-destructive mixing process includes a resonant acoustic mixing process.

25. The method according to any one of claims 20 to 24, wherein at least one of the premixing process, the first mixing process, and the second mixing process includes a high-shear process.

26. The method according to claim 25, wherein the high-shear process includes a jet mill pulverization process.

27. The method according to any one of claims 20 to 26, wherein the dry graphite material includes primary graphite particles (PG particles) and secondary graphite particles (SG particles).

28. wherein the PG particles have a primary particle size of from about 15 μm to about 30 μm, the method according to claim 27. ５０ ​

29. The SG particles have a secondary particle size of from about 2 μm to about 10 μm, the method according to claim 27 or 28. ５０ ​

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