Binder for lower pyrolysis temperature of silicon-dominant anodes

Abstract

Systems and methods for direct coating of silicon-dominant anodes with carbon additives are provided. An exemplary composition for direct coating of an anode can include a silicon-dominant anode active material, a carbon-based binder, and a carbon-based additive, wherein the composition is configured for low temperature pyrolysis. The low temperature pyrolysis can be performed at < 600 °C. The composition can be used in a direct coating method on a current collector to form an anode. The anode active material results in silicon that makes up 86% to 97% by weight of the anode formed after pyrolysis. The carbon-based additive results in carbon that makes up 2% to 6% by weight of the anode formed after pyrolysis.

Description

[0001] Cross-references / citations of related applications are incorporated.

[0002] This application claims priority to U.S. Patent Application No. 16 / 681,401, filed November 12, 2019, which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to aspects of energy generation and storage. More specifically, certain embodiments of this disclosure relate to methods and systems for using binders with low pyrolysis temperatures. Such binders can be used in cells having silicon-dominant anodes. Background Technology

[0004] Conventional methods for battery anodes can be expensive, cumbersome, and / or inefficient; for example, they may be complex and / or time-consuming to implement and may limit battery life.

[0005] Other limitations and disadvantages of conventional and traditional methods will become apparent to those skilled in the art by comparing such a system with some aspects of this disclosure as set forth with reference to the accompanying drawings in the remainder of this application. Summary of the Invention

[0006] Systems and / or methods are provided for binders having low pyrolysis temperatures, wherein such binders are used in cells having silicon-dominant anodes, generally as shown in at least one figure and / or as described with respect to at least one figure, as set forth more fully in the claims.

[0007] These and other advantages, aspects and novel features of this disclosure, as well as details of the embodiments shown therein, will be more fully understood from the following description and accompanying drawings. Attached Figure Description

[0008] Figure 1 This is a diagram of a cell with anode expansion configured via silicon particle size, according to an exemplary embodiment of this disclosure.

[0009] Figure 2 An example of anodic expansion during lithiation according to an exemplary embodiment of this disclosure is illustrated.

[0010] Figure 3A Thermogravimetric analysis (TGA) of a cured anode containing PAI is illustrated according to an exemplary embodiment of the present disclosure.

[0011] Figure 3B A comparison between the TGA of an uncured PAI and the TGA of a cured PAI is illustrated in an exemplary embodiment according to this disclosure.

[0012] Figure 3C The TGA of a PI is illustrated in an exemplary embodiment according to this disclosure.

[0013] Figure 4 This is a flowchart of a method for directly coating an electrode according to an exemplary embodiment of the present disclosure.

[0014] Figure 5 This is a flowchart of an alternative method for transferring laminated electrodes according to an exemplary embodiment of the present disclosure.

[0015] Figure 6 This is a drawing illustrating the discharge capacity performance of an anolyte formulation having 92% silicon and a binder containing PAI (polyamide-imide) or PI (polyimide) according to an exemplary embodiment of the present disclosure.

[0016] Figure 7 This is a drawing illustrating the discharge capacity performance of an anolyte formulation having 86% silicon and a binder containing PAI (polyamide-imide) or PI (polyimide) according to an exemplary embodiment of the present disclosure. Detailed Implementation

[0017] Figure 1 This is a diagram of a cell with a silicon-dominant anode undergoing anodic expansion according to an exemplary embodiment of this disclosure. Reference Figure 1 A battery 100 is shown, comprising a separator 103 sandwiched between an anode 101 and a cathode 105, and current collectors 107A and 107B. A load 109 coupled to the battery 100 is also shown, illustrating the situation when the battery 100 is in a discharge mode. In this disclosure, the term "battery" can be used to refer to a single electrochemical cell, multiple electrochemical cells formed as modules, and / or multiple modules formed as components.

[0018] The development of portable electronic devices and the electrification of transportation have driven the demand for high-performance electrochemical energy storage. Compared to other rechargeable battery chemicals, small-scale (<100Wh) to large-scale (>10KWh) devices primarily use lithium-ion batteries due to their high performance.

[0019] Anode 101 and cathode 105, together with current collectors 107A and 107B, may include electrodes, which may be contained within an electrolyte material or in a plate or membrane that houses the electrolyte material. The plate may provide a physical barrier for containing the electrolyte and conductive contact with an external structure. In other embodiments, the anode / cathode plates are immersed in the electrolyte, while a housing provides electrolyte containment. Anode 101 and cathode 105 are electrically coupled to current collectors 107A and 107B, which contain metal or other conductive material to provide electrical contact with the electrodes and physical support for the active material during electrode formation.

[0020] Figure 1 The configuration shown illustrates a battery 100 in a discharge mode, while in a charging configuration, a charger can be used instead of load 109 to reverse the process. In one type of battery, separator 103 is typically a membrane material made of, for example, an electrically insulating polymer, which prevents electrons from flowing from anode 101 to cathode 105, or vice versa, while being porous enough to allow ions to pass through separator 103. Typically, separator 103, cathode 105, and anode 101 are formed as sheets, films, or foils coated with active materials, respectively. Sheets of cathode, separator, and anode are sequentially stacked or rolled such that separator 103 separates cathode 105 from anode 101 to form battery 100. In some embodiments, separator 103 is a sheet and is typically manufactured using winding and stacking methods. In these methods, anode, cathode, and current collector (e.g., electrodes) may comprise membranes.

[0021] In an exemplary embodiment, battery 100 may comprise a solid, liquid, or gel electrolyte. Separator 103 is preferably insoluble in typical battery electrolytes, such as compositions comprising ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and dissolved LiBF4, LiAsF6, LiPF6, and LiClO4. Separator 103 may be wetted or soaked with a liquid or gel electrolyte. Furthermore, in an exemplary embodiment, separator 103 does not melt at temperatures below about 100°C to 120°C and exhibits sufficient mechanical properties for battery applications. During operation, the battery may undergo expansion and contraction of the anode and / or cathode. In an exemplary embodiment, separator 103 may expand and contract by at least about 5% to 10% without failure and may also be flexible.

[0022] The separator 103 can be porous enough that ions can pass through it once wetted with, for example, a liquid or gel electrolyte. Alternatively (or additionally), the separator can absorb electrolytes by gelation or other methods, even without significant porosity. The porosity of the separator 103 is generally not so high that it allows electrons to be transferred between the anode 101 and the cathode 105.

[0023] Anode 101 and cathode 105 include electrodes for battery 100, providing electrical connection to means for transferring charge in charging and discharging states. For example, anode 101 may comprise silicon, carbon, or a combination of these materials. Typical anode electrodes comprise carbon materials and include current collectors such as copper sheets. Carbon is commonly used because it has excellent electrochemical properties and is also conductive. Anodes currently used in rechargeable lithium-ion batteries typically have a specific capacity of about 200 mAh / g. Graphite, the active material used in most lithium-ion battery anodes, has a theoretical energy density of 372 mAh / g. In contrast, silicon has a high theoretical capacity of 4200 mAh / g. To increase the volumetric and gravimetric energy densities of lithium-ion batteries, silicon can be used as the active material for the cathode or anode. Silicon anodes can be formed from, for example, silicon composites having more than 50% silicon.

[0024] In this exemplary embodiment, anode 101 and cathode 105 store ions, such as lithium, for charge separation. In this example, the electrolyte carries positively charged lithium ions from anode 101 to cathode 105 in discharge mode, for example as... Figure 1 As shown, and conversely, in charging mode, current flows through separator 105. The movement of lithium ions generates free electrons in anode 101, which creates a charge at positive current collector 107B. Current then flows from said current collector through load 109 to negative current collector 107A. Separator 103 blocks the flow of electrons within battery 100, allows the flow of lithium ions, and prevents direct contact between electrodes.

[0025] When the battery 100 discharges and provides current, lithium ions are released from the anode 101 and reach the cathode 105 via the separator 103, thereby generating an electron flow from one side to the other via the connected load 109. When the battery is charged, the opposite occurs, in which lithium ions are released by the cathode 105 and received by the anode 101.

[0026] The materials selected for the anode 101 and cathode 105 are important for the potential reliability and energy density of the battery 100. Current lithium-ion batteries need improvements in energy, power, cost, and safety to compete, for example, with internal combustion engine (ICE) technology and allow for the widespread adoption of electric vehicles (EVs). With the development of high-capacity, high-voltage cathodes, high-capacity anodes, and functional, non-flammable electrolytes with high voltage stability and interfacial compatibility with the electrodes, lithium-ion batteries with high energy density, high power density, and improved safety have been achieved. Furthermore, using materials with low toxicity as battery materials is beneficial for reducing process costs and promoting consumer safety.

[0027] While the performance of electrochemical electrodes depends on many factors, it largely depends on the robustness of the electrical contacts between electrode particles and between the current collector and electrode particles. The conductivity of silicon anode electrodes can be controlled by incorporating conductive additives with different morphological properties. Carbon black (Super P), vapor-grown carbon fiber (VGCF), and mixtures of both have previously been individually incorporated into anode electrodes, resulting in improved anode performance. The synergistic interaction between the two carbon materials can promote electrical contact during the large volume changes of the silicon anode during charging and discharging.

[0028] Existing lithium-ion batteries typically use graphite-dominant anodes as the lithium intercalation material. However, silicon-dominant anodes offer improvements compared to graphite-dominant lithium-ion batteries. Silicon exhibits high gravimetric capacity (3579 mAh / g vs. graphite's 372 mAh / g) and volumetric capacity (2194 mAh / L vs. graphite's 890 mAh / L). Furthermore, silicon-based anodes show advantages over Li / Li... + It exhibits a lithiation / delithiation voltage plateau in the range of approximately 0.3V to 0.4V, which maintains its open-circuit potential and prevents undesirable Li precipitation and dendrite formation. While silicon displays excellent electrochemical activity, achieving stable cycle life for silicon-based anodes is challenging due to the large volume changes during lithiation and delithiation. The silicon region may lose electrical contact with the anode because the large volume changes, combined with its low conductivity, separate the silicon from the surrounding material in the anode.

[0029] Furthermore, large silicon volume changes exacerbate the formation of the solid electrolyte interphase (SEI), which can further lead to electrical insulation and thus capacity loss. During charge-discharge cycling, the expansion and contraction of silicon particles cause particle fragmentation, increasing their specific surface area. As the silicon surface area changes and increases between cycles, the SEI repeatedly disintegrates and reassembles. Therefore, the SEI continuously accumulates around the fragmented silicon regions during cycling, forming a thick electronic and ionic insulating layer. This accumulated SEI increases electrode impedance and reduces electrode electrochemical reactivity, which is detrimental to cycle life.

[0030] Figure 2 An example of anolytical expansion during lithiation according to an exemplary embodiment of this disclosure is illustrated. Reference Figure 2 The diagram illustrates a current collector 201, an optional binder 203, and an active material 205. It should be noted that the binder 203 may be present or absent depending on the type of anode manufacturing process used, as the binder is not necessarily required in direct coating processes where the active material is directly formed onto the current collector. In an exemplary embodiment, the active material 205 comprises silicon particles in a binder material and solvent, and the active material 205 is pyrolyzed to transform the binder into glassy carbon, which provides a structural framework around the silicon particles and also provides conductivity. The active material can be attached to the current collector 201 using the optional binder 203. The current collector 201 may include a metal film, such as copper, nickel, or titanium, but other conductive foils may be used depending on the required tensile strength.

[0031] Figure 2 Lithium ions grafted onto and lithiated to the active material 205 are also illustrated. Lithification of the silicon-dominant anode causes expansion of the material, where horizontal expansion is represented by the x and y axes, while thickness expansion is represented by the z axis, as shown. The current collector 201 has a thickness t, where a thicker foil provides greater strength, and if the binder 203 is strong enough, it restricts expansion in the x and y directions, resulting in greater expansion in the z direction, thus producing anisotropic expansion. For example, for copper, the thickness of the exemplary thicker foil can be greater than 6 μm, such as 10 μm or 20 μm, while the thickness of the thinner foil for copper can be less than 6 μm.

[0032] In another exemplary case, when the current collector 201 is thinner, for example on the order of 5 to 6 μm for copper foil, the active material 205 can expand more easily in the x and y directions, but expansion in the z direction is still even easier in the absence of other constraints. In this case, the expansion is anisotropic, but not as much as in the case of higher xy constraints.

[0033] Furthermore, different materials with varying tensile strengths can be used to configure the allowable expansion in the x and y directions. For example, for current collector 201, nickel is a more rigid and mechanically strong metal, and therefore, when a sufficiently strong binder is used, the nickel current collector constrains xy expansion. In this case, even compared to a thicker copper foil, expansion in the x and y directions may be more restricted, resulting in more expansion in the z direction, i.e., more anisotropy. In the anode formed with a 5 μm nickel foil current collector, very low expansion and no cracking are produced. Furthermore, different metal alloys can be used, for example, to obtain the desired thermal conductivity, electrical conductivity, and tensile strength.

[0034] In an exemplary embodiment, when an adhesive is used, adhesive 203 comprises a polymer such as polyimide (PI) or polyamide-imide (PAI), which provides adhesive strength between the active material membrane 205 and the current collector 201, while also providing electrical contact with the current collector 201. Other adhesives may be used depending on the required strength, as long as they can provide adhesive strength with sufficient conductivity after processing. If adhesive 203 provides a stronger, more rigid bond, assuming the current collector is also strong, expansion in the x and y directions can be more restricted. Conversely, a more flexible and / or thicker adhesive can allow for greater xy expansion, reducing the anisotropic nature of anodic expansion.

[0035] Figure 3A Thermogravimetric analysis (TGA) of a cured anode containing PAI according to an exemplary embodiment of this disclosure is illustrated. TGA is a thermal analysis method in which the mass of a sample is measured over time as temperature changes. As shown, carbonization of the cured anode occurs below 600°C. PAI exhibits a multi-stage mass loss pattern, presumably due to solvent loss prior to the onset of pyrolysis. The first stage of mass loss begins at approximately 140°C and results in a mass loss of approximately 1%. The IR spectrum from this degassing is compared with that of N-methyl-2-pyrrolidone (NMP) (1783, 1414, 1287 cm⁻¹). -1 The spectra of the N-methyl-2-pyrrolidone (NMP) are consistent with those of the PAI material, which is a commonly used solvent in the manufacture of PAI materials. The pyrolysis of the PAI material in the cured anode (starting at approximately 470°C) corresponds to a further mass loss of approximately 3%. The IR spectrum of the pyrolysis products at 500°C shows a mixture of several substances, including CO2 (~2300, 669 cm⁻¹). -1 ) and CO (~2100, 2200cm) -1 In addition, possible products include imide compounds (based on 1727-1784 cm⁻¹). -1 Peaks within the range) and multiple substituted aromatic rings (based on ~3050 cm⁻¹) -1 Peaks within the range). At 600℃, peaks with NH3 (966, 930 cm⁻¹) can be observed. -1 The existence of peaks related to )

[0036] Figure 3B An example is provided comparing the TGA of an uncured PAI film with that of a cured PAI according to an exemplary embodiment of this disclosure. As shown, the first-order derivative weight loss peak during the pyrolysis of uncured PAI occurs at a lower temperature compared to the first-order derivative weight loss peak during the pyrolysis of cured PAI. The total weight loss of uncured PAI is also greater than that of cured PAI.

[0037] Figure 3CThe TGA of a PI is illustrated in an exemplary embodiment according to this disclosure. Figure 3C The example shows that the weight loss change of PI occurs at 602°C, which is higher than the temperature of PAI. Therefore, PAI, especially PAI films, is more suitable for low-temperature pyrolysis.

[0038] Figure 4 This is a flowchart of a method for directly coating an electrode according to an exemplary embodiment of this disclosure. The method includes physically mixing an active material, a conductive additive, and a binder together, and then directly coating it onto a current collector. This exemplary method includes a direct coating method in which an anode slurry is directly coated onto a copper foil using a binder such as CMC, SBR, sodium alginate, PAI, PAA, PI, and mixtures and combinations thereof. Another exemplary method includes forming an active material on a substrate and then transferring it to a current collector, as per [the previous section / concept]. Figure 5 As stated above.

[0039] In step 401, the original electrode active material can be mixed using a binder / resin (e.g., PI, PAI), a solvent, and optionally conductive carbon. For example, silicon powder with the desired particle size can be dispersed into PI and PAI under high shear dispersion for 1 hour, followed by the addition of conductive carbon (e.g., graphite, graphene, Super P, ECP, or combinations thereof) and redispersed for, for example, 1 to 2 hours. When using carbon additives with high surface area such as Super P and ECP, the mixture can be dispersed under ultrasonic treatment for, for example, 30 to 60 minutes to increase homogeneity. In addition to ultrasonic mixing, ball milling can also be used as a high-energy mixing method. The mixture can then be diluted with a solvent such as N-methylpyrrolidone (NMP) at, for example, 1000 rpm using high shear dispersion to achieve a slurry viscosity in the range of 2000 to 4000 cP and a total solids content greater than 30%. Depending on the material, the mixing method, speed, and duration can be varied to obtain a homogeneous mixture. The particle size of the silicon powder and carbon additives can be varied to configure the density and / or roughness of the active material.

[0040] In step 403, the slurry can be, for example, at a concentration of 3 to 4 mg / cm³. 2 The coating is applied to the foil, which can be dried in step 405 to produce a residual solvent content of less than 15%. In step 407, an optional calendering process can be used, in which a series of hard rollers can be used to trim the film / substrate into a smoother and denser sheet of material.

[0041] In step 409, the active material can be pyrolyzed by heating to 500 to 800°C, causing the carbon precursor to be partially or completely converted into glassy carbon. When the anode is heated to 400°C or higher, the pyrolysis step can produce an anode active material with a silicon content greater than or equal to 50% by weight. Pyrolysis 409 can be performed before or after stamping 411. If stamping 411 is performed after pyrolysis 409, pyrolysis can be performed in the form of a roller. The pyrolyzed and stamped electrodes can be sandwiched between a separator and a cathode, and an electrolyte can be added to form a battery. In step 413, the battery can undergo a formation process including initial charging and discharging steps to lithiate the anode, where some residual lithium remains.

[0042] Figure 5 This is a flowchart of an alternative method for transferring laminated electrodes according to an exemplary embodiment of this disclosure. While previous methods for manufacturing composite anodes employed a direct coating process, this method physically mixes active materials, conductive additives, and binders together and combines them with a peeling and lamination process.

[0043] This method is in Figure 5 The flowchart shows that it begins at step 501, where the active material can be mixed with a binder / resin (e.g., polyimide (PI) or polyamide-imide (PAI)) and a solvent. Optional additives include silosilazane, conductive carbon, and / or surface-modifying additives (e.g., surfactants, silanes, and silazane). Figure 4 Similar to the method described above, silica powder can be directly dispersed into a binder such as PI or PAI under high shear dispersion for up to 1 hour, followed by the addition of optional conductive carbon and / or other additives. When using high surface area carbon additives such as Super P and ECP, the mixture can be dispersed under ultrasonic treatment for, for example, 30 to 60 minutes to increase homogeneity. In addition to ultrasonic treatment, ball milling can also be used as a high-energy mixing method. The mixture can then be diluted with a solvent such as N-methylpyrrolidone (NMP) at, for example, 500 to 2000 rpm using high shear dispersion to achieve a slurry viscosity of 2000 to 4000 cP and a total solids content of approximately 20 to 40%. Depending on the materials used, the order of addition, mixing method, speed, and duration can be varied to obtain a homogeneous mixture. Particle size can be varied to configure the density and / or roughness of the active material.

[0044] In step 503, the slurry can be coated onto a polymer substrate, such as polyethylene terephthalate (PET, e.g., Mylar) or polypropylene (PP). The slurry can be applied at a concentration of 3 to 4 mg / cm³. 2A loading amount (with a solvent content of 13 to 20%) is coated onto a PET / PP / Mylar film, and then dried in step 505 to remove a portion of the solvent. An optional calendering process can be used, in which a series of hard rollers are used to trim the film / substrate into a smooth and dense sheet of material.

[0045] In step 507, the green film can then be removed from the PET, where the active material can be peeled off from the polymer substrate. This peeling process is optional for polypropylene (PP) substrates, as PP can leave approximately 2% carbon residue upon pyrolysis. Following peeling, a curing and pyrolysis step 509 can be performed, where the film can be cut into sheets and vacuum dried using a two-stage method (100 to 140°C for 12 to 16 hours, followed by 200 to 240°C for 4 to 6 hours). The dried film can be heat-treated at 1000 to 1300°C to convert the polymer matrix into carbon. The pyrolysis step, by heating the anode to 400°C or higher, can produce an anode active material with a silicon content greater than or equal to 50% by weight.

[0046] In step 511, the pyrolyzed material can be flat-pressed or rolled onto the collector, wherein a nominal loading of 0.35 to 0.75 mg / cm³ can be used. 2 A copper foil is coated with a 15-20% residual solvent of polyamide-imide (applied as a 5-7 wt% varnish in NMP and vacuum dried at 100-140°C for 10-20 hours). In a flatbed lamination process, a heated hydraulic press (30-70 seconds, 250-350°C, and 3000-5000 psi) is used to laminate the silicon-carbon composite film onto the coated copper, thereby forming the final silicon composite electrode. In another embodiment, the pyrolytic material can be roll-laminated onto the current collector.

[0047] In step 513, the electrodes can then be sandwiched together with the electrolyte using a separator and a cathode to form a battery. The battery can undergo a formation process including initial charging and discharging steps to lithimate the anode, where some residual lithium remains. The expansion of the anode can be measured to confirm the reduction in expansion and the anisotropy of the expansion. Larger silicon particle sizes result in a rougher surface, higher porosity, and less dense material, which reduces the expansion of the active material during lithiation.

[0048] PI (polyimide) can be used for direct coating onto copper. However, the properties of PI are compromised after pyrolysis. For example, performance may be impaired due to its high carbonization and pyrolysis temperature limitations. While increasing Si can improve PI performance, the use of PAI (polyamide-imide) produces a better precursor for pyrolytic carbon than PI. PAI is more suitable for low-temperature methods of direct coating because it carbonizes faster and at lower temperatures than PI. At higher temperatures, Ni formation occurs. x Si or Cu x The risk of Si is that it could damage the current collector.

[0049] Figure 6 This is a graph illustrating the discharge capacity performance of an anolyte formulation having 92% silicon and a binder comprising PAI (polyamide-imide) or PI (polyimide) according to an exemplary embodiment of this disclosure. To compare PAI and PI as binders for direct coating, cycling performance of the two polymers was performed in formulations with different silicon and binder contents. A pyrolysis temperature of 550°C was used to maintain the integrity of the copper foil as a current collector.

[0050] Figure 6 Example G1 illustrates the discharge capacity of an anode with pyrolytic PAI as a binder under test conditions of charging to 4.2V at a 2C rate and discharging to 2.7V at a 0.5C rate, at a pyrolysis temperature of 550°C and a residence time of 30 seconds. Figure 6 G2 in the example illustrates the discharge capacity of an anode with pyrolytic PI at 2C (4.2V) / 0.5C (2.7V), a pyrolysis temperature of 550°C, and a residence time of 30. Figure 6 Example G3 illustrates the discharge capacity of an anode with pyrolytic PAI at a pyrolysis temperature of 550°C and a residence time of 30°C under test conditions of 4C (4.2V) / 0.5C (3.1V). Figure 6 Example G4 illustrates the discharge capacity of an anode with pyrolytic PI at a pyrolysis temperature of 550°C and a residence time of 30°C under test conditions of 4C (4.2V) / 0.5C (3.1V). As shown, in 92% silicon, 4% Super P, and 4% hard carbon from the binder formulation, the PAI groups (G1 and G3) exhibit higher initial capacity and better capacity retention than the PI resins (G2 and G4).

[0051] Figure 7 This is a drawing illustrating the discharge capacity performance of an anolyte formulation having 86% silicon and a binder containing PAI (polyamide-imide) or PI (polyimide) according to an exemplary embodiment of the present disclosure.

[0052] Figure 7G1 in the example shows the PAI discharge capacity at a pyrolysis temperature of 550°C and a residence time of 30 under test conditions of 2C (4.2V) / 0.5C (2.7V). Figure 7 G2 in the example shows the PI discharge capacity at 2C (4.2V) / 0.5C (2.7V), a pyrolysis temperature of 550°C, and a residence time of 30 seconds. Figure 7 Example G3 illustrates the PAI discharge capacity at a pyrolysis temperature of 550°C and a residence time of 30°C under test conditions of 4C (4.2V) / 0.5C (3.1V). Figure 7 Example G4 illustrates the PI discharge capacity at a pyrolysis temperature of 550°C and a residence time of 30°C under test conditions of 4C (4.2V) / 0.5C (3.1V). As shown, in 86% silicon slurry compositions, PAI groups (G1 and G3) exhibit higher initial capacity and better capacity retention than PI resins (G2 and G4).

[0053] An exemplary composition for a directly coated anode according to this disclosure comprises a silicon-dominant anolyte, a carbon-based binder, and a carbon-based additive, said composition being configured for low-temperature pyrolysis. Pyrolysis can begin below 500°C. Carbonization can occur below 600°C.

[0054] An exemplary method according to this disclosure includes mixing a composition for direct coating of an anode, said composition comprising: a silicon-dominant anode active material, a carbon-based binder, and a carbon-based additive. The composition is configured for low-temperature pyrolysis, which can be carried out at <600°C. The anode can be formed using a direct coating process on a current collector using the composition.

[0055] In an exemplary embodiment, the anodic active material produces up to 92% by weight of silicon constituting the anode formed after pyrolysis.

[0056] In an exemplary embodiment, the anodic active material produces silicon comprising at least 86% by weight of the anode formed after pyrolysis.

[0057] In an exemplary embodiment, a carbon-based binder produces 4% to 5% by weight of carbon that constitutes the anode formed after pyrolysis.

[0058] In an exemplary embodiment, carbon-based additives produce 2% to 6% by weight of carbon constituting the anode formed after pyrolysis.

[0059] In an exemplary embodiment, the carbon-based additive includes at least one of ECP, ECP600, Super-P, and SLP.

[0060] In an exemplary embodiment, the carbon-based additive includes additives with a surface area >800m².2 / g of carbon particles.

[0061] In an exemplary embodiment, the anolyte material includes polyamide-imide (PAI).

[0062] As used herein, the terms “circuits” and “circuitry” refer to physical electronic components (i.e., hardware) and any software and / or firmware (“code”) that can configure, be executed by, and / or otherwise associate with the hardware. As used herein, for example, a particular processor and memory may include a first “circuit” executing one or more lines of first code, and may include a second “circuit” executing one or more lines of second code. As used herein, “and / or” means any one or more items in the list connected by “and / or”. As an example, “x and / or y” means any element in the three-element set {(x),(y),(x,y)}. In other words, “x and / or y” means “one or both of x and y”. As another example, “x, y, and / or z” means any element in the seven-element set {(x),(y),(z),(x,y),(x,z),(y,z),(x,y,z)}. In other words, “x, y, and / or z” means “one or more of x, y, and z”. As used herein, the term “exemplary” means used as a non-limiting instance, example, or illustration. As used herein, the terms “e.g.” and “for example” introduce a list of one or more non-limiting instances, examples, or illustrations. As used herein, a battery, circuit, or device is “operable” to perform a function whenever it includes the hardware and code necessary to perform the function, if required, regardless of whether the performance of the function is disabled or not enabled (e.g., through user-configurable settings, factory adjustments, configuration, etc.).

[0063] Although the invention has been described with reference to certain embodiments, those skilled in the art will understand that various changes and substitutions can be made without departing from the scope of the invention. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of the invention without departing from the scope of the invention. Therefore, the invention is not intended to be limited to the specific embodiments disclosed, but rather to include all embodiments falling within the scope of the appended claims.

Claims

1. An anode, the anode comprising: Collector; as well as An active material membrane on the current collector, the active material membrane comprising: Silicon particles, which provide 86% to 97% of the silicon by weight in the anode. Glassy carbon, formed by low-temperature pyrolysis of polyamide-imide, provides a structural framework around the silicon particles. The low-temperature pyrolysis is initiated at below 500°C and carried out below 550°C, and the glassy carbon forms carbon accounting for 4% to 5% of the weight of the anode.

2. The anode of claim 1, wherein the battery includes the anode.

3. The anode of claim 1, wherein the active material membrane further comprises a carbon-based additive.

4. The anode of claim 3, wherein the carbon-based additive produces 2% to 6% by weight of carbon constituting the anode formed after pyrolysis.

5. The anode of claim 3, wherein the carbon-based additive comprises at least one of ECP, ECP600, Super-P, and SLP.

6. A method for forming an anode of a lithium-ion battery, the method comprising: A composition for direct coating of an anode, the composition comprising: a silicon-dominant anode active material; Carbon-based binders, including polyamide-imide; and carbon-based additives, and The anode of a lithium-ion battery is formed using a direct coating method with the aforementioned composition. The composition is configured for low-temperature pyrolysis. The anodic active material produces silicon particles, which provide 86% to 97% of the silicon by weight of the anode; Glassy carbon is formed by low-temperature pyrolysis of polyamide-imide, which provides a structural framework around the silicon particles and forms 4% to 5% carbon by weight in the anode. The low-temperature pyrolysis described therein begins below 500°C and continues below 550°C.

7. The method of claim 6, wherein the carbon-based additive produces 2% to 6% by weight of carbon constituting the formed anode.

8. The method of claim 6, wherein the carbon-based additive comprises at least one of ECP, ECP600, Super-P, and SLP.

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