Energy storage devices

Abstract

An abstract is provided on page 30 of the specification.

Description

[Technical Field]

[0001] (Cross-reference of related applications) This application claims the interests of U.S. Application No. 63 / 454,818, filed on 27 March 2023, which is incorporated herein by reference in its entirety. [Background technology]

[0002] This disclosure relates to electrodes for use in energy storage devices such as capacitors, ultracapacitors, and batteries. In particular, this disclosure relates to the preparation of slurries for manufacturing electrodes for energy storage devices such as capacitors, ultracapacitors, and batteries. This disclosure also relates to energy storage devices that do not use polyvinylidene fluoride as a binder and do not use N-methylpyrrolidone as a solvent.

[0003] Slurry preparation is a critical step in battery manufacturing, as it can significantly impact subsequent processes. The anodes and cathodes of lithium batteries are prepared using highly viscous slurries containing a high proportion of solid particles of various chemical compositions, sizes, and shapes. Battery production faces significant challenges in facilitating the mixing of these slurries. Mixer selection and mixing sequence are among the many factors to consider when creating the slurry.

[0004] Therefore, in order to improve battery characteristics, quality, and manufacturing processes, it is desirable to determine the relationship between the rheological behavior of the slurry and the structural, mechanical, and electrochemical properties of lithium ferrophosphate (LFP) and lithium nickel manganese cobalt oxide (NMC) electrodes. [Overview of the Initiative]

[0005] Disclosed herein is a method that includes mixing a first polymer binder with a carbonaceous conductive material to produce a first formulation, adding a second polymer binder in a first solvent to the first formulation to produce a second formulation, mixing the second formulation, adding a third polymer binder in a second solvent to the second formulation to produce a third formulation, mixing the third formulation, adding an active material to the third formulation to form an active material composition, and mixing the active material composition.

[0006] Disclosed herein is a Li-ion battery cell including a cathode current collector and a cathode active layer, the cathode active layer including one or more of LFP, LiCoO2, LiNiO2, LiNiMnCoO2, LiNiO2, LiMn2O4, LiFePO4, and LiNi x Mn y Co 1-x-y O2, NCMA, or a combination thereof, wherein x has a value of 0.7 to 0.85 and y is greater than 0.1, including a cathode active material, the cathode active layer contacting the cathode current collector, an anode current collector and an anode active layer, the anode active layer including Li x Si y O z graphite mixed with, wherein x is 1 to 15, y is 1 to 4, and z is 1 to 9, including an anode active material, the anode active layer contacting the anode current collector, an anode, and wherein both the anode active layer and the cathode active layer each include a high aspect ratio carbon element, the high aspect ratio carbon element capturing the anode active material and the cathode active material within voids within the high aspect ratio carbon element, a Li-ion battery cell.

Brief Description of the Drawings

[0007] [Figure 1] A diagram of an electrode (anode or cathode) according to various embodiments. [Figure 2] A general depiction of a mixing process for forming an active material composition. [Figure 3] This describes various methods for mixing components to form an active material composition. [Figure 4] This describes various methods for mixing components to form an active material composition. [Figure 5] This describes various methods for mixing components to form an active material composition. [Figure 6] This graph shows the viscosity versus shear rate of a composition produced by the process described herein. [Figure 7] This graph shows the viscosity versus shear rate of a composition produced by the process described herein. [Figure 8] This graph shows the electrochemical performance of an LFP half-cell using an NX LFP cathode paired with a lithium metal pair electrode. [Figure 9] This graph shows the electrochemical performance of an LFP half-cell using an NX LFP cathode paired with a lithium metal pair electrode. [Modes for carrying out the invention]

[0008] Longer charging ranges, faster charging speeds, greater safety, greater durability, and affordable storage devices such as ultracapacitors, batteries, and capacitors are being used more frequently to facilitate the transition to an EV (electric vehicle) society powered by renewable energy. Currently, the performance of EV batteries is limited by cathode electrodes based on conventional PVDF-NMP processing, which have lower electrical and ionic conductivity. High molecular weight PVDF binders are the main cause of non-uniform porosity distribution, material aggregation in the active layer, and insufficient conductivity. This problem is more pronounced in thick cathodes (>5mAh / cm2) with high mass loads required in high energy density Li-ion battery designs. On the anode side, graphite (Gr) or Gr / SiO (5~10%SiO) anode electrodes are widely used in the EV battery industry.

[0009] However, due to the low potential of Gr relative to Li / Li+ during the battery charging process (0.05~0.1V relative to Li / Li+), the fast-charging (FC) performance is particularly affected by the high-load Gr anode, compared to the high-load PVDF / NMP cathode electrode (>5mAh / cm²). 2 When this is the case, it is extremely difficult to achieve for long-term battery FC cycles. For example, these conventional NMP / PVDF cathodes combined with Gr anode electrodes have high impedance and do not allow for moderate to high C rates in both charging and discharging, and are therefore not suitable for fast charging.

[0010] Disclosed herein are energy storage devices that do not use polymer binders such as PVDF (polyvinylidene fluoride) in the preparation of the active layer. Solvents such as N-methylpyrrolidone (NMP) are also avoided. This dramatically improves the performance of Li-ion ultracapacitors and battery cells while reducing manufacturing costs and capital expenditures associated with mixing, coating and drying, NMP solvent recovery, and calendering.

[0011] In NX electrodes, the 3D nanocarbon matrix functions as a mechanical scaffold for the electrode active material, mimicking the entanglement of polymer chains. NX electrodes are fabricated via the NX process, which includes a novel high-shear mixing process developed for homogeneously blending and mixing electrode slurries in multiple steps or a single step (e.g., one-pot). Compositions produced by this high-shear process are free of polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) and are referred to as the NX high-shear mixing process.

[0012] The designed surface chemistry of nanocarbon materials, active materials (hybrid lithium nickel cobalt manganese aluminum oxide (NCMA) and lithium manganese iron phosphate (LMFP)) promotes safer performance, and the current collector promotes excellent mechanical stability of the resulting electrode structure. In contrast to PVDF polymers, the 3D nanocarbon matrix has high conductivity, allowing for a significantly thicker cathode active layer while improving electrode conductivity. By using an environmentally friendly solvent that evaporates easily, electrode throughput is increased, and more importantly, energy consumption from the electrode drying process is reduced by 30% due to the reduction in the temperature required by NMP from 150°C-180°C to 60°C-70°C. When paired with aqueous-based NX Si-dominant anodes, a dramatic increase in the energy density and FC capacity of EV battery cells can be achieved.

[0013] Disclosed herein are active materials for cathodes and anodes that do not contain polyvinylidene fluoride and do not use NMP as a solvent for processing.

[0014] Disclosed herein is a method for producing an improved electrode active layer that can be used in the electrodes of an electrocell, comprising high shear of a slurry. The high shear process produces electrodes with high electrochemical performance by combining a number of different mixing tools and methods with a multi-step mixing sequence.

[0015] Portable electronic devices, electric vehicles, and hybrid electric vehicles all use rechargeable lithium-ion batteries (LIBs) to supply power and energy. Due to LIBs' high energy and power density, established reliability, long cycle life, and flexible design, the LIB market has experienced rapid growth over the past decade.

[0016] Scalable LIB manufacturing involves mixing high-solids slurries. Consequently, electrode structure can be influenced by the type of mixer and mixing process parameters, particularly the order in which materials are introduced ("mixing sequence"), as well as the intensity and duration of each step, which are crucial in determining battery quality and electrochemical performance. Various mixing sequences have been studied to produce well-mixed slurries for diverse electrode materials. Kim et al. discovered that maximum capacity and charge-discharge cycle stability can be achieved by dry-mixing LiCoO2 (LCO) and a conductive agent, and then adding a solution of polyvinylidene fluoride (PVDF) in N-methyl-2-pyrrolidone (NMP) to form a slurry. According to Bauer et al., the composition of PVDF and carbon black (CB) dispersions can affect the stability and rheological properties of slurries utilizing NMP as a solvent. The addition of CB to PVDF can help form a stable solidified gel system and provide resistance to the rapid sedimentation of LiNiMnCoO2 (NMC) particles. Subsequently, Bauer et al. discovered that the drying and mixing process of the NMC / CB powder mixture before adding the PVDF solution could cause CB shells on the NMC surface, reducing the viscosity and stability of the slurry. When PVDF is coated onto the CB shells after drying, conductive contact with the NMC is inhibited. This problem was solved by adding additional CB or graphite during the homogenization process.

[0017] For laboratory use, the effectiveness of various mixing equipment, including ball mills, magnetic stirrers, and ultrasonic mixers, has been investigated. In industrial settings, large-scale mixers such as planetary mixers, high-speed mixers, universal mixers, and static mixers are frequently used. Well-dispersed slurry mixtures can only be achieved by selecting appropriate mixers for high-viscosity anode and cathode slurries, and by following specific protocols for introducing solid particles and binders into the solvent.

[0018] For example, a ball mill mixer may seem like a suitable tool for mixing electrode slurries, but its effectiveness is diminished by long mixing times. Therefore, it is preferable to seek an alternative mixer that can accelerate the mixing process and reduce the mixing time. The effectiveness of a mixer can be empirically evaluated using a grindometer and rheological measurements.

[0019] The first step in battery (cell) assembly is to deposit a slurry containing active material, conductive material, and an optional polymer binder onto a copper film or aluminum film (current collector) in a solvent. This is followed by electrode drying, calendering, and dimensional setting. To achieve the desired electrochemical performance, the multi-stage manufacturing process of energy storage device electrodes must be strictly controlled.

[0020] A slurry is a highly complex suspension system containing a high proportion of solid particles of different chemicals, sizes, and shapes in a highly viscous medium. Complete mixing of the slurry is desirable for homogeneity. The rheological properties of the slurry affect important attributes: slurry stability, ease of mixing, and coating performance, which in turn affect the finished electrode. The composition and applied processing conditions can influence the rheology of the resulting slurry. Density and viscosity quantify the flow properties and characterize the degree of structure within the sample and the extent to which solid- or liquid-like behavior prevails. In electrode manufacturing processes, the viscosity of the components during the process plays a crucial role in battery fabrication processes such as coating.

[0021] The viscosity of the polymer binder solution affects coating performance. It influences how easily the powder disperses within it, the force used for mixing, and the rate at which a uniform coating is applied. Porous Electrode Theory (PET), experimentally validated, suggests a correlation between cathode density and the overall performance of lithium-ion battery cells. Cells with high cathode density exhibit slightly higher discharge capacity at low current rates, while at high current rates, cells with low cathode density perform better.

[0022] This disclosure describes the development of a novel high-shear mixing process for homogeneously compounding and mixing electrode slurries in multiple stages or in a single stage (e.g., one-pot). Compositions produced by this high-shear process are free of polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) and are referred to as the NX high-shear mixing process. The performance of the mixing process was initially evaluated using a particle size approach with a Hegman gauge. Subsequently, rheological analysis using shear viscosity and dynamic tests was performed to determine how well the anode and cathode materials were mixed. Electrical performance tests were conducted on batteries produced from slurries generated by various mixers and mixing schemes.

[0023] This one-pot approach significantly reduces manufacturing costs by limiting the infrastructure used in the coating process. Typically, processes used to produce active layers containing carbonaceous materials use significant amounts of NMP to generate a slurry that is coated onto the current collector. Using solvents such as NMP to facilitate coating involves significant degassing, handling, safety, and recycling protocols, all of which are eliminated from the NX high-shear mixing process. The NX high-shear mixing process uses water or alcohols that are miscible with water at all temperatures.

[0024] The aqueous lithium ferrophosphate (LFP) process, combined with the NX high-shear mixing process for manufacturing battery electrodes, can be used with standard high-speed, high-volume manufacturing equipment without the need for additional infrastructure upgrades. Electrodes (manufactured using this process) are also improved for current and future battery designs. This NX manufacturing process for battery electrodes is relevant across the Li-ion battery market and the solid-state battery market, particularly to the electric vehicle market.

[0025] Figure 1 shows electrodes (anode or cathode) according to various embodiments. In the illustrated example, electrode 100 is provided. According to various embodiments, electrode 100 includes a current collector 102 and an active layer 106. Electrode 100 may optionally include an adhesive layer 104. As an example, the adhesive layer 104 includes a material that promotes adhesion between the current collector 102 and the active layer 106.

[0026] In some embodiments, with respect to Figure 1, the electrode (anode or cathode) includes a current collector 102 which is a conductive layer. For example, the current collector 102 may be a metal, a metal alloy, etc. In another embodiment, the current collector 102 is a metal foil. In some embodiments, the current collector 102 is an aluminum foil or an aluminum alloy foil. In some embodiments, the current collector 102 is a copper foil or a copper alloy foil. The current collector 102 has a thickness of less than 30 μm, preferably less than 10 μm, preferably less than 8 μm, and more preferably less than 5 μm.

[0027] In an embodiment, the current collector 102 has a thickness of 3 to 15 μm. In some preferred embodiments, the current collector 102 has a thickness of about 6 μm to about 8 μm. In some embodiments, the current collector 102 is an aluminum foil or an aluminum alloy foil, and the current collector 102 has a thickness of about 10 to about 15 μm.

[0028] The electrodes of a lithium battery include complex combinations of materials and mixtures. Important components in the cathode are lithium ferrophosphate (LFP), LiCoO2, LiNiO2, or LiNi x Mn y Co z O2 and other active materials. Other components in the formulation often include a binder such as polyvinylidene fluoride (PVDF), a solvent such as N-methyl-2-pyrrolidone (NMP), and a carbon additive such as carbon black (CB) to enhance the conductivity of the battery.

[0029] The active constituent components in the anode combination include silicon and graphite, while other components such as binders, solvents, and conductive agents are often the same as those used in the cathode. In a typical formulation, the solid composition of the anode and cathode active materials ranges from 50% to 99.9%. The content of the binder ranges from 0.1% to 15%. A higher binder concentration can improve adhesion but increase the resistivity. The compositions of the cathode active layer and the anode active layer will be discussed in detail below.

[0030] Active Material for the Cathode The active layer slurry for the cathode (disposed on the current collector) includes an active material, a carbonaceous conductor, a solvent, and an optional binder. The active material, the carbonaceous conductor, the solvent, and the optional binder are all mixed together to form a slurry. The mixing will be described in detail later. After proper mixing, the slurry is disposed on the current collector, and then the solvent is evaporated to form an active layer.

[0031] In embodiments, the active material used in the cathode may include lithium cobalt oxide (LCO, sometimes called "lithium cobaltate" or "lithium cobaltite"). One variation of the possible LCO formulations is LiCoO2, and lithium nickel manganese cobalt oxide (LiNi x Mn y Co( 1-x-y )NMC, which has a modified formula for O2, lithium nickel cobalt manganese aluminum oxide (LiNi x Mn y Co z Al (1-x-y-z) Lithium manganese oxide (NCMA) with a modified formula for O2, LiMn2O4, Li2MnO3, etc., or LMO with a modified formula for a combination thereof), lithium titanate (LTO, one modified formula is Li4Ti5O 12 Lithium iron phosphate (LiFePO4, LFP), lithium manganese iron phosphate (LMFP), lithium nickel cobalt aluminum oxide (LiNi x Co y Al z This includes O2, as well as other similar materials. Other variations of those described above may also be included. In some embodiments in which NMC is used as the active material, nickel-rich NMC may be used.

[0032] LiRing x Co y Al z O2 and LiNi x Mn y Co z For formulations such as O2, x≧0.8, z≦0.05, and x+y+z=1. In some embodiments, the variation of NMC is LiNi x Mn y Co (1-x-y)x can be approximately 0.7, 0.75, 0.80, or 0.85 or greater. In embodiments, y may be 0.1, 0.15, 0.2, or 0.25 or greater. In some embodiments, an NMC811 can be used in which x is approximately 0.8 and y is approximately 0.1.

[0033] In some embodiments, the active material may include lithium cobalt oxide (LiCoO2). The LiCoO2 material may be further doped with certain metal species to increase its high-voltage stability. A battery containing LiCoO2 (doped or undoped) as the cathode active material can increase the cell energy density at high voltages (Li / Li + It can be charged up to >4.7V.

[0034] In some embodiments, the active material may include lithium manganese iron phosphate (LMFP). The chemical formula for LMFP is LiMn x Fe 1-x It may be PO4, where x is in the range of 0.1 to 0.9, preferably 0.3 to 0.7. Increasing the Mn content in the LMFP material is beneficial for increasing the energy density. In embodiments, the polymer binder for LMFP and LCO can be an aqueous polymer for high-voltage applications for aqueous (solvent is water or a water-containing solvent) processing.

[0035] In the case of ethanol as a solvent, the binder can be polyacrylic acid combined with a certain amount of polyamide and polyvinyl pyrollidone (PVP).

[0036] In the case of a water-containing solvent, the polymer binder may be a copolymer of polyacrylonitrile and polyether.

[0037] In some embodiments, the active material is another form of lithium nickel manganese cobalt oxide (LiNi x Mn y Co 1-x-yIt contains O2). Variations of this formula that can be used in the active material layer include NMC111 (detailed below) and NMC532 (LiNi 0.5 Mn 0.3 Co 0.2 O2), NMC622 (LiNi 0.6 Mn 0.2 Co 0.2 O2), or combinations thereof.

[0038] In embodiments, the active material used in the cathode may include a combination of nickel, manganese, and cobalt. Lithium nickel manganese cobalt oxide (LiNiMnCoO2), abbreviated as NMC, provides the high overall performance, excellent specific energy, and lowest self-heating rate of all mainstream cathode powders. NMC powder may contain 20–40 atomic percent of nickel, 20–40 atomic percent of manganese, and 20–40 atomic percent of cobalt, based on the total weight of the NMC formulation. While the term “NMC powder” can refer to various formulations, it is preferable to use a formulation containing 33 atomic percent of nickel, 33 atomic percent of manganese, and 33 atomic percent of cobalt. This formulation, sometimes called 1-1-1 (NMC111), is useful for applications with frequent cycles (automotive, energy storage) due to the reduced material cost resulting from its lower cobalt content.

[0039] The active material is contained in the active layer in an amount of 67-99% by weight, preferably 90-99% by weight, based on the total weight of the active layer (without solvent).

[0040] Activating substance for the anode The anode active material may include silicon (Si), germanium (Ge), tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), titanium (Ti), nickel (Ni), cobalt (Co), cadmium (Cd); alloys thereof, or two or more of these, or alloys of these with other elements; oxides, carbides, nitrides, sulfides, phosphides, selenides, and tellurides of these metals, and mixtures thereof or lithium-containing composites; salts and hydroxides of Sn; lithium titanate, lithium manganate, lithium aluminate, lithium-containing titanium oxide, lithium transition metal oxides; pre-lithified forms thereof; Li, Li alloys, or surface-stabilized Li having at least 60% by weight of lithium, or particles of combinations thereof. The active material may include graphite instead of, or in addition to, the anode active material. As an example, the anode active material may include silicon oxide and / or silicon carbonate. Such an anode active material containing silicon dioxide or silicon carbon dioxide may further contain graphite.

[0041] In this embodiment, the active material used in the anode is a lithium-based active material. An example of a lithium-based active material is Li x Si y O z Here, x is 1 to 15, preferably 2 to 7, y is 0 to 4, preferably 1 or 2, and z is 0 to 9, preferably 1 to 5. SiO is synthesized by mixing silicon and silica in a 1:1 molar ratio, and then sublimating the mixture to collect amorphous SiO (a-SiO) material. Because the silicon atoms in a-SiO are randomly distributed, their valence numbers can be 0, 1+, 2+, 3+, and 4+ depending on the bonding conditions with different numbers of oxygen atoms. Some of the silicon atoms aggregate to form minute silicon crystals surrounded by other amorphous material, which have Si-O bonds with different silicon valences. In LIB, these minute silicon crystals in a-SiO are Li + It reacts with ions, Li 15It forms Si4 and functions as an active material for energy storage. Due to the nanoscale silicon crystals, no pulverization is performed after lithiation. Therefore, good reversibility can be obtained.

[0042] Examples of lithium-based active materials include Li 15 Examples include Si4, Li2SiO3, Li2Si2O5, Li6Si2O7, Li4SiO4, Li2O, or combinations thereof.

[0043] In the embodiment, the lithium-based active material can be blended with a carbonaceous material to form a Li-SiOx-C active material. In other words, the active material may include lithium, silicate, and carbon. Carbon in the form of carbon black, carbon nanotubes, or graphite, Li x Si y O z (Here, the x, y, and z values ​​are detailed above) may be blended and ground to form aggregates and granules of Li-SiOx-C active material.

[0044] In the production of Li-SiOx-C active material, elemental silicon (Si) can first be reacted with a silicate material (SiOx) and then blended. The silicon-silica combination is subjected to a reaction and grinding process to produce a powder. Carbon is added to this powder in a carbon coating process, and lithium is added in a lithium doping process. After the carbon and lithium doping processes, the formed Li-SiOx-C material enters a classification process to form a final usable anode active material called Li-SiO with a carbon coating. The relative density of the formed material is approximately 2.1 g / cm³ at 25°C. 3 It is possible.

[0045] In the embodiment, the energy storage device may have an initial charge ratio capacity of 1500 to 1600 mAh / g, preferably 1400 to 1500 mAh / g, with an initial Coulomb efficiency of 90 to 94%, and preferably 1350 to 1400 mAh / g with an initial Coulomb efficiency of 87 to 89%.

[0046] Lithium can be added in elemental form or in compound form. Some of these lithium compounds are listed herein. The D50 particle size of the Li-SiOx-C particles prepared in this way is 6 to 9 micrometers. The BET surface area of ​​the formed Li-SiOx-C material is 3 to 4 m² based on the total weight of the Li-SiOx-C active material, with a carbon content of 3 to 4 wt%. 2 It can be / g. Li / Li of a cell (also called an energy storage device) having a Li-SiOx-C anode. + The initial charge ratio capacity for 5mV may be 1500~1600mAh / g, and the Li / Li of a cell having a Li-SiOx-C anode material. + The initial discharge ratio capacity for 2.0mV may be 1400-1500mAh / g with an initial Coulomb efficiency of 90-94%, and the initial discharge ratio capacity for 1.0V of a cell having Li-SiOx-C material for Li / Li+ may be 1350-1400mAh / g with an initial Coulomb efficiency of 87-89%.

[0047] The production of Li-SiOx and Li-SiOx-C active materials, as well as the corresponding electrodes, are described in detail in U.S. Patent No. 9,825,290(B2) and U.S. Patent Application No. 2019 / 0237761(A1), the entire contents of which are incorporated by reference.

[0048] In embodiments, the anode active material may include graphite flakes. Preferably, the graphite flakes are high-aspect-ratio graphite flakes in which at least one dimension is greater than any other dimension. The graphite flakes may be naturally occurring flakes or commercially synthesized flakes. The graphite flakes are particulate and may have an elliptical shape. The aspect ratio of these graphite flakes may range from 2:1 to 20:1, preferably from 5:1 to 12:1. In embodiments, the graphite flakes may be intercalated with metal ions. In another embodiment, the graphite flakes may be exfoliated flakes.

[0049] Graphite flakes may be present in the solid anode active layer (the solid active layer is solvent-free and contains a conductive material, a binder material, and an electrode active material) in an amount of 5 to 90% by weight, preferably 8 to 65% by weight, based on the total weight of the (solvent-free) solid anode active layer.

[0050] The anode active material may be present in the anode active layer in an amount of 40-95% by weight, based on the total weight of the anode active layer (without solvent).

[0051] carbonaceous conductive material Carbonaceous conductive materials are used separately in both the anode and cathode active layers and contain conductive elements. These conductive elements (also referred to as conductive materials) may contain carbon. For example, conductive elements may be high-aspect-ratio carbon elements. The term "high-aspect-ratio carbon element" refers to a carbonaceous element whose size in one or more dimensions ("long dimensions") is significantly larger than its size in the lateral dimension ("short dimension"). High-aspect-ratio carbon elements may comprise a substantially cylindrical network of carbon atoms. Conductive materials may comprise carbon nanotubes or bundles of carbon nanotubes.

[0052] In some embodiments, the conductive material used for the anode and / or cathode may include graphite flakes, which will be discussed later.

[0053] A conductive material can form a conductive penetration network that can transmit electric current between any two isolated points located on the surface of a solid active layer (which does not contain a solvent). In other words, electric current can be transmitted from one surface or end of the active layer to the opposite surface or end of the active layer by physical contact between conductive elements in the electrode active layer or by electron hopping. The penetration network may contain voids between high aspect ratio carbon elements that may contain or accommodate the electrode active material. The high aspect ratio conductive material can be substantially oriented in a direction substantially parallel to the current collector within the electrode active layer 106 to facilitate the conduction of current from one end to the other of the electrode while still maintaining less orientation throughout the thickness of the active layer.

[0054] The conductive material may be present in the mixture in an amount of 0.1 to 1.3, 0.15 to 1.2, or 0.3 to 1% by weight, based on the total weight of the mixture (the mixture includes the conductive material, electrode active material, binder material, and solvent). The conductive material may be present in the active layer in an amount of 0.2 to 3.5, 0.3 to 3, or 0.5 to 2% by weight, based on the total weight of the solids in the active layer (the total weight of the solids does not include the solvent and includes the conductive material, binder material, and electrode active material). In this specification, the electrode active material may mean the anode active material or the cathode active material.

[0055] High aspect ratio carbon elements may be single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWNTs), multi-walled carbon nanotubes (MWNTs), thin-walled nanotubes (TWNTs), carbon black, carbon nanofibers, carbon nanotube fibers, porous carbon, or mixtures of different types.

[0056] Single-walled carbon nanotubes may have an outer diameter of 0.5 to 5.0 nanometers, preferably 1.0 to 3.5 nanometers. Single-walled carbon nanotubes may have an aspect ratio (ratio of length to diameter) greater than about 2.0, preferably greater than 5.0, preferably greater than 10.0, greater than 50, and more preferably greater than 100. In exemplary embodiments, single-walled carbon nanotubes may have an average aspect ratio of 5 to 200.

[0057] Single-walled carbon nanotubes may have a length greater than 6 nanometers, preferably greater than 10 nanometers, preferably greater than 15 nanometers, preferably greater than 30 nanometers, preferably greater than 50 nanometers, more preferably greater than 100 nanometers, preferably greater than 1 micrometer, preferably greater than 5 micrometers, preferably greater than 10 micrometers, more preferably greater than 15 micrometers, and at least up to 200 micrometers. In exemplary embodiments, single-walled carbon nanotubes may have an average length of 10 to 20 micrometers, preferably 20 to 15 micrometers.

[0058] Single-walled carbon nanotubes may be present in a mixture of conductive material, binder material, electrode active material, and solvent in an amount of 0.1 to 0.3% by weight, preferably 0.15 to 0.25% by weight, based on the total weight of the mixture.

[0059] Single-walled carbon nanotubes are present in the electrode active layer (solvent-free conductive material, binder material, and electrode active material) in an amount of 0.2 to 0.6% by weight, preferably 0.3 to 0.5% by weight, based on the total weight of the electrode active layer.

[0060] In another embodiment, SWNTs may comprise a mixture of metallic nanotubes and semiconductor nanotubes. Metallic nanotubes exhibit electrical properties similar to those of metals, while semiconductor nanotubes are electrically semiconductor. Generally, the method of winding graphene sheets produces nanotubes with various helical structures. Zigzag and armchair nanotubes constitute two possible conformations. To minimize the amount of SWNT used in a composition, it is generally desirable that the composition contains as large a proportion of metallic SWNTs as possible. Generally, it is desirable that the SWNTs used in a composition contain metallic nanotubes in an amount of about 1% by weight or more, preferably about 20% by weight or more, more preferably about 30% by weight or more, even more preferably about 50% by weight or more, and most preferably about 99.9% by weight or more, of the total weight of the SWNTs. In certain circumstances, it is generally desirable that the SWNTs used in the composition contain semiconductor nanotubes in an amount of about 1% by weight or more, preferably about 20% by weight or more, more preferably about 30% by weight or more, even more preferably about 50% by weight or more, and most preferably about 99.9% by weight or more, of the total weight of the SWNTs.

[0061] In the embodiment, metallic single-walled carbon nanotubes are present in the electrode active layer (solvent-free conductive material, binder material, and electrode active material) in an amount of 0.2 to 0.6% by weight, preferably 0.3 to 0.5% by weight, based on the total weight of the electrode active layer. The electrode active layer referred to herein may be either a cathode active layer or an anode active layer.

[0062] The number of carbon layers in a multi-walled carbon nanotube can be 2 or more, 5 or more, 10 or more, or 50 or more. On average, a multi-walled carbon nanotube may contain 3 to 15 layers, 4 to 12 layers, 5 to 10 layers, or 6 to 8 layers.

[0063] The D50 particle size distribution of carbon black or porous carbon may be in the range of 0.1 μm to 100 μm. The total Brunauer-Emmett-Teller (BET) surface area of ​​carbon black or porous carbon is at least 50 m².2 / g, preferably at least 500m 2 It may be / g. Carbon black or porous carbon may be present in the electrode active layer (solvent-free conductive material, binder material, and electrode active material) in an amount of 0.2 to 1.0% by weight, preferably 0.3 to 0.5% by weight, based on the total weight of the electrode active layer.

[0064] The active layer 106 (see Figure 1) may include multi-walled carbon nanotubes and single-walled carbon nanotubes. Multi-walled carbon nanotubes swell more than single-walled carbon nanotubes when wetted with the electrolyte in the energy storage device where electrode 100 is located. For example, multi-walled carbon nanotubes may swell by at least 15%, at least 25%, or at least 50% more than single-walled carbon nanotubes when wetted with the electrolyte in the energy storage device where electrode 100 is located. For example, the length of a multi-walled carbon nanotube may expand by at least 15%, at least 25%, or at least 50% more than the length of a single-walled carbon nanotube when wetted with the electrolyte. In another example, a multi-walled carbon nanotube may swell by up to 50% when wetted (e.g., the length of the multi-walled carbon nanotube increases by 50% after wetting with the electrolyte, and / or the diameter of the multi-walled carbon nanotube increases by 50% after wetting).

[0065] Multi-walled carbon nanotubes may have an outer diameter of 2.0–50 nanometers, 5.0–40 nanometers, or 6–10 nanometers. Multi-walled carbon nanotubes may have lengths greater than 10 nanometers, greater than 15 nanometers, greater than 30 nanometers, greater than 50 nanometers, greater than 100 nanometers, greater than 500 nanometers, greater than 1 micrometer, greater than 5 micrometers, greater than 10 micrometers, or greater than 15 micrometers. Simultaneously, multi-walled carbon nanotubes may have an average length of up to 25 micrometers or up to 20 micrometers. In exemplary embodiments, multi-walled carbon nanotubes have an average length of 10–20 micrometers, or 20–15 micrometers. Multi-walled carbon nanotubes may have aspect ratios (ratio of length to diameter) greater than 5.0, greater than 10.0, greater than 50, greater than 100, or greater than 500.

[0066] The electrodes contain multilayer carbon nanotubes, which may be relatively long compared to those found in electrodes of related technologies. The use of relatively long multilayer carbon nanotubes in electrodes has been found to have beneficial mechanical and / or electrical properties. For example, multilayer carbon nanotubes provide relatively good output at low densities. As another example, shorter multilayer carbon nanotubes generally do not swell (e.g., expand) as much as longer multilayer carbon nanotubes. Therefore, the use of shorter multilayer carbon nanotubes loses (or reduces) some of the beneficial properties associated with the swelling of carbon nanotubes. As an extreme example, carbon black does not swell because it is simply a collection of carbon particles without entanglement (e.g., the entanglement exhibited by a set of multilayer carbon nanotubes). The indicator that a certain amount of multi-walled carbon nanotubes has a length exceeding a threshold length and therefore possesses sufficient swelling properties is an observation during the calendering process, and a relatively large amount of pressure or effort for calendering the active layer in connection with coating onto foil indicates that the collective swelling (e.g., average swelling) of the multi-walled carbon nanotubes in the active layer meets a certain performance threshold. However, multi-walled carbon nanotubes are generally difficult to process.

[0067] The processing of multi-walled carbon nanotubes related to the preparation / formation of the active layer and / or electrode is milder than the process for electrodes in related technologies. Therefore, the process according to various embodiments maintains longer multi-walled carbon nanotubes (e.g., fewer multi-walled carbon nanotubes are fractured, fragmented, or destroyed). In some embodiments, the active layer of the electrode includes a set of multi-walled carbon nanotubes having an average length longer than the average length of multi-walled carbon nanotubes in electrodes of related technologies. According to various embodiments, the length distribution of the set of multi-walled carbon nanotubes is distorted relative to the nominal length of the multi-walled carbon nanotubes. As an example, the nominal length of the multi-walled carbon nanotubes is approximately 16 microns. For example, the multi-walled carbon nanotubes are processed and / or applied to reduce or minimize fracture or destruction of the multi-walled carbon nanotubes. The length of multi-walled carbon nanotubes in a network of high-aspect-ratio carbon elements is generally the nominal length of the multi-walled carbon nanotubes, or such lengths tend to be more distorted relative to the nominal length. In some embodiments, at least 75% of the multi-walled carbon nanotubes in the network of high-aspect-ratio carbon elements are within 10% of their nominal length (e.g., 13.4 microns to about 15 microns). In some embodiments, at least 75% of the multi-walled carbon nanotubes in the network of high-aspect-ratio carbon elements have a length of at least 12 microns. In some embodiments, at least 75% of the multi-walled carbon nanotubes in the network of high-aspect-ratio carbon elements have a length of at least 13 microns. In some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high-aspect-ratio carbon elements are within 10% of their nominal length (e.g., 13.4 microns to about 15 microns). In some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high-aspect-ratio carbon elements have a length of at least 12 microns. In some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high-aspect-ratio carbon elements have a length of at least 8 microns.In some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements have a length of at least 13 microns.

[0068] According to various embodiments, the length distribution of a set of multi-walled carbon nanotubes is distorted relative to the nominal length of the multi-walled carbon nanotubes. For example, multi-walled carbon nanotubes are treated and / or applied to reduce or minimize the fracturing or breakage of the multi-walled carbon nanotubes. The length of multi-walled carbon nanotubes in a network of high aspect ratio carbon elements is generally the nominal length of the multi-walled carbon nanotube, or the length of such multi-walled carbon nanotubes tends to be more distorted relative to the nominal length.

[0069] In some embodiments, at least 75% of the multi-walled carbon nanotubes in the network of high-aspect-ratio carbon elements are within 10% of their nominal length (e.g., 13.4 micrometers to about 15 micrometers). In some embodiments, at least 75% of the multi-walled carbon nanotubes in the network of high-aspect-ratio carbon elements have a length of at least 12 micrometers. In some embodiments, at least 75% of the multi-walled carbon nanotubes in the network of high-aspect-ratio carbon elements have a length of at least 13 micrometers. In some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high-aspect-ratio carbon elements are within 10% of their nominal length (e.g., 13.4 micrometers to about 15 micrometers). In some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high-aspect-ratio carbon elements have a length of at least 12 micrometers. In some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high-aspect-ratio carbon elements have a length of at least 13 micrometers.

[0070] Multiwalled carbon nanotubes may be present in a mixture (the mixture includes a conductive material, an electrode active material, a binder material, and a solvent or a combination of solvents) in an amount of 0.3 to 1.0% by weight, preferably 0.4 to 0.9% by weight, based on the total weight of the mixture. Multiwalled carbon nanotubes may also be present in a solid anode active layer (the solid active layer includes a conductive material, a binder material, and an electrode active material, but does not contain a solvent) in an amount of 0.8 to 2.6% by weight, preferably 1.0 to 1.8% by weight, based on the total weight of the solid anode active material (which does not contain a solvent).

[0071] In examples where both multi-walled and single-walled carbon nanotubes are used, the ratio of the weight of multi-walled carbon nanotubes to the weight of single-walled carbon nanotubes in the mixture or solid active material layer may be at least 2:1.

[0072] In one example, a three-dimensional network of high aspect ratio carbon elements 10⁸ contains carbon nanotubes, and these carbon nanotubes consist of multi-walled carbon nanotubes and / or fragments of such carbon nanotubes.

[0073] In another example, multi-walled carbon nanotubes are present in a mixture or solid anode active material layer in an amount at least twice that of single-walled carbon nanotubes, based on the weight of the conductive material.

[0074] In the embodiment, the carbon nanotubes may include randomly dispersed carbon nanotubes in which clumps of brush-shaped oriented nanotubes are dispersed. The brush-shaped oriented nanotubes are randomly dispersed within the randomly dispersed carbon nanotubes, but within each brush-shaped clump, the nanotubes are aligned. The aligned nanotubes within the brush-shaped clumps may have a length greater than the thickness of the active layer (i.e., the cathode active layer or the anode active layer).

[0075] A three-dimensional network of high aspect ratio carbon elements 108 may contain at least 99% by weight of carbon.

[0076] In addition to high aspect ratio carbon elements (carbon nanotubes), the conductive material may optionally include graphite flakes, carbon black, or a combination thereof.

[0077] In addition to carbon nanotubes, carbon black or porous carbon may also be used. These carbon materials are typically 50 square meters / gram (m²). 2 Greater than / gm, preferably 200m 2 Larger than / gm, more comfortable 500m 2 This refers to high-surface-area carbon having a surface area greater than / gm. An example of high-surface-area carbon black is KELTJEN Black. The carbon material is optional and may be present in the solid anode active layer (the solid active layer is solvent-free and contains conductive material, binder material, and electrode active material) in an amount of 0.5 to 2.0 wt%, preferably 0.8 to 1.6 wt%, based on the total weight of the solid anode active material. The presence of high-aspect-ratio carbon nanotubes is beneficial for conductivity and cell rate performance, but 1D carbon materials (carbon black or porous carbon) are generally less expensive and can enable optimal slurry rheological properties with a high slurry solid content.

[0078] A three-dimensional network of high aspect ratio carbon elements 108 may include an electrically interconnected network of carbon elements exhibiting connectivity above a penetration threshold, the network defining one or more highly conductive paths having a length greater than 100 μm. The penetration threshold is a threshold that provides a conductive network where conductive elements are in contact with each other and measured across any two points on any surface of the network.

[0079] Polymer additives / binders In the embodiment, the electrode active material (anode active material or cathode active material) and the carbonaceous conductive material are held together by a binder. Examples of binders include cellulose, polyacetal, polycarbonate, polyalkyd, polystyrene, polyolefin, polyester, polyamide, polyaramid, polyamideimide, polyarylate, polyurethane, epoxy, phenols, silicone, polyarylsulfone, polyethersulfone, polyphenylene sulfide, polysulfone, polyimide, polyacrylate, polyetherimide, polytetrafluoroethylene, polyetherketone, polyetheretherketone, polyetherketoneketone, polybenzoxazole, polyoxadiazole, polybenzothiadinophenothiazine, polybenzothiazole, polypyrradinoquinoxaline, polymethylacrylate, polyisobutyl methacrylate, polypyromelliimide, polygynoxaline, polybenzimidazole, and polyoxyin Examples of organic polymer materials include polyoxoisoindoline, polydioxoisoindoline, polytriazine, polypyridazine, polypiperazine, polypyridine, polypiperidine, polytriazole, polypyrazole, polycarborane, polyoxabicyclononane, polydibenzofuran, polyphthalide, polyacetal, polyanhydride, polyvinyl ether, polyvinyl thioether, polyvinyl butyral, polyvinyl alcohol, polyvinyl ketone, polyvinyl nitrile, polyvinyl ester, polysulfonate, polysulfide, polythioester, polyacrylonitrile, styrene-butadiene rubber, polysulfone, polysulfonamide, polyurea, polyphosphazene, polysilazane, polypropylene, polyethylene, polyethylene terephthalate, polysiloxane, etc., or combinations thereof.

[0080] The binder is present in the active layer in an amount of 0.1 to 15% by weight, preferably 1 to 10% by weight, and more preferably 1.5 to 5% by weight, based on the total weight of the active layer (without solvent). In embodiments, the binder is present in the form of an emulsion before being mixed with the active material placed on the current collector. The binder is preferably water-soluble or compatible with a water-soluble polymer so as to be soluble in water. A water-soluble solvent may also be used to disperse the binder and the high aspect ratio carbon element 108.

[0081] solvent In the preparation of the slurry, a solvent is used to facilitate the blending of the active material (either anode or cathode active material), carbonaceous conductive material, binder, and any other additives as desired. The solvent is preferably capable of dissolving the binder. Suitable solvents are water, alcohol, or a combination thereof. Examples of alcohols include ethanol, methanol, propanol, butyl alcohol, ethylene glycol, propylene glycol, or a combination thereof. In addition to water and alcohol, other solvents may be added to promote the solubilization and / or dispersion of the polymer. Other solvents include polar solvents and nonpolar solvents. The addition of other solvents should preferably not alter the solubility of the polymer in water or alcohol. Liquid aprotic polar solvents, such as propylene carbonate, ethylene carbonate, butyrolactone, acetonitrile, benzonitrile, nitromethane, nitrobenzene, sulfolane, dimethylformamide, N-methylpyrrolidone, or a combination thereof, can be added to water or alcohol for the dissolution of the polymer. Polar protic solvents, such as acetonitrile, nitromethane, acetone, dimethyl sulfoxide, dimethylformamide, or combinations thereof, can be used. Other nonpolar solvents, such as benzene, toluene, methylene chloride, carbon tetrachloride, hexane, diethyl ether, tetrahydrofuran, or combinations thereof, can also be used. Cosolvents comprising at least one aprotic polar solvent and at least one nonpolar solvent can also be used to modify the solubilizing power of the solvent.

[0082] In one embodiment, the solvent contains only water and does not contain ethanol. In another embodiment, the solvent contains only ethanol and does not contain water. In yet another embodiment, the solvent may be a mixture of water and ethanol. When water and alcohol are used as solvents for the active layer, the water-to-alcohol ratio is 80:20 to 95:5, preferably 88:12 to 92:8. In an exemplary embodiment, the water-to-alcohol ratio is 90:10. The choice of solvent system depends on the compatibility of the active material, the availability of the binder, and the slurry rheological properties.

[0083] The solvent is present in an amount of 30-60% by weight, preferably 40-55% by weight, based on the total weight of the first slurry. The solvent is preferably removed from the active layer after it has been placed on the current collector. The solid active layer preferably does not contain the solvent (water and alcohol).

[0084] Treatment for forming active material Figures 3–5 illustrate a general mixing strategy for cathode slurries with NX HS treatment. Using unique optimizations of the NX process, the NX mother slurry can be completely dispersed and homogeneously mixed for downstream processing with additional polymer solutions, carbon additives, and active materials. In this method, detailed in Figure 3, the carbonaceous material and polymer binder are first mixed in a solvent or solvent mixture in step 1002 to form the mother slurry. In one embodiment, the solvent contains only water and does not contain ethanol. In another embodiment, the solvent contains only ethanol and does not contain water. In yet another embodiment, the solvent may be a mixture of water and ethanol. When water and alcohol are used as solvents for the active layer, the water-to-alcohol ratio is 80:20–95:5, preferably 88:12–92:8. In an exemplary embodiment, the water-to-alcohol ratio is 90:10. The process for forming the active material first involves compounding a portion of the components in an NX high-shear (HS) process to form a homogeneous formulation. Machines used for this purpose may be ball milling machines, magnetic stirrs, ultrasonic or planetary dispersion (PD) mixers. In exemplary embodiments, a commercially available PD mixer from MTI Corporation may be used. During the mixing of the components in the PD mixer, the stirring blades can be set to a stirring speed of 20 to 70 rpm, preferably 30 to 60 rpm. The dispersion blades can be set to a dispersion speed of 600 to 2000 rpm, preferably 1000 to 1800 rpm. This first formulation may be a dry formulation or may be carried out in a portion of a solvent used to facilitate formulation. If a dispersant is used to facilitate the formulation of the conductive material into the active material, the dispersant is also added at this stage. The mixing in step 1002 is carried out for 5 to 120 minutes, preferably 10 to 60 minutes.

[0085] The mixing in steps 1004 to 1012 is carried out using commercially available mixers, blades, and dispersion mixers, including ball milling machines, magnetic stirrs, ultrasonic or PD mixers. In exemplary embodiments, a commercially available PD mixer from MTI Corporation may be used. During the mixing of the components in the PD mixer, the stirring blades can be set to an stirring speed of 20 to 70 rpm, preferably 30 to 60 rpm. The dispersion blades can be set to a dispersion speed of 600 to 2000 rpm, preferably 1000 to 1800 rpm.

[0086] The mother slurry produced in step 1002 contains a carbonaceous conductive material, a binder, and any preferred dispersant, either under a dry mixing process or with a solvent. First, the mother slurry is mixed until the desired distribution of the carbonaceous conductive material in the binder (and the optional dispersant) is achieved. After this, additional polymer binders in the solvent are added to the mother slurry in several steps, particularly steps 1004-1012. In steps 1004 and 1006, additional binders may be added to the container in one or more batches. Note that the entire sequence of steps 1002 to 1010 is carried out in a single container. More than one container may be used if desired. However, it is preferable to carry out the entire mixing in a single container.

[0087] In each batch of binder addition in steps 1004 and 1006, further mixing is performed using a blade and dispersion mixer. In these steps, the binder is added in solution form. In other words, a solvent may be added to the binder to solubilize it, and then the solution of the binder in the solvent is added in batches in these steps. The mixing in steps 1004 and 1006 may be carried out for 5 to 120 minutes, preferably 10 to 60 minutes.

[0088] Next, in step 1008, an active material such as NCM / NCMA / LFP, LFMP, etc., is added to the same mixing vessel. It may be added continuously or in stages. Mixing for the addition of the active material is carried out for 5 to 120 minutes, preferably 10 to 60 minutes. Step 1010 is optional and is characterized by the addition of an additional solvent to the mixture in the vessel. Mixing in step 1010 is carried out for 5 to 120 minutes, preferably 10 to 60 minutes, to form a final cathode slurry (see step 1012). The cathode slurry obtained in step 1012 is placed on a metal film (current collector) and dried to form an active material layer. The active material layer thus placed on the current collector forms an electrode that can be used in an energy storage device. This process is described in detail for producing a cathode active layer, but can also be used to produce anode active material and anode active layer.

[0089] Figure 4 depicts an alternative process involving steps 2002–2012. The manufacturing process in Figure 4 is similar to that in Figure 3, except that step 1010, the second to last step in Figure 3, becomes step 2004 in Figure 4. Figure 4 depicts an alternative method of mixing the components to form the cathode active layer. In this method, water and alcohol are added to the mother slurry (in Figure 3) immediately after it is formed (see step 2002) (see step 2004). The mother slurry, along with the water and alcohol, is subjected to additional blade and dispersion mixing (see step 2004). Subsequently, additional binders, along with the solvent, are added to the mixture of the mother slurry and water and alcohol in several steps, with some mixing between each step (see steps 2006 and 2008). After sufficient mixing, the active material is added to the mixture of solvent, binder, and carbonaceous conductive material to form the cathode (or anode) active material (see step 2010). Next, the cathode (or anode) active material is placed on the current collector and dried (by removing the solvent, water, and alcohol) to form an active layer (see step 2012).

[0090] Figure 5 depicts another process involving steps 3002-3012. The manufacturing process in Figure 5 is similar to that in Figure 4, except that step 2008 in Figure 4 becomes step 3010, the second to last step in Figure 5. Additionally, step 2006 in Figure 4 becomes an optional step in step 3006 in Figure 5, depending on the rheological properties of the slurry.

[0091] The mixing steps disclosed herein can be illustrated by the following non-limiting examples. [Examples]

[0092] Example 1 The examples shown in Tables 1-3 illustrate compositions prepared using the processes described herein. Tables 1-3 detail compositions containing each component.

[0093] As noted above, both cathode slurries and anode slurries typically contain four main components: a binder, a solvent, a carbonaceous conductive material, and an active material. The solid powders constituting the active material and conductive material range in size from nanoscale to microscale. These solid powders are combined with the binder in an organic solvent (ethanol) or an aqueous solvent (H2O). For example, N-methyl-2-pyrrolidone (NMP) and polyvinylidene fluoride (PVDF) are typically used as industrial standards, respectively.

[0094] Li-containing complex inorganic compounds are the most common active ingredients for cathodes. These include LiCoO2, LiNiO2, LiMn2O4, LiFePO4, and LiNi x Mn y Co 1-x-y It contains O2. Batteries made from these active materials exhibited high energy capacity, long lifespan, and good heat resistance. They are widely used as cathode materials in home appliances and electric vehicles.

[0095] For example, the active material used in the inventors' investigation was LFP. These particles ranged in size from 0.5 to 12 μm on average. The conductive agents were two carbon powders: 0.5 to 2 wt% carbon black with an average size of approximately 1 to 10 μm, and 0.5 to 2 wt% carbon nanotubes (CNTs) with an average size of 20 to 100 nm. The slurry had a solid content of 40 to 70 wt% based on the total weight of the slurry. After coating and drying, the dry weight of the LFP electrodes had a final composition exceeding 80 to 99 wt%. Table 1 includes a list of various compositions of the cathode material.

[0096] [Table 1]

[0097] The viscosity of formulations of mother slurries mixed with one or more binders / dispersants and LFPs is shown in the graph in Figure 6. In Figure 6, the viscosity of each formulation decreases as the shear rate increases. Figure 7 depicts the viscosity of several formulations containing mother slurries mixed with binders / dispersants and NCMs, each formulation being mixed with increasing time. From Figure 7, it can be seen that the viscosity of the formulations decreases with increasing mixing time.

[0098] The following preliminary results indicate that LFP cathode (16-35 mg / cm³) 3 ) can be coated without cracking problems and with good flexibility, and at 2.4~2.7 g / cm³ 3 This shows that the following compression density can be achieved (Figure 9): 5.5 mAh / cm². 2High-area capacity-loaded cathodes containing the above LFPs can be generated. The electrochemical performance of LFP half-cells using NX LFP cathodes paired with lithium metal pair electrodes is shown in Figures 8 and 9. When the LFP cathode is paired with an NX Si / C anode, an LFP full-cell energy density greater than 240 Wh / kg, preferably 560 Wh / L or higher, is generated. The energy density of LFP-SiGr battery cells can range from 200 to 250 Wh / kg and 490 to 570 Wh / L for large EV battery cells, depending on the battery cell design and electrode load. This represents an improvement of more than 30% compared to the cell standard in the LFP industry. The cell cycle life is 1000 cycles (70% of nominal capacity) or more. Si-dominant anodes can be pre-lithified to achieve a longer cycle life for NX LFP-Si cells, allowing the anode potential relative to Li / Li+ to be controlled within the range of 0.05V to 0.8V for the entire battery cell cycle life. The anode electrode may not be pre-lithified. Alternatively, the anode electrode may be pre-lithified to a degree of 10-20% lithiumization based on the total anode area capacity to control the anode potential relative to Li / Li+ within the range of 0.05V-0.8V for the entire battery cell cycle life. The anode potential during the cell cycle life is preferably 0.1V-0.75V relative to Li / Li+. The electrolyte contains salt-type and solvent-type additives, including LiFSI and FEC. The separator is coated with a PVDF material having a thickness range of 1-2 μm. The ratio of anode active layer area capacity to cathode active layer area capacity is 1.05-1.25. The electrolyte used in the battery cell is disclosed in Hyde's patent application, International Publication No. 2021226483(A1), which is incorporated herein by reference in its entirety.

[0099] Examples of solvents that can be used as electrolytes in battery cells are shown below.

[0100] [Table 2]

[0101] As detailed above, a novel NX HS mixing process was developed for homogeneously compounding and mixing electrode slurries in multiple stages or in a single pot. The performance of the mixing process was initially evaluated using a particle size approach with Hegman gauges. Subsequently, rheological analysis using shear viscosity and dynamic tests was performed to determine how well the anode and cathode materials were mixed. Electrical performance tests were conducted on batteries produced from slurries generated by various mixers and mixing schemes.

[0102] This one-pot approach significantly reduces manufacturing costs by limiting the infrastructure required for the coating process. This aqueous LFP process, with its NX HS mixing process for manufacturing battery electrodes, can be used with standard, high-speed, high-volume manufacturing equipment without additional infrastructure upgrades. The electrodes will also be improved in most current and future battery designs. This NX manufacturing process for battery electrodes is relevant across the Li-ion battery market and the solid-state battery market, particularly the electric vehicle market.

[0103] The resulting energy storage device is a high-mass-loaded PVDF-free NCMA / LMFP containing a cathode electrode with a thin Si-dominant anode. This energy storage device enables rapid charging (10 minutes to an 80% state of charge (SOC)) while also allowing for a significant leap in the energy density of EV battery cells (estimated to be over 350-400 Wh / kg and over 900 Wh / L).

[0104] The following table shows a comparison between current battery performance and the proposed cell.

[0105] [Table 3]

Claims

1. It is a method, The first polymer binder is mixed with a carbonaceous conductive material to produce a first formulation, The second polymer binder in the first solvent is added to the first formulation to produce the second formulation, Mixing the second formulation described above, The third polymer binder in the second solvent is added to the second formulation to produce the third formulation, Mixing the third compound described above, The active material is added to the third formulation to form an active material composition, A method comprising mixing the aforementioned active material composition.

2. The method according to claim 1, wherein the first polymer binder is different from the second polymer binder.

3. The method according to claim 1, wherein the second polymer binder is different from the third polymer binder.

4. The method according to claim 1, wherein the first polymer binder is the same as the second polymer binder.

5. The method according to claim 1, wherein the second polymer binder is the same as the third polymer binder.

6. The method according to claim 1, wherein the first polymer binder, the second polymer binder, and the third polymer binder are all soluble in water, alcohol, or a combination thereof.

7. The method according to claim 6, wherein the alcohol is ethanol.

8. The method according to claim 1, wherein the first solvent is different from the second solvent.

9. The method according to claim 1, wherein the first solvent is the same as the second solvent.

10. The method according to claim 1, wherein the mixing for producing the first formulation, the second formulation, or the third formulation is carried out in the same mixing container.

11. The method according to claim 1, wherein the mixer used to perform the mixing to produce the first formulation, the second formulation, or the third formulation is a planetary blender.

12. The method according to claim 1, further comprising adding an additional first or second solvent to the first, second, or third formulation.

13. The method according to claim 1, wherein the active material may be an anode active material, a cathode active material, or a combination thereof.

14. The method according to claim 13, wherein the anode active material includes silicon, graphite, or a combination thereof.

15. The anode active material is Li ｘ Si ｙ O ｚ The method according to claim 14, wherein the formula includes, where x is 1 to 15, y is 1 to 4, and z is 1 to 9.

16. where the cathode active material is LFP, LiCoO ２ , LiNiO ２ , LiNiMnCoO ２ , LiNiO ２ , LiMn ２ O ４ , LiFePO ４ , and LiNi ｘ Mn ｙ Co １－ｘ－ｙ O ２ and x has a value of 0.7 to 0.85 and y is greater than 0.1, the method according to claim 13.

17. Li-ion battery cell, The cathode current collector and the cathode active layer are made of LFP, LiCoO ２ LiNiO ２ , LiNiMnCoO ２ LiNiO ２ LiMn ２ O ４ LiFePO ４ , and LiNi ｘ Mn ｙ Co １－ｘ－ｙ O ２ A cathode active material comprising one or more of NCMA, or a combination thereof, wherein x has a value of 0.7 to 0.85 and y is greater than 0.1, wherein the cathode active layer is in contact with the cathode current collector, The anode current collector and the anode active layer are made of Li ｘ Si ｙ O ｚ The anode comprises a graphite mixed with a formula in which x is 1 to 15, y is 1 to 4, and z is 1 to 9, and the anode comprises an anode in which the anode active layer is in contact with the anode current collector. A battery cell in which both the anode active layer and the cathode active layer each contain high aspect ratio carbon elements, and the high aspect ratio carbon elements trap the anode active material and the cathode active material in the voids within the high aspect ratio carbon elements, respectively.

18. The battery cell according to claim 17, wherein the anode active layer is not pre-lithiumized.

19. The battery cell according to claim 17, wherein the anode active layer is pre-lithiumized in an amount of 10 to 20% based on the total anode area capacity.

20. The battery cell according to claim 17, wherein the anode potential relative to Li / Li+ is controlled between 0.05 and 0.8 V relative to Li / Li+ during the battery cell cycle.

21. The battery cell according to claim 17, wherein a high-mass-loaded PVDF-free NX NCMA / LMFP cathode electrode having a thin Si-dominant anode of NX enables rapid charging (10 minutes, 80% SOC) while having a substantial jump in the energy density of the EV battery cell (expected to be ≥350–400 Wh / kg, ≥900 Wh / L).

22. The battery cell according to claim 17, wherein the electrolyte used in the battery cell comprises a salt and a solvent, and the salt and solvent are shown in the following table. Table 1

23. The battery cell according to claim 17, wherein the separator used in the battery cell is coated with a polyvinylidene (PVDF) material having a thickness of 1 to 2 micrometers, and the PVDF is laminated onto the separator at 1 to 10 MPa and 80 to 100°C for a period of 10 to 60 seconds.

Images