Cathode and cathode slurry for secondary battery

Abstract

The cathode slurry contains a cathode active material, particularly a nickel-containing cathode active material, and has improved stability in water. Treating the nickel-containing cathode active material with a lithium compound can prevent undesired decomposition of the material and improve the stability of the cathode. Also provided herein is a cathode for a secondary battery, comprising a current collector and an electrode layer coated on the current collector, the electrode layer comprising a cathode active material, a binder material, and a lithium compound.

Description

[Technical Field]

[0001] The present invention relates to the field of batteries, and in particular to cathodes and cathode slurries for lithium ion batteries. [Background technology]

[0002] Over the past few decades, lithium-ion batteries (LIBs) have become widely used in various applications, especially in home appliances, due to their excellent energy density, long cycle life, and high discharge capacity. With the rapid market development of electric vehicles (EVs) and grid energy storage, high-performance, low-cost LIBs currently offer one of the most promising options for large-scale energy storage devices.

[0003] The use of multi-element lithium transition metal oxides, such as lithium nickel manganese cobalt oxide (NMC) and lithium nickel cobalt aluminum oxide (NCA), is gaining popularity due to their superior electrochemical properties over traditional cathode active materials such as LiMnO2, LiCoO2, and LiNiO2. These superior electrochemical properties include high energy density and excellent capacity performance.

[0004] Currently, cathodes are often prepared by dispersing the cathode active material, binder, and conductive agent in an organic solvent such as N-methyl-2-pyrrolidone (NMP) to form a cathode slurry, which is then coated onto a current collector and dried.

[0005] Using aqueous solutions instead of organic solvents is preferable for environmental reasons and ease of handling, and aqueous slurries have therefore been explored. However, nickel-containing cathode active materials react with water during electrode fabrication, causing the metal in the cathode active material to leach out of the cathode active material, leading to performance degradation. Dissolution of lithium on the cathode active material surface generates soluble bases. High levels of soluble bases increase the pH of the cathode slurry, potentially affecting the uniformity of dispersion of components (e.g., cathode active material) and the binding strength of the binder. This can also adversely affect the metal components of the electrode (e.g., current collector), thereby adversely affecting the performance of the cathode active material. For example, the cathode active material reacts with the aluminum current collector to form Al(OH)3 precipitates, which inhibit lithium ion migration and reduce battery capacity retention. Both of these factors lead to reduced electrochemical performance. Traditionally, pH adjusters have been used to adjust the pH of the cathode slurry. However, such additives can adversely affect the electrochemical processes occurring in the cathode, especially at high voltages and temperatures, and ultimately reduce battery performance. Therefore, it is desirable to prevent lithium dissolution from the surface of the cathode active material during the preparation of the cathode slurry.

[0006] EP Patent Application Publication No. 3044822A discloses an aqueous lithium transition metal oxide cathode slurry. This slurry contains a lithium transition metal oxide powder consisting of primary particles that form a polymer-containing coating layer. The coating layer is composed of two layers. The outer layer contains a fluorine-containing polymer, which reduces the surface coverage of the water, thereby preventing pH-raising ion exchange reactions with water. The inner layer contains a product of the reaction between the outer layer polymer and the lithium transition metal oxide, such as LiF. This reaction decomposes the surface base, lowering the base potential of the oxide. However, fluorine-containing polymers increase electrical resistance, leading to reduced battery performance and also posing risks to human health and the environment.

[0007] In view of the above, there is a continuing need for cathodes and cathode slurries having nickel-containing cathode active materials for lithium ion batteries that have good electrochemical performance in a simple, fast, and environmentally friendly manner. Summary of the Invention

[0008] The aforementioned needs are met by various aspects and embodiments disclosed herein. In one aspect, provided herein is a cathode for a secondary battery, comprising a current collector and an electrode layer coated on the current collector, the electrode layer comprising a cathode active material, a binder material, and a lithium compound.

[0009] In another aspect, provided herein is a cathode slurry for a secondary battery, comprising a cathode material, a binder material, and a lithium compound.

[0010] In some embodiments, the lithium compound comprises one or more of lithium borate, lithium bromide, lithium chloride, lithium bicarbonate, lithium hydroxide, lithium iodide, lithium nitrate, lithium sulfate, lithium acetate, lithium lactate, lithium citrate, lithium succinate, or a combination thereof.

[0011] In certain embodiments, the cathode active material is Li 1+x Ni a Mn b Co c Al (1-a-b-c) O2, LiNi 0.33 Mn 0.33 Co 0.33 O2, LiNi 0.4 Mn 0.4 Co 0.2 O2, LiNi 0.5 Mn 0.3 Co 0.2 O2, LiNi 0.6 Mn 0.2 Co 0.2 O2, LiNi 0.7 Mn 0.15 Co 0.15 O2, LiNi 0.8 Mn 0.1 Co0.1 O2, LiNi 0.92 Mn 0.04 Co 0.04 O2, LiNi 0.8 Co 0.15 Al 0.05 The cathode active material is selected from the group consisting of O2, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, Li2MnO3, and combinations thereof, where -0.2≦x≦0.2, 0≦a<1, 0≦b<1, 0≦c<1, and a+b+c≦1. In a further embodiment, the cathode active material is doped with a dopant selected from the group consisting of Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof.

[0012] In another embodiment, the cathode active material is Li 1+x Ni a Mn b Co c Al (1-a-b-c) O2, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, Li2MnO3, LiCrO2, Li4Ti5O 12 , LiV2O5, LiTiS2, LiMoS2, and combinations thereof, or is a core-shell composite, wherein -0.2≦x≦0.2, 0≦a<1, 0≦b<1, 0≦c<1, and a+b+c≦1. In certain embodiments, the shell comprises a different lithium transition metal oxide than the core, and Li 1+x Ni a Mn b Co c Al (1-a-b-c) O2, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, Li2MnO3, LiCrO2, Li4Ti5O 12, LiV2O5, LiTiS2, LiMoS2, and combinations thereof, where -0.2≦x≦0.2, 0≦a<1, 0≦b<1, 0≦c<1, and a+b+c≦1. In further embodiments, each of the core and shell is independently doped with a dopant selected from the group consisting of Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof.

[0013] In some embodiments, the electrode layer further comprises a conductive agent selected from the group consisting of carbon, carbon black, graphite, expanded graphite, graphene, graphene nanoplatelets, carbon fibers, carbon nanofibers, graphitized carbon flakes, carbon tubes, carbon nanotubes, activated carbon, mesoporous carbon, and combinations thereof.

[0014] In certain embodiments, the binder material is a polymer comprising one or more functional groups comprising halogen, O, N, S, or a combination thereof, In further embodiments, the one or more functional groups are selected from the group consisting of alkoxy, aryloxy, nitro, thiol, thioether, imine, cyano, amide, amino (primary, secondary, or tertiary), carboxyl, ketone, aldehyde, ester, hydroxyl, and combinations thereof.

[0015] In one embodiment, the concentration of lithium ions in the cathode slurry is from about 0.0001 M to about 1 M. In one embodiment, the cathode slurry has a pH of from about 8 to about 14, or from about 11 to about 13.

[0016] In some embodiments, the electrode layer has a lithium ion content of between 0.01 percent and 20 percent, based on the total weight of the electrode layer.

[0017] In certain embodiments, lithium loss from the cathode active material is inhibited at a rate of between about 1 percent and about 15 percent. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a flow chart of one embodiment showing steps for preparing a cathode.

[0019] [Figure 2] FIG. 2 shows the D50 particle size distribution of the organic-treated slurry and the base-treated slurry.

[0020] [Figure 3] Figure 3 is a bar graph showing the peel strength of electrodes prepared by different methods.

[0021] [Figure 4] FIG. 4 shows three specific capacity-voltage curves for the first discharge cycle of NMC811.

[0022] [Figure 5] Figure 5 shows infrared spectroscopy data of polyacrylamide after mixing with LiOH.

[0023] [Figure 6] Figure 6 shows infrared spectroscopy data of polyacrylamide after mixing with LiI. DETAILED DESCRIPTION OF THE INVENTION

[0024] Provided herein is a cathode for a secondary battery comprising a current collector and an electrode layer coated on the current collector, the electrode layer including a cathode active material, a binder material, and a lithium compound.

[0025] The term "electrode" means either a "cathode" or an "anode."

[0026] The term "positive electrode" is used interchangeably with "cathode." Similarly, the term "negative electrode" is used interchangeably with "anode."

[0027] The term "binder material" refers to a chemical or substance used to hold the electrode materials and / or conductive agents in place and adhere them onto the conductive metal parts to form the electrode. In some embodiments, the electrode does not include any conductive agents.

[0028] A "conductive agent" is a chemically inert material with good electrical conductivity. Therefore, a conductive agent is often mixed with an electrode active material during electrode formation to improve the electrode's conductivity.

[0029] "Polymer" refers to a macromolecular compound prepared by polymerizing the same or different monomers. The general term "polymer" encompasses the terms "homopolymer," "copolymer," "terpolymer," and "interpolymer."

[0030] "Interpolymer" refers to a polymer prepared by the polymerization of at least two different types of monomers. The generic term "interpolymer" includes the term "copolymer" (which generally refers to a polymer prepared from two different monomers) as well as the term "terpolymer" (which generally refers to a polymer prepared from three different types of monomers). It also includes polymers in which four or more types of monomers are polymerized.

[0031] The term "homogenizer" refers to a device that can be used to homogenize materials. The term "homogenization" refers to the process of distributing materials evenly throughout a fluid. Any conventional homogenizer can be used in the methods disclosed herein. Some non-limiting examples of homogenizers include agitator mixers, planetary agitator mixers, blenders, and ultrasonic generators.

[0032] The term "planetary mixer" refers to a device that can be used to mix or stir different materials to produce a homogeneous mixture and is composed of blades that perform planetary motion within a vessel. In some embodiments, the planetary mixer is composed of at least one planetary blade and at least one high-speed dispersing blade. The planetary blade and high-speed dispersing blade rotate on their axes and continuously rotate around the vessel. The rotational speed can be expressed in units of revolutions per minute (rpm), which refers to the number of revolutions the rotor completes per minute.

[0033] The term "ultrasonicator" refers to a device that can apply ultrasonic energy to agitate particles in a sample. Any ultrasonic generator that can disperse the slurries disclosed herein can be used herein. Some non-limiting examples of ultrasonic devices include ultrasonic baths, probe-type ultrasonicators, and ultrasonic flow cells.

[0034] The term "ultrasonic bath" refers to an apparatus in which ultrasonic energy is transmitted to a liquid sample through the walls of the ultrasonic bath's container.

[0035] The term "probe-type ultrasonic device" refers to an ultrasonic probe that is immersed in a medium for direct sonication. The term "direct sonication" means that ultrasound waves are coupled directly into the treatment liquid.

[0036] The term "ultrasonic flow cell" or "ultrasonic reactor chamber" refers to a device capable of performing a sonication process in a flow-through mode. In some embodiments, the ultrasonic flow cell is in a single-pass, multi-pass, or recirculation configuration.

[0037] The term "applying" refers to the act of laying or spreading a substance on a surface.

[0038] The term "current collector" refers to any conductive substrate that is in contact with an electrode layer and can conduct current to the electrode during discharge or charging of a secondary battery. Some non-limiting examples of current collectors include a single conductive metal layer or substrate and a single conductive metal layer or substrate having a conductive coating layer thereon, such as a carbon black-based coating layer. The conductive metal layer or substrate can be in the form of a foil or a porous body having a three-dimensional network structure, and can be a polymeric material, a metallic material, or a metallized polymer. In some embodiments, the three-dimensional porous current collector is covered with a conformal carbon layer.

[0039] The term "electrode layer" refers to a layer of electrochemically active material in contact with a current collector. In some embodiments, the electrode layer is made by applying a coating onto the current collector. In some embodiments, the electrode layer is located on the surface of the current collector. In other embodiments, a three-dimensional porous current collector is conformally coated with the electrode layer.

[0040] The term "doctor blading" refers to a process for producing large area films on rigid or flexible substrates. Coating thickness can be controlled by an adjustable gap width between the coating blade and the coating surface, allowing for the deposition of variable wet layer thicknesses.

[0041] The term "slot die coating" refers to a process for producing large-area films on rigid or flexible substrates. The slurry is applied to the substrate by continuously pumping it through a nozzle, attached to a roller that is constantly fed toward the nozzle. The thickness of the coating is controlled in various ways, such as by varying the slurry flow rate or the roller speed.

[0042] The term "room temperature" refers to an indoor temperature of about 18°C ​​to about 30°C, e.g., 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30°C. In some embodiments, room temperature refers to a temperature of about 20°C ± 1°C, or ± 2°C, or ± 3°C. In other embodiments, room temperature refers to a temperature of about 22°C or about 25°C.

[0043] The term "particle size D50" refers to the particle size at the 50% point on a cumulative curve plotted to obtain a particle size distribution on a volume basis, where the total is 100% (i.e., the diameter of the particle at 50% (median) of the particle volume). This refers to the volume-based cumulative 50% size (D50). Furthermore, with respect to the cathode active material of the present invention, particle size D50 refers to the volume-average particle size of secondary particles that may be formed by the mutual aggregation of primary particles. In the case of a cathode active material composed solely of primary particles, particle size D50 refers to the volume-average particle size of the primary particles.

[0044] The term "solids" refers to the amount of non-volatile material remaining after evaporation.

[0045] The term "peel strength" refers to the amount of force required to separate two materials that are adhered to one another, such as a current collector and an electrode active material coating. It is a measure of the adhesive strength between such two materials and is usually expressed in N / cm.

[0046] The term "C-rate" refers to the charge or discharge rate of a cell or battery and its total storage capacity in Ah or mAh. For example, a rate of 1C means that all of the stored energy is utilized in 1 hour, 0.1C means that 10% of the energy is utilized in 1 hour or the entire energy is utilized in 10 hours, and 5C means that the entire energy is utilized in 12 minutes.

[0047] The term "ampere-hour (Ah)" refers to the unit used to specify the capacity of a battery. For example, a battery with a capacity of 1 Ah can supply a current of 1 A for 1 hour, 0.5 A for 2 hours, etc. Therefore, 1 Ah (ampere-hour) is equivalent to 3,600 coulombs of charge. Similarly, the term "miniature ampere-hour (mAh)" refers to the unit of capacity of a battery, which is 1 / 1000 of an ampere-hour.

[0048] The term "battery cycle life" means the number of complete charge / discharge cycles that a battery can undergo before its nominal capacity drops below 80% of its initial rated capacity.

[0049] The term "capacity" is a property of an electrochemical cell, such as a battery, that refers to the total amount of charge that the cell can hold. Capacity is usually expressed in units of ampere-hours. The term "specific capacity" refers to the capacity output of an electrochemical cell, such as a battery, per unit weight, usually expressed in units of Ah / kg or mAh / g.

[0050] In the following description, all numerical values ​​disclosed herein are approximate, regardless of whether the word "about" or "approximately" is used in connection therewith. They may vary by 1%, 2%, 5%, or in some cases 10-20%. Lower Limit R L and upper limit R U Whenever a numerical range is disclosed, any number falling within that range is specifically disclosed. Specifically, numbers within the following ranges are specifically disclosed: R = R L +k*(R U -R L ), where k is a variable ranging from 0% to 100%. Additionally, any numerical range defined by two R numbers as defined above is also specifically disclosed.

[0051] Typically, electrodes for lithium-ion batteries are fabricated by casting an organic-based slurry onto a metal current collector. The slurry contains the electrode active material, conductive carbon, and a binder in an organic solvent, most commonly N-methyl-2-pyrrolidone (NMP). The binder, most commonly polyvinylidene fluoride (PVDF), is dissolved in the solvent, suspending the conductive additive and electrode active material in the slurry. PVDF is electrochemically stable and exhibits strong adhesion to the electrode material and current collector. However, PVDF requires special handling because it dissolves only in certain organic solvents, such as N-methyl-2-pyrrolidone (NMP), which is flammable and toxic.

[0052] To recover NMP vapor, an NMP recovery device must be installed during the drying process. This requires a large capital investment, which adds significant costs to the manufacturing process. The use of inexpensive, environmentally friendly solvents, such as aqueous solvents, is preferable because it reduces the capital investment required for the recovery system. Attempts to replace the organic NMP coating process with aqueous solutions have been successful for negative electrodes. Aqueous slurries for anode coating typically contain carboxymethyl cellulose (CMC) and styrene butadiene rubber (SBR). In a battery, the cathode operates at a high voltage. Most rubbers, including SBR, are stable only at the low anode voltage and decompose at high voltages. Therefore, unlike the anode, aqueous coating of the cathode is extremely difficult.

[0053] Another concern with aqueous processing is that many cathode active materials are not inert to water, which can lead to problems and complications when performing aqueous coating processes on the cathode. Lithium in the cathode active material can react with HO to form LiOH, potentially degrading electrochemical performance. The surface of the cathode active material is typically coated with an ionically conductive solid compound to enhance its stability and compatibility with aqueous processes. Acids are sometimes added to the solution to neutralize the base on the cathode active material surface and adjust the pH of the slurry. However, when exposed to water, significant amounts of the soluble base LiOH are continuously formed, significantly damaging the cathode active material.

[0054] Accordingly, the present invention provides a method for preparing a cathode through the use of an aqueous slurry. Figure 1 is a flow chart of an embodiment showing the steps of a method 100 for preparing a cathode. Slurries prepared by the methods disclosed herein can exhibit improved stability by minimizing the reactivity of the cathode active material with water, thereby improving battery performance.

[0055] In general, Ni-rich NMC materials react with water during electrode fabrication, potentially causing metal dissolution, structural changes, and performance degradation. When NMC materials are mixed with water, delithiated surface regions rapidly form within minutes, and the formation of surface impurities such as LiOH in the delithiated surface regions significantly reduces capacity. However, adding an excess amount of LiOH or other lithium compounds beyond the concentrations described herein instead has the unexpected effect of improving the capacity and electrochemical performance of cathodes formed therefrom.

[0056] In some embodiments, the first suspension is formed by dispersing a binder material in water in step 101. In other embodiments, the first suspension further comprises a conductive agent dispersed in the water.

[0057] In certain embodiments, the binder material is selected from the group consisting of styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), acrylonitrile copolymer, polyacrylic acid (PAA), polyacrylonitrile (PAN), polyacrylamide (PAM), LA132, LA133, LA138, latex, salts of alginic acid, polyvinylidene fluoride (PVDF), poly(vinylidene fluoride)-hexafluoropropene (PVDF-HFP), polytetrafluoroethylene (PTF), and the like. E), polystyrene, poly(vinyl alcohol) (PVA), poly(vinyl acetate), polyisoprene, polyaniline, polyethylene, polyimide, polyurethane, polyvinyl butyral, polyvinylpyrrolidone (PVP), gelatin, chitosan, starch, agar, xanthan gum, gum arabic, gellan gum, guar gum, karaya gum, tara gum, tragacanth gum, casein, amylose, pectin, PEDOT:PSS, carrageenan, and combinations thereof. In certain embodiments, the salt of alginic acid comprises a cation selected from Na, Li, K, Ca, NH4, Mg, Al, or combinations thereof. In certain embodiments, the binder material is free of styrene butadiene rubber, carboxymethyl cellulose, acrylonitrile copolymer, polyacrylic acid, polyacrylonitrile, LA132, LA133, LA138, TRD202A, latex, salts of alginic acid, polyvinylidene fluoride, poly(vinylidene fluoride)-hexafluoropropene, polytetrafluoroethylene, polystyrene, poly(vinyl alcohol), poly(vinyl acetate), polyisoprene, polyaniline, polyethylene, polyimide, polyurethane, polyvinyl butyral, polyvinylpyrrolidone, gelatin, chitosan, starch, agar, xanthan gum, gum arabic, gellan gum, guar gum, karaya gum, tara gum, tragacanth gum, casein, amylose, pectin, or carrageenan, etc. In certain embodiments, the binder material is not a fluorine-containing polymer such as PVDF, PVDF-HFP, or PTFE.

[0058] In some embodiments, the binder material is a polymer containing one or more functional groups including halogen, O, N, S, or combinations thereof. Some non-limiting examples of suitable functional groups include alkoxy, aryloxy, nitro, thiol, thioether, imine, cyano, amide, amino (primary, secondary, or tertiary), carboxyl, ketone, aldehyde, ester, hydroxyl, and combinations thereof. In some embodiments, the functional group is or includes alkoxy, aryloxy, carboxy (i.e., —COOH), nitrile, —CO2CH3, —CONH2, —OCH2CONH2, or —NH2.

[0059] In certain embodiments, the binder material is a polymer comprising one or more monomers selected from the group consisting of optionally substituted vinyl ethers, vinyl acetate, acrylonitrile, acrylamide, methacrylamide, acrylic acid, methacrylic acid, acrylic esters, methacrylic esters, 2-hydroxyethyl acrylate, and combinations thereof.

[0060] In some embodiments, the binder materials disclosed herein are derived from at least one olefin monomer and at least one monomer containing a functional group selected from the group consisting of amino, cyano, carboxyl, and combinations thereof. Olefin refers to an unsaturated hydrocarbon-based compound having at least one carbon-carbon double bond. In certain embodiments, the olefin is a conjugated diene. Some non-limiting examples of suitable olefins include C olefins containing vinylic unsaturation. 2~20 Aliphatic and C 8~20Suitable olefin monomers include aromatic compounds and cyclic compounds such as cyclobutene, cyclopentene, dicyclopentadiene, and norbornene. Non-limiting examples of suitable olefin monomers include styrene, ethylene, propylene, isobutylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 1-dodecene, 1-tetradene, 1-hexadene, 1-octadene, 1-eicosene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 4,6-dimethyl-1-heptene, 4-vinylcyclohexene, vinylcyclohexane, norbornadiene, ethylidenenorbornene, cyclopentene, cyclohexene, dicyclopentadiene, cyclooctene, C 4-40 In certain embodiments, the olefin monomer is propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, or a combination thereof. 4-40 Dienes include, but are not limited to, 1,3-butadiene, 1,3-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,7-octadiene, 1,9-decadiene, isoprene, myrcene, and combinations thereof.

[0061] In certain embodiments, the binder materials disclosed herein are derived from at least two vinyl monomers selected from styrene, substituted styrene, vinyl halide, vinyl ether, vinyl acetate, vinylpyridine, vinylidene fluoride, acrylonitrile, acrylic acid, acrylic ester, methacrylic acid, methacrylic ester, acrylamide, methacrylamide, and combinations thereof. In certain embodiments, the binder materials disclosed herein are derived from acrylonitrile or methacrylonitrile and acrylic acid or methacrylic acid. In certain embodiments, the binder materials disclosed herein are derived from acrylonitrile or methacrylonitrile and acrylamide or methacrylamide. In certain embodiments, the binder materials disclosed herein are derived from acrylonitrile or methacrylonitrile, acrylic acid or methacrylic acid, and acrylamide or methacrylamide. In some embodiments, the binder materials disclosed herein are derived from acrylonitrile or methacrylonitrile, acrylic acid or methacrylic acid, methyl acrylate or methyl methacrylate, and acrylamide or methacrylamide.

[0062] In some embodiments, the binder materials disclosed herein are random interpolymers. In other embodiments, the binder materials disclosed herein are random interpolymers in which at least two monomer units are randomly distributed. In some embodiments, the binder materials disclosed herein are alternating interpolymers. In other embodiments, the binder materials disclosed herein are alternating interpolymers in which at least two monomer units are alternately distributed. In certain embodiments, the binder materials are block interpolymers.

[0063] In certain embodiments, the conductive agent is a carbonaceous material selected from the group consisting of carbon, carbon black, graphite, expanded graphite, graphene, graphene nanoplatelets, carbon fibers, carbon nanofibers, graphitized carbon flakes, carbon tubes, carbon nanotubes, activated carbon, mesoporous carbon, and combinations thereof, hi certain embodiments, the conductive agent does not comprise a carbonaceous material.

[0064] In some embodiments, the conductive agent is a conductive polymer selected from the group consisting of polypyrrole, polyaniline, polyacetylene, polyphenylene sulfide (PPS), polyphenylene vinylene (PPV), poly(3,4-ethylenedioxythiophene) (PEDOT), polythiophene, and combinations thereof. In some embodiments, the conductive agent simultaneously functions as both a conductive agent and a binder. In certain embodiments, the positive electrode layer includes two components: a cathode active material and a conductive polymer. In other embodiments, the positive electrode layer includes a cathode active material, a conductive agent, and a conductive polymer. In certain embodiments, the conductive polymer is an additive, and the positive electrode layer includes a cathode active material, a conductive agent, a binder, and a conductive polymer. In other embodiments, the positive electrode layer does not include a conductive polymer.

[0065] In certain embodiments, the amount of each of the binder material and the conductive material in the first suspension is independently about 1% to about 50%, about 1% to about 40%, about 1% to about 30%, about 1% to about 20%, about 1% to about 15%, about 1% to about 10%, about 1% to about 5%, about 3% to about 20%, about 5% to about 20%, about 5% to about 10%, about 10% to about 20%, about 10% to about 15%, or about 15% to about 20%, by weight based on the total weight of the first suspension. In some embodiments, the amount of each of the binder material and the conductive material in the first suspension is independently less than 20%, less than 15%, less than 10%, less than 8%, or less than 6%, by weight based on the total weight of the first suspension.

[0066] In some embodiments, the solids content of the first suspension is about 10% to about 40%, about 10% to about 35%, about 10% to about 30%, about 10% to about 25%, about 10% to about 20%, about 10% to about 18%, about 12% to about 25%, about 12% to about 20%, about 12% to about 18%, about 15% to about 25%, about 15% to about 20%, or about 18% to about 25%, by weight based on the total weight of the first suspension. In certain embodiments, the solids content of the first suspension is about 10%, about 12%, about 15%, about 18%, about 20%, or about 25%, by weight based on the total weight of the first suspension. In certain embodiments, the solids content of the first suspension is at least 10%, at least 12%, at least 15%, at least 18%, or at least 20% by weight based on the total weight of the first suspension, hi certain embodiments, the solids content of the first suspension is less than 25%, less than 20%, less than 18%, or less than 15% by weight based on the total weight of the first suspension.

[0067] In certain embodiments, the first suspension is mixed at a temperature of about 10°C to about 40°C, about 10°C to about 35°C, about 10°C to about 30°C, about 10°C to about 25°C, about 10°C to about 20°C, or about 10°C to about 15°C. In some embodiments, the first suspension is mixed at a temperature of less than 40°C, less than 35°C, less than 30°C, less than 25°C, less than 20°C, less than 15°C, or less than 10°C. In some embodiments, the first suspension is mixed at a temperature of about 40°C, about 35°C, about 30°C, about 25°C, about 20°C, about 15°C, or about 10°C.

[0068] In some embodiments, the aqueous solution containing the lithium compound is prepared by dissolving the lithium compound in water. The second suspension is formed in step 102 by adding the aqueous solution containing the lithium compound to the first suspension.

[0069] In certain embodiments, the lithium compound is selected from the group consisting of lithium borate, lithium bromide, lithium chloride, lithium bicarbonate, lithium hydroxide, lithium iodide, lithium nitrate, lithium sulfate, lithium acetate, lithium lactate, lithium citrate, lithium succinate, and combinations thereof.

[0070] The second suspension is formed by adding an aqueous solution containing a lithium compound to the first suspension. It has been found that the second suspension should be stirred for less than about 1 hour, as stirring times longer than 60 minutes may be harmful to the binder or conductive agent. In some embodiments, the second suspension is stirred for about 1 minute to about 60 minutes, about 1 minute to about 50 minutes, about 1 minute to about 40 minutes, about 1 minute to about 30 minutes, about 1 minute to about 20 minutes, about 1 minute to about 10 minutes, about 5 minutes to about 60 minutes, about 5 minutes to about 50 minutes, about 5 minutes to about 40 minutes, about 5 minutes to about 30 minutes, about 5 minutes to about 20 minutes, about 5 minutes to about 10 minutes, about 10 to about 60 minutes, about 10 minutes ... The mixture is stirred for a period of time ranging from about 15 to about 50 minutes, from about 10 to about 40 minutes, from about 10 to about 30 minutes, from about 10 to about 20 minutes, from about 15 to about 60 minutes, from about 15 to about 50 minutes, from about 15 to about 40 minutes, from about 15 to about 30 minutes, from about 15 to about 20 minutes, from about 20 to about 50 minutes, from about 20 to about 40 minutes, or from about 20 to about 30 minutes.

[0071] In certain embodiments, the second suspension is stirred for a period of less than 60 minutes, less than 55 minutes, less than 50 minutes, less than 45 minutes, less than 40 minutes, less than 35 minutes, less than 30 minutes, less than 25 minutes, less than 20 minutes, less than 15 minutes, less than 10 minutes, or less than 5 minutes. In some embodiments, the second suspension is stirred for a period of at least about 55 minutes, at least about 50 minutes, at least about 45 minutes, at least about 40 minutes, at least about 35 minutes, at least about 30 minutes, at least about 25 minutes, at least about 20 minutes, at least about 15 minutes, at least about 10 minutes, or at least about 5 minutes.

[0072] In certain embodiments, the second suspension is stirred at a temperature ranging from about 5°C to about 35°C, from about 5°C to about 30°C, from about 5°C to about 25°C, from about 5°C to about 20°C, from about 5°C to about 15°C, or from about 5°C to about 10°C. In certain embodiments, the second suspension is stirred at a temperature less than 35°C, less than 30°C, less than 25°C, less than 20°C, less than 15°C, or less than 10°C. In some embodiments, the second suspension is stirred at a temperature greater than about 25°C, greater than about 20°C, greater than about 15°C, greater than about 10°C, or greater than about 5°C.

[0073] The lithium ions (Li + The concentration of Li in the second suspension critically affects battery performance. + The concentration of Li in the second suspension is about 0.0005 M to 0.5 M or about 0.001 M to 0.5 M. In certain embodiments, the concentration of Li in the second suspension is about 0.0005 M to 0.5 M or about 0.001 M to 0.5 M. + The concentration of is about 0.001M to about 0.4M, about 0.001M to about 0.3M, about 0.001M to about 0.25M, about 0.001M to about 0.2M, about 0.001M to about 0.15M, about 0.001M to about 0.1M, about 0.001M to about 0.05M, about 0.001M to about 0.01M, about 0.005M or In some embodiments, the concentration of Li in the second suspension is from about 0.5M to about 0.4M, from about 0.005M to about 0.35M, from about 0.005M to about 0.3M, from about 0.005M to about 0.25M, from about 0.005M to about 0.2M, from about 0.005M to about 0.15M, from about 0.005M to about 0.1M, or from about 0.005M to about 0.05M. + The concentration of Li in the second suspension is less than about 0.5 M, less than about 0.4 M, less than about 0.35 M, less than about 0.3 M, less than about 0.25 M, less than about 0.2 M, less than about 0.15 M, or less than about 0.1 M. In some embodiments, the concentration of Li in the second suspension is less than about 0.5 M, less than about 0.4 M, less than about 0.35 M, less than about 0.3 M, less than about 0.25 M, less than about 0.2 M, less than about 0.15 M, or less than about 0.1 M. + The concentration of is greater than about 0.001M, greater than about 0.005M, greater than about 0.01M, greater than about 0.05M, greater than about 0.1M, greater than about 0.15M, or greater than about 0.2M.

[0074] Conventional cathode slurry preparation processes often use organic compounds, such as NMP, as solvents. However, the use of organic solvents poses serious environmental concerns. One advantage of the present invention is that the cathode slurry is prepared using an aqueous process using water as the solvent. A lithium compound is added to the aqueous slurry to stabilize the cathode active material. Therefore, the lithium compound must be soluble in water. In some embodiments, the solubility of the lithium compound in water at 20°C is about 1 g / 100 ml to about 200 g / 100 ml, about 1 g / 100 ml to about 180 g / 100 ml, about 1 g / 100 ml to about 160 g / 100 ml, about 1 g / 100 ml to about 140 g / 100 ml, about 1 g / 100 ml to about 120 g / 100 ml, or about 1 g / 100 ml to about 140 g / 100 ml. 100g / 100ml, about 1g / 100ml to about 90g / 100ml, about 1g / 100ml to about 80g / 100ml, about 1g / 100ml to about 70g / 100ml, about 1g / 100ml to about 60g / 100ml, about 1g / 100ml to about 50g / 100ml, about 1g / 100ml to about 40g / 100ml, about 1g / 100ml to about 30g / 100ml. About 1g / 100ml to about 20g / 100ml, about 1g / 100ml to about 10g / 100ml, about 20g / 100ml to about 100g / 100ml, about 20g / 100ml to about 80g / 100ml, about 20g / 100ml to about 60g / 100ml, about 20g / 100ml to about 40g / 100ml, about 20g / 100ml to about 30g / 100ml, about 40g / 100ml to about 100g / 100ml, about 40g / 100ml to about 80g / 100ml, about 40g / 100ml to about 60g / 100ml, about 60g / 100ml to about 100g / 100ml, about 60g / 100ml to about 80g / 100ml, about 100g / 100ml to about 200g / 100ml, about 100g / 100ml to about 180g / 100ml, or about 120g / 100ml to about 180g / 100ml.In some embodiments, the solubility of the lithium compound in water at 20° C. is less than 200 g / 100 ml, less than 180 g / 100 ml, less than 160 g / 100 ml, less than 140 g / 100 ml, less than 120 g / 100 ml, less than 100 g / 100 ml, less than 80 g / 100 ml, less than 60 g / 100 ml, less than 40 g / 100 ml, or less than 20 g / 100 ml. In some embodiments, it is desirable that the solubility of the lithium compound in water at 20°C is greater than about 1 g / 100 ml, greater than about 10 g / 100 ml, greater than about 20 g / 100 ml, greater than about 30 g / 100 ml, greater than about 40 g / 100 ml, greater than about 50 g / 100 ml, greater than about 60 g / 100 ml, greater than about 70 g / 100 ml, greater than about 80 g / 100 ml, greater than about 90 g / 100 ml, greater than about 100 g / 100 ml, greater than about 120 g / 100 ml, or greater than about 140 g / 100 ml.

[0075] In some embodiments, the third suspension is formed in step 103 by dispersing the cathode active material in the second suspension, which includes a binder, a conductive agent, and at least one lithium compound.

[0076] In some embodiments, the active battery electrode material is a cathode active material, and the cathode active material is LiCoO, LiNiO 2、 LiNi x Mn y O2, Li 1+z Ni x Mn y Co 1-x-y O2, LiNi x Co y Al z In certain embodiments, the cathode active material is selected from the group consisting of LiCoO2, LiNi ... x Mny O2, Li 1+z Ni x Mn y Co 1-x-y O2(NMC), LiNi x Co y Al z In another embodiment, the cathode active material is selected from the group consisting of LiCoO2, LiNiO2, LiV2O5, LiTiS2, LiMoS2, LiMnO2, LiCrO2, LiMn2O4, LiFeO2, LiFePO4, and combinations thereof, where each x is independently 0.4 to 0.6, each y is independently 0.2 to 0.4, and each z is independently 0 to 0.1. In another embodiment, the cathode active material is not LiCoO2, LiNiO2, LiV2O5, LiTiS2, LiMoS2, LiMnO2, LiCrO2, LiMn2O4, LiFeO2, or LiFePO4. In a further embodiment, the cathode active material is LiNi x Mn y O2, Li 1+z Ni x Mn y Co 1-x-y O2 or LiNi x Co y Al z each x is independently 0.2 to 0.9, each y is independently 0.1 to 0.45, and each z is independently 0 to 0.2. In certain embodiments, the cathode active material is Li 1+x Ni a Mn b Co c Al (1-a-b-c) O2, where -0.2≦x≦0.2, 0≦a<1, 0≦b<1, 0≦c<1, and a+b+c≦1. In some embodiments, the cathode active material is represented by the general formula Li 1+x Ni a Mn b Co c Al (1-a-b-c)O2, wherein 0.33≦a≦0.92, 0.33≦a≦0.9, 0.33≦a≦0.8, 0.5≦a≦0.92, 0.5≦a≦0.9, 0.5≦a≦0.8, 0.6≦a≦0.92, or 0.6≦a≦0.9; 0≦b≦0.5, 0≦b≦0.3, 0.1≦b≦0.5, 0.1≦b≦0.4, 0.1≦b≦0.3, 0.1≦b≦0.2, or 0.2≦b≦0.5; 0≦c≦0.5, 0≦c≦0.3, 0.1≦c≦0.5, 0.1≦c≦0.4, 0.1≦c≦0.3, 0.1≦c≦0.2, or 0.2≦c≦0.5.

[0077] In certain embodiments, the cathode active material is doped with a dopant selected from the group consisting of Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof. In some embodiments, the dopant is not Fe, Ni, Mn, Mg, Zn, Ti, La, Ce, Ru, Si, or Ge. In certain embodiments, the dopant is not Al, Sn, or Zr.

[0078] The methods disclosed herein are particularly suitable for preparing cathodes using nickel-containing cathode active materials. Nickel-containing cathodes prepared by the methods disclosed herein exhibit improved electrochemical performance and long-term stability.

[0079] In some embodiments, the cathode active material is LiNi 0.33 Mn 0.33 Co 0.33 O2(NMC333), LiNi 0.5 Mn 0.3 Co 0.2 O2(NMC532), LiNi 0.6 Mn 0.2 Co 0.2 O2(NMC622), LiNi 0.6 Mn 0.2 Co 0.2 O2(NMC622), LiNi 0.7 Mn 0.15 Co 0.15 O 2、 LiNi 0.8 Mn 0.1 Co0.1 O2(NMC811), LiNi 0.92 Mn 0.04 Co 0.04 O 2、 LiNi 0.8 Co 0.15 Al 0.05 O2 (NCA), LiNiO2 (LNO), and their combinations.

[0080] In other embodiments, the cathode active material is not LiCoO2, LiNiO2, LiMnO2, LiMn2O4, or Li2MnO3. In further embodiments, the cathode active material is LiNi 0.33 Mn 0.33 Co 0.33 O2, LiNi 0.4 Mn 0.4 Co 0.2 O2, LiNi 0.5 Mn 0.3 Co 0.2 O2, LiNi 0.6 Mn 0.2 Co 0.2 O2, LiNi 0.7 Mn 0.15 Co 0.15 O2, LiNi 0.8 Mn 0.1 Co 0.1 O2, LiNi 0.92 Mn 0.04 Co 0.04 O2 or LiNi 0.8 Co 0.15 Al 0.05 Not O2.

[0081] In certain embodiments, the cathode active material comprises or is a core-shell composite having a core and a shell structure, wherein the core and shell are each independently Li 1+x Ni a Mn b Co c Al (1-a-b-c) O2, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, Li2MnO3, LiCrO2, Li4Ti5O 12, LiV2O5, LiTiS2, LiMoS2, and combinations thereof, where -0.2≦x≦0.2, 0≦a<1, 0≦b<1, 0≦c<1, and a+b+c≦1. In other embodiments, the core and shell each independently comprise two or more lithium transition metal oxides. In some embodiments, one of the core or shell comprises only one lithium transition metal oxide, and the other comprises two or more lithium transition metal oxides. The lithium transition metal oxide or oxides of the core and shell may be the same, or they may be different or partially different. In some embodiments, the two or more lithium transition metal oxides are uniformly distributed throughout the core. In certain embodiments, the two or more lithium transition metal oxides are not uniformly distributed throughout the core. In some embodiments, the cathode active material is not a core-shell composite.

[0082] In some embodiments, each of the core and shell lithium transition metal oxides is independently doped with a dopant selected from the group consisting of Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof. In certain embodiments, the core and shell each independently comprise two or more doped lithium transition metal oxides. In certain embodiments, the two or more doped lithium transition metal oxides are uniformly distributed on the core and / or shell. In certain embodiments, the two or more doped lithium transition metal oxides are not uniformly distributed on the core and / or shell.

[0083] In some embodiments, the cathode active material comprises or is a core-shell composite comprising a core comprising a lithium transition metal oxide and a shell comprising a transition metal oxide. In certain embodiments, the lithium transition metal oxide is Li 1+x Ni a Mn b Co c Al (1-a-b-c)O2, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, Li2MnO3, LiCrO2, Li4Ti5O 12 , LiV2O5, LiTiS2, LiMoS2, and combinations thereof, where -0.2≦x≦0.2, 0≦a<1, 0≦b<1, 0≦c<1, and a+b+c≦1. In some embodiments, the transition metal oxide is selected from the group consisting of Fe2O3, MnO2, Al2O3, MgO, ZnO, TiO2, La2O3, CeO2, SnO2, ZrO2, RuO2, and combinations thereof. In certain embodiments, the shell comprises a lithium transition metal oxide and a transition metal oxide.

[0084] In some embodiments, the core diameter is from about 1 μm to about 15 μm, from about 3 μm to about 15 μm, from about 3 μm to about 10 μm, from about 5 μm to about 10 μm, from about 5 μm to about 45 μm, from about 5 μm to about 35 μm, from about 5 μm to about 25 μm, from about 10 μm to about 45 μm, from about 10 μm to about 40 μm, or from about 10 μm to about 35 μm, from about 10 μm to about 25 μm, from about 15 μm to about 45 μm, from about 15 μm to about 30 μm, from about 15 μm to about 25 μm, from about 20 μm to about 35 μm, or from about 20 μm to about 30 μm. In certain embodiments, the shell thickness is about 1 μm to about 45 μm, about 1 μm to about 35 μm, about 1 μm to about 25 μm, about 1 μm to about 15 μm, about 1 μm to about 10 μm, about 1 μm to about 5 μm, about 3 μm to about 15 μm, about 3 μm to about 10 μm, about 5 μm to about 10 μm, about 10 μm to about 35 μm, about 10 μm to about 20 μm, about 15 μm to about 30 μm, about 15 μm to about 25 μm, or about 20 μm to about 35 μm. In certain embodiments, the ratio of the diameter or thickness of the core to the shell is within the range of 15:85 to 85:15, 25:75 to 75:25, 30:70 to 70:30, or 40:60 to 60:40. In certain embodiments, the volume or weight ratio of core to shell is in the range of 95:5, 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, or 30:70.

[0085] In some embodiments, mixing the binder material and conductive agent in the first suspension can be performed before adding the aqueous solution containing the lithium compound. This is advantageous because it allows for better dispersion of the materials in the second suspension. In some embodiments, the binder material, conductive agent, and lithium compound (or aqueous solution) can be mixed to form the first suspension. The second suspension can then be formed by dispersing the cathode active material in the first suspension. In other embodiments, the binder material and lithium compound (or aqueous solution) can be mixed to form the first suspension. The second suspension can then be formed by dispersing the cathode active material and / or conductive agent in the first suspension. If only one of the cathode active material or conductive agent is added to form the second suspension, the other can then be dispersed in the second suspension to form a third suspension.

[0086] The conductive agent may be added at any step before the homogenized cathode slurry is formed, however, it is necessary to mix the binder material and lithium compound before adding the cathode active material.

[0087] In some embodiments, prior to homogenizing the third suspension, the third suspension is degassed under reduced pressure for a short period of time to remove any trapped air bubbles. In some embodiments, the second suspension is degassed at a pressure of about 1 kPa to about 20 kPa, about 1 kPa to about 15 kPa, about 1 kPa to about 10 kPa, about 5 kPa to about 20 kPa, about 5 kPa to about 15 kPa, or about 10 kPa to about 20 kPa. In certain embodiments, the suspension is degassed at a pressure of less than 20 kPa, less than 15 kPa, or less than 10 kPa. In certain embodiments, the suspension is degassed for a period of about 30 minutes to about 4 hours, about 1 hour to about 4 hours, about 2 hours to about 4 hours, or about 30 minutes to about 2 hours. In certain embodiments, the second suspension is degassed for a period of less than 4 hours, less than 2 hours, or less than 1 hour.

[0088] In certain embodiments, the third suspension is degassed after homogenization. The homogenized third suspension may also be degassed at the pressures and time durations set forth in the step of degassing the third suspension prior to homogenization.

[0089] The third suspension is homogenized in a homogenizer at a temperature of about 10°C to about 30°C to obtain a homogenized cathode slurry. The homogenizer may be equipped with a temperature control system, and the temperature of the third suspension can be controlled by the temperature control system. Any homogenizer that can reduce or eliminate particle agglomeration and / or promote uniform distribution of the slurry components can be used herein. Uniform distribution plays an important role in producing a battery with good battery performance. In some embodiments, the homogenizer is a planetary agitator mixer, an agitator mixer, a blender, or an ultrasonic generator.

[0090] In some embodiments, the third suspension is homogenized at a temperature of about 10° C. to about 30° C., about 10° C. to about 25° C., about 10° C. to about 20° C., or about 10° C. to about 15° C. In some embodiments, the third suspension is homogenized at a temperature less than 30° C., less than 25° C., less than 20° C., or less than 15° C.

[0091] In some embodiments, the planetary agitation mixer includes at least one planetary blade and at least one high-speed dispersing blade. In certain embodiments, the rotation speed of the planetary blade is about 20 rpm to about 200 rpm, about 20 rpm to about 150 rpm, about 30 rpm to about 150 rpm, or about 50 rpm to about 100 rpm. In certain embodiments, the rotation speed of the dispersing blade is in the range of about 1,000 rpm to about 4,000 rpm, about 1,000 rpm to about 3,500 rpm, about 1,000 rpm to about 3,000 rpm, about 1,000 rpm to about 2,000 rpm, about 1,500 rpm to about 3,000 rpm, or about 1,500 rpm to about 2,500 rpm.

[0092] In certain embodiments, the ultrasonic generator is an ultrasonic bath, a probe ultrasonic generator, or an ultrasonic flow cell. In some embodiments, the ultrasonic generator is operated at a power density of about 10 W / L to about 100 W / L, about 20 W / L to about 100 W / L, about 30 W / L to about 100 W / L, about 40 W / L to about 80 W / L, about 40 W / L to about 70 W / L, about 40 W / L to about 60 W / L, about 40 W / L to about 50 W / L, about 50 W / L to about 60 W / L, about 20 W / L to about 80 W / L, about 20 W / L to about 60 W / L, or about 20 W / L to about 40 W / L. In certain embodiments, the ultrasonic generator is operated at a power density of about 10 W / L, about 20 W / L, about 30 W / L, about 40 W / L, about 50 W / L, about 60 W / L, about 70 W / L, about 80 W / L, about 90 W / L, or about 100 W / L.

[0093] If the cathode active material is homogenized in the aqueous slurry for an extended period of time, the water may damage the cathode active material, even in the presence of the lithium compound in the third suspension. In some embodiments, the third suspension is homogenized for about 10 minutes to about 6 hours, about 10 minutes to about 5 hours, about 10 minutes to about 4 hours, about 10 minutes to about 3 hours, about 10 minutes to about 2 hours, about 10 minutes to about 1 hour, about 10 minutes to about 30 minutes, about 30 minutes to about 3 hours, about 30 minutes to about 2 hours, about 30 minutes to about 1 hour, about 1 hour to about 6 hours, about 1 hour to about 5 hours, about 1 hour to about 4 hours, about 1 hour to about 3 hours, about 1 hour to about 2 hours, about 2 hours to about 6 hours, about 2 hours to about 4 hours, about 2 hours to about 3 hours, about 3 hours to about 5 hours, or about 4 hours to about 6 hours. In certain embodiments, the third suspension is homogenized for a period of less than 6 hours, less than 5 hours, less than 4 hours, less than 3 hours, less than 2 hours, less than 1 hour, or less than 30 minutes. In some embodiments, the third suspension is homogenized for a period of about 6 hours or more, about 5 hours or more, about 4 hours or more, about 3 hours or more, about 2 hours or more, about 1 hour or more, about 30 minutes or more, about 20 minutes or more, or about 10 minutes or more.

[0094] The most common method for achieving homogeneity is to use a high stirring speed, ideally inducing turbulence. However, increasing the stirring speed typically results in a significant increase in energy demand, and the stress required to achieve turbulence often exceeds the capabilities of the equipment. Furthermore, because some cathode active materials are sensitive to shear, such stress can damage the cathode active material. An advantage of the present invention is that the addition of a lithium compound stabilizes the pH of the slurry, thereby stabilizing the viscosity of the slurry. This facilitates homogenization of the slurry and allows for efficient mixing under gentle stirring conditions. Another advantage of the present invention is that it reduces the time it takes for the mixed components to become homogeneous.

[0095] If the pH value of the slurry fluctuates or deviates from a certain range during homogenization, it may affect the dispersion uniformity and particle size distribution of water-insoluble components in the slurry, such as the electrode active material and conductive agent, resulting in poor electrode performance. Therefore, it is desirable to maintain a constant pH value of the slurry during homogenization.

[0096] In some embodiments, the pH of the homogenized cathode slurry is from about 8 to about 14, from about 8 to about 13.5, from about 8 to about 13, from about 8 to about 12.5, from about 8 to about 12, from about 8 to about 11.5, from about 8 to about 11, from about 8 to about 10.5, from about 8 to about 10, from about 8 to about 9, from about 9 to about 14, from about 9 to about 13, from about 9 to about 12, from about 9 to about 11, from about 10 to about 14, from about 10 to about 15, from about 15 to about 16, from about 16 to about 17, from about 17 to about 18, from about 18 to about 20, from about 18 to about 21, from about 18 to about 22, from about 18 to about 23, from about 18 to about 24, from about 18 to about 25, from about 18 to about 26, from about 18 to about 27, from about 18 to about 28, from about 18 to about 29, from about 19 to about 29, from about 29 to about 30, from about 29 to about 31, from about 29 to about 32, from about 29 to about 33, from about 29 to about 34, from about 29 to about 35, from about 29 to about 36, from about 29 to about 37, from about 29 to about 38, from about 38 to about 40, from about 38 to about 41, from about 38 to about 42, from about 38 to about 43, from about 38 to about 44, from about 38 to about 45, from about 38 to about 4 to about 13, about 10 to about 12, about 10 to about 11, about 10.5 to about 14, about 10.5 to about 13.5, about 10.5 to about 13, about 10.5 to about 12.5, about 10.5 to about 12, about 10.5 to about 11.5, about 11 to about 14, about 11 to about 13, about 11 to about 12, about 11.5 to about 12.5, about 11.5 to about 12, or about 12 to about 14. In certain embodiments, the pH of the homogenized cathode slurry is less than 14, less than 13.5, less than 13, less than 12.5, less than 12, less than 11.5, less than 11, less than 10.5, less than 10, less than 9.5, less than 9, less than 8.5, or less than 8. In some embodiments, the pH of the homogenized cathode slurry is about 7.5, about 8, about 8.5, about 9, about 9.5, about 10, about 10.5, about 11, about 11.5, about 12, about 12.5, about 13, about 13.5, or about 14.

[0097] In certain embodiments, the amount of conductive agent in the homogenized cathode slurry is about 0.5% to about 5%, about 0.5% to about 3%, about 1% to about 5%, about 1% to about 4%, or about 2% to about 3%, by weight based on the total weight of the homogenized cathode slurry. In some embodiments, the amount of conductive agent in the homogenized cathode slurry is at least about 0.5%, at least about 1%, at least about 2%, at least about 3%, or at least about 4%, by weight based on the total weight of the homogenized cathode slurry. In certain embodiments, the amount of conductive agent in the homogenized cathode slurry is at most about 1%, at most about 2%, at most about 3%, at most about 4%, or at most about 5%, by weight based on the total weight of the homogenized cathode slurry.

[0098] In certain embodiments, the amount of binder material in the homogenized cathode slurry is about 1% to about 15%, about 1% to about 10%, about 1% to about 5%, about 3% to about 15%, about 5% to about 15%, about 5% to about 10%, or about 10% to about 15%, by weight based on the total weight of the homogenized cathode slurry. In some embodiments, the amount of binder material in the homogenized cathode slurry is less than 15%, less than 10%, less than 8%, or less than 6%, by weight based on the total weight of the homogenized cathode slurry.

[0099] In some embodiments, the weight of the binder material is greater than, less than, or equal to the weight of the conductive agent in the homogenized cathode slurry. In certain embodiments, the ratio of the weight of the binder material to the weight of the conductive agent is about 1:10 to about 10:1, about 1:10 to about 5:1, about 1:10 to about 1:1, about 1:10 to about 1:5, about 1:5 to about 5:1, about 1:3 to about 3:1, about 1:2 to about 2:1, or about 1:1.5 to about 1.5:1.

[0100] In certain embodiments, the amount of cathode active material in the homogenized cathode slurry is at least 20%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, or at least 60% by weight, based on the total weight of the homogenized cathode slurry. In some embodiments, the amount of cathode active material in the homogenized cathode slurry is at most 50%, at most 55%, at most 60%, at most 65%, at most 70%, or at most 75% by weight, based on the total weight of the homogenized cathode slurry.

[0101] In some embodiments, the amount of cathode active material in the homogenized cathode slurry is about 20% to about 70%, about 20% to about 65%, about 20% to about 60%, about 20% to about 55%, about 20% to about 50%, about 20% to about 40%, about 20% to about 30%, about 30% to about 70%, about 30% to about 65%, about 30% to about 60%, about 30% to about 55%, about 30% to about 50%, about 40% to about 70%, about 40% to about 65%, about 40% to about 60%, about 40% to about 55%, about 40% to about 50%, about 50% to about 70%, or about 50% to about 60%, by weight based on the total weight of the homogenized cathode slurry. In certain embodiments, the amount of cathode active material in the homogenized cathode slurry is about 20%, about 30%, about 45%, about 50%, about 65%, or about 70% by weight based on the total weight of the homogenized cathode slurry.

[0102] In some embodiments, the solids content of the homogenized cathode slurry is about 40% to about 80%, about 45% to about 75%, about 45% to about 70%, about 45% to about 65%, about 45% to about 60%, about 45% to about 55%, about 45% to about 50%, about 50% to about 75%, about 50% to about 70%, about 50% to about 65%, about 55% to about 75%, about 55% to about 70%, about 60% to about 75%, or about 65% to about 75%, by weight based on the total weight of the homogenized cathode slurry. In certain embodiments, the solids content of the homogenized cathode slurry is about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, or about 80%, by weight based on the total weight of the homogenized cathode slurry. In certain embodiments, the solids content of the homogenized cathode slurry is at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, or at least 70%, by weight based on the total weight of the homogenized cathode slurry. In certain embodiments, the solids content of the homogenized cathode slurry is less than 75%, less than 70%, less than 65%, less than 60%, less than 55%, or less than 50%, by weight based on the total weight of the homogenized cathode slurry.

[0103] The homogenized cathode slurry of the present invention can have a higher solids content than conventional cathode slurries, which allows more cathode active material to be prepared at one time for further processing, thus improving efficiency and maximizing productivity.

[0104] The solvent used in the homogenized cathode slurry disclosed herein can include at least one alcohol. The addition of an alcohol can improve the processability of the slurry and lower the freezing point of water. Some non-limiting examples of suitable alcohols include ethanol, isopropanol, n-propanol, tert-butanol, n-butanol, and combinations thereof. The total amount of alcohol can range from about 1% to about 30%, about 1% to about 20%, about 1% to about 10%, about 1% to about 5%, about 1% to about 3%, about 3% to about 30%, about 3% to about 20%, about 3% to about 10%, about 5% to about 20%, about 5% to about 15%, about 5% to about 10%, or about 8% to about 15% by weight based on the total weight of the homogenized cathode slurry. In some embodiments, the slurry is alcohol-free.

[0105] The viscosity of the homogenized cathode slurry is preferably less than about 8,000 mPa·s. In some embodiments, the viscosity of the homogenized cathode slurry is about 1,000 mPa·s to about 8,000 mPa·s, about 1,000 mPa·s to about 7,000 mPa·s, about 1,000 mPa·s to about 6,000 mPa·s, about 1,000 mPa·s to about 5,000 mPa·s, about 1,000 mPa·s to about 4,000 mPa·s, about 1,000 mPa·s to about 3,000 mPa·s, or about 1,000 mPa·s to about 2,000 mPa·s. In certain embodiments, the viscosity of the homogenized cathode slurry is less than 8,000 mPa·s, less than 7,000 mPa·s, less than 6,000 mPa·s, less than 5,000 mPa·s, less than 4,000 mPa·s, less than 3,000 mPa·s, or less than 2,000 mPa·s. In some embodiments, the viscosity of the homogenized cathode slurry is about 1,000 mPa·s, about 2,000 mPa·s, about 3,000 mPa·s, about 4,000 mPa·s, about 5,000 mPa·s, about 6,000 mPa·s, about 7,000 mPa·s, or about 8,000 mPa·s. Thus, the resulting slurry can be thoroughly mixed or homogenous.

[0106] At alkaline pH, the surface chemistry of the cathode active material changes, which can affect the dispersion uniformity and particle size distribution of the electrode components (eg, cathode active material and conductive agent) in the cathode slurry.

[0107] The cathode slurry disclosed herein has a small D50 and a uniform, narrow particle size distribution. Figure 2 shows the D50 size of cathode active material particles in an NMP-based slurry and the base-treated slurry of the present invention. While the D50 of the NMP-based slurry is somewhat large and fluctuates significantly, the D50 of the base-treated slurry is small and remains constant over time. This indicates that the particles of the base-treated slurry of the present invention do not aggregate or disintegrate over time, maintaining a highly stable dispersion state even after long-term storage. This not only improves the life of lithium-ion batteries using the slurry, but also improves production efficiency because the dispersion state of the slurry particles does not change even after long-term use after preparation.

[0108] The cathode slurries disclosed herein have a small D50 and a uniform, narrow particle size distribution. In some embodiments, the cathode slurries of the present invention have a particle size of about 1 μm to about 15 μm, about 1 μm to about 12 μm, about 1 μm to about 10 μm, about 1 μm to about 8 μm, about 1 μm to about 6 μm, about 3 μm to about 15 μm, about 3 μm to about 12 μm, about 3 μm to about 10 μm, about 3 μm to about 8 μm, about 3 μm to about 6 μm, about 4 μm to about 15 μm, about 4 μm to about 12 μm, about 4 μm to about 15 ... The cathode active material has a particle size D50 in the range of about 10 μm, about 4 μm to about 8 μm, about 4 μm to about 6 μm, about 6 μm to about 15 μm, about 6 μm to about 12 μm, about 6 μm to about 10 μm, about 6 μm to about 8 μm, about 6 μm to about 15 μm, about 8 μm to about 15 μm, about 8 μm to about 12 μm, about 8 μm to about 10 μm, about 10 μm to about 15 μm, about 10 μm to about 12 μm, or about 11 μm to about 15 μm. In certain embodiments, the particle size D50 of the cathode active material is less than 15 μm, less than 12 μm, less than 10 μm, less than 8 μm, less than 6 μm, or less than 4 μm. In some embodiments, the particle size D50 of the cathode active material is greater than 1 μm, greater than 3 μm, greater than 4 μm, greater than 6 μm, greater than 8 μm, greater than 10 μm, or greater than 11 μm.

[0109] In conventional methods for preparing a cathode slurry, a dispersant can be used to aid in dispersing the cathode active material, conductive agent, and binder material in the slurry. Some non-limiting examples of dispersants include polymeric acids and surfactants that can reduce the surface tension between liquids and solids. In some embodiments, the dispersant is a nonionic surfactant, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, or a combination thereof.

[0110] One advantage of the present invention is that the slurry components can be homogeneously dispersed at room temperature without the use of a dispersant. In some embodiments, the method of the present invention does not include adding a dispersant to the first suspension, the second suspension, the third suspension, or the homogenized cathode slurry. In certain embodiments, each of the first suspension, the second suspension, the third suspension, and the homogenized cathode slurry independently does not contain a dispersant.

[0111] Some non-limiting examples of polymeric acids include polylactic acid, polysuccinic acid, polymaleic acid, pyromucic acid, polyfumaric acid, polysorbic acid, polylinoleic acid, polylinolenic acid, polyglutamic acid, polymethacrylic acid, polylicanic acid, polyglycolic acid, polyaspartic acid, polyamic acid, polyformic acid, polyacetic acid, polypropionic acid, polybutidic acid, polysebacic acid, copolymers thereof, and combinations thereof. In certain embodiments, the homogenized cathode slurry does not include a polymeric acid.

[0112] Some non-limiting examples of suitable non-ionic surfactants include carboxylic acid esters, polyethylene glycol esters, and combinations thereof. In some embodiments, the homogenized cathode slurry is free of non-ionic surfactants.

[0113] Some non-limiting examples of suitable anionic surfactants include alkyl sulfates, alkyl polyethoxylate ether sulfates, alkyl benzene sulfonates, alkyl ether sulfates, sulfonates, sulfosuccinates, sarcosinates, and salts of combinations thereof. In some embodiments, the anionic surfactant comprises a cation selected from the group consisting of sodium, potassium, ammonium, and combinations thereof. In certain embodiments, the anionic surfactant is sodium dodecylbenzene sulfonate, sodium stearate, lithium dodecyl sulfate, or combinations thereof. In some embodiments, the homogenized cathode slurry does not comprise an anionic surfactant.

[0114] Some non-limiting examples of suitable cationic surfactants include ammonium salts, phosphonium salts, imidazolium salts, sulfonium salts, and combinations thereof. Some non-limiting examples of suitable ammonium salts include stearyltrimethylammonium bromide (STAB), cetyltrimethylammonium bromide (CTAB), myristyltrimethylammonium bromide (MTAB), trimethylhexadecylammonium chloride, and combinations thereof. In some embodiments, the homogenized cathode slurry does not contain a cationic surfactant.

[0115] Some non-limiting examples of suitable amphoteric surfactants are surfactants containing both cationic and anionic groups. The cationic groups are ammonium, phosphonium, imidazolium, sulfonium, or combinations thereof. The anionic hydrophilic groups are carboxylate, sulfonate, sulfate, phosphonate, or combinations thereof. In some embodiments, the homogenized cathode slurry does not contain an amphoteric surfactant.

[0116] After the slurry components are uniformly mixed, the homogenized cathode slurry is applied to a current collector to form a coating on the current collector, which is then dried in step 104. The current collector serves to collect electrons generated by the electrochemical reaction of the cathode active material or to supply electrons required for the electrochemical reaction. In some embodiments, the current collector can be in the form of a foil, sheet, or film. In certain embodiments, the current collector is made of stainless steel, titanium, nickel, aluminum, copper, or alloys thereof, or an electrically conductive resin. In certain embodiments, the current collector has a two-layer structure consisting of an outer layer and an inner layer, where the outer layer comprises a conductive material and the inner layer comprises an insulating material or another conductive material; for example, aluminum attached with a conductive resin layer or a polymer insulating material coated with an aluminum film. In some embodiments, the current collector has a three-layer structure consisting of an outer layer, an intermediate layer, and an inner layer, where the outer layer and the inner layer comprise a conductive material and the intermediate layer comprises an insulating material or another conductive material; for example, a plastic substrate coated with a metal film on both sides. In certain embodiments, the outer layer, intermediate layer, and inner layer are each independently stainless steel, titanium, nickel, aluminum, copper, or alloys thereof, or a conductive resin. In some embodiments, the insulating material is a polymeric material selected from the group consisting of polycarbonate, polyacrylate, polyacrylonitrile, polyester, polyamide, polystyrene, polyurethane, polyepoxy, poly(acrylonitrile butadiene styrene), polyimide, polyolefin, polyethylene, polypropylene, polyphenylene sulfide, poly(vinyl ester), polyvinyl chloride, polyether, polyphenyl oxide, cellulose polymer, and combinations thereof. In certain embodiments, the current collector has three or more layers. In some embodiments, the current collector is coated with a protective coating. In certain embodiments, the protective coating includes a carbon-containing material. In some embodiments, the current collector is not coated with a protective coating.

[0117] In certain embodiments, the thickness of each of the cathode and anode electrode layers on the current collector is independently about 5 μm to about 50 μm, about 5 μm to about 25 μm, about 10 μm to about 90 μm, about 10 μm to about 50 μm, about 10 μm to about 30 μm, about 15 μm to about 90 μm, about 20 μm to about 90 μm, about 25 μm to about 90 μm, about 25 μm to about 80 μm, about 25 μm to about 75 μm, about 25 μm to about 50 μm, about 30 μm to about 90 μm, about 30 μm to about 80 μm, about 35 μm to about 90 μm, about 35 μm to about 85 μm, about 35 μm to about 80 μm, or about 35 μm to about 75 μm. In some embodiments, the thickness of the electrode layer on the current collector is about 25 μm, about 30 μm, about 35 μm, about 40 μm, about 45 μm, about 50 μm, about 55 μm, about 60 μm, about 65 μm, about 70 μm, or about 75 μm.

[0118] In some embodiments, the surface density of each of the cathode and anode electrode layers on the current collector is independently about 1 mg / cm 2 to approximately 40 mg / cm 2 , about 1mg / cm 2 to approximately 35 mg / cm 2 , about 1mg / cm 2 to approximately 30 mg / cm 2 , about 1mg / cm 2 to approximately 25 mg / cm 2 , about 1mg / cm 2 to approximately 15 mg / cm 2 , about 3mg / cm 2 to approximately 40 mg / cm 2 , about 3mg / cm 2 to approximately 35 mg / cm 2 , about 3mg / cm 2 to approximately 30 mg / cm 2 , about 3mg / cm 2 to approximately 25 mg / cm 2 , about 3mg / cm 2 to approximately 20 mg / cm 2 , about 3mg / cm 2 to approximately 15 mg / cm 2 , about 5mg / cm 2 to approximately 40 mg / cm 2 , about 5mg / cm 2to approximately 35 mg / cm 2 , about 5mg / cm 2 to approximately 30 mg / cm 2 , about 5mg / cm 2 to approximately 25 mg / cm 2 , about 5mg / cm 2 to approximately 20 mg / cm 2 , about 5mg / cm 2 to approximately 15 mg / cm 2 , about 8mg / cm 2 to approximately 40 mg / cm 2 , about 8mg / cm 2 to approximately 35 mg / cm 2 , about 8mg / cm 2 to approximately 30 mg / cm 2 , about 8mg / cm 2 to approximately 25 mg / cm 2 , about 8mg / cm 2 ~about 20mg / cm 2 , about 10mg / cm 2 ~about 40mg / cm 2 , about 10mg / cm 2 ~about 35mg / cm 2 , about 10mg / cm 2 ~about 30mg / cm 2 , about 10mg / cm 2 ~about 25mg / cm 2 , about 10mg / cm 2 ~about 20mg / cm 2 , about 15mg / cm 2 ~about 40mg / cm 2 , or about 20 mg / cm 2 ~about 40mg / cm 2 It is possible to select from among:

[0119] In some embodiments, a conductive layer can be coated on an aluminum current collector to improve its current conductivity. In certain embodiments, the conductive layer is composed of a material selected from the group consisting of carbon, carbon black, graphite, expanded graphite, graphene, graphene nanoplatelets, carbon fibers, carbon nanofibers, graphitized carbon flakes, carbon tubes, carbon nanotubes, activated carbon, mesoporous carbon, and combinations thereof. In some embodiments, the conductive agent is not carbon, carbon black, graphite, expanded graphite, graphene, graphene nanoplatelets, carbon fibers, carbon nanofibers, graphitized carbon flakes, carbon tubes, carbon nanotubes, activated carbon, or mesoporous carbon.

[0120] In some embodiments, the conductive layer has a thickness of about 0.5 μm to about 5.0 μm. The thickness of the conductive layer affects the volume occupied by the current collector in the battery and the amount of electrode material, and therefore the capacity in the battery.

[0121] In certain embodiments, the thickness of the conductive layer on the current collector is about 0.5 μm to about 4.5 μm, about 1.0 μm to about 4.0 μm, about 1.0 μm to about 3.5 μm, about 1.0 μm to about 3.0 μm, about 1.0 μm to about 2.5 μm, about 1.0 μm to about 2.0 μm, about 1.1 μm to about 2.0 μm, about 1.2 μm to about 2.0 μm, about 1.5 μm to about 2.0 μm, about 1.8 μm to about 2.0 μm, about 1.0 μm to about 1.8 μm, about 1.2 μm to about 1.8 μm, about 1.5 μm to about 1.8 μm, about 1.0 μm to about 1.5 μm, or about 1.2 to about 1.5 μm. In some embodiments, the thickness of the conductive layer on the current collector is less than 4.5 μm, less than 4.0 μm, less than 3.5 μm, less than 3.0 μm, less than 2.5 μm, less than 2.0 μm, less than 1.8 μm, less than 1.5 μm, or less than 1.2 μm. In some embodiments, the thickness of the conductive layer on the current collector is 1.0 μm or more, 1.2 μm or more, 1.5 μm or more, 1.8 μm or more, 2.0 μm or more, 2.5 μm or more, 3.0 μm or more, or 3.5 μm or more.

[0122] Furthermore, the cathodes fabricated according to the present invention exhibit strong adhesion between the electrode layer and the current collector. Having good peel strength between the electrode layer and the current collector is important for preventing electrode peeling or separation, which significantly affects the mechanical stability of the electrode and the cycleability of the battery. Therefore, the electrodes must have sufficient peel strength to withstand the rigors of battery manufacturing.

[0123] 3 is a bar graph showing the peel strength of cathodes coated with an organic slurry, an aqueous slurry of untreated cathode active material, and an aqueous slurry prepared according to the present invention. The graph demonstrates increased peel strength of the coating to the current collector for electrodes prepared by the methods disclosed herein.

[0124] In some embodiments, the peel strength between the current collector and the electrode layer is from about 1.0 N / cm to about 8.0 N / cm, from about 1.0 N / cm to about 6.0 N / cm, from about 1.0 N / cm to about 5.0 N / cm, from about 1.0 N / cm to about 4.0 N / cm, from about 1.0 N / cm to about 3.0 N / cm, from about 1.0 N / cm to about 2.5 N / cm, from about 1.0 N / cm to about 2.0 N / cm, from about 1.2 N / cm to about 3.0 N / cm, from about 1.2 N / cm to about 2.5 N / cm, from about 1.2 N / cm to about 2.0 N / cm, from about 0 N / cm to about 3.0 N / cm, m, about 1.5 N / cm to about 2.5 N / cm, about 1.5 N / cm to about 2.0 N / cm, about 1.8 N / cm to about 3.0 N / cm, about 1.8 N / cm to about 2.5 N / cm, about 2.0 N / cm to about 6.0 N / cm, about 2.0 N / cm to about 5.0 N / cm, about 2.0 N / cm to about 3.0 N / cm, about 2.0 N / cm to about 2.5 N / cm, about 2.2 N / cm to about 3.0 N / cm, about 2.5 N / cm to about 3.0 N / cm, about 3.0 N / cm to about 8.0 N / cm, about 3.0 N / cm to about 6.0 N / cm, or about 4.0 N / cm to about 6.0 N / cm. In some embodiments, the peel strength between the current collector and the electrode layer is 1.0 N / cm or more, 1.2 N / cm or more, 1.5 N / cm or more, 2.0 N / cm or more, 2.2 N / cm or more, 2.5 N / cm or more, 3.0 N / cm or more, 3.5 N / cm or more, 4.5 N / cm or more, 5.0 N / cm or more, or 5.5 N / cm or more. In some embodiments, the peel strength between the current collector and the electrode layer is less than 6.5 N / cm, less than 6.0 N / cm, less than 5.5 N / cm, less than 5.0 N / cm, less than 4.5 N / cm, less than 4.0 N / cm, less than 3.5 N / cm, less than 3.0 N / cm, less than 2.8 N / cm, less than 2.5 N / cm, less than 2.2 N / cm, less than 2.0 N / cm, less than 1.8 N / cm, or less than 1.5 N / cm.

[0125] During coating, pH affects key slurry properties, such as viscosity and dispersibility, making it a critical parameter for controlling slurry stability. Changes in slurry pH result in changes in these key properties. To avoid pH instability, the slurry must be applied to the current collector immediately after homogenization. However, this is extremely difficult to achieve in a mass-production environment where the coating process can last for hours. Fluctuations in key physical properties during coating can seriously affect coating stability. One advantage of the present invention is that the pH of the slurry, and therefore its key properties, remain stable during and after homogenization. While the pH of conventional aqueous slurries increases significantly during storage, the pH of the slurries disclosed herein has been found to remain relatively constant during long-term stagnant storage periods of up to two weeks. Due to pH stability, the slurries disclosed herein remain homogenous and uniform during such long-term storage, allowing sufficient time for the slurry to be transported and proceed to the coating process.

[0126] In some embodiments, the lithium ions (Li + ) is from about 0.0001 M to about 1 M. In certain embodiments, the concentration of Li in the cathode slurry +The concentrations are about 0.0001M to about 0.9M, 0.0001M to about 0.85M, 0.0001M to about 0.8M, 0.0001M to about 0.75M, 0.0001M to about 0.7M, 0.0001M to about 0.65M, 0.0001M to about 0.6M, 0.0001M to about 0.55M, about 0.0001M to about 0.5M, 0.0001M to about 0.45M, about 0.0001M to about 0.4M, about 0.0001M to about 0.35M, about 0.0001M to about 0.3M, about 0.0001M to about 0.25M, about 0.0001M to about 0.2M, and about 0.0001M to about 0. 15M, about 0.0001M to about 0.1M, about 0.0001M to about 0.05M, about 0.0001M to about 0.01M, about 0.0001M to about 0.005M, about 0.0001M to about 0.001M, about 0.0.001M to about 0.6M, 0.001M to about 0.55M, 0.001M to about 0.5M, 0.001M to about 0.45M, 0.001M to about 0.4M, 0.001M to about 0.35M, 0.001M to about 0.3M, about 0.001M to about 0.25M, about 0.001M to about 0.2M, about 0.001M to about 0.1M, about 0.001 M to about 0.05M, about 0.001M to about 0.01M, about 0.01M to about 0.6M, about 0.01M to about 0.55M, 0.01M to about 0.5M, 0.01M to about 0.45M, about 0.01M to about 0.4M, 0.01M to about 0.35M, 0.01M to about 0.3M, about 0.01M to about 0.25M, about 0.01M to about 0.2M, about 0.01M to about 0.1M, about 0.1M to about 0.6M, about 0.1M to about 0.55M, about 0.1M to about 0.5M, about 0.1M to about 0.45M, about 0.1M to about 0.4M, about 0.1M to about 0.35M, about 0.1M to about 0.3M, about 0.2M to about 0.6M, about 0.2M to about 0.55M, about 0.2M to about 0.5M, about 0.2M to about 0.45M, about 0.2M to about 0.4M, about 0.2M to about 0.35M, about 0.2M to about 0.3M, about 0.3M to about 0.6M, about 0.3M to about 0.55M, about 0.3M to about 0.5M, about 0.35M to about 0.6M, about 0.35M to about 0.55M, about 0.35M to about 0.5M, about 0.4M to about 0.6M, about 0.4M to about 0.55M, or about 0.4M to about 0.5M. +The concentration of Li in the cathode slurry is at least about 0.0001M, at least about 0.0005M, at least about 0.001M, at least about 0.005M, at least about 0.01M, at least about 0.05M, at least about 0.1M, at least about 0.2M, at least about 0.3M, at least about 0.35M, at least about 0.4M, at least about 0.45M, at least about 0.5M, at least about 0.55M, at least about 0.6M, at least about 0.65M, at least about 0.7M, at least about 0.75M, at least about 0.8, at least about 0.85M, or at least about 0.9. + is less than about 1 M, less than about 0.95 M, less than about 0.9 M, less than about 0.85 M, less than about 0.8 M, less than about 0.75 M, less than about 0.7 M, less than about 0.65 M, less than about 0.6 M, less than about 0.55 M, less than about 0.5 M, less than about 0.45 M, less than about 0.4 M, less than about 0.35 M, less than about 0.35 M, less than about 0.3 M, less than about 0.25 M, less than about 0.2 M, less than about 0.15 M, less than about 0.1 M, less than about 0.05 M, less than about 0.01 M, less than about 0.005 M, or about 0.001 M or less.

[0127] In certain embodiments, the pH of the cathode slurry ranges from about 10 to about 14, from about 10 to about 13, from about 10 to about 12, from about 10 to about 11.8, from about 10 to about 11.5, from about 10.3 to about 11.8, from about 11 to about 14, from about 11 to about 13, or from about 12 to about 14. In some embodiments, the pH of the cathode slurry is less than about 13, less than about 12.5, less than about 12, less than about 11.5, less than about 11, less than about 10.5, less than about 10, or less than about 9. In certain embodiments, the pH of the cathode slurry is greater than about 10, greater than about 10.5, greater than about 11, greater than about 11.5, greater than about 12, greater than about 12.5, or greater than about 13.

[0128] The slurry must maintain a stable pH during homogenization, as an unstable pH can significantly reduce battery life. Generally, it has been found that when a lithium compound is present in the slurry, the slurry pH changes slightly during homogenization. In certain embodiments, the observed pH change during homogenization is between about 0.01 pH units and about 0.5 pH units, between about 0.01 pH units and about 0.45 pH units, between about 0.01 pH units and about 0.4 pH units, between about 0.01 pH units and about 0.35 pH units, between about 0.01 pH units and about 0.3 pH units, between about 0.01 pH units and about 0.25 pH units, between about 0.01 pH units and about 0.2 pH units, between about 0.01 pH units and about 0.15 pH units, or between about 0.01 pH units and about 0.1 pH units. In certain embodiments, the decrease in pH observed during homogenization is less than 0.5 pH units, less than 0.45 pH units, less than 0.4 pH units, less than 0.35 pH units, less than 0.3 pH units, less than 0.2 pH units, or less than 0.1 pH units.

[0129] The thickness of the current collector affects the volume it occupies in the battery, the amount of electrode active material required, and ultimately the battery capacity. In some embodiments, the current collector has a thickness of about 5 μm to about 30 μm. In specific embodiments, the current collector has a thickness of about 5 μm to about 20 μm, about 5 μm to about 15 μm, about 10 μm to about 30 μm, about 10 μm to about 25 μm, or about 10 μm to about 20 μm.

[0130] In certain embodiments, the coating step is carried out using a doctor blade coater, a slot die coater, a transfer coater, a spray coater, a roll coater, a gravure coater, a dip coater, or a curtain coater.

[0131] To fabricate a battery, the solvent must be evaporated to create a dried porous electrode. After the homogenized cathode slurry is applied to a current collector, the coating on the current collector is dried in a dryer to obtain a battery electrode. Any dryer capable of drying the coating on the current collector can be used herein. Some non-limiting examples of dryers include a batch drying oven, a conveyor drying oven, and a microwave drying oven. Some non-limiting examples of conveyor drying ovens include a conveyor hot air drying oven, a conveyor resistance drying oven, a conveyor induction drying oven, and a conveyor microwave drying oven.

[0132] In some embodiments, a conveyor drying oven for drying a coated film on a current collector includes one or more heating sections, each of which is individually temperature controlled, and each of which may include an independently controlled heating zone.

[0133] In one embodiment, the conveyor drying oven includes a first heating section located on one side of the conveyor and a second heating section located on the opposite side of the conveyor from the first heating section, each of the first and second heating sections independently including one or more heating elements and a temperature control system connected to the heating elements of the first and second heating sections and configured to monitor and selectively control the temperature of each heating section.

[0134] In some embodiments, the conveyor drying oven comprises multiple heating sections, each containing an independent heating element that operates to maintain a constant temperature within the heating section.

[0135] In certain embodiments, each of the first and second heating sections has an independent inlet heating zone and an outlet heating zone, each of the inlet and outlet heating zones independently comprising one or more heating elements and a temperature control system connected to the heating elements of the inlet and outlet heating zones in a manner that monitors and selectively controls the temperature of each heating zone independently of the temperature control of the other heating zones.

[0136] The coating on the current collector is preferably dried within approximately 20 minutes at a temperature of approximately 75° C. or less. Drying the coated positive electrode at a temperature above 75° C. may cause undesirable deformation of the cathode, affecting the performance of the positive electrode.

[0137] In some embodiments, the coating on the current collector can be dried at a temperature of about 25°C to about 75°C. In certain embodiments, the coating on the current collector can be dried at a temperature of about 25°C to about 70°C, about 25°C to about 65°C, about 25°C to about 60°C, about 25°C to about 55°C, about 25°C to about 50°C, about 25°C to about 45°C, about 25°C to about 40°C, about 30°C to about 75°C, about 30°C to about 70°C, about 30°C to about 65°C, about 30°C to about 60°C, about 30°C to about 55°C, about 30°C to about 50°C, about 35°C to about 75°C, about 35°C to about 70°C, about 35°C to about 65°C, about 35°C to about 60°C, about 40°C to about 75°C, about 40°C to about 70°C, about 40°C to about 65°C, or about 40°C to about 60°C. In some embodiments, the coating on the current collector is dried at a temperature below 75° C., below 70° C., below 65° C., below 60° C., below 55° C., or below 50° C. In some embodiments, the coating on the current collector is dried at a temperature above about 70° C., above about 65° C., above about 60° C., above about 55° C., above about 50° C., above about 45° C., above about 40° C., or above about 35° C., above about 30° C., or above about 25° C.

[0138] In certain embodiments, the conveyor may have a speed of about 1 meter / minute to about 120 meters / minute, about 1 meter / minute to about 100 meters / minute, about 1 meter / minute to about 80 meters / minute, about 1 meter / minute to about 60 meters / minute, about 1 meter / minute to about 40 meters / minute, about 1 meter / minute to about 120 meters / minute, about 10 meters / minute to about 80 meters / minute, about 10 meters / minute to about 60 meters / minute, about 10 meters / minute to about 40 meters / minute, about 25 meters / minute to about 120 meters / minute, about 25 meters / minute to about 100 meters / minute, about 25 meters / minute to about 80 meters / minute, meters / minute, about 25 meters / minute to about 60 meters / minute, about 50 meters / minute to about 120 meters / minute, about 50 meters / minute to about 100 meters / minute, about 50 meters / minute to about 80 meters / minute, about 75 meters / minute to about 120 meters / minute, about 75 meters / minute to about 100 meters / minute, about 2 meters / minute to about 25 meters / minute, about 2 meters / minute to about 20 meters / minute, about 2 meters / minute to about 16 meters / minute, about 3 meters / minute to about 30 meters / minute, about 3 meters / minute to about 20 meters / minute, or about 3 meters / minute to about 16 meters / minute.

[0139] The drying time of the coating can be adjusted by controlling the length and speed of the conveyor. In some embodiments, the coating on the current collector can be dried in about 1 minute to about 30 minutes, about 1 minute to about 25 minutes, about 2 minutes to about 20 minutes, about 2 minutes to about 17 minutes, about 2 minutes to about 15 minutes, about 2 minutes to about 14 minutes, about 2 minutes to about 10 minutes, about 2 minutes to about 11 minutes, about 2 minutes to about 8 minutes, about 5 minutes to about 30 minutes, about 5 minutes to about 20 minutes, about 5 minutes to about 11 minutes, about 5 minutes to about 14 minutes, about 5 minutes to about 17 minutes, about 5 minutes to about 10 minutes, about 10 minutes to about 30 minutes, or about 10 minutes to about 20 minutes. In certain embodiments, the coating on the current collector can be dried in less than 5 minutes, less than 8 minutes, less than 10 minutes, less than 11 minutes, less than 14 minutes, less than 17 minutes, or less than 20 minutes. In some embodiments, the coating on the current collector can dry in about 5 minutes, about 8 minutes, about 10 minutes, about 11 minutes, about 14 minutes, about 17 minutes, or about 20 minutes.

[0140] Because the cathode active material is sufficiently active to chemically react with water, it is necessary to control the total treatment time of the present method, particularly steps 1) through 5). In some embodiments, the total treatment time for steps 1) through 5) is about 2 hours to about 8 hours, about 2 hours to about 7 hours, about 2 hours to about 6 hours, about 2 hours to about 5 hours, about 2 hours to about 4 hours, or about 2 hours to about 3 hours. In certain embodiments, the total treatment time for steps 1) through 5) is less than 8 hours, less than 7 hours, less than 6 hours, less than 5 hours, less than 4 hours, or less than 3 hours. In some embodiments, the total treatment time for steps 1) through 5) is about 8 hours, about 7 hours, about 6 hours, about 5 hours, about 4 hours, about 3 hours, or about 2 hours.

[0141] In some embodiments, the total treatment time for steps 1) to 4) or steps 3) to 5) is about 2 to about 8 hours, about 2 to about 7 hours, about 2 to about 6 hours, about 2 to about 5 hours, about 2 to about 4 hours, or about 2 to about 3 hours. In certain embodiments, the total treatment time for steps 1) to 4) is less than 8 hours, less than 7 hours, less than 6 hours, less than 5 hours, less than 4 hours, less than 3 hours, or less than 2 hours.

[0142] In some embodiments, the total treatment time for steps 4) and 5) is about 5 minutes to about 2 hours, about 5 minutes to about 1.5 hours, about 5 minutes to about 1 hour, about 5 minutes to about 30 minutes, about 10 minutes to about 2 hours, about 10 minutes to about 1.5 hours, about 10 minutes to about 1 hour, about 10 minutes to about 30 minutes, about 15 minutes to about 2 hours, about 15 minutes to about 1.5 hours, about 15 minutes to about 1 hour, or about 15 minutes to about 30 minutes. In certain embodiments, the total treatment time for steps 4) and 5) is less than 2 hours, less than 1.5 hours, less than 1 hour, less than 45 minutes, less than 30 minutes, less than 25 minutes, less than 20 minutes, less than 10 minutes, or less than 5 minutes.

[0143] After the coating on the current collector is dried, the cathode is formed. In some embodiments, the cathode is mechanically compressed to densify the cathode.

[0144] In some embodiments, the cathode electrode layer has a lithium ion content of between 0.01 and 20 percent, based on the total weight of the electrode layer. In certain embodiments, the cathode electrode layer has a lithium ion content of between 0.05 and 20 percent, between 0.1 and 20 percent, between 0.15 and 20 percent, between 0.2 and 20 percent, between 0.25 and 20 percent, between 0.3 and 20 percent, between 0.35 and 20 percent, between 0.4 and 20 percent, between 0.5 and 20 percent, between 0.8 and 20 percent, based on the total weight of the electrode layer. Between 20 percent, between 1 percent and 20 percent, between 1.5 percent and 20 percent, between 2 percent and 20 percent, between 2.5 percent and 20 percent, between 3 percent and 20 percent, between 5 percent and 20 percent, between 8 percent and 20 percent, between 10 percent and 20 percent, between 0.01 percent and 15 percent, between 0.05 percent and 15 percent, between 0.1 percent and 15 percent, 0.15 percent Between 0.1 percent and 15 percent, Between 0.2 percent and 15 percent, Between 0.25 percent and 15 percent, Between 0.3 percent and 15 percent, Between 0.35 percent and 15 percent, Between 0.4 percent and 15 percent, Between 0.5 percent and 15 percent, Between 1 percent and 15 percent, Between 1.5 percent and 15 percent, Between 2 percent and 15 percent, Between 2.5 percent and 15 percent, Between 3 percent and 15 percent Between 5 percent and 15 percent, between 8 percent and 15 percent, between 0.01 percent and 10 percent, between 0.05 percent and 10 percent, between 0.1 percent and 10 percent, between 0.15 percent and 10 percent, between 0.2 percent and 10 percent, between 0.25 percent and 10 percent, between 0.3 percent and 10 percent, between 0.35 percent and 10 percent, between 0.4 percent and 10 percent, 0.Between 5 percent and 10 percent, Between 1 percent and 10 percent, Between 1.5 percent and 10 percent, Between 2 percent and 10 percent, Between 2.5 percent and 10 percent, Between 3 percent and 10 percent, Between 5 percent and 10 percent, Between 0.01 percent and 8 percent, Between 0.05 percent and 8 percent, Between 0.1 percent and 8 percent, Between 0.15 percent and 8 percent, Between 0.2 percent and 8 percent, Between 0.25 percent and 8 percent, 0 Between 0.3 percent and 8 percent, between 0.35 percent and 8 percent, between 0.4 percent and 8 percent, between 0.5 percent and 8 percent, between 1 percent and 8 percent, between 1.5 percent and 8 percent, between 2 percent and 8 percent, between 2.5 percent and 8 percent, between 3 percent and 8 percent, between 0.01 percent and 5 percent, between 0.05 percent and 5 percent, between 0.1 percent and 5 percent, between 0.15 percent and 5 percent, and 0.2 percent between 0.25 percent and 5 percent, between 0.3 percent and 5 percent, between 0.35 percent and 5 percent, between 0.4 percent and 5 percent, between 0.5 percent and 5 percent, between 1 percent and 5 percent, between 1.5 percent and 5 percent, or between 2 percent and 5 percent, between 0.01 percent and 2 percent, between 0.05 percent and 2 percent, between 0.1 percent and 2 percent, between 0.15 percent and 2 percent, 0.2 percent Between cents and 2 percent, between 0.25 percent and 2 percent, between 0.3 percent and 2 percent, between 0.35 percent and 2 percent, between 0.4 percent and 2 percent, between 0.5 percent and 2 percent, between 0.01 percent and 1 percent, between 0.05 percent and 1 percent, between 0.1 percent and 1 percent, between 0.15 percent and 1 percent, between 0.2 percent and 1 percent, between 0.25 percent and 1 percent, between 0.3 percent and 1 percent, 0.The lithium ion content may be between 35 percent and 1 percent, between 0.4 percent and 1 percent, between 0.01 percent and 0.5 percent, between 0.01 percent and 0.5 percent, between 0.05 percent and 0.5 percent, between 0.1 percent and 0.5 percent, between 0.15 percent and 0.5 percent, between 0.2 percent and 0.5 percent, between 0.25 percent and 0.5 percent, or between 0.3 percent and 0.5 percent.

[0145] In certain embodiments, the cathode electrode layer has a lithium ion content of 0.01 percent or more, 0.05 percent or more, 0.1 percent or more, 0.15 percent or more, 0.2 percent or more, 0.25 percent or more, 0.3 percent or more, 0.35 percent or more, 0.4 percent or more, 0.5 percent or more, 0.6% or more, 0.7% or more, 0.8% or more, 0.9% or more, 1% or more, 1.5% or more, 2% or more, 2.5% or more, 3% or more, 3.5% or more, 4% or more, or 5% or more, based on the total weight of the electrode layers. In other embodiments, the cathode electrode layer has a lithium ion content of 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 percent or more, based on the total weight of the electrode layers. In some embodiments, the electrode layer of the cathode has a lithium ion content of 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 percent or less, based on the total weight of the electrode layer.

[0146] The method disclosed herein has the advantages of being able to use aqueous solvents in the manufacturing process, thereby saving processing time and equipment, and improving safety by eliminating the need to handle and recycle hazardous organic solvents. Furthermore, the overall process is simplified, reducing costs. Therefore, this method is particularly suitable for industrial processes due to its low cost and ease of handling.

[0147] As described above, by adding a cathode active material to the lithium compound disclosed herein, the slurry preparation method disclosed herein can control the pH of the cathode slurry and advantageously improve the stability of the slurry. The present invention achieves the development of an aqueous cathode slurry without compromising battery performance, such as cyclability and capacity. Batteries containing positive electrodes prepared according to the present invention exhibit high cycle stability. Furthermore, the drying temperature of the coating film is low, and the drying time is shortened, significantly improving battery performance.

[0148] Figure 4 shows the discharge curves of three batteries containing cathodes prepared using an NMP-based slurry, an untreated aqueous slurry, and a LiOH-treated aqueous slurry according to the present invention. As shown in the graph, the batteries using the LiOH-treated aqueous slurry of the present invention exhibit better discharge performance than the batteries using the conventional untreated aqueous slurry. This result further demonstrates that the method for preparing the LiOH-treated slurry of the present invention significantly improves the electrochemical performance of the batteries. Furthermore, the method disclosed in the present invention is clearly advantageous over conventional aqueous methods.

[0149] As shown in Figure 4, batteries using the LiOH-treated aqueous slurry of the present invention exhibit similar discharge performance compared to batteries using an NMP-based slurry. However, the method of the present invention reduces the environmental impact of the manufacturing process by using aqueous solvents and water-soluble materials. Furthermore, since water-soluble materials are generally inexpensive and require less specialized equipment for handling, manufacturing costs can be reduced. Therefore, the present invention allows for the production of lithium-ion batteries in a cheaper, more environmentally friendly manner without sacrificing battery performance.

[0150] Analysis of the cathode slurry and its components revealed useful physical and chemical properties resulting from the method of the present invention. Figures 5 and 6 show infrared spectroscopy data for polyacrylamide (PAM) exposed to lithium hydroxide and lithium iodide, respectively. The solid line shows the transmittance spectrum of untreated PAM after only mixing NMC811 and water for 3 hours. The dashed line shows the transmittance spectrum of PAM mixed with lithium salt for 30 minutes and then with NMC811 for 3 hours. Comparison with the spectrum of untreated PAM reveals changes in the intensity of many peaks after exposure to lithium salt. This demonstrates that PAM undergoes significant chemical changes after exposure to lithium salt, as performed in step b) of the method.

[0151] Table 3a below shows ICP-MS data for diluted slurries of NMC811 with various concentrations of LiOH added. The formulation for the undiluted slurry is shown in Table 3b. This data demonstrates that the addition of lithium salt reduces the dissolution of lithium from the cathode active material into the solvent, and that the lithium salt inhibits lithium loss from the cathode active material. It also demonstrates that the concentration of lithium salt added is directly proportional to its effect on inhibiting lithium loss from the cathode active material.

[0152] In some embodiments, the lithium loss of the cathode active material is retarded by between 1 percent and 50 percent relative to the lithium loss of the cathode material in pure water. In certain embodiments, the lithium loss of the cathode active material is retarded by between 1 percent and 20 percent relative to the lithium loss of the cathode material in pure water. In certain embodiments, the lithium loss of the cathode active material is between 1 percent and 30 percent, between 1.5 percent and 20 percent, between 2 percent and 20 percent, between 2.5 percent and 20 percent, between 3 percent and 20 percent, between 4 percent and 20 percent, between 5 percent and 20 percent, between 10 percent and 20 percent, between 1.5 percent and 18 percent, between 2 percent and 18 percent, between 2.5 percent and 18 percent, between 3 percent and 18 percent, between 4 percent and 18 percent, between 5 percent and 18 percent, between 8 percent and 18 percent, between 1.5 percent and 15 percent, between 2 percent and 15 percent, between 2.5 percent and 15 percent, between 3 percent, between 4 percent and 15 percent, between 1 and 12 percent, between 1.5 percent and 12 percent, between 2 and 12 percent, between 2.5 percent and 12 percent, between 3 and 14 percent, between 4 and 14 percent, between 5 and 14 percent, between 1 and 13 percent, between 1.5 percent and 13 percent, between 2 and 13 percent, between 2.5 percent and 13 percent, between 3 and 13 percent, between 4 and 13 percent, between 5 and 13 percent, between 1 and 12 percent, between 1.5 percent and 12 percent, between 2 and 12 percent, between 2.5 percent and 12 percent, between 3 and 12 percent, between 4 and 12 percent, or between 5 and 12 percent.In some embodiments, the lithium loss of the cathode active material is inhibited by 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15% or more relative to the lithium loss of the cathode active material in pure water. In some embodiments, the lithium loss of the cathode active material is inhibited by 20, 19, 18, 17, 16, 15, 14.5, 14, 13.5, 13, 12.5, 12, 11.5, 11, 10.5, 10, 9.5, 9, 8.5, 8, 7.5, 7, 6.5, 6, 5.5, 5, 4.5, 4, 3.5, 3, 2.5, 2, 1.5, 1% or less relative to the lithium loss of the cathode active material in pure water.

[0153] Also provided herein is an electrode assembly including a cathode prepared by the method described below. The electrode assembly includes at least one cathode, at least one anode, and at least one separator disposed between the cathode and the anode.

[0154] In certain embodiments, the electrode assembly is dried after assembly to reduce its moisture content. In other embodiments, at least one of the components of the electrode assembly is dried before the electrode assembly is assembled. In some embodiments, at least one of the components is pre-dried before assembling the electrode assembly. In certain embodiments, the separator is pre-dried before being assembled into the electrode assembly.

[0155] It is not necessary to dry the separator to a very low moisture content. The remaining moisture content of the pre-dried separator can be further reduced by a subsequent drying step. In some embodiments, the moisture content in the pre-dried separator is about 50 ppm to about 800 ppm, about 50 ppm to about 700 ppm, about 50 ppm to about 600 ppm, about 50 ppm to about 500 ppm, about 50 ppm to about 400 ppm, about 50 ppm to about 300 ppm, about 50 ppm to about 200 ppm, about 50 ppm to about 100 ppm, about 100 ppm to about 500 ppm, or about 50 ppm to about 600 ppm, by weight based on the total weight of the pre-dried separator. 00 ppm, 100 ppm to 400 ppm, 100 ppm to about 300 ppm, about 100 ppm to about 200 ppm, about 200 ppm to about 500 ppm, about 200 ppm to about 400 ppm, about 300 ppm to about 800 ppm, about 300 ppm to about 600 ppm, about 300 ppm to about 500 ppm, about 300 ppm to about 00 ppm, about 400 ppm to about 800 ppm, or about 400 ppm to about 500 ppm. In some embodiments, the moisture content in the pre-dried separator is less than 500 ppm, less than 400 ppm, less than 300 ppm, less than 200 ppm, less than 100 ppm, or less than 50 ppm by weight based on the total weight of the pre-dried separator.

[0156] In certain embodiments, the dried electrode assembly has a carbon content of about 20 ppm to 350 ppm, about 20 ppm to 300 ppm, about 20 ppm to 250 ppm, about 20 ppm to 200 ppm, about 20 ppm to about 100, about 20 ppm to about 50 ppm, about 50 ppm to about 350 ppm, about 50 ppm to about 250 ppm, about 50 ppm to about 150 ppm, about 100 ppm to about 350 ppm, about 100 ppm to about 300 ppm, about 100 ppm to about 250 ppm, about 100 ppm to about 200 ppm, about 100 ppm to about 150 ppm, about 150 ppm to about 350 ppm, about 150 ppm to about 300 ppm, about 150 ppm to about 250 ppm, about 150 ppm to about 200 ppm, about 200 ppm to about 350 ppm, about 250 ppm to about 350 ppm, or about 300 ppm to about 350 ppm.

[0157] The following examples are presented to illustrate embodiments of the present invention, but are not intended to limit the invention to the specific embodiments set forth. Unless otherwise indicated, all parts and percentages are by weight. All numerical values ​​are approximate. When numerical ranges are given, it should be understood that embodiments outside the stated ranges may still fall within the scope of the invention. The specific details set forth in each example should not be construed as necessary features of the invention. Example

[0158] The pH value of the slurry was measured using an electrode-type pH meter (ION2700, manufactured by Eutec Instruments Co., Ltd.), and the viscosity of the slurry was measured using a rotational viscometer (NDJ-5S, Shanghai JT Electronics Technology Co., Ltd., China).

[0159] The peel strength of the dried electrode layer was measured using a tensile tester (DZ-106A, Dongguan Zonhow Test Equipment Co. Ltd., China). This test measures the average force, in Newtons, per 18 mm of test sample width required to peel the electrode layer from the current collector at a 180° angle. An 18 mm-wide strip of adhesive tape (3M; USA, Model No. 810) was attached to the surface of the cathode electrode layer. The cathode strip was clamped in the tester, the tape was folded back 180°, placed in the movable jaw, and pulled at a peel rate of 200 mm / min at room temperature. The maximum peel force measured was taken as the peel strength. The measurement was repeated three times to determine the average value.

[0160] The amount of moisture in the electrode assembly was measured by Karl Fischer titration. In a glove box filled with argon gas, the electrode assembly was cut into 1 cm x 1 cm pieces. The cut 1 cm x 1 cm pieces were placed in a sample vial and weighed. The weighed electrode assembly was then placed in a titration vial and subjected to Karl Fischer titration using a Karl Fischer Coulometry moisture meter (831 KF Coulometer, Metrohm, Switzerland). Measurements were repeated three times to determine the average value.

[0161] The moisture content in the separator was measured by Karl Fischer titration. The electrode assembly was cut into 1 cm x 1 cm pieces in a glove box filled with argon gas. The electrode assembly was separated into an anode, a cathode, and a separator layer. The moisture content of the separated separator layer was analyzed by Karl Fischer titration as described above. The measurement was repeated three times to obtain an average value. Example 1 A) Preparation of the positive electrode

[0162] While stirring with an overhead stirrer (R20, IKA), 0.9 g of a conductive agent (SuperP; obtained from Timcal Ltd, Bodio, Switzerland) and 6 g of poly(acrylamide) (PAM) (solid content 15%) was dispersed in 7.4 g of deionized water to prepare a first suspension. After the addition, the first suspension was further stirred at 25° C. for about 30 minutes at a speed of 1,200 rpm.

[0163] To prepare a lithium aqueous solution with a 0.01M LiOH concentration at 25°C, 0.02g of LiOH was dissolved in 100g of deionized water. After addition, the solution was stirred for an additional 5 minutes at 25°C. 7.5g of the aqueous solution was then added to the first suspension to prepare a second suspension. After addition, the second suspension was stirred for an additional 30 minutes at 25°C.

[0164] Then, 28.2 g of NMC532 (obtained from Shandong Tianqiao New Energy Co., Ltd., China) was added to the second suspension at 25°C while stirring with an overhead stirrer to prepare a third suspension. The third suspension was then degassed under a pressure of approximately 10 kPa for 1 hour. The third suspension was then further stirred at 25°C for approximately 60 minutes at 1,200 rpm to form a homogenized cathode slurry.

[0165] This homogenized cathode slurry was applied to one side of a 14 μm-thick aluminum foil current collector using a doctor blade coater with a gap width of 60 μm. The slurry film coated on the aluminum foil was dried at 50°C and a conveyor speed of approximately 5 m / min in an electric heating conveyor oven (TH-1A, obtained from Nanjing East High-Drying Equipment Co., Ltd., China) to form a cathode electrode layer. The drying time was approximately 6 minutes. The electrode was then pressed to reduce the thickness of the cathode electrode layer to 35 μm. B) Preparation of the negative electrode

[0166] A negative electrode slurry was prepared by mixing 90 wt.% hard carbon (BTR New Energy Materials Inc., Shenzhen, Guangdong Province, China), 1.5 wt.% carboxymethyl cellulose (CMC, BSH-12, DKS Co. Ltd., Japan), 3.5 wt.% SBR (AL-2001, NIPPON A&L INC., Japan) as a binder, and 5 wt.% carbon black as a conductive agent in deionized water. The solids content of the anode slurry was 50 wt.%. This slurry was applied to one side of an 8 μm-thick copper foil using a doctor blade with a gap width of approximately 55 μm. The coating on the copper foil was dried in a hot air dryer at approximately 50 °C for 2.4 minutes to obtain a negative electrode. The electrode was then pressed to reduce the coating thickness to 30 μm and the areal density to 10 mg / cm. 2 It was decided. C) Coin Cell Assembly

[0167] CR2032 coin-type Li-ion batteries were assembled in an argon-filled glove box. The coated cathode and anode plates were cut into disc-shaped positive and negative electrodes. The cathode and anode plates were alternately stacked to form an electrode assembly, which was then housed in a CR2032-type stainless steel case. The anode and cathode plates were separated by a separator. The separator was a ceramic-coated nonwoven microporous membrane (MPM, Japan) with a thickness of approximately 25 μm. The electrode assembly was then dried at 105°C for approximately 16 hours in a box resistance furnace (DZF-6020, obtained from Shenzhen Kejing Star Technology Co. Ltd., China). The moisture contents of the separator and electrode assembly after drying were 200 ppm and 300 ppm, respectively.

[0168] Next, an electrolyte was poured into the case holding the housed electrodes under a high-purity argon atmosphere with moisture and oxygen levels below 3 ppm. The electrolyte was a solution of LiPF6 (1M) mixed with ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 1:1:1. After filling with the electrolyte, the coin cell was vacuum-sealed and mechanically pressed using a standard circular punch die. D) Electrochemical measurements

[0169] The coin cells were analyzed in constant current mode using a multi-channel battery tester (BTS-4008-5V10mA, obtained from Neware Electronics Co. Ltd, China). After completing one cycle at C / 20, they were charged and discharged at a rate of C / 2. The battery was cycled between 3.0 and 4.3 V at a current density of C / 2 at 25°C to determine the discharge capacity. The electrochemical performance of the coin cell of Example 1 was measured and is shown in Table 1 below.

[0170] Example 2 A positive electrode was prepared in the same manner as in Example 1, except that 0.12 g of LiOH was dissolved in 100 g of deionized water to form an aqueous solution having a LiOH concentration of 0.05 M, and 7.5 g of this aqueous solution was added to the first suspension to prepare a second suspension.

[0171] Example 3 A positive electrode was prepared in the same manner as in Example 1, except that 1.20 g of LiOH was dissolved in 100 g of deionized water to form an aqueous solution having a LiOH concentration of 0.5 M, and 7.5 g of this aqueous solution was added to the first suspension to prepare a second suspension.

[0172] Example 4 A positive electrode was produced in the same manner as in Example 2, except that the second suspension was further stirred at 25° C. for about 5 minutes.

[0173] Example 5 A positive electrode was prepared in the same manner as in Example 2, except that the second suspension was further stirred at 25° C. for about 60 minutes.

[0174] Example 6 A positive electrode was prepared in the same manner as in Example 2, except that 0.67 g of LiI was dissolved in 100 g of deionized water to produce an aqueous solution having a LiI concentration of 0.05 M at 25°C.

[0175] Example 7 A positive electrode was prepared in the same manner as in Example 2, except that 0.33 g of LiAc was dissolved in 100 g of deionized water to produce an aqueous solution having a LiAc concentration of 0.05 M at 25°C. Comparative Example 1

[0176] A positive electrode slurry was prepared by dispersing 28.2 g of NMC532 (obtained from Shandong Tianqiao New Energy Co., Ltd., China), 0.9 g of a conductive agent (SuperP; obtained from Timcal Ltd, Bodio, Switzerland), and 6 g of PAM binder (15% solids) in 14.9 g of deionized water while stirring with an overhead stirrer. The slurry was degassed for 1 hour under a pressure of approximately 10 kPa. The slurry was then further stirred at 1,200 rpm for approximately 60 minutes at 25°C.

[0177] The homogenized cathode slurry was applied to one side of a 14 μm-thick aluminum foil current collector using a doctor blade coater with a gap width of 60 μm. The slurry film coated on the aluminum foil was dried at 50°C and a conveyor speed of approximately 5 m / min in an electric heating conveyor oven (TH-1A, obtained from Nanjing East High-Drying Equipment Co., Ltd., China) to form a cathode electrode layer. The drying time was approximately 6 minutes. The electrode was then pressed to reduce the thickness of the cathode electrode layer to 35 μm. Comparative Example 2

[0178] A positive electrode slurry was prepared by dispersing 28.2 g of NMC532 (obtained from Shandong Tianqiao New Energy Co., Ltd., China), 0.9 g of conductive agent (SuperP; obtained from Timcal Ltd, Bodio, Switzerland), and 9 g of vinylidene fluoride binder (PVDF; 10 wt.% solution, Solef® 5130, obtained from Solvay SA, Belgium) in 11.9 g of N-methyl-2-pyrrolidone (NMP; ≥99%, Sigma-Aldrich, USA) with overhead stirring. The slurry was degassed for 1 hour under a pressure of approximately 10 kPa. The slurry was then further stirred at 1,200 rpm at 25°C for approximately 60 minutes.

[0179] The homogenized cathode slurry was applied to one side of a 14-μm-thick aluminum foil current collector using a doctor blade coater with a gap width of 60 μm. The slurry film coated on the aluminum foil was dried at 50°C and a conveyor speed of approximately 5 m / min in an electric heating conveyor oven (TH-1A, obtained from Nanjing Dong Gao Drying Equipment Co., Ltd., China) to form a cathode electrode layer. The drying time was approximately 6 minutes. The electrode was then pressed to reduce the thickness of the cathode electrode layer to 35 μm. Preparation of negative electrodes in Examples 2 to 7 and Comparative Examples 1 and 2

[0180] The negative electrodes of Examples 2 to 7 and Comparative Examples 1 and 2 were produced in the same manner as in Example 1. Assembly of coin batteries of Examples 2 to 7 and Comparative Examples 1 and 2

[0181] The coin batteries of Examples 2-7 and Comparative Examples 1-2 were assembled in the same manner as in Example 1. Electrochemical measurements of Examples 2-7 and Comparative Examples 1-2

[0182] The electrochemical performance of the coin batteries of Examples 2 to 7 and Comparative Examples 1 and 2 was measured in the same manner as in Example 1, and the test results are shown in Table 1 below.

[0183] Example 8:A positive electrode was produced in the same manner as in Example 1, except that 28.2 g of NMC532 was replaced with the same weight of NMC622 (obtained from Shandong Tianqiao New Energy Co., Ltd., China).

[0184] Example 9 A positive electrode was prepared in the same manner as in Example 8, except that 0.12 g of LiOH was dissolved in 100 g of deionized water to form an aqueous solution having a LiOH concentration of 0.05 M, and 7.5 g of this aqueous solution was added to the first suspension to prepare a second suspension.

[0185] Example 10 A positive electrode was fabricated in the same manner as in Example 8, except that a second suspension was prepared by dissolving 1.20 g of LiOH in 100 g of deionized water to form an aqueous solution having a LiOH concentration of 0.5 M, and adding 7.5 g of the aqueous solution to the first suspension.

[0186] Example 11 A positive electrode was prepared in the same manner as in Example 9, except that the second suspension was further stirred at 25°C for about 5 minutes.

[0187] Example 12: A positive electrode was fabricated in the same manner as in Example 9, except that the second suspension was further stirred at 25° C. for about 60 minutes.

[0188] Example 13 A positive electrode was prepared in the same manner as in Example 9, except that 0.67 g of LiI was dissolved in 100 g of deionized water to form an aqueous solution at 25° C. with a LiI concentration of 0.05 M.

[0189] Example 14 A positive electrode was prepared in the same manner as in Example 9, except that 0.33 g of LiAc was dissolved in 100 g of deionized water to prepare an aqueous solution of LiAc at 25° C. with a concentration of 0.05 M. Comparative Example 3

[0190] A positive electrode was produced in the same manner as in Comparative Example 1, except that 28.2 g of NMC533 was replaced with the same weight of NMC622. Comparative Example 4

[0191] A positive electrode was produced in the same manner as in Comparative Example 2, except that 28.2 g of NMC533 was replaced with the same weight of NMC622. Preparation of negative electrodes in Examples 8 to 14 and Comparative Examples 3 and 4

[0192] The negative electrodes of Examples 8 to 14 and Comparative Examples 3 and 4 were prepared in the same manner as in Example 1. Assembly of coin batteries of Examples 8 to 14 and Comparative Examples 3 and 4

[0193] The coin batteries of Examples 8 to 14 and Comparative Examples 3 and 4 were assembled in the same manner as in Example 1. Electrochemical measurements of Examples 8 to 14 and Comparative Examples 3 to 4

[0194] The electrochemical performance of the coin batteries of Examples 8 to 14 and Comparative Examples 3 and 4 was measured in the same manner as in Example 1, and the test results are shown in Table 1 below. Example 15 A) Preparation of the positive electrode

[0195] A first suspension was prepared by dispersing 0.9 g of a conductive agent (SuperP; available from Timcal Ltd, Bodio, Switzerland) and 6 g of the binder described in Example 1 in 4.9 g of deionized water while stirring with an overhead stirrer (R20, IKA). After addition, the second suspension was further stirred at 1,200 rpm for approximately 30 minutes at 25°C.

[0196] 0.02 g of LiOH was dissolved in 100 g of deionized water to prepare a lithium aqueous solution with a LiOH concentration of 0.01 M at 25°C. After the addition, this aqueous solution was further stirred at 25°C for approximately 5 minutes. Then, 10 g of the aqueous solution was added to the first suspension to prepare a second suspension. After the addition, the second suspension was further stirred at 25°C for approximately 30 minutes.

[0197] Then, 28.2 g of NMC811 (obtained from Shandong Tianqiao New Energy Co., Ltd., China) was added to the second suspension at 25°C while stirring with an overhead stirrer to prepare a third suspension. The third suspension was then degassed under a pressure of approximately 10 kPa for 1 hour. The third suspension was then further stirred at 25°C for approximately 60 minutes at 1,200 rpm to form a homogenized cathode slurry.

[0198] The homogenized cathode slurry was applied to one side of a 14 μm-thick carbon-coated aluminum foil as a current collector using a doctor blade coater with a gap width of 60 μm. The carbon coating thickness was 1 μm. The slurry film coated on the aluminum foil was dried at 50 °C and a conveyor speed of approximately 5 m / min in an electric heating conveyor oven (TH-1A, obtained from Nanjing Dong Gao Drying Equipment Co., Ltd., China) to form a cathode electrode layer. The drying time was approximately 6 minutes. The electrode was then pressed to reduce the thickness of the cathode electrode layer to 35 μm.

[0199] Example 16 A positive electrode was prepared in the same manner as in Example 15, except that 0.12 g of LiOH was dissolved in 100 g of deionized water to form an aqueous solution with a LiOH concentration of 0.05 M, and 10 g of this aqueous solution was added to the first suspension to prepare the second suspension.

[0200] Example 17 A positive electrode was prepared in the same manner as in Example 15, except that 1.20 g of LiOH was dissolved in 100 g of deionized water to form an aqueous solution with a LiOH concentration of 0.5 M, and 10 g of this aqueous solution was added to the first suspension to prepare a second suspension.

[0201] Example 18 A positive electrode was prepared in the same manner as in Example 16, except that the second suspension was further stirred at 25° C. for about 5 minutes.

[0202] Example 19 A positive electrode was prepared in the same manner as in Example 16, except that the second suspension was further stirred at 25° C. for about 60 minutes.

[0203] Example 20 A positive electrode was prepared in the same manner as in Example 16, except that 0.67 g of LiI was dissolved in 100 g of deionized water to form an aqueous solution at 25° C. with a LiI concentration of 0.05 M.

[0204] Example 21 A positive electrode was prepared in the same manner as in Example 16, except that 0.33 g of LiAc was dissolved in 100 g of deionized water to prepare an aqueous solution of LiAc at 25° C. with a concentration of 0.05 M.

[0205] Example 22 A positive electrode was prepared in the same manner as in Example 16, except that 0.34 g of LiNO3 was dissolved in 100 g of deionized water to prepare an aqueous solution of LiNO3 at 25°C with a concentration of 0.05 M. Comparative Example 5

[0206] A positive electrode slurry was prepared by dispersing 28.2 g of NMC811 (obtained from Shandong Tianqiao New Energy Co., Ltd., China), 0.9 g of a conductive agent (SuperP; obtained from Timcal Ltd, Bodio, Switzerland), and 10 g of PAM binder (15% solids) in deionized water while stirring with an overhead stirrer. The slurry was degassed for 1 hour under a pressure of approximately 10 kPa. The slurry was then further stirred at 25°C and 1200 rpm for approximately 60 minutes.

[0207] This homogenized cathode slurry was applied to one side of a 14 μm-thick carbon-coated aluminum foil as a current collector using a doctor blade coater with a gap width of 60 μm. The carbon coating thickness was 1 μm. The slurry film coated on the aluminum foil was dried at 50°C and a conveyor speed of approximately 5 m / min in an electric heating conveyor oven (TH-1A, obtained from Nanjing East High-Drying Equipment Co., Ltd., China) to form a cathode electrode layer. The drying time was approximately 6 minutes. The electrode was then pressed to reduce the thickness of the cathode electrode layer to 35 μm. Comparative Example 6

[0208] A positive electrode slurry was prepared by dispersing 28.2 g of NMC811 (obtained from Shandong Tianqiao New Energy Co., Ltd., China), 0.9 g of a conductive agent (SuperP; obtained from Timcal Ltd, Bodio, Switzerland), and PVDF (Solef® 5130, obtained from Solvay SA, Belgium) in 11.9 g of NMP (≥99%, Sigma-Aldrich, USA) with overhead stirring. The slurry was degassed for 1 hour under a pressure of approximately 10 kPa. The slurry was then further stirred at 1,200 rpm for approximately 60 minutes at 25°C.

[0209] This homogenized cathode slurry was applied to one side of a 14 μm-thick carbon-coated aluminum foil as a current collector using a doctor blade coater with a gap width of 60 μm. The carbon coating thickness was 1 μm. The coated slurry film on the aluminum foil was dried at 50°C and a conveyor speed of approximately 5 m / min in an electric heating conveyor oven (TH-1A, obtained from Nanjing East High-Drying Equipment Co., Ltd., China) to form a cathode electrode layer. The drying time was approximately 6 minutes. The electrode was then pressed to reduce the thickness of the cathode electrode layer to 35 μm. Preparation of negative electrodes in Examples 15 to 22 and Comparative Examples 5 to 6

[0210] The negative electrodes of Examples 15 to 22 and Comparative Examples 5 to 6 were prepared in the same manner as in Example 1. Assembly of coin cells in Examples 15 to 22 and Comparative Examples 5 and 6

[0211] The coin batteries of Examples 15 to 22 and Comparative Examples 5 and 6 were assembled in the same manner as in Example 1. Electrochemical measurements of Examples 15 to 22 and Comparative Examples 5 to 6

[0212] The electrochemical performance of the coin batteries of Examples 15 to 22 and Comparative Examples 5 and 6 was measured in the same manner as in Example 1, and the test results are shown in Table 2 below.

[0213] Example 23 A positive electrode was prepared in the same manner as in Example 15, except that 28.2 g of NMC811 was replaced with the same weight of NCA.

[0214] Example 24 A positive electrode was prepared in the same manner as in Example 23, except that 0.12 g of LiOH was dissolved in 100 g of deionized water to form an aqueous solution, and a third suspension having a LiOH concentration of 0.05 M was prepared, and 10 g of the aqueous solution was added to the first suspension to prepare a second suspension.

[0215] Example 25 A positive electrode was prepared in the same manner as in Example 23, except that 1.20 g of LiOH was dissolved in 100 g of deionized water to form an aqueous solution, which was used as a third suspension with a LiOH concentration of 0.5 M, and 10 g of the aqueous solution was added to the first suspension to prepare a second suspension.

[0216] Example 26 A positive electrode was prepared in the same manner as in Example 24, except that the second suspension was further stirred at 25° C. for about 5 minutes.

[0217] Example 27 A positive electrode was prepared in the same manner as in Example 24, except that the second suspension was further stirred at 25° C. for about 60 minutes.

[0218] Example 28 A positive electrode was prepared in the same manner as in Example 24, except that 0.67 g of LiI was dissolved in 100 g of deionized water to form an aqueous solution at 25° C. with a LiI concentration of 0.014 M.

[0219] Example 29 A positive electrode was prepared in the same manner as in Example 24, except that 0.33 g of LiAc was dissolved in 100 g of deionized water to form an aqueous solution at 25° C. with a LiAc concentration of 0.014 M.

[0220] Example 30 A positive electrode was prepared in the same manner as in Example 2, except that a copolymer of acrylamide and acrylonitrile (solid content: 15%) was used as the binder.

[0221] Example 31 A positive electrode was produced in the same manner as in Example 2, except that a copolymer of acrylamide and methacrylic acid (solid content 15%) was used as the binder.

[0222] Example 32 : NMC532 as core and Li0.95Ni as shell 0.53 Mn 0.29 Co 0.15 Al 0.03 A positive electrode was fabricated in the same manner as in Example 2, except that a core-shell cathode active material (CS) containing O was used. The cathode active material had a particle size D50 of approximately 35 μm. The shell thickness was approximately 3 μm. Comparative Example 7

[0223] A positive electrode was produced in the same manner as in Comparative Example 5, except that 28.2 g of NMC811 was replaced with the same weight of NCA. Comparative Example 8

[0224] A positive electrode was produced in the same manner as in Comparative Example 6, except that 28.2 g of NMC811 was replaced with the same weight of NCA. Preparation of negative electrodes in Examples 23 to 32 and Comparative Examples 7 and 8

[0225] In the same manner as in Example 1, negative electrodes of Examples 23 to 32 and Comparative Examples 7 and 8 were produced. Assembly of coin batteries of Examples 23 to 32 and Comparative Examples 7 and 8

[0226] The coin batteries of Examples 23 to 32 and Comparative Examples 7 and 8 were assembled in the same manner as in Example 1. Electrochemical measurements of Examples 23 to 32 and Comparative Examples 7 to 8

[0227] The electrochemical performance of the coin batteries of Examples 23 to 32 and Comparative Examples 7 and 8 was measured in the same manner as in Example 1, and the test results are shown in Table 2 below. [Table 1] [Table 2] [Table 3a] [Table 3b] The inventions described in the original claims of this application are set forth below. [1] A cathode for a secondary battery comprising a current collector and an electrode layer coated on the current collector, the electrode layer including a cathode active material, a binder material, and a lithium compound. [2] The cathode according to [1], wherein the lithium loss of the cathode active material is suppressed at a rate of about 1 percent to about 15 percent. [3] [1] The cathode of [1], wherein the lithium compound comprises one or more of lithium borate, lithium bromide, lithium chloride, lithium bicarbonate, lithium hydroxide, lithium iodide, lithium nitrate, lithium sulfate, lithium acetate, lithium lactate, lithium citrate, lithium succinate, or a combination thereof. [4] The cathode active material is Li 1+x Ni a Mn b Co c Al (1-a-b-c) O 2 , LiNi 0.33 Mn 0.33 Co 0.33 O 2 , LiNi 0.4 Mn 0.4 Co 0.2 O 2 , LiNi 0.5 Mn 0.3 Co 0.2 O 2 , LiNi 0.6 Mn 0.2 Co 0.2 O 2 , LiNi 0.7 Mn 0.15 Co 0.15 O 2 , LiNi 0.8 Mn 0.1 Co 0.1 O 2 , LiNi 0.92 Mn 0.04 Co0.04 O 2 , LiNi 0.8 Co 0.15 Al 0.05 O 2 , LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , Li 2 MnO 3 and combinations thereof, wherein -0.2≦x≦0.2, 0≦a<1, 0≦b<1, 0≦c<1, and a+b+c≦1; and the cathode active material is doped with a dopant selected from the group consisting of Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof. [5] The cathode active material includes a core containing the lithium transition metal oxide according to [4] and a lithium transition metal oxide different from the core, and Li 1+x Ni a Mn b Co c Al (1-a-b-c) O 2 , LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , Li 2 MnO 3 , LiCrO 2 , Li 4 Ti 5 O 12 , LiV 2 O 5 , LiTiS 2 , LiMoS 2 and a shell, wherein -0.2≦x≦0.2, 0≦a<1, 0≦b<1, 0≦c<1, and a+b+c≦1, and wherein each of the core and shell is independently doped with a dopant selected from the group consisting of Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof. [6] The cathode according to [1], wherein the electrode layer further comprises a conductive agent selected from the group consisting of carbon, carbon black, graphite, expanded graphite, graphene, graphene nanoplatelets, carbon fiber, carbon nanofiber, graphitized carbon flakes, carbon tubes, carbon nanotubes, activated carbon, mesoporous carbon, and combinations thereof. [7] The cathode according to [1], wherein the binder material is a polymer containing one or more functional groups including halogen, O, N, S, or a combination thereof. [8] [7] The cathode according to [7], wherein the one or more functional groups are selected from the group consisting of alkoxy, aryloxy, nitro, thiol, thioether, imine, cyano, amide, amino (primary, secondary, or tertiary), carboxyl, ketone, aldehyde, ester, hydroxyl, and combinations thereof. [9] 10. The cathode of claim 1, wherein the electrode layer has a lithium ion content of between 0.01 percent and 20 percent, based on the total weight of the electrode layer.

[10] A cathode slurry for a secondary battery comprising a cathode active material, a binder, and a lithium compound.

[11]

[10] The cathode slurry according to

[10] , wherein the lithium compound is one or more of lithium borate, lithium bromide, lithium chloride, lithium bicarbonate, lithium hydroxide, lithium iodide, lithium nitrate, lithium sulfate, lithium acetate, lithium lactate, lithium citrate, lithium succinate, or a combination thereof.

[12] The cathode active material is Li 1+x Ni a Mn b Co c Al (1-a-b-c) O 2 , LiNi 0.33 Mn 0.33 Co 0.33 O 2 , LiNi 0.4 Mn 0.4 Co 0.2 O 2 , LiNi 0.5 Mn 0.3 Co 0.2 O 2 , LiNi 0.6 Mn 0.2 Co 0.2 O 2 , LiNi 0.7 Mn 0.15 Co 0.15 O 2 , LiNi 0.8 Mn 0.1 Co 0.1 O 2 , LiNi 0.92 Mn 0.04 Co 0.04 O 2 , LiNi 0.8 Co 0.15 Al 0.05 O 2 , LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , Li 2 MnO 3 and combinations thereof, wherein -0.2≦x≦0.2, 0≦a<1, 0≦b<1, 0≦c<1, and a+b+c≦1; and the cathode active material is doped with a dopant selected from the group consisting of Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof.

[13] The cathode active material includes a core containing the lithium transition metal oxide according to

[12] and a lithium transition metal oxide different from the core, and Li 1+x Ni a Mn b Co c Al (1-a-b-c) O 2 , LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , Li 2 MnO 3 , LiCrO 2 , Li 4 Ti 5 O 12 , LiV 2 O 5 , LiTiS 2 , LiMoS 2 and a shell, wherein -0.2≦x≦0.2, 0≦a<1, 0≦b<1, 0≦c<1, and a+b+c≦1, and wherein each of the core and shell is independently doped with a dopant selected from the group consisting of Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof.

[14]

[10] The cathode slurry according to

[10] , further comprising a conductive agent selected from the group consisting of carbon, carbon black, graphite, expanded graphite, graphene, graphene nanoplatelets, carbon fiber, carbon nanofiber, graphitized carbon flakes, carbon tubes, carbon nanotubes, activated carbon, mesoporous carbon, and combinations thereof.

[15]

[14] The cathode slurry according to

[14] , wherein the binder material is a polymer containing one or more functional groups including halogen, O, N, S, or a combination thereof.

[16]

[14] The cathode slurry according to

[13] , wherein the one or more functional groups are selected from the group consisting of alkoxy, aryloxy, nitro, thiol, thioether, imine, cyano, amide, amino (primary, secondary, or tertiary), carboxyl, ketone, aldehyde, ester, hydroxyl, and combinations thereof.

[17] The cathode slurry according to

[10] , wherein the concentration of lithium ions in the cathode slurry is about 0.0001 M to about 1 M.

[18]

[10] The cathode slurry according to

[10] , wherein the cathode slurry has a pH of about 8 to about 14, or about 11 to about 13.

[19] The cathode slurry according to

[10] , wherein lithium loss in the cathode active material is suppressed at a rate of about 1 percent to about 15 percent.

Claims

1. 1. A cathode for a lithium-ion secondary battery, comprising: a current collector; and an electrode layer coated on the current collector, the electrode layer comprising a cathode active material, a binder material, and a lithium compound, the lithium compound comprising one or more of lithium borate, lithium bromide, lithium chloride, lithium bicarbonate, lithium hydroxide, lithium iodide, lithium nitrate, lithium sulfate, lithium acetate, lithium lactate, lithium citrate, lithium succinate, or a combination thereof; the binder material is a polymer comprising one or more monomers selected from the group consisting of acrylamide, methacrylamide, and a combination thereof; the binder material is not a fluorine-containing polymer; and the proportion of the lithium compound in the electrode layer is less than 0.394% by weight, based on the total weight of the electrode layer.

2. The cathode active material is Li １+ｘ Ni ａ Mn ｂ Co c Al (１-a-b-c) O ２ , LiNi ０.３３ Mn ０.３３ Co ０.３３ O ２ , LiNi ０.４ Mn ０.４ Co ０.２ O ２ , LiNi ０.５ Mn ０.３ Co ０.２ O ２ , LiNi ０.６ Mn ０.２ Co ０.２ O ２ , LiNi ０.７ Mn ０.１５ Co ０.１５ O ２ , LiNi ０.８ Mn ０.１ Co ０.１ O ２ , LiNi ０.９２ Mn ０.０４ Co ０.０４ O ２ , LiNi ０.８ Co ０.１５ Al ０.０５ O ２ , LiCoO ２ , LiNiO ２ , LiMnO ２ , LiMn ２ O ４ , Li ２ MnO ３ , and combinations thereof, wherein -0.2≦x≦0.2, 0≦a<1, 0≦b<1, 0≦c<1, and a+b+c≦1; and the cathode active material is doped with a dopant selected from the group consisting of Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof.

3. The cathode active material includes a core containing the lithium transition metal oxide of claim 2 and a lithium transition metal oxide different from the core, and Li １+ｘ Ni ａ Mn ｂ Co c Al (１-a-b-c) O ２ , LiCoO ２ , LiNiO ２ , LiMnO ２ , LiMn ２ O ４ , Li ２ MnO ３ , LiCrO ２ , Li ４ Ti ５ O １２ , LiV ２ O ５ , LiTiS ２ , LiMoS ２ and a shell, wherein -0.2≦x≦0.2, 0≦a<1, 0≦b<1, 0≦c<1, and a+b+c≦1, and wherein each of the core and shell is independently doped with a dopant selected from the group consisting of Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof.

4. 10. The cathode of claim 1, wherein the electrode layer further comprises a conductive agent selected from the group consisting of carbon, carbon black, graphite, expanded graphite, graphene, graphene nanoplatelets, carbon fibers, carbon nanofibers, graphitized carbon flakes, carbon tubes, carbon nanotubes, activated carbon, mesoporous carbon, and combinations thereof.

5. 10. The cathode of claim 1, wherein the binder material is a polymer containing one or more functional groups including halogen, O, N, S, or a combination thereof.

6. 1. A cathode slurry for a lithium-ion secondary battery, comprising: a cathode active material, a binder material, a lithium compound, and water; wherein the lithium compound comprises one or more of lithium borate, lithium bromide, lithium chloride, lithium bicarbonate, lithium hydroxide, lithium iodide, lithium nitrate, lithium sulfate, lithium acetate, lithium lactate, lithium citrate, lithium succinate, or a combination thereof; the binder material is a polymer comprising one or more monomers selected from the group consisting of acrylamide, methacrylamide, and a combination thereof; the binder material is not a fluorine-containing polymer; and a proportion of the lithium compound in a solid portion of the cathode slurry is less than 0.394% by weight, based on a total weight of the solid portion of the cathode slurry.

7. The cathode active material is Li １+ｘ Ni ａ Mn ｂ Co c Al (１-a-b-c) O ２ , LiNi ０.３３ Mn ０.３３ Co ０.３３ O ２ , LiNi ０.４ Mn ０.４ Co ０.２ O ２ , LiNi ０.５ Mn ０.３ Co ０.２ O ２ , LiNi ０.６ Mn ０.２ Co ０.２ O ２ , LiNi ０.７ Mn ０.１５ Co ０.１５ O ２ , LiNi ０.８ Mn ０.１ Co ０.１ O ２ , LiNi ０.９２ Mn ０.０４ Co ０.０４ O ２ , LiNi ０.８ Co ０.１５ Al ０.０５ O ２ , LiCoO ２ , LiNiO ２ , LiMnO ２ , LiMn ２ O ４ , Li ２ MnO ３ 7. The cathode slurry of claim 6, wherein the cathode active material is selected from the group consisting of Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof, and wherein -0.2≦x≦0.2, 0≦a<1, 0≦b<1, 0≦c<1, and a+b+c≦1; and the cathode active material is doped with a dopant selected from the group consisting of Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof.

8. The cathode active material includes a core containing the lithium transition metal oxide of claim 7 and a lithium transition metal oxide different from the core, and Li １+ｘ Ni ａ Mn ｂ Co c Al (１-a-b-c) O ２ , LiCoO ２ , LiNiO ２ , LiMnO ２ , LiMn ２ O ４ , Li ２ MnO ３ , LiCrO ２ , Li ４ Ti ５ O １２ , LiV ２ O ５ , LiTiS ２ , LiMoS ２ and a shell wherein -0.2≦x≦0.2, 0≦a<1, 0≦b<1, 0≦c<1, and a+b+c≦1, wherein each of the core and shell is independently doped with a dopant selected from the group consisting of Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof.

9. 7. The cathode slurry of claim 6, further comprising a conductive agent selected from the group consisting of carbon, carbon black, graphite, expanded graphite, graphene, graphene nanoplatelets, carbon fibers, carbon nanofibers, graphitized carbon flakes, carbon tubes, carbon nanotubes, activated carbon, mesoporous carbon, and combinations thereof.

10. 7. The cathode slurry according to claim 6, wherein the concentration of lithium ions in the cathode slurry is 0.0001M to 1M.

11. 7. The cathode slurry of claim 6, wherein the cathode slurry has a pH of from 8 to 14, or from 11 to 13.

12. 7. The cathode slurry of claim 6, wherein lithium loss of the cathode active material is inhibited by 1 percent to 15 percent.

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