Electrode material, electrode, battery and preparation method of electrode material

Abstract

The invention provides an electrode material, an electrode, a battery and a preparation method of the electrode material. The electrode material comprises an active particle and a coating layer partially or completely covering the surface of the active particle. The coating layer comprises 5 to 70 parts by weight of a conduction additive; and 30 to 95 parts by weight of a first polymer, wherein the total weight of the first polymer and the conductive additive is 100 parts by weight. The first polymer is a product of a polymerization reaction of a compound having two acrylate groups and an ethylene / vinyl acetate copolymer, the compound having two acrylate groups has a structure # imgabs0 # as shown in formula (I), and A1, R1 and R2 are described in the specification.

Description

Technical Field

[0001] The present invention relates to an electrode material, an electrode, a battery, and a method for preparing the electrode material. Background Art

[0002] Lithium batteries have become the mainstream of commercial batteries and are striving to be thinner, shorter, and lighter, with higher energy density, longer lifespan, and greater safety.

[0003] One of the key steps in manufacturing lithium batteries is the formation of electrodes. The formation steps of traditional electrodes include electrode slurry preparation, electrode coating, drying, and pressing. In the electrode slurry preparation step, an electrode active material, a binder (used to bond powder-like electrode active materials to each other and fix them to the current collector), and a solvent (used to disperse the powder-like electrode active material and enable sufficient contact between the binder and the powder-like material) are mixed to prepare a flowable electrode slurry. After the electrode slurry is prepared, it is coated onto the current collector, the solvent contained in the electrode slurry is removed, and the coating is pressed to a predetermined thickness. However, when the solvent in the electrode slurry is removed using the drying step, defects such as pinholes or cracks may occur in the pre-formed electrode active layer. Additionally, due to differences in the solvent evaporation rate, the drying degree inside and outside the coating formed by the electrode slurry may vary, resulting in gaps formed within the electrode and reducing the quality of the resulting electrode.

[0004] To address the problems caused by traditional electrode preparation using electrode slurries, the industry has proposed a dry electrode process technology that does not use any solvents, including kneading a fluorine-based binder (such as polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF)) with a conductive material and an electrode active material, and forming the electrode using a hot pressing process. However, when using a fluorine-based binder, it needs to be subjected to high-torque fibrillation treatment first. In addition, the dry electrode material containing a fluorine-based binder requires a processing temperature above 200°C during hot rolling lamination. Such a high processing temperature easily causes wrinkles in the formed electrode, reducing the capacity, energy density, and stability of the resulting electrode. Summary of the Invention

[0005] According to an embodiment of the present invention, the present invention provides an electrode material, wherein the electrode material includes an active particle and a coating layer. The coating layer partially or completely covers the surface of the active particle. The coating layer may include 5 to 70 parts by weight of a conductive additive; and 30 to 95 parts by weight of a first polymer, wherein the total weight of the first polymer and the conductive additive is 100 parts by weight. The first polymer is a product of a polymerization reaction of a compound having two acrylate groups and an ethylene / vinyl acetate copolymer, wherein the compound having two acrylate groups has the structure shown in formula (I)

[0006]

[0007] wherein A 1 can be a single bond, oxygen, or -CH=CH-; each R 1 can be independently hydrogen or methyl; each R 2 can be independently hydrogen or methyl; and each R 3 can be independently hydrogen, methyl or ethyl.

[0008] According to an embodiment of the present invention, the present invention provides an electrode, wherein the electrode may include a current collector layer and an active layer. The active layer may be disposed on the current collector layer, wherein the active layer includes the electrode material described in the present invention.

[0009] According to an embodiment of the present invention, the present invention provides a battery, wherein the battery includes a positive electrode, a separator, and a negative electrode, wherein the negative electrode is separated from the positive electrode by the separator, and at least one of the positive electrode and the negative electrode is the electrode described in the present invention.

[0010] According to an embodiment of the present invention, the present invention provides a method for preparing an electrode material for preparing the electrode material described in the present invention. The method for preparing the electrode material includes providing a composition, the composition including the active particle, the conductive additive, and the first polymer; and performing a spray granulation process or a melt mixing on the composition to obtain the electrode material. Description of the Drawings

[0011] Figure 1 is a schematic cross-sectional view of the electrode material according to an embodiment of the present invention.

[0012] Figure 2 is a schematic cross-sectional view of the electrode material according to another embodiment of the present invention.

[0013] Figure 3 is a step flow chart of the method for preparing the electrode material according to an embodiment of the present invention.

[0014] Figure 4 Schematic diagram of the electrode according to an embodiment of the present invention.

[0015] Figure 5 Schematic diagram of the electrode according to another embodiment of the present invention.

[0016] Figure 6 Schematic diagram of the battery according to an embodiment of the present invention.

[0017] Figure 7 Scanning electron microscope (SEM) spectrum of the electrode material (1).

[0018] Figure 8 Scanning electron microscope (SEM) spectrum of the electrode material (8).

[0019] Figure 9 Transmission electron microscopy (TEM) spectrum of the electrode material (1).

[0020] Wherein, reference numerals:

[0021] 10 Electrode material;

[0022] 12 Active particles;

[0023] 14 Coating layer;

[0024] 100 Preparation method;

[0025] 102, 104 Steps;

[0026] 200 Electrode;

[0027] 202 Current collector layer;

[0028] 204 Active layer / First active layer;

[0029] 206 Second active layer;

[0030] 300 Battery;

[0031] 302 Positive electrode;

[0032] 304 Separator membrane;

[0033] 306 Negative electrode; and

[0034] 308 Electrolyte. Detailed implementation manners

[0035] The following provides a detailed description of the electrode material, electrode, battery, and preparation method of the electrode material according to the present invention. It should be understood that the following description provides many different embodiments for implementing different aspects of the present invention. The specific components and arrangements described below are only for a simple description of the present invention. Of course, these are only for illustration and not for limiting the present invention. In the present invention, the term "about" means that the specified quantity can be increased or decreased by an amount that can be recognized by those skilled in the art as being of a general and reasonable magnitude.

[0036] The ordinal numbers used in the specification and claims, such as "first", "second", "third", etc., are used to modify the components of the claims. They do not themselves imply or represent that there is any previous ordinal number for the claimed component, nor do they represent the order of one claimed component and another claimed component, or the order in the manufacturing method. The use of these ordinal numbers is only to clearly distinguish one claimed component with a certain name from another claimed component with the same name.

[0037] It must be understood that the components specifically described or illustrated may exist in various forms known to those skilled in the art. In addition, when a layer is "on" another layer or substrate, it may mean "directly" on another layer or substrate, or it may mean that a layer is on another layer or substrate, or there are other layers interposed between other layers or substrates.

[0038] In the drawings, the shape or thickness of the embodiments may be enlarged for simplicity or convenience of labeling. Furthermore, the parts of each component in the drawings will be described separately. It should be noted that the components not shown or described in the drawings are in forms known to those with common general knowledge in the technical field. In addition, the specific embodiments are only for disclosing the specific ways of using the present invention, and they are not used to limit the present invention.

[0039] The present invention provides an electrode material, which is applicable to an electrode process (such as a dry electrode process) to form an electrode applied to a battery, such as a positive electrode or a negative electrode of a lithium battery. The electrode material of the present invention includes an active particle, and a cladding layer partially or completely covering the surface of the active particle. The cladding layer includes a first polymer and a conductive additive. It should be noted that due to the appropriate rheology, adhesiveness, and melting point of the first polymer, the conductive additive can be uniformly dispersed in the cladding layer through a spray granulation process or a melt mixing process, and the cladding layer can cover and bond to the surface of the active particle to obtain the electrode material of the present invention. In addition, through the specific composition and structure of the electrode material of the present invention, the electrode material of the present invention can form an active layer composed of the electrode material on the surface of the current collector layer at a relatively low operating temperature (below 200°C, even below 150°C) using a dry process (such as a hot pressing process) without being prepared into an electrode paste (that is, without dispersing the electrode material of the present invention in a solvent and without adding an additional binder to mix with the electrode material of the present invention). In this way, the formed active layer not only has better mechanical strength and good adhesiveness (between the active layer and the current collector layer), but also can improve the mass loading, compacted density, and stability of the active layer of the obtained electrode (that is, overcome the problems of uneven distribution and poor adhesion caused by the wet electrode process), thereby improving the capacity and energy density of the battery, and increasing the life cycle, charge / discharge performance, and C-rate discharge ability during high-temperature / high-voltage operation.

[0040] The present invention provides an electrode material for forming an electrode (such as a negative electrode or a positive electrode) applied to a battery (such as a lithium-ion battery) or a lithium secondary electrode. Please refer to Figure 1 , which is a schematic cross-sectional view of the electrode material according to an embodiment of the present invention. The electrode material 10 may include an active particle 12 and a cladding layer 14. According to an embodiment of the present invention, the cladding layer 14 may be disposed on the surface of the active particle 12 to completely cover the surface of the active particle, as Figure 1 shown. In other words, the electrode material 10 has a core-shell structure, which is composed of a core and a shell layer covering the core, where the core is the active particle 12 and the shell layer is the cladding layer 14.

[0041] According to an embodiment of the present invention, the particle size of the active particle 12 (e.g., the maximum distance between any two points on the surface of the active particle) can be about 50 nm to 100 μm, such as about 60 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, or 80 μm. According to an embodiment of the present invention, the active particle can have a circular, oval, polygonal, or approximately circular cross-section. According to an embodiment of the present invention, the thickness of the coating layer 14 (e.g., the average thickness, or the shortest distance from the outer surface of the coating layer 14 to the surface of the active particle 12) can be 10 nm to 5 μm, such as about 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 2 μm, 3 μm, or 4 μm. The particle size of the active particle and the thickness of the coating layer can be measured using an electron microscope.

[0042] According to an embodiment of the present invention, the electrode material of the present invention has a functional coating layer (as a protective layer and a conductive layer) on the surface of the active particle, and is formed by a spray granulation process or a melt kneading process, which can reduce the volume swelling of the electrode prepared using the electrode material, reduce water absorption, increase stability, inhibit the dissolution of the metal components (such as manganese, iron, or nickel) of the active particle, and improve the ion / electron conduction efficiency.

[0043] According to an embodiment of the present invention, the coating layer 14 (cladding layer) can be disposed on the surface of the active particle 12 to partially or completely cover the surface of the active particle, as Figure 2 shown. Here, the coating layer 14 partially covering the surface of the active particle means that 30% to 100% (such as 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 99.99%) of the surface of the active particle is covered by the coating layer 14.

[0044] According to an embodiment of the present invention, the weight ratio of the coating layer to the active particles may be about 3:97 to 10:90, such as 4:96, 5:95, 6:94, 7:93, 8:92, 9:91. If the weight ratio of the coating layer to the active particles is too low, it is likely that the surface area of the active particles covered by the coating layer is too low, or the thickness difference of the coating layer is too large, resulting in a decrease in the structural toughness, stability, adhesiveness of the electrode material, and the electrical properties of the subsequently formed electrode. If the weight ratio of the coating layer to the active particles is too high, both the mass loading and the compacted density of the active layer will decrease, and at the same time, it is also likely to cause an increase in the impedance of the subsequently formed electrode, as well as a decrease in electrical properties, capacity, and energy density.

[0045] According to an embodiment of the present invention, the electrode material may have at least one coating layer as described in the present invention. For example, the electrode material is composed of active particles, a first coating layer, and a second coating layer, wherein the first coating layer covers the active particles and the second coating layer covers the first coating layer. Among them, the material components and compositions of the first coating layer and the second coating layer may be the same or different. According to some embodiments, the electrode material may further include other coating layers, and the other coating layers contain, for example, electrolyte materials.

[0046] According to an embodiment of the present invention, the active particles may be a positive electrode active material or a negative electrode active material, which is selected according to the electrical properties of the electrode to be formed. In other words, the electrode material described in the present invention may be a positive electrode active material or a negative electrode active material.

[0047] According to an embodiment of the present invention, if the active particles are positive electrode active materials, the active particles may be sulfur, organic sulfides, sulfur-carbon composites, metal-containing lithium oxides, metal-containing lithium sulfides, metal-containing lithium selenides, metal-containing lithium tellurides, metal-containing lithium silicides, metal-containing lithium borides, metal-containing lithium phosphates, or combinations thereof, wherein the metal may be selected from at least one of the group consisting of aluminum, vanadium, titanium, chromium, copper, molybdenum, niobium, iron, nickel, cobalt, and manganese. For example, the active particles may be lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium cobalt manganese oxide, lithium nickel cobalt oxide, lithium nickel manganese oxide, lithium nickel manganese cobalt oxide, lithium chromium-manganese oxide, lithium nickel vanadium oxide, lithium manganese nickel oxide, lithium cobalt vanadium oxide, lithium nickel cobalt aluminum oxide (NMC), lithium iron phosphate (LFP), lithium manganese iron phosphate (LMFP), or combinations thereof.

[0048] According to an embodiment of the present invention, if the active particles are negative electrode active materials, the active particles can be silicon, silicon carbide, silicon-containing oxide, titanium-containing oxide, tin, tin-containing compounds, silicon alloys, carbon materials, lithium, lithium alloys, lithium carbide containing metal, lithium nitride containing metal, or a combination of the above, wherein the metal is selected from at least one of the group consisting of aluminum, chromium, copper, iron, nickel, cobalt, and manganese. According to an embodiment of the present invention, the carbon material can include metastable phase spherical carbon (MCMB), vapor grown carbon fiber (VGCF), carbon nanotube (CNT), coke, carbon black, graphite, graphene, fluorocarbons, acetylene black, carbon fiber, vitreous carbon, or a combination of the above. According to an embodiment of the present invention, the carbon nanotube can be a single-walled carbon nanotube (SWCNT), a double-walled carbon nanotube (DWCNT), a multi-walled carbon nanotube (MWCNT), or a combination of the above. According to an embodiment of the present invention, the silicon-containing oxide can be, for example, silicon oxycarbide.According to an embodiment of the present invention, the lithium alloy or metal-containing lithium nitride may be an aluminum-containing lithium alloy, a magnesium-containing lithium alloy, a zinc-containing lithium alloy, a bismuth-containing lithium alloy, a cadmium-containing lithium alloy, an antimony-containing lithium alloy, a silicon-containing lithium alloy, a lead-containing lithium alloy, a tin-containing lithium alloy, a lithium iron nitride, a lithium cobalt nitride, or a lithium copper nitride.

[0049] According to an embodiment of the present invention, the coating layer may include 5 to 70 parts by weight (such as 8 parts by weight, 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 50 parts by weight, 55 parts by weight, 60 parts by weight, or 65 parts by weight) of a conductive additive, and 30 to 95 parts by weight (such as 32 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 50 parts by weight, 55 parts by weight, 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, 80 parts by weight, 85 parts by weight, or 90 parts by weight) of a first polymer. Here, the total weight of the first polymer and the conductive additive is 100 parts by weight. If the addition amount of the first polymer is too low, it is easy to reduce the structural toughness, stability, adhesiveness, and electrode free-standing of the electrode material. If the addition amount of the first polymer is too high, it is easy to cause a decrease in the mass loading, compacted density, electrical properties, capacity, and energy density of the active layer of the subsequently formed electrode.

[0050] According to an embodiment of the present invention, the conductive additive is uniformly dispersed in the first polymer. According to an embodiment of the present invention, the conductive additive may be a conductive additive, an ion-conductive additive, or a combination of the above. For example, the conductive additive may be a combination of a conductive additive and an ion-conductive additive. In the present invention, a conductive additive refers to an additive having conductive properties. The conductive additive described in the present invention may also have ion-conductive properties at the same time. If its conductive properties are superior to its ion-conductive properties (or those skilled in the art tend to consider the material as a conductive material), it is still referred to as a conductive additive in the present invention. On the other hand, in the present invention, an ion-conductive additive refers to an additive having ion-conductive properties. The ion-conductive additive described in the present invention may also have conductive properties at the same time. If its ion-conductive properties are superior to its conductive properties (or those skilled in the art tend to consider the material as an ion-conductive material), it is still referred to as an ion-conductive additive in the present invention.

[0051] According to an embodiment of the present invention, the conductive additive may be a conductive polymer material, a conductive inorganic material, or a combination of the above. According to an embodiment of the present invention, the conductivity of the conductive additive may be greater than or equal to 10 S / cm (for example, 15 S / cm, 20 S / cm, 25 S / cm, 30 S / cm, 35 S / cm, 40 S / cm, 45 S / cm, 50 S / cm, 55 S / cm, 60 S / cm, 65 S / cm, 70 S / cm, 75 S / cm, or 80 S / cm). According to an embodiment of the present invention, the conductive polymer material may be polyacetylene, polydiacetylene, polyaniline, polypyrrole, polythiophene, or a combination of the above. There is no particular limitation on the weight average molecular weight of the conductive polymer material described in the present invention, and those with common general knowledge in the technical field can adjust it according to actual needs. According to an embodiment of the present invention, the weight average molecular weight (Mw) of the conductive polymer material may be about 10,000 (g / mol) to 5,000,000 (g / mol), for example, about 30,000 (g / mol), 50,000 (g / mol), 80,000 (g / mol), 100,000 (g / mol), 200,000 (g / mol), 300,000 (g / mol), 400,000 (g / mol), 500,000 (g / mol), 800,000 (g / mol), 1,000,000 (g / mol), 2,000,000 (g / mol), 3,000,000 (g / mol), or 4,000,000 (g / mol). The weight average molecular weight (Mw) of the conductive polymer material can be measured by gel permeation chromatography (GPC) (using polystyrene as a standard to make a calibration curve).

[0052] According to an embodiment of the present invention, the conductive inorganic material may be conductive carbon black, conductive graphite, fluorocarbon, reduced graphene oxide, nitrogen-doped graphite, nitrogen-doped graphene, carbon fiber, carbon nanotube, or a combination of the above. According to an embodiment of the present invention, the conductive inorganic material may be granular. According to an embodiment of the present invention, the value of the particle size distribution D90 of the conductive inorganic material may be from about 0.1 nm to 200 nm, such as about 0.2 nm, 0.5 nm, 1 nm, 2 nm, 5 nm, 10 nm, 20 nm, 30 nm, 50 nm, 80 nm, 100 nm, 120 nm, 150 nm, 170 nm, or 190 nm. The particle size distribution D90 represents that the particle size of 90% of the total volume of the conductive inorganic material is less than the value defined by the D90. According to an embodiment of the present invention, the particle size distribution D90 is measured according to the method specified in ISO 13322-1:2004.

[0053] According to an embodiment of the present invention, the ionic conductivity of the ionic additive may be 1×10 -6 S / cm to 9×10 -3 S / cm (such as 2×10 -6 S / cm, 5×10 -6 S / cm, 8×10 -6 S / cm, 1×10 -5 S / cm, 2×10 -5 S / cm, 5×10 -5 S / cm, 8×10 -5 S / cm, 1×10 -4 S / cm, 2×10 -4 S / cm, 5×10 -4 S / cm, 8×10 -4 S / cm, 1×10 -3 S / cm, 2×10 -3 S / cm, 5×10 -3 S / cm, or 8×10 -3S / cm). According to an embodiment of the present invention, the ionic conductive additive may be a hyperbranched polymer, an ethyl cellulose resin, a lithium-ion-containing polythiophene polymer, a polymer having a lithium sulfonate group, a polymer having an organosilicon group, or a combination of the above.

[0054] According to an embodiment of the present invention, the hyperbranched polymer of the present invention may be a nitrogen-containing hyperbranched polymer. The hyperbranched polymer may be polymerized from imide compounds. In addition, according to an embodiment of the present invention, the hyperbranched polymer may be copolymerized from imide compounds and barbituric acid. The imide compounds may be bismaleimide (such as N,N'-bismaleimide-4,4'-diphenylmethane), maleimide (such as benzylmethane maleimide), or a combination of the above. For example, the nitrogen-containing hyperbranched polymer may be a copolymer of bismaleimide and barbituric acid, or a copolymer of maleimide oligomer and barbituric acid. According to an embodiment of the present invention, the hyperbranched polymer and its preparation may refer to Chinese Patent CN112993383B. According to an embodiment of the present invention, the lithium-ion-containing polythiophene polymer may have a repeating unit with the structure of where R aIt is an alkyl group with 6 to 30 carbon atoms. According to an embodiment of the present invention, the preparation of the lithium-ion-containing thiophene polymer can be referred to US Patent US11539046B2. According to an embodiment of the present invention, the polymer having a lithium sulfonate group can be poly(2-acrylamido-2-methyl-1-propanesulfonic acid lithium salt), poly(styrenesulfonic acid lithium salt), poly(vinylsulfonic acid lithium salt), poly(perfluorosulfonic acid lithium salt), poly((methyl)acrylic acid lithium salt), poly(lithium maleate), poly(lithium fumarate), poly(lithium itaconate), poly(lithium adipate), acrylonitrile / butadiene / lithium acrylate copolymer, tert-butyl acrylate / ethyl acrylate / lithium methacrylate copolymer, ethylene / lithium acrylate copolymer, and methyl methacrylate / lithium methacrylate copolymer, or a combination of the above. According to an embodiment of the present invention, the polymer having an organosilicon group can be a polyester-modified polysiloxane, a polyester polysiloxane graft copolymer, or a combination of the above. According to an embodiment of the present invention, the preparation of the polymer having an organosilicon group can be referred to Chinese Patent CN103187588B.

[0055] The weight average molecular weight of the ion-conductive polymer (i.e., highly branched polymer, ethyl cellulose resin, lithium-ion-containing thiophene polymer, polymer having a lithium sulfonate functional group, or polymer having an organosilicon group) described in the present invention is not particularly limited, and those with common general knowledge in the technical field can adjust it according to actual needs on the premise of maintaining the ionic conductivity. According to an embodiment of the present invention, the weight average molecular weight (Mw) of the ion-conductive polymer can be about 10,000 (g / mol) to 5,000,000 (g / mol), such as about 30,000 (g / mol), 50,000 (g / mol), 80,000 (g / mol), 100,000 (g / mol), 200,000 (g / mol), 300,000 (g / mol), 400,000 (g / mol), 500,000 (g / mol), 800,000 (g / mol), 1,000,000 (g / mol), 2,000,000 (g / mol), 3,000,000 (g / mol), or 4,000,000 (g / mol). The weight average molecular weight (Mw) of the ion-conductive polymer material can be measured by gel permeation chromatography (GPC) (using polystyrene as a standard to prepare a calibration curve).

[0056] According to an embodiment of the present invention, the coating layer can be composed of the first polymer and the conductive additive. According to other embodiments of the present invention, the coating layer can be substantially composed of the first polymer and the conductive additive, that is, the total weight of the first polymer and the conductive additive accounts for more than 95 wt% of the weight of the coating layer. If the coating layer contains other components, the other components can be additives conventionally used to form electrodes. According to an embodiment of the present invention, the electrode material described in the present invention does not contain a fluorine-containing polymer. In other words, the active particles do not contain a fluorine-containing polymer, and the coating layer also does not contain a fluorine-containing polymer.

[0057] According to an embodiment of the present invention, in addition to the first polymer and the conductive additive, the coating layer may further contain 0.1 to 30 parts by weight (such as 0.5 part by weight, 1 part by weight, 2 parts by weight, 3 parts by weight, 5 parts by weight, 10 parts by weight, 15 parts by weight, 20 parts by weight, or 25 parts by weight) of a second polymer, based on the total weight of the first polymer and the conductive additive being 100 parts by weight. Herein, the second polymer refers to the polymer added in the spray granulation process or the melt mixing process. Therefore, the second polymer and the first polymer are mixed and independently present in the coating layer (the second polymer does not react with the first polymer). According to an embodiment of the present invention, by adding the second polymer, the mechanical strength, electrolyte erosion resistance, wettability and infiltration to the electrolyte, electrochemical stability, safety protection, and adhesiveness of the coating layer can be adjusted. According to an embodiment of the present invention, the first polymer is different from the second polymer.

[0058] According to an embodiment of the present invention, the weight average molecular weight of the first polymer may be about 12,000 g / mol to 10,000,000 g / mol, such as about 15,000 (g / mol), 20,000 (g / mol), 50,000 (g / mol), 80,000 (g / mol), 100,000 (g / mol), 200,000 (g / mol), 300,000 (g / mol), 400,000 (g / mol), 500,000 (g / mol), 800,000 (g / mol), 1,000,000 (g / mol), 2,000,000 (g / mol), 3,000,000 (g / mol), 4,000,000 (g / mol), 5,000,000 (g / mol), 8,000,000 (g / mol), or 9,000,000 (g / mol). The weight average molecular weight (Mw) of the first polymer can be measured by gel permeation chromatography (GPC) (using polystyrene as the standard to make the calibration curve).

[0059] According to an embodiment of the present invention, the first polymer may be a product of a polymerization reaction between a compound having two acrylate groups and an ethylene / vinyl acetate copolymer.

[0060] According to an embodiment of the present invention, the first polymer is a product of a polymerization reaction of a composition, wherein the composition comprises the compound having two acrylate groups and the ethylene / vinyl acetate copolymer. According to an embodiment of the present invention, in addition to the compound having two acrylate groups and the ethylene / vinyl acetate copolymer, the composition may comprise a solvent, a reaction initiator, or a catalyst. According to some embodiments of the present invention, the only components in the composition that can undergo a polymerization reaction are the compound having two acrylate groups and the ethylene / vinyl acetate copolymer. The solvent, reaction initiator, or catalyst may be a solvent, reaction initiator, or catalyst conventionally used in olefin polymerization. For example, the solvent may be N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), pyrrolidone, N-dodecylpyrrolidone, γ-butyrolactone, 1,2-Propanediol monomethyl ether acetate, toluene, xylene, cyclopentanone, or a combination of the above. According to an embodiment of the present invention, when the composition has the solvent, the solid content of the composition may be about 1 wt% to 90 wt% (e.g., about 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, or 85 wt%). Here, the solid content refers to the weight percentage of all components of the composition except the solvent, and is based on the total weight of the composition. According to an embodiment of the present invention, the composition consists of the compound having two acrylate groups, the ethylene / vinyl acetate copolymer, a solvent, and a reaction initiator.

[0061] According to an embodiment of the present invention, the composition used to prepare the first polymer, in addition to the compound having two acrylate groups and the ethylene / vinyl acetate copolymer, may further comprise a reactive monomer or a third polymer, wherein the reactive monomer or the third polymer may react with the compound having two acrylate groups and / or the ethylene / vinyl acetate. In other words, the components capable of undergoing polymerization reaction in the composition may be the compound having two acrylate groups, the ethylene / vinyl acetate copolymer, and the reactive monomer (or the third polymer). According to an embodiment of the present invention, by adding the reactive monomer and / or the third polymer, the structural toughness, adhesiveness, rheology, electrochemical stability, and processability of the resulting first polymer can be adjusted.

[0062] According to an embodiment of the present invention, the compound having two acrylate groups may have the structure shown in formula (I)

[0063]

[0064] , wherein A 1 may be a single bond, oxygen, or -CH=CH-; each R 1 may independently be hydrogen or methyl; each R 2 may independently be hydrogen or methyl; and each R 3 may independently be hydrogen, methyl, or ethyl.

[0065] According to an embodiment of the present invention, the compound having two acrylate groups may be

[0066]

[0067]

[0068] wherein the definitions of R 1 , R 2 , and R 3 are the same as those described above.

[0069] According to an embodiment of the present invention, the ethylene / vinyl acetate copolymer may have the repeating unit shown in formula (II) and the repeating unit shown in formula (III)

[0070]

[0071] , wherein the number ratio of the repeating unit represented by the formula (II) and the repeating unit represented by the formula (III) is from 1:1,250 to 300:1, such as 1:1,000, 1:900, 1:800, 1:700, 1:500, 1:250, 1:100, 1:50, 1:25, 1:10, 1:8, 1:5, 1:3, 1:2, 1:1, 2:1, 3:1, 5:1, 8:1, 10:1, 15:1, 20:1, 25:1, 80:1, 100:1, 150:1, 200:1, or 250:1. According to an embodiment of the present invention, the first repeating unit of the ethylene / vinyl acetate copolymer may repeat with the second repeating unit in a random or block manner.

[0072] According to an embodiment of the present invention, the ethylene / vinyl acetate copolymer has n repeating units represented by the formula (II) and m repeating units represented by the formula (III), where n may be from 300 to 300,000 (such as 500, 1,000, 2,000, 3,000, 5,000, 8,000, 10,000, 10,000, 15,000, 20,000, 30,000, 50,000, 70,000, 80,000, 90,000, 100,000, 150,000, 200,000, or 250,000); and m may be from 1,000 to 250,000 (such as 1500, 2,000, 3,000, 5,000, 8,000, 10,000, 10,000, 15,000, 20,000, 30,000, 50,000, 70,000, 80,000, 90,000, 100,000, 150,000, or 200,000).

[0073] According to an embodiment of the present invention, the weight average molecular weight of the ethylene / vinyl acetate copolymer may be about 90,000 g / mol to 30,000,000 g / mol, such as about 100,000 (g / mol), 200,000 (g / mol), 300,000 (g / mol), 400,000 (g / mol), 500,000 (g / mol), 800,000 (g / mol), 1,000,000 (g / mol), 2,000,000 (g / mol), 3,000,000 (g / mol), 4,000,000 (g / mol), 5,000,000 (g / mol), 8,000,000 (g / mol), 10,000,000 (g / mol), 12,000,000 (g / mol), 15,000,000 (g / mol), 20,000,000 (g / mol), or 25,000,000 (g / mol). The weight average molecular weight (Mw) of the ethylene / vinyl acetate copolymer can be measured by gel permeation chromatography (GPC) (using polystyrene as the standard to prepare the calibration curve). According to an embodiment of the present invention, the ethylene / vinyl acetate copolymer will first dissociate into smaller molecular weight substances with reactivity during the copolymerization reaction.

[0074] According to an embodiment of the present invention, the ethylene / vinyl acetate copolymer may have a melt index (MI) between about 1 g / 10 min and 2,000 g / 10 min, such as about 200 g / 10 min, 300 g / 10 min, 400 g / 10 min, 500 g / 10 min, 800 g / 10 min, 1,000 g / 10 min, 1,200 g / 10 min, 1,500 g / 10 min, or 1,700 g / 10 min. When the melt index is larger, the fluidity is better, and it is easier to perform a full - range coating operation during the coating process, but it is not easy to form a fibrous structural morphology; when the melt index is lower, the fluidity is worse, although a full - range coating operation cannot be performed, but under the action of shear force, it is easier to generate a fibrous structural morphology. When the melt index of the ethylene / vinyl acetate copolymer is within the above - mentioned specific range, an electrode material with multiple advantages such as a full - range coating effect, high adhesiveness, high structural toughness, and no use of a binder can be obtained. In addition, the active particles can be in closer contact with the conductive additive, which helps to improve the electrical properties of the electrode material. In this way, lithium ions can be better inserted and removed on the surface of the active material, improving the battery capacity and enhancing the rate discharge performance. According to an embodiment of the present invention, the melt index of the ethylene / vinyl acetate copolymer is measured according to the method specified in ASTM D1238 at about 190 °C and a load of about 2.16 kg.

[0075] According to an embodiment of the present invention, the weight ratio of the compound having two acrylate groups to the ethylene / vinyl acetate copolymer may be from about 1:99 to 99:1, such as about 2:98, 3:97, 4:96, 5:95, 6:94, 7:93, 8:92, 9:91, 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1, 91:9, 92:8, 93:7, 94:6, 95:5, 96:4, 97:3, or 98:2. When the electrode material is prepared by replacing the first polymer with the homopolymer of the compound having two acrylate groups, the overall structure of the obtained electrode material will be too hard and brittle (i.e., insufficient softness and viscoelasticity), the electrochemical stability performance will be poor, and it is easy to crack, resulting in the disintegration of the structure of the electro-material (when the processing temperature is too high). In addition, when the electrode material is prepared by replacing the first polymer with the ethylene / vinyl acetate copolymer, the structure of the obtained electrode material will be too soft, resulting in insufficient strength, easy deformation and aging, the heat resistance stability performance will also be poor, and corrosive decomposition products will be released when the processing temperature is too high.

[0076] According to an embodiment of the present invention, the second polymer may be polyamide, polyimide, polymaleimide, polybismaleimide, polyacrylate, poly(acrylic acid), polyvinylalcohol, sodium carboxymethyl cellulose, polystyrene, styrene-butadiene rubber, polyurethane, polyvinylpyrrolidone, polyvinylchloride, polyacrylonitrile, polybutadiene, or a combination of the foregoing. According to an embodiment of the present invention, the weight average molecular weight of the second polymer may be about 2,000 g / mol to 3,000,000 g / mol, such as about 3,000 (g / mol), 5,000 (g / mol), 8,000 (g / mol), 10,000 (g / mol), 12,000 (g / mol), 15,000 (g / mol), 20,000 (g / mol), 50,000 (g / mol), 80,000 (g / mol), 100,000 (g / mol), 200,000 (g / mol), 300,000 (g / mol), 400,000 (g / mol), 500,000 (g / mol), 800,000 (g / mol), 1,000,000 (g / mol), 2,000,000 (g / mol), or 2,500,000 (g / mol). The weight average molecular weight (Mw) of the second polymer can be measured by gel permeation chromatography (GPC) (using polystyrene as a standard to prepare a calibration curve).

[0077] According to an embodiment of the present invention, the reaction monomer may be ethylene, propylene, isobutylene, 1-butene, ethyl acetate, acrylic acid, acrylate, vinyl aromatic monomer, maleimide, bismaleimide, barbituric acid, or a combination of the foregoing.

[0078] According to an embodiment of the present invention, the third polymer may be polyacrylate, poly(acrylic acid), polyvinyl alcohol, sodium carboxymethyl cellulose, ethyl cellulose, polystyrene, styrene-butadiene rubber, polybutadiene, or a combination thereof. According to an embodiment of the present invention, the weight-average molecular weight of the third polymer may be about 2,000 g / mol to 3,000,000 g / mol, such as about 3,000 (g / mol), 5,000 (g / mol), 8,000 (g / mol), 10,000 (g / mol), 12,000 (g / mol), 15,000 (g / mol), 20,000 (g / mol), 50,000 (g / mol), 80,000 (g / mol), 100,000 (g / mol), 200,000 (g / mol), 300,000 (g / mol), 400,000 (g / mol), 500,000 (g / mol), 800,000 (g / mol), 1,000,000 (g / mol), 2,000,000 (g / mol), or 2,500,000 (g / mol). The weight-average molecular weight (Mw) of the third polymer can be measured by gel permeation chromatography (GPC) (using polystyrene as a standard to prepare a calibration curve).

[0079] According to an embodiment of the present invention, the preparation of the first polymer of the present invention may include the following steps. First, a compound having two acrylate groups and an ethylene / vinyl acetate copolymer are dispersed in the solvent, and an initiator and / or a catalyst are added as needed to obtain a composition. Then, the above composition is heated to react the compound having two acrylate groups with the ethylene / vinyl acetate copolymer to form the first polymer.

[0080] According to other embodiments of the present invention, the preparation of the first polymer of the present invention may include the following steps. First, a compound having two acrylate groups and an ethylene / vinyl acetate copolymer are dispersed in the solvent, and a reactive monomer, a third polymer, an initiator, and / or a catalyst are added as needed to obtain a composition. Then, the above composition is heated to react the compound having two acrylate groups with the ethylene / vinyl acetate copolymer to form the first polymer.

[0081] According to an embodiment of the present invention, please refer toFigure 3 , the preparation method 100 of the electrode material according to the present invention may include the following steps. First, a composition for preparing the electrode material is provided, and the composition includes the active particles, the conductive additive, and the first polymer (step 102). Then, a spray granulation process or a melt-kneading process is performed on the composition to obtain the electrode material (step 104). According to an embodiment of the present invention, in the composition, the weight ratio of the conductive additive to the first polymer is 5:95 to 70:30, such as 10:90, 20:80, 30:70, 40:60, 50:50, or 60:40. According to an embodiment of the present invention, the total weight of the conductive additive and the first polymer and the weight ratio of the active particles is 4:96 to 10:90, such as 5:95 to 70:30, such as 5:95, 6:94, 7:93, 8:92, or 9:91. In addition, the composition further includes a second polymer, wherein the total weight of the conductive additive, the first polymer, and the second polymer and the weight ratio of the active particles is 3:97 to 10:90, such as 4:96, 5:95, 6:94, 7:93, 8:92, or 9:91. According to an embodiment of the present invention, since the electrode material is formed from the composition for preparing the electrode material, the weight ratio of the conductive additive to the first polymer in the composition is approximately equal to the weight ratio of the conductive additive to the first polymer in the coating layer; and the total weight of the conductive additive and the first polymer (or the total weight of the conductive additive, the first polymer, and the second polymer) and the weight ratio of the active particles in the composition is approximately equal to the weight ratio of the coating layer to the active particles in the electrode material.

[0082] According to an embodiment of the present invention, the preparation method of the electrode material according to the present invention may include the following steps. First, a first composition for preparing the electrode material is provided, and the first composition includes the active particles, the conductive additive, and the first polymer. Then, a spray granulation process is performed on the first composition to obtain a core-shell particle (composed of active particles and a first coating layer). Then, the core-shell particles, the conductive additive, and the first polymer are mixed to obtain a second composition. Then, a spray granulation process is performed on the first composition to obtain the electrode material according to the present invention.

[0083] According to an embodiment of the present invention, since the electrode material according to the present invention is formed by a spray granulation process or a melt-kneading process, the volume swelling of the electrode prepared using the electrode material can be reduced, the water absorption can be decreased, the stability can be increased, the dissolution of the metal components of the active particles (such as manganese, iron, or nickel) can be inhibited, and the ion conduction / electron conduction efficiency can be improved.

[0084] According to an embodiment of the present invention, when preparing the electrode material by a spray granulation process, the preparation method of the electrode material of the present invention may include the following steps. First, the conductive additive is uniformly dispersed in a solvent to obtain a first solution. Then, the active particles are added to the first solution and uniformly dispersed to obtain a second solution. Then, the first polymer (or a combination of the second polymer and the first polymer) is added to the second solution and uniformly mixed to obtain a slurry. Then, the slurry is used for the spray granulation process to obtain the electrode material. According to an embodiment of the present invention, the diameter of the atomizing nozzle, the frequency of the atomizer, the operating temperature, the inlet temperature, the outlet temperature, and the feed flow rate used in the spray granulation process can be adjusted by those with ordinary knowledge in the technical field according to actual needs. For example, the closed inert gas circulation spray drying equipment system (CL-8 model) of Okawara Chemical Machinery Co., Ltd. and the centrifugal ceramic pin atomizing disk (MC-50-8-14C) can be used. The rotation frequency of the atomizer can be 20 Hz to 60 Hz; the operating temperature can be 50 °C to 200 °C; the inlet temperature can be 30 °C to 200 °C; the outlet temperature can be 30 °C to 200 °C; and the feed flow rate can be 1 ml / min to 100 ml / min. In addition, the spray granulation process may include a drying step to dry the product after granulation of the slurry, wherein the temperature of the drying step can be adjusted according to the solvent used, for example, it is 50 °C to 200 °C. For example, the spray granulation process can be carried out through a spray drying system. For example, the solvent can be N-methylpyrrolidone (NMP), N,N-dimethylformamide (dimethylformamide, DMF), N,N-dimethylacetamide (DMAc), pyrrolidone, N-dodecylpyrrolidone, γ-butyrolactone, 1,2-Propanediol monomethyl ether acetate, toluene, xylene, cyclopentanone, or a combination of the above.

[0085] According to an embodiment of the present invention, when preparing the electrode material by a melt-kneading process, the preparation method of the electrode material of the present invention may include the following steps. First, the conductive additive, the active particles, and the first polymer (or further including the second polymer) are fully mixed to obtain a mixture. Then, the mixture is subjected to a melt-kneading process to obtain the electrode material. Herein, the "melt" in the present invention refers to a substance state that becomes a fluid after being heated to the melting point of the first polymer reactant or heated to a temperature above which the first polymer can be deformed. The "kneading" in the present invention refers to a process of uniformly mixing the conductive additive, the active particles, and the polymer by mechanical action (such as an extruder), and the kneading step can also be carried out in a discontinuous or batch method. According to an embodiment of the present invention, since the present invention uses a specific polymer (i.e., the first polymer) to prepare the electrode material, the temperature of the melt-kneading process can be 60°C to 200°C, such as about 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, or 190°C.

[0086] According to an embodiment of the present invention, the present invention also provides an electrode (such as a positive electrode or a negative electrode) for a battery (such as a lithium-ion battery or a lithium secondary electrode). According to an embodiment of the present invention, please refer to Figure 4 , the electrode 200 of the present invention may include a current collector layer 202 and an active layer 204, wherein the active layer 204 is disposed on the current collector layer 202. According to an embodiment of the present invention, the active layer 204 is directly disposed on the current collector layer 202, such that the lower surface of the active layer 204 is in direct contact with the upper surface of the current collector layer 202 (i.e., there is no intervening film layer (continuous or discontinuous) between the active layer 204 and the current collector layer 202). For example, there is good adhesion between the active layer 204 and the current collector layer 202 of the electrode 200 of the present invention, so there is no need to additionally use an adhesive (or an adhesive layer) to fix the active layer 204 on the current collector layer 202, or there is no need to mix the electrode material with an adhesive to form the active layer. According to an embodiment of the present invention, the electrode 200 of the present invention is composed of the current collector layer 202 and the active layer 204. According to an embodiment of the present invention, the active layer 204 of the present invention is composed of the electrode material.

[0087] According to an embodiment of the present invention, the electrode 200 of the present invention may include two such active layers (i.e., the first active layer 204 and the second active layer 206) and a current collector layer 202, wherein the current collector layer 202 is disposed between the two active layers 204. Here, the first active layer 204 is directly disposed on the current collector layer 202 such that the lower surface of the first active layer 204 is in direct contact with the upper surface of the current collector layer 202; and the current collector layer 202 is directly disposed on the second active layer 206 such that the lower surface of the current collector layer 202 is in direct contact with the upper surface of the second active layer 206.

[0088] According to an embodiment of the present invention, the electrode of the present invention may be a positive electrode for a battery, wherein the active particles of the electrode material for the active layer are positive electrode active materials. According to an embodiment of the present invention, the electrode of the present invention may be a negative electrode for a battery, wherein the active particles of the electrode material for the active layer are negative electrode active materials.

[0089] According to an embodiment of the present invention, the thickness of the active layer is not particularly limited, and those skilled in the art can adjust it according to actual needs. For example, the thickness of the active layer may be about 50 μm to 500 μm (such as about 70 μm, 100 μm, 120 μm, 150 μm, 180 μm, 2000 μm, 250 μm, 300 μm, 350 μm, 400 μm, or 450 μm).

[0090] According to an embodiment of the present invention, the current collector layer may be a conductive carbon substrate, a metal foil (such as a nickel foil, an aluminum foil, a copper foil, a carbon-coated aluminum foil, or a stainless steel foil), or a metal material with a porous structure, such as a carbon cloth, a carbon felt, or a carbon paper, a nickel mesh, a copper mesh, a molybdenum mesh, a foamed nickel, a foamed copper, or a foamed molybdenum. According to an embodiment of the present invention, the metal material with a porous structure may have a porosity of about 10% to 99.9% (such as: 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%). According to an embodiment of the present invention, the thickness of the current collector layer is not particularly limited, and those skilled in the art can adjust it according to actual needs. For example, the thickness of the current collector layer may be about 5 μm to 50 μm (such as about 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, or 45 μm).

[0091] According to an embodiment of the present invention, the preparation method of the electrode of the present invention may include the following steps. Provide the electrode material of the present invention and a current collector layer. Then, dispose the electrode material on the current collector layer and perform a hot pressing process on the electrode material to convert the electrode material into an active layer, thereby obtaining the electrode, wherein the active layer is in direct contact with the current collector layer. According to an embodiment of the present invention, the hot pressing process may be, for example, hot roll pressing or hot rolling. Since each electrode material of the present invention has the coating layer and the coating layer has the first polymer of the present invention, the active particles, the conductive additive, and the first polymer naturally meet the requirement of uniform mixing. In addition, due to the specific chemical structure, the first polymer of the present invention has appropriate melting point, rheology, and adhesiveness, enabling the hot pressing process to be carried out at a lower temperature. According to an embodiment of the present invention, the operating temperature of the hot pressing process may be about 80°C to 200°C, such as about 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, or 190°C. According to an embodiment of the present invention, the pressure applied in the hot pressing process can be adjusted according to the common general knowledge of those skilled in the art according to actual needs. For example, the pressure applied in the hot pressing process may be greater than or equal to 100 psi. The electrode of the present invention can avoid the problems caused by the additional use of a binder and improve the uniform mixing of the active material and the conductive material, thereby improving the active layer mass loading, compacted density, and stability of the obtained electrode (i.e., overcoming the problems caused by the wet electrode process).

[0092] According to an embodiment of the present invention, the preparation method of the electrode of the present invention may include the following steps. Provide the electrode material of the present invention and a current collector layer. Then, perform a hot pressing process on the electrode material to obtain an electrode material film. Next, dispose the electrode material film on the current collector layer and perform a hot pressing process on the electrode material to convert the electrode material film into an active layer, thereby obtaining the electrode, wherein the active layer is in direct contact with the current collector layer. According to an embodiment of the present invention, the hot pressing process may be, for example, a thermal rolling process or a thermal milling process.

[0093] According to an embodiment of the present invention, the method for preparing the electrode of the present invention may include the following steps. Provide a composition for preparing an electrode material and a current collector layer, the composition comprising the active particles, the conductive additive, and the first polymer of the present invention. Then, introduce the composition into a spray granulation process, and use the current collector layer to carry the formed electrode material (i.e., directly form the electrode material on the current collector layer by the spray granulation process). Then, perform a hot pressing process on the electrode material to convert the electrode material into an active layer, thereby obtaining the electrode.

[0094] According to an embodiment of the present invention, the method for preparing the electrode of the present invention may include the following steps. Provide a composition for preparing an electrode material and a current collector layer, the composition comprising the active particles, the conductive additive, and the first polymer. Then, introduce the composition into a melt-kneading process, and directly coat the extruded electrode material on the current collector layer. Then, perform a thermal pressing process on the electrode material to convert the electrode material into an active layer, thereby obtaining the electrode.

[0095] According to an embodiment of the present invention, please refer to Figure 5 , the present invention also provides a battery 300, such as a lithium battery, a lithium-ion battery, or a lithium secondary battery. The battery 300 includes a positive electrode 302, a separator 304, and a negative electrode 306, wherein the negative electrode 306 is separated from the positive electrode 302 by the separator 304. According to an embodiment of the present invention, at least one of the positive electrode 302 or the negative electrode 306 is the electrode of the present invention. If the positive electrode 302 is the electrode of the present invention, then in the positive electrode 302, the active particles of the electrode material for the active layer are positive electrode active materials. If the negative electrode 306 is the electrode of the present invention, then in the negative electrode 306, the active particles of the electrode material for the active layer are negative electrode active materials.

[0096] According to an embodiment of the present invention, when the positive electrode is not the electrode of the present invention, the positive electrode may be a positive electrode conventionally used in a battery (such as a lithium battery). For example, the positive electrode may include a positive electrode active layer (including positive electrode active materials) and a positive electrode current collector layer. According to an embodiment of the present invention, when the negative electrode is not the electrode of the present invention, the negative electrode may be a negative electrode conventionally used in a battery (such as a lithium battery). For example, the negative electrode may include a negative electrode active layer (including negative electrode active materials) and a negative electrode current collector layer. According to an embodiment of the present invention, the definitions of the positive electrode current collector layer and the negative electrode current collector layer may be the same as the current collector layer of the present invention.

[0097] According to an embodiment of the present invention, the positive electrode 302 may be in direct contact with the separator 304, and / or the negative electrode 306 may be in direct contact with the separator 304. According to an embodiment of the present invention, the positive electrode 302 may be spaced apart from the separator 304 by a distance, and / or the negative electrode 306 may be spaced apart from the separator 304 by a distance. According to an embodiment of the present invention, the battery 300 may further include an electrolyte 308, and the electrolyte is disposed between the positive electrode 302 and the negative electrode 306. In other words, the stacked structure of the positive electrode 302, the separator 304, and the negative electrode 306 is immersed in the electrolyte 308. That is, the electrolyte is distributed throughout the battery 300.

[0098] According to certain embodiments of the present invention, the active layer of the positive electrode described in the present invention may be disposed between the separator 304 and the current collector layer of the positive electrode. According to an embodiment of the present invention, the active layer of the negative electrode described in the present invention may be disposed between the separator 304 and the current collector layer of the negative electrode.

[0099] According to an embodiment of the present invention, the separator 304 may include an insulating material, such as polyethylene (PE), polypropylene, polytetrafluoroethylene film, polyamide film, polyvinyl chloride film, polyvinylidene fluoride film, polyaniline film, polyimide film, non-woven fabric, polyethylene terephthalate, polystyrene (PS), cellulose, or a combination thereof. For example, the separator 304 may be, for example, a PE / PP / PE multi-layer composite structure. According to an embodiment of the present invention, the separator may have a porous structure. That is, the pores of the separator are uniformly distributed throughout the entire separator. According to an embodiment of the present invention, the thickness of the separator is not particularly limited, and those skilled in the art can adjust it according to actual needs. For example, the thickness of the separator may be about 1 μm to 100 μm (such as about 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, or 90 μm).

[0100] According to an embodiment of the present invention, the electrolyte 308 may include a solvent and a lithium salt (or a lithium-containing compound). According to an embodiment of the present invention, the concentration of the lithium salt in the solvent is about 0.8 M to 1.6 M, such as about 0.9 M, 1.0 M, 1.1 M, 1.2 M, 1.3 M, 1.4 M, or 1.5 M. According to an embodiment of the present invention, the solvent may be an organic solvent, such as an ester solvent, a ketone solvent, a carbonate solvent, an ether solvent, an alkane solvent, an amide solvent, or a combination of the above. According to an embodiment of the present invention, the solvent may be 1,2-diethoxyethane, 1,2-dimethoxyethane, 1,2-dibutoxyethane, tetrahydrofuran, 2-methyl tetrahydrofuran, dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), methyl acetate, ethyl acetate, methyl butyrate, ethyl butyrate, methyl propionate, ethyl propionate, propyl acetate (PA), γ-butyrolactone (GBL), ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), dimethyl carbonate (DMC), vinylene carbonate, butylene carbonate, dipropyl carbonate, or a combination of the above.According to an embodiment of the present invention, the lithium salt may be lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), bis(fluorosulfonyl)imide lithium (LiN(SO2F)2) (LiFSI), lithium difluoro(oxalato)borate (LiBF2(C2O4)) (LiDFOB), lithium tetrafluoroborate (LiBF4), lithium trifluoromethanesulfonate (LiSO3CF3), bis(trifluoromethane)sulfonimide lithium (LiN(SO2CF3)2) (LiTFSI), lithium bis perfluoroethanesulfonimide (LiN(SO2CF2CF3)2), lithium hexafluoroarsenate (LiAsF6), lithium hexafluoroantimonate (LiSbF6), lithium tetrachloroaluminate (LiAlCl4), lithium tetrachlorogallate (LiGaCl4), lithium nitrate (LiNO3), tris(trifluoromethanesulfonyl)methyllithium (LiC(SO2CF3)3), lithium thiocyanate hydrate (LiSCN), LiO3SCF2CF3, LiC6F5SO3, LiO2CCF3, lithiumfluorosulfonate (LiSO3F), Lithium tetrakis(pentafluorophenyl)borate (LiB(C6H5)4), lithiumbis(oxalato)borate (LiB(C2O4)2) (LiBOB), or a combination of the above.

[0101] According to an embodiment of the present invention, the battery of the present invention may use a solid electrolyte and does not include the electrolyte solution. For example, the battery of the present invention may include a solid electrolyte membrane (not shown) disposed between the positive electrode and the negative electrode. According to an embodiment of the present invention, the solid electrolyte may be disposed on the separator to form a composite separator. In addition, the battery of the present invention may use a solid electrolyte membrane to replace the separator.

[0102] To make the above - mentioned content, other purposes, features, and advantages of the present invention more obvious and understandable, the following preferred embodiments are specifically given and described in detail as follows.

[0103] Preparation of a compound having two acrylate groups

[0104] Preparation Example 1

[0105] 4 - Hydroxyacetophenone (1 mol), methacrylic anhydride (1.2 mol), and sodium bicarbonate (0.1 mol) were added to a reaction flask. The reaction flask was purged with nitrogen and heated to 80 °C. Then, after reacting for 2 hours, 700 mL of an aqueous sodium hydroxide solution (2 M) was added to the reaction flask. After reacting for 8 hours, the resulting product was filtered, the solid was collected, washed with water, and dried to obtain compound (1) (yield was about 97%). The reaction formula of the above - mentioned reaction is shown as follows:

[0106]

[0107] Compound (1) (0.97 mol), hydrazine sulfate (0.49 mol), triethylamine (NEt3) (0.49 mol), and ethanol (200 g) were added to a reaction flask. Then, the reaction flask was heated to reflux. After reacting for 5 hours, the reaction flask was cooled to room temperature, and after the product precipitated, the product was washed with ethanol and deionized water and dried to obtain a compound (1) having two acrylate groups. The reaction formula of the above - mentioned reaction is shown as follows:

[0108]

[0109] The compound (1) having two acrylate groups was analyzed by nuclear magnetic resonance spectroscopy, and the obtained spectral information is as follows. 1 HNMR(400MHz,d6 - DMSO):7.97(d,4H,J = 8.0Hz),7.26(d,4H,J = 8.0Hz),6.30(s,2H),5.91(s,20 2H),2.29(s,6H),2.01(s,6H).

[0110] Preparation of a polymer

[0111] Preparation Example 2

[0112] 95 parts by weight of ethylene-vinyl acetate copolymer (EVA) (product number UE647-04, purchased from Polymer Corporation, Taiwan, China, VA content 28%, MI value 800), 5 parts by weight of compound (1) having two acrylate groups, and toluene were added to a reaction flask. Then, the reaction flask was heated to 105 °C. After reacting for 6 hours, the resulting product was concentrated by rotary evaporation to remove the solvent, obtaining polymer (1). Subsequently, the decomposition temperature (Td), melt flow rate (MFR), melting point (Tm), surface resistivity, and volume resistivity of the obtained polymer (1) were evaluated, and the results are shown in Table 1.

[0113] The decomposition temperature (Td) of the polymer of the present invention was analyzed using a thermogravimetric analyzer (TGA). The melt flow rate (MFR) of the polymer of the present invention was measured by a melt flow indexer at 230 °C with a test weight of 2.16 kg according to the method specified in ASTM D 1238-A. The melting point of the polymer of the present invention was measured using a differential scanning calorimeter (DSC) (model Discovery DAS25, manufactured by TA Instruments, Inc.). The surface resistivity of the polymer of the present invention was measured using a four-point probe impedance meter (model DU-5211 Ohm Meter, purchased from DELTA UNITED INSTRUMENT CO., LTD). The measurement method includes the following steps: placing the sample into the four-point probe impedance meter. Contacting the probe with the surface of the sample at a pressure of 0.07 MPa. After contact, standing still for 3 seconds and reading the impedance value (unit: ohm) on the meter. The volume resistivity of the polymer of the present invention was measured according to the method specified in IEC 62788-1-2.

[0114] Preparation Example 3

[0115] Production Example 3 was carried out in the same manner as described in Production Example 2, except that the weight ratio of the ethylene / vinyl acetate copolymer to the compound (1) having two acrylate groups was adjusted from 95:5 to 20:80 to obtain Polymer (2). Subsequently, the decomposition temperature (Td), melt flow rate (MFR), melting point (Tm), surface resistivity, and volume resistivity of the obtained Polymer (2) were evaluated, and the results are shown in Table 1.

[0116] Production Example 4

[0117] Production Example 4 was carried out in the same manner as described in Production Example 2, except that the weight ratio of the ethylene / vinyl acetate copolymer to the compound (1) having two acrylate groups was adjusted from 95:5 to 90:10 to obtain Polymer (3). Subsequently, the decomposition temperature (Td), melt flow rate (MFR), melting point (Tm), surface resistivity, and volume resistivity of the obtained Polymer (3) were evaluated, and the results are shown in Table 1.

[0118] Production Example 5

[0119] Production Example 5 was carried out in the same manner as described in Production Example 2, except that the weight ratio of the ethylene / vinyl acetate copolymer to the compound (1) having two acrylate groups was adjusted from 95:5 to 5:95 to obtain Polymer (4). Subsequently, the decomposition temperature (Td), melt flow rate (MFR), melting point (Tm), surface resistivity, and volume resistivity of the obtained Polymer (4) were evaluated, and the results are shown in Table 1.

[0120] Production Example 6

[0121] 95 parts by weight of ethylene-vinyl acetate copolymer (EVA) (product number UE630, purchased from Polymer Corporation, Taiwan, China, VA content 16%, MI value 1.5 g / 10 min), 5 parts by weight of the compound (1) having two acrylate groups, and 200 parts by weight of toluene (as a solvent) were added to a reaction flask. Then, the reaction flask was heated to 105 °C. After reacting for 6 hours, the resulting product was concentrated by rotary evaporation to remove the solvent, obtaining polymer (5). Subsequently, the thermal decomposition temperature (Td), melt flow rate (MFR), melting point (Tm), surface resistivity, and volume resistivity of the obtained polymer (5) were evaluated, and the results are shown in Table 1.

[0122] Preparation Example 7

[0123] 84 g of polymer (6) (polyvinylidene fluoride, purchased from Kynar, product number PVDF-HVS900) was dissolved in 616 g of N-methylpyrrolidone (NMP) to prepare a PVDF-HVS900 solution with a solid content of 12 wt%. After coating it into a wet film on a glass plate with a 200-μm gap doctor blade, it was then placed in an oven at 180 °C to dry into a polymer (6) film. The thermal decomposition temperature (Td), melt flow rate (MFR), melting point (Tm), surface resistivity, and volume resistivity of the obtained polymer (6) were evaluated, and the results are shown in Table 1.

[0124] Table 1

[0125]

[0126] As can be seen from Table 1, the polymer prepared from the compound having two acrylate groups and ethylene / vinyl acetate according to the present invention has a high thermal decomposition temperature, an appropriate melting point (which can be less than 150 °C), and a high melt flow rate.

[0127] Next, a rheometer (TA ARES-G2) was used to evaluate the rheological properties of polymers (1), (3)-(6) (evaluated sample diameter: 20 mm) (test conditions: shear rate of 10 1 / s and heating rate of 5.0 °C / min), and it was found that polymers (1), (3)-(6) had good melting properties.

[0128] Next, cyclic voltammetry was used to test polymers (1) and (3) to evaluate the material activity and reaction kinetics, and at the same time, the stability and durability of the materials were observed. The test conditions were that polymer (1) and (3) membranes were introduced into Formosa Plastics lithium iron phosphate batteries in a voltage range of 0 to 4.8 V. The results showed that polymers (1) and (3) had high electrochemical stability and hardly reacted with the electrolyte.

[0129] Preparation of Electrode Materials

[0130] Example 1

[0131] 2,500 grams of lithium iron phosphate (LFP) (purchased from Formosa Plastics Lithium Iron Technology Co., Ltd. in Taiwan, China, product number: LFP-3005E), 62.50 grams of highly branched polymer / ethyl cellulose resin solution (solid content: 6 wt%) (ethyl cellulose resin purchased from Dow Chemical, product number: ETHOCEL STD 100) (the highly branched structure is a polymer structure thermally polymerized from bismaleimide monomers dissolved in N-methyl-2-pyrrolidone (NMP), and during the process of forming its highly branched polymer molecular structure, ethyl cellulose was introduced to integrate and match into a poly-highly branched and linear through-combined polymer structure, and the weight ratio of highly branched polymer bismaleimide to ethyl cellulose resin was 2:1) (as an ion-conducting additive, ionic conductivity was 3.4×10 -4S / cm), 178.57 g of carbon nanotube dispersion (product number CNT-SP, purchased from Tiannai Beijing, as a conductive additive) (solid content 4.2 wt%, dispersed in N-methylpyrrolidone (NMP)), 601.65 g of polymer solution (120.33 g of polymer (1) dissolved in toluene), and 706 g of toluene were mixed to obtain Composition (1) (solid content 65%). In Composition (1), the weight ratio of the ionic conductive additive, conductive additive, and polymer (1) is 2.85:5.70:91.45; and, the weight ratio of lithium iron phosphate to the total weight of the ionic conductive additive, conductive additive, and polymer (1) is 95:5. Then, Composition (1) was subjected to a spray granulation process using a spray drying system (model CL-8, manufactured by Okawara Chemical Machinery Co., Ltd.), and the obtained product was collected to obtain a powdery electrode material (1). The conditions of the spray granulation process are as follows: (1) a centrifugal ceramic pin atomization disk (MC-50-8-14C) was used; (2) the inlet temperature and outlet temperature were set at 130°C and 80°C, respectively; (3) the circulation fan frequency was 35 Hz; (4) the atomizer frequency was 40 Hz; and (5) the feed flow rate was 10.030 ml / min.

[0132] Example 2

[0133] 1,500 g of lithium iron phosphate (LFP) (purchased from Yancheng Core Materials, product number LFP-GF19), 37.50 g of a highly branched polymer / hydroxyethyl cellulose resin solution (solid content 6 wt%) (hydroxyethyl cellulose resin purchased from Dow Chemical, product number ETHOCEL STD 100) (the highly branched structure is a polymer structure obtained by thermal polymerization of bismaleimide monomers dissolved in N-methyl-2-pyrrolidone (NMP), and during the formation of its highly branched polymer molecular structure, hydroxyethyl cellulose was introduced to be incorporated into the highly branched structure to form a poly-highly branched and linearly penetrating combined polymer structure. The weight ratio of the highly branched polymer bismaleimide to the hydroxyethyl cellulose resin is 2:1) (as an ionic conductive additive, ionic conductivity 3.4×10 -4107.14 g of carbon nanotube dispersion (product number CNT-SP, purchased from Tiannai Beijing, as a conductive additive) (solid content 4.2 wt%, dispersed in N-methylpyrrolidone (NMP)), 360.99 g of polymer solution (120.33 g of polymer (1) dissolved in toluene), and 424 g of toluene were mixed to obtain Composition (2) (solid content 65%). In Composition (2), the weight ratio of the ionic conductive additive, conductive additive, and polymer (1) is 3:6:91; and the weight ratio of lithium iron phosphate to the total weight of the ionic conductive additive, conductive additive, and polymer (1) is 95:5. Then, Composition (2) was subjected to a spray granulation process using a spray drying system (model CL-8, manufactured by Okawara Chemical Machinery Co., Ltd.), and the resulting product was collected to obtain a powdery electrode material (2). The conditions of the spray granulation process were as follows: (1) a centrifugal ceramic pin atomization disk (MC-50-8-14C) was used; (2) the inlet temperature and outlet temperature were set at 145°C and 110°C, respectively; (3) the circulation fan frequency was 35 Hz; (4) the atomizer frequency was 30 Hz; and (5) the feed flow rate was 12.070 ml / min.

[0134] Example 3

[0135] 1,500 g of lithium iron phosphate (LFP) (purchased from Yancheng Core Material Co., product number LFP-GF19), 37.47 g of a highly branched polymer / ethyl cellulose resin solution (solid content 6 wt%) (ethyl cellulose resin purchased from Dow Chemical, product number ETHOCEL STD 100) (the highly branched structure is a polymer structure thermally polymerized from bismaleimide monomers dissolved in N-methyl-2-pyrrolidone (NMP), and during the formation of its highly branched polymer molecular structure, ethyl cellulose was introduced to be incorporated into the highly branched structure to form a poly-highly branched and linearly penetrating combined polymer structure by matching. The weight ratio of the highly branched polymer bismaleimide to the ethyl cellulose resin is 2:1) (as an ionic conductive additive, the ionic conductivity is 3.4×10 -4375.94 g of a carbon nanotube dispersion (product number CNT-SP, purchased from Tiannai Beijing, as a conductive additive) (solid content 4.2 wt%, dispersed in N-methylpyrrolidone (NMP)), 607.89 g of a polymer solution (60.79 g of polymer (3) dissolved in toluene), and 50 g of toluene were mixed to obtain Composition (3) (solid content 61.36%). In Composition (3), the weight ratio of the ionic conductive additive, conductive additive, and polymer (3) is 3:20:77; and the weight ratio of lithium iron phosphate to the total weight of the ionic conductive additive, conductive additive, and polymer (3) is 95:5. Next, Composition (3) was subjected to a spray granulation process using a spray drying system (model CL-8, manufactured by Okawara Kako Co., Ltd.), and the resulting product was collected to obtain a powdery electrode material (3). The conditions of the spray granulation process were as follows: (1) a centrifugal ceramic pin atomization disk (MC-50-8-14C) was used; (2) the inlet temperature and outlet temperature were set at 145°C and 110°C, respectively; (3) the circulation fan frequency was 50 Hz; (4) the atomizer frequency was 30 Hz; and (5) the feed flow rate was 12.070 ml / min.

[0136] Example 4

[0137] 2,000 g of lithium iron phosphate (LFP) (purchased from Yancheng Core Material Co., product number LFP-GF19), 106.38 g of a highly branched polymer / ethyl cellulose resin solution (solid content 6 wt%) (ethyl cellulose resin purchased from Dow Chemical, product number ETHOCEL STD 100) (the highly branched structure is a polymer structure thermally polymerized from bismaleimide monomers dissolved in N-methyl-2-pyrrolidone (NMP), and during the formation of its highly branched polymer molecular structure, ethyl cellulose was introduced to integrate into the highly branched structure and form a poly-highly branched and linearly penetrating combined polymer structure by matching. The weight ratio of the highly branched polymer bismaleimide to the ethyl cellulose resin is 2:1) (as an ionic conductive additive, ionic conductivity 3.4×10 -4506.59 g of carbon nanotube dispersion (product number CNT-SP, purchased from Tiannai Beijing, as a conductive additive) (solid content 4.2 wt%, dispersed in N-methylpyrrolidone (NMP)), 666.67 g of polymer solution (100.00 g of polymer (3) dissolved in toluene), and 975.68 g of N-methylpyrrolidone (NMP) were mixed to obtain Composition (4) (solid content 61.36%). In Composition (4), the weight ratio of the ionic conductive additive, conductive additive, and polymer (3) was 5:16.67:78.33; and the weight ratio of lithium iron phosphate to the total weight of the ionic conductive additive, conductive additive, and polymer (3) was 94:6. Then, Composition (4) was subjected to a spray granulation process using a spray drying system (model CL-8, manufactured by Okawara Chemical Machinery Co., Ltd.), and the obtained product was collected to obtain a powdery electrode material (4). The conditions of the spray granulation process were as follows: (1) a centrifugal ceramic pin atomization disk (MC-50-8-14C) was used; (2) the inlet temperature and outlet temperature were set at 140 °C and 120 °C, respectively; (3) the circulating fan frequency was 45 Hz; (4) the atomizer frequency was 25 Hz; and (5) the feed flow rate was 25.160 ml / min.

[0138] Example 5

[0139] 1,800 g of lithium iron phosphate (LFP) (purchased from Yancheng Core Material Co., product number LFP-GF19), 157.89 g of highly branched polymer / ethyl cellulose resin solution (solid content 6 wt%) (ethyl cellulose resin purchased from Dow Chemical, product number ETHOCEL STD 100) (the highly branched structure is a polymer structure thermally polymerized from bismaleimide monomers dissolved in N-methyl-2-pyrrolidone (NMP), and during the formation of its highly branched polymer molecular structure, ethyl cellulose was introduced to be incorporated into the highly branched structure to form a poly-highly branched and linearly penetrating combined polymer structure by combination and matching. The weight ratio of the highly branched polymer bismaleimide to the ethyl cellulose resin was 2:1) (as an ionic conductive additive, the ionic conductivity was 3.4×10 -46,000 g of lithium iron phosphate (LFP) (purchased from Wanrun Technology Co., Ltd., product number LFP-A8-4E), 64.17 g of graphite (product number KS6, purchased from TIMCAL Taiwan Boli Co., Ltd. in China, as a conductive additive), 160.435 g of conductive carbon powder (product number Super-P, purchased from TIMCAL Taiwan Boli Co., Ltd. in China, as a conductive additive), and 192.51 g of polymer (3) were mixed to obtain Composition (6). The Composition (6) was subjected to a melt mixing process (temperature: 120 °C, melt mixing time: 1 hour) using a Banbury mixer (Lina Machinery Industry Co., Ltd., KD-3-7.5) to obtain a powdery electrode material (6). In Composition (6), the weight ratio of KS6, Super-P, and polymer (3) was 2:5:6; and the weight ratio of lithium iron phosphate to the total weight of the conductive additive and polymer (3) was 93.5:6.5.

[0140] Example 6

[0141] 6,000 g of lithium iron phosphate (LFP) (purchased from Wanrun Technology Co., Ltd., product number LFP-A8-4E), 64.17 g of graphite (product number KS6, purchased from TIMCAL Taiwan Boli Co., Ltd. in China, as a conductive additive), 160.435 g of conductive carbon powder (product number Super-P, purchased from TIMCAL Taiwan Boli Co., Ltd. in China, as a conductive additive), and 192.51 g of polymer (3) were mixed to obtain Composition (6). The Composition (6) was subjected to a melt mixing process (temperature: 120 °C, melt mixing time: 1 hour) using a Banbury mixer (Lina Machinery Industry Co., Ltd., KD-3-7.5) to obtain a powdery electrode material (6). In Composition (6), the weight ratio of KS6, Super-P, and polymer (3) was 2:5:6; and the weight ratio of lithium iron phosphate to the total weight of the conductive additive and polymer (3) was 93.5:6.5.

[0142] Example 7

[0143] Mix 1,800 grams of lithium iron phosphate (LFP) (purchased from Wanrun Technology Co., Ltd., product number LFP-A8-4E), 19.25 grams of graphite (product number KS6, purchased from Bolv Co., Ltd., Taiwan, China, as a conductive additive), 48.13 g of conductive carbon powder (product number Super-P, purchased from Bolv Co., Ltd., Taiwan, China, as a conductive additive), 57.75 grams of polymer (5), and 1,036.61 grams of toluene to obtain Composition (7) (solid content: 65.00%). In Composition (7), the weight ratio of KS6, Super-P, and polymer (5) is 1:2.5:3; and the weight ratio of lithium iron phosphate to the total weight of KS6, Super-P, and polymer (5) is 93.5:6.5. Then, use a spray drying system (model CL-8, manufactured by Okawara Chemical Machinery Co., Ltd.) to perform a spray granulation process on Composition (7) and collect the resulting product to obtain a powdery electrode material (7). The conditions of the spray granulation process are as follows: (1) Use a centrifugal ceramic pin atomization disk (MC-50-8-14C); (2) Set the inlet temperature and outlet temperature at 120°C and 70°C, respectively; (3) The circulating fan frequency is 35 Hz; (4) The atomizer frequency is 35 Hz; and (5) The feed flow rate is 50.150 ml / min.

[0144] Example 8

[0145] Mix 1,800 grams of lithium iron phosphate (LFP) (purchased from Wanrun Technology Co., Ltd., product number LFP-A8-4E), 19.25 grams of graphite (product number KS6, purchased from Bolv Co., Ltd., Taiwan, China, as a conductive additive), 48.13 g of conductive carbon powder (product number Super-P, purchased from Bolv Co., Ltd., Taiwan, China, as a conductive additive), 28.9 g of polymer (3), 28.9 g of polymer (5), and 1,036.61 grams of toluene to obtain composition (8) (with a solid content of 65.00%). In composition (8), the weight ratio of KS6, Super-P, polymer (3), and polymer (5) is 1:2.5:1.5:1.5; and the weight ratio of lithium iron phosphate to the total weight of KS6, Super-P, polymer (3), and polymer (5) is 93.5:6.5. Then, use a spray drying system (model CL-8, manufactured by Okawara Chemical Machinery Co., Ltd.) to perform a spray granulation process on composition (8) and collect the resulting product to obtain a powdery electrode material (8). The conditions of the spray granulation process are as follows: (1) Use a centrifugal ceramic pin atomization disk (MC-50-8-14C); (2) Set the inlet temperature and outlet temperature at 120°C and 70°C respectively; (3) The circulation fan frequency is 35 Hz; (4) The atomizer frequency is 35 Hz; and (5) The feed flow rate is 25.160 ml / min.

[0146] Here, taking electrode material (1) as an example, its morphology is evaluated as follows: Evaluate the particle size distribution, tapped density of the powder, and BET specific surface area of the lithium iron phosphate (i.e., active particles) used to prepare electrode material (1) and electrode material (1). The results are shown in Table 2. The particle size distribution is measured according to the method specified in ISO 13322-1:2004; the specific surface area can be measured using a specific surface area analyzer (Micromeritics Instrument Corporation ASAP2400); and the tapped density of the powder is measured using a tapped density tester according to the method specified in ISO 3953.

[0147] Table 2

[0148]

[0149]

[0150] The overall particle size distribution of the original lithium iron phosphate is relatively broad. After modification, due to the effect of smaller particles being agglomerated into spheres during the spray drying process, its specific surface area decreases. Therefore, the particle size, particle size distribution uniformity, and tapped density of the electrode material (1) described in the present invention increase, which is beneficial to improving the density of the active layer when forming the active layer using the hot pressing process in the subsequent process. In addition, after modification, the specific surface area of the electrode material (1) decreases, indicating that the profile of the electrode material (1) is more spherical. Furthermore, after the above-mentioned surface modification and spray granulation operations on the ternary cathode material of lithium nickel cobalt manganese oxide (NMC / Geshi Technology Co., Ltd.), the same results can be obtained. There are fewer small and large structures (for example, the proportion of those less than 1 μm decreases from 0.5% to 0%, and the proportion of those greater than 25 μm decreases from 3.5% to 1.6%), the structure size is more uniform (for example, the proportion of those between 1 and 25 μm increases from 96.0% to 98.4%), and the powder particles tend to be more spherical, which are all beneficial to improving the density of the active layer when forming the active layer using the hot pressing process in the subsequent process, as shown in Table 2.

[0151] Next, the obtained electrode materials (1) and (8) were observed with a scanning electron microscope (SEM), and the results are shown respectively as Figure 7 and 8 shown. From Figure 7 and 8 it can be seen that the electrode material (1) is spherical-like particles, and the particle size distribution is relatively uniform. Particles exceeding 30 μm were not observed. Next, the obtained electrode material (1) was observed with a focused ion beam (FIB) transmission electron microscope (TEM), and the result is shown as Figure 9 shown. From Figure 9 it can be seen that the thickness of the coating layer of the electrode material (1) is about 40 nm to 60 nm. Based on the above, the electrode material described in the present invention can be spherical-like particles and have a core-shell structure.

[0152] Comparative Example 1

[0153] Mix 1,800 g of lithium iron phosphate (LFP) (purchased from Wanrun Technology Co., Ltd., product number LFP-A8-4E), 19.25 g of graphite (product number KS6, purchased from Bolv Co., Ltd., Taiwan, China, as a conductive additive), 48.13 g of conductive carbon powder (product number Super-P, purchased from Bolv Co., Ltd., Taiwan, China, as a conductive additive), 57.75 g of polymer (6) (purchased from Kynar HSV900), and 1,036.61 g of N-methylpyrrolidone (NMP) to obtain Composition (9) (solid content: 65.00%). In Composition (9), the weight ratio of the conductive additive to polymer (6) is 7:6; and the weight ratio of lithium iron phosphate to the total weight of the conductive ion additive and polymer (6) is 93.5:6.5. Then, use a spray drying system (model CL-8, manufactured by Okawara Chemical Machinery Co., Ltd.) to perform a spray granulation process on Composition (9) and collect the resulting product to obtain a powdery electrode material (9). The conditions of the spray granulation process are as follows: (1) Use a centrifugal ceramic pin atomization disk (MC-50-8-14C); (2) Set the inlet temperature and outlet temperature at 1,350 °C and 100 °C, respectively; (3) The circulating fan frequency is 40 Hz; (4) The atomizer frequency is 45 Hz; and (5) The feed flow rate is 10.030 ml / min.

[0154] Dry electrode film process

[0155] Example 9

[0156] Method I: Use a tabletop tablet press (Retsch PP35, pressure 35 tons) equipment system. Place the electrode material (1) into a 40 mm tablet die set (with an automatic sheet ejection function) and perform a room temperature tableting operation on the dry electrode composition powder. Increase the pressure from 5 tons to 25 tons. After sheet ejection, a dry electrode film (1-I) is obtained. The weight (cut into an area of 3 cm × 3 cm), thickness, electrode active material coating weight, and electrode material compaction density of the dry electrode film (1-I) are shown in Table 3.

[0157] Method II: Add the electrode material (1) to a small extruder with a modified homogenized feeding module for preheating and uniform mixing. Conduct quantitative feeding through a transfer screw (the temperature in the three sections of the front, middle, and rear areas of the transfer screw pipeline (i.e., the preheating temperature) is 90 °C, the screw speed is 1100 rpm, and the extrusion volume is 46.8 kg / hr). Then, after the electrode material (1) comes out of the extruder evenly and quantitatively, the powder is uniformly transferred through a flat die head (the width can reach 145 mm) and enters the hot rolling module system (the line pressure control value is 200 N / mm, and the heating temperature of the two roller wheels (i.e., the roller temperature) is 90 °C) to prepare a dry electrode film (1-II). The weight (cut into an area of 3 cm × 3 cm), thickness, coating weight of the electrode active material, and compaction density of the electrode material of this dry electrode film are shown in Table 3.

[0158] Repeat Method II, but change the process parameters according to Table 3 to obtain a dry electrode film (1-III).

[0159] Examples 10 - 16

[0160] Examples 10 - 16 are carried out according to Method I and Method II described in Example 9. Except that the electrode materials (2) - (8) are respectively used to replace the electrode material (1) and the process parameters are changed according to Table 3, dry electrode films (2-I) to (8-II) are obtained respectively. The weight, thickness of the electrode film, coating weight of the electrode active material, and compaction density of the electrode material of these dry electrode films (2-I) to (8-II) are shown in Table 3.

[0161] Comparative Example 2

[0162] Comparative Example 2 is carried out according to Method I and Method II described in Example 9. Except that the electrode material (9) (Comparative Example 1) is used to replace the electrode material (1) and the process parameters are changed according to Table 3 to obtain dry electrode films (9-I) and (9-II). The weight, thickness of the electrode film, coating weight of the electrode active material, and compaction density of the electrode material of these dry electrode films (9-I) and (9-II) are shown in Table 3.

[0163] Comparative Example 3

[0164] The preparation method of the wet-process positive electrode plate is as follows: Lithium iron phosphate active material, super P conductive additive, KS-6 conductive additive, and an appropriate amount of solvent such as N-methylpyrrolidone (NMP) are stirred and mixed for 3 hours, and then an NMP solution containing PVDF-HSV900 binder (containing 10 wt% of PVDF) is added and stirred and mixed for another 3 hours to obtain a lithium iron phosphate positive electrode slurry with a solid content of 65 wt%. The solid composition is lithium iron phosphate active material (93.5 wt%), PVDF-HSV900 binder (3 wt%), super P conductive additive (2.5 wt%), and KS-6 conductive additive (1 wt%). After the positive electrode slurry is coated on a current collector (such as aluminum metal foil), it is heated to 150 °C to dry the coating and rolled to form a positive electrode active layer with a thickness of 100 microns on the metal foil, obtaining an electrode membrane (10).

[0165] The electrode membrane (10) is transferred into a hot rolling module system (the line pressure control value is 200 N / mm, and the heating temperature of the two rollers (i.e., the roller temperature) is 90 °C) to prepare an electrode membrane (11). The weights (cut into an area of 3 cm × 3 cm), thicknesses, coating weights of the electrode active materials, and compaction densities of the electrode materials of the electrode membrane (10) and the electrode membrane (11) are measured as shown in Table 3.

[0166] Table 3

[0167]

[0168]

[0169]

[0170] As can be seen from Table 3, in the general wet process, since it is necessary to evaporate the NMP solvent as much as possible without residue, the coating weight of the lithium iron phosphate active material of the electrode membrane is usually between 15 and 25 mg / cm 2 and rarely exceeds 25 mg / cm 2, so it is not easy to significantly increase the capacitance. Because too much coating of the active material will increase the thickness of the electrode film, making it difficult for the solvent to completely evaporate and leaving residues. Moreover, the excessive solvent will lead to the instability of the negative electrode material structure, which will have a negative impact on the subsequent electrode and battery performance, especially reducing its capacity and cycle life. In addition, during the upward evaporation of the solvent, it often causes the binder to form a gradient distribution in the electrode structure, which will also affect the structural stability, bonding strength and cycle performance of the electrode film. Furthermore, the structure of the electrode film obtained through the coating and drying processes is relatively loose and the bonding performance is also poor, and it needs to be compacted by high roll pressing to increase the structural compaction density and bonding strength of the electrode film. However, due to excessive roll pressing, the electrode active material (with high hardness) will be deeper embedded in the relatively soft aluminum foil structure, causing the aluminum foil to strain and tear or produce break marks, and resulting in break marks or fragmentation of the electrode film structure. Therefore, the compaction density of the lithium iron phosphate electrode film is usually controlled between 2.3 and 2.5 g / cm 3 and rarely exceeds 2.5 g / cm 3 . Using the electrode material composition of the present invention, the dry electrode film and dry electrode can be directly produced by hot roll pressing without going through the wet coating and drying process. The process can greatly reduce the solvent usage requirements and VOC emissions and provide an environmentally friendly production mode. From the test and measurement results of the active material coating weight and the compaction density of the electrode film of the electrode compositions in each example of Table 3 prepared by Method I or Method II, the dry electrode composition of the present invention has structural elasticity and toughness and good adhesion, and can withstand high roll pressure and high shear force. Therefore, when the film thickness of the dry electrode film needs to be increased (such as above 150 μm), it is less likely to produce rigid cracking and flexural fracture. Therefore, for the electrode film prepared by the present invention, the coating weight of the active material can be adjusted to more than 30 mg / cm 2 (even exceeding 45 mg / cm 2 ), and the initial compaction density of the electrode film before being laminated and roll pressed with the aluminum foil can be adjusted to more than 2.2 g / cm 3 (even exceeding 2.4 g / cm 3 ). Since the high initial compaction density of the electrode film can increase the structural stability and reduce the expansion and deformation, the weather resistance storage and processability of the electrode film can be improved.

[0171] Single-sided dry electrode

[0172] The above electrode diaphragms (1-II), (2-II), (3-II), (4-II), (5-II), (6-II), (7-II), (8-II), (9-II), and the electrode diaphragm (11) are respectively subjected to roll lamination and diaphragm compaction operations with an aluminum foil substrate (purchased from Nano BLUEGLOWNANO Co., Ltd., thickness: 12 μm) using a roll press (purchased from TOKYO, model: ōNO 2RM-350DRR), and the roll pressure (0 - 30 kgf / cm 2 ) and the roll speed (1 m / min) are adjusted to obtain the single-sided dry electrodes (1) to (9) and the electrode (10) after roll compaction. The compaction density of the corresponding electrodes is shown in Table 4.

[0173] Peel strength

[0174] Measure the peel strength between the current collector layer and the active layer of the dry electrodes (1) to (9) and the electrode (10). The results are shown in Table 4. The measurement of the peel strength is carried out using a universal tensile testing machine (purchased from SHIMADZU Corporation, model: AG-XPLIS), and referring to the 180-degree peel strength test specified in ASTM D903-98, the above-mentioned roll-pressed single-sided dry electrode sheets are cut into rectangular strips of 120 mm × 25 mm to obtain the electrode sheet samples to be tested. Stick an insulating tape with a specification of 18 mm * 35 mm on the top of a stainless steel plate, stick one side of a double-sided tape with a specification of 30 mm * 100 mm on the stainless steel plate with the insulating tape adhered, and the other side on the front of the dressing layer of the single-sided dry electrode sheet. Cut the base paper of the double-sided tape into a rectangular strip with a specification of 30 mm * 30 mm and stick it under the electrode sheet, and a rectangular strip of the base paper of the double-sided tape with a specification of 30 mm * 50 mm on the upper surface of the electrode plate. After rolling the electrode plate covered with the base paper back and forth 2 times with a rubber roller weighing 2 kg, fix the free end of the electrode plate to the upper mold of the tensile testing machine, and fix the bottom end of the stainless steel plate to the lower mold of the tensile testing machine. Set the parameters of the tensile tester, the peel length is 40 mm, the width is 18 mm, start the tensile tester to perform a 180° peel test at a peel speed of 50 mm / min to obtain the peel strength, as shown in Table 4.

[0175] Table 4

[0176]

[0177] Electrode diaphragms with high compaction density have multiple advantages and benefits, especially in battery technology, including: increased energy density, improved conductivity (reduced internal resistance), enhanced charge and discharge performance of the battery, improved structural stability, increased cycle life, reduced battery swelling and deformation (enhanced safety), and improved thermal conductivity of the battery (enhanced thermal management performance). As shown in Table 4, the compaction density of dry electrodes (1) to (8) in the examples all exceeded 2.35 g / cm 3 (even reaching 2.50 g / cm 3 or above), having more advantages and benefits compared to electrodes of the wet process.

[0178] The peel strength of the electrode is one of the important indicators for evaluating its stability and reliability during battery use. It reflects the bonding force between the electrode composite material and the metal foil. Insufficient peel strength may lead to problems such as electrode detachment and current transmission interruption during battery use. The greater the peel strength, the more it can ensure the performance, cycle life, and safety of the battery. As shown in Table 4, at a comparable electrode compaction density (such as 2.3 - 2.4 g / cm 3 ), the peel strength of the dry electrode is greater than that of the wet process electrode, and the greater the compaction density of the electrode, the higher the peel strength of the electrode will be.

[0179] Evaluating electrode performance with a half-cell

[0180] Example 17

[0181] Provide electrode (4) as the positive plate, provide a polypropylene separator (product number 2320, purchased from Celgard, thickness about 20 μm), and provide an electrolyte for lithium iron phosphate battery (purchased from Formosa Plastics Corporation, Taiwan, China, model: LE), with lithium metal as the negative plate.

[0182] Next, arrange them in the order of negative plate / separator / positive plate (where the active layer of the positive electrode faces the separator), pour the electrolyte (purchased from Formosa Plastics Corporation, product number FPC - 401) between the positive plate and the negative plate, so that the separator is in the electrolyte, and assemble into a CR2032 button-type battery (size: 3.2 mm (thick) x 20 mm (wide) x 20 mm (long)) to obtain button-type battery (1). Let it stand for one day to allow the electrolyte to diffuse and infiltrate the positive plate and the negative plate. Then place button-type battery (1) in the test mold of a button-type battery charger / discharger (MACCOR SERIER4000), charge it to 3.75 V at a current of 0.1C, and discharge it to 2.5 V at a current of 0.1C (cut-off = 0.01C). Repeat the charge and discharge cycle three times to complete the formation process, measure and record the electrical properties of button-type battery (1), and the results are shown in Table 5.

[0183] Example 18

[0184] Provide an electrode (7) as the positive electrode plate, provide a polypropylene separator (product number 2320, purchased from Celgard, thickness about 20 μm), and provide an electrolyte for a lithium iron phosphate battery (purchased from Formosa Plastics Corporation, Taiwan, China, model: LE), with lithium metal as the negative electrode plate.

[0185] Next, arrange them in the order of negative electrode plate / separator / positive electrode plate (where the active layer of the positive electrode faces the separator), pour the electrolyte (purchased from Formosa Plastics Corporation, Taiwan, China, product number of lithium iron phosphate electrolyte is FPC-401) between the positive electrode plate and the negative electrode plate, make the separator located in the electrolyte, assemble into a CR2032 button-type battery (size: 3.2 mm (thickness) x 20 mm (width) x 20 mm (length)), and obtain the button-type battery (2). Let it stand for one day to allow the electrolyte to diffuse and infiltrate the positive electrode plate and the negative electrode plate. Then, place the button-type battery (2) in the test mold of a button-type battery charger / discharger (MACCOR SERIER4000), charge it to 3.75 V at a current of 0.1C, and discharge it to 2.5 V at a current of 0.1C (cut-off = 0.01C). Repeat the charge and discharge cycle three times to complete the formation process, measure and record the electrical properties of the button-type battery (2), and the results are shown in Table 5.

[0186] Comparative Example 4

[0187] Provide an electrode (9) as the positive electrode plate, provide a polypropylene separator (product number 2320, purchased from Celgard, thickness about 20 μm), and provide an electrolyte for a lithium iron phosphate battery (purchased from Formosa Plastics Corporation, Taiwan, China, model: LE), with lithium metal as the negative electrode plate.

[0188] Next, arrange them in the order of negative electrode plate / separator / positive electrode plate (where the active layer of the positive electrode faces the separator), pour the electrolyte (purchased from Formosa Plastics Corporation, Taiwan, China, product number is FPC-401) between the positive electrode plate and the negative electrode plate, make the separator located in the electrolyte, assemble into a CR2032 button-type battery (size: 3.2 mm (thickness) x 20 mm (width) x 20 mm (length)), and obtain the button-type battery (3). Let it stand for one day to allow the electrolyte to diffuse and infiltrate the positive electrode plate and the negative electrode plate. Then, place the button-type battery (3) in the test mold of a button-type battery charger / discharger (MACCOR SERIER4000), charge it to 3.75 V at a current of 0.1C, and discharge it to 2.5 V at a current of 0.1C (cut-off = 0.01C). Repeat the charge and discharge cycle three times to complete the formation process, measure and record the electrical properties of the button-type battery (3), and the results are shown in Table 5.

[0189] Comparative Example 5

[0190] Provide an electrode (10) as the positive electrode plate, provide a polypropylene separator (product number 2320, purchased from Celgard, thickness about 20 μm), and provide an electrolyte for a lithium iron phosphate battery (purchased from Formosa Plastics Corporation, Taiwan, China, model: LE), with lithium metal as the negative electrode plate.

[0191] Next, arrange them in the order of negative electrode plate / separator / positive electrode plate (where the active layer of the positive electrode faces the separator), pour the electrolyte (purchased from Formosa Plastics Corporation, product number FPC-401) between the positive electrode plate and the negative electrode plate, so that the separator is located in the electrolyte, and assemble it into a CR2032 button-type battery (size: 3.2 mm (thick) x 20 mm (wide) x 20 mm (long)) to obtain a button-type battery (4). Let it stand for one day to allow the electrolyte to diffuse and infiltrate the positive electrode plate and the negative electrode plate. Then, place the button-type battery (4) in the test mold of a button-type battery charger / discharger (MACCOR SERIER4000), charge it to 3.75 V at a current of 0.1C, and discharge it to 2.5 V at a current of 0.1C (cut-off = 0.01C). Repeat the charge-discharge cycle three times to complete the formation process, measure and record the electrical properties of the button-type battery (4), and the results are shown in Table 5.

[0192] Table 5

[0193]

[0194]

[0195] As can be seen from Table 5, the impedance value of the half-cell formed by the dry electrode described in the present invention after formation is only about 7-9 Ω. Compared with the battery containing the electrode formed by the wet process (impedance value about 21-23 Ω), it has a lower impedance, can improve the energy efficiency, enhance the battery performance, extend the battery life, increase the stability and safety, and improve the discharge stability.

[0196] In summary, through the electrode material with a specific structure and composition described in the present invention, the electrode material described in the present invention can be used to form an active layer on the surface of the current collector layer at a relatively low operating temperature by an electrode process (such as a dry electrode process). In this way, the formed active layer not only has better mechanical strength and good adhesion, but also can improve the active layer coating weight (mass loading), compacted density, and stability of the obtained electrode, thereby increasing the charge-discharge capacity and energy density of the battery, and significantly reducing the internal resistance, which can improve the energy efficiency, enhance the battery performance, extend the battery life, increase the stability and safety, and improve the discharge stability.

[0197] Although the present invention has been disclosed above by way of several embodiments, it is not intended to limit the present invention. Any person having ordinary knowledge in the technical field to which the present invention pertains may make any changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the appended claims.

Claims

1. An electrode material comprising: an active particle; and A cladding layer partially or completely covers the surface of the active particle, wherein the cladding layer comprises: 5 to 70 parts by weight of a conductive additive; and 30 to 95 parts by weight of a first polymer, wherein the total weight of the first polymer and the conductive additive is 100 parts by weight, wherein the first polymer is a product of a polymerization reaction of a compound having two acrylate groups and an ethylene / vinyl acetate copolymer, wherein the compound having two acrylate groups has a structure shown in formula (I): ， Among them A 1 For single bonds, oxygen, or -CH=CH-; each R 1 is independently hydrogen or methyl; each R 2 is independently hydrogen or methyl; and each R 3 are independently hydrogen, methyl, or ethyl. 2 . The electrode material according to claim 1 , wherein a weight ratio of the compound having two acrylate groups to the ethylene / vinyl acetate copolymer is 1:99 to 99:

1.

3. The electrode material according to claim 1, wherein the ethylene / vinyl acetate copolymer has a repeating unit represented by formula (II) and a repeating unit represented by formula (III) ， The quantity ratio of the repeating unit represented by formula (II) to the repeating unit represented by formula (III) is 1:1250 to 300:

1.

4. The electrode material according to claim 1, wherein the coating layer further comprises: 0.1 to 30 parts by weight of a second polymer, wherein the second polymer is polyamide, polyimide, polymaleimide, polybismaleimide, polyacrylate, polyacrylic acid, polyvinyl alcohol, sodium carboxymethyl cellulose, polystyrene, polystyrene butadiene copolymer, polyurethane, polyvinyl pyrrolidone, polyvinyl chloride, polyacrylonitrile, polybutadiene, or a combination thereof. The electrode material according to claim 1 , wherein the active particles are positive electrode active materials or negative electrode active materials. 6 . The electrode material according to claim 1 , wherein the conductive additive is a conductive additive, an ion conductive additive, or a combination thereof. The electrode material according to claim 1 , wherein the particle size of the active particles is 50 nm to 100 μm. The electrode material according to claim 1 , wherein the coating layer has a thickness of 10 nm to 5 μm. 9 . The electrode material according to claim 1 , wherein a weight ratio of the coating layer to the active particles is 3:97 to 10:

90. 10 . The electrode material according to claim 1 , wherein the electrode material has a core-shell structure, consisting of a core and a shell layer coating the core, wherein the core is the active particle, and the shell layer is the coating layer.

11. An electrode comprising: a current collecting layer; and An active layer is disposed on the current collecting layer, wherein the active layer comprises the electrode material according to any one of claims 1-10. The electrode according to claim 11 , wherein the active layer is composed of the electrode material.

13. A battery comprising: A positive electrode; a separation membrane; and A negative electrode, wherein the negative electrode is separated from the positive electrode by the isolation film, wherein at least one of the positive electrode and the negative electrode is the electrode according to claim 11.

14. A method for preparing an electrode material, for preparing the electrode material according to claim 1, comprising: Providing a composition comprising the active particle, the conductive additive, and the first polymer; The composition is subjected to a spray granulation process or a melt kneading process to obtain the electrode material. 15 . The method for preparing an electrode material according to claim 14 , wherein when the spray granulation process is performed on the composition, the composition further comprises a solvent, so that the active particles, the conductive additive, and the first polymer are uniformly dispersed in the solvent.

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