Electrode for rechargeable lithium battery, method of manufacturing the electrode, and rechargeable lithium battery comprising the electrode

Abstract

Some example embodiments include an electrode for a rechargeable lithium battery, a method of manufacturing the electrode, and a rechargeable lithium battery including the electrode. The electrode includes a current collector, an electrode active material layer on the current collector, and a coating layer on the electrode active material layer. The coating layer includes nanofibers and a curable polymer distributed in an island shape between the nanofibers.

Description

Technical Field

[0001] This disclosure relates to an electrode for a rechargeable lithium battery, a method for manufacturing the electrode, and a rechargeable lithium battery including the electrode. Background Technology

[0002] With the increasing use of batteries in electronic devices such as mobile phones, laptops, and electric vehicles, the demand for rechargeable lithium batteries with high energy density and high capacity is growing. Therefore, improving the performance of rechargeable lithium batteries can be beneficial.

[0003] A rechargeable lithium battery includes a positive electrode and a negative electrode as well as an electrolyte. The positive and negative electrodes include active materials capable of inserting and deintercalating lithium ions, and generate electrical energy through oxidation and reduction reactions that occur when lithium ions are inserted and deintercalated from the positive and negative electrodes. Summary of the Invention

[0004] Some example embodiments include a rechargeable lithium battery with electrodes having desired or improved strength, adhesive strength, and permeability, as well as low resistance, and the rechargeable lithium battery has desired or improved safety and improved electrochemical performance (such as cycle life characteristics) by reducing or suppressing gas generation during operation.

[0005] Some example embodiments provide an electrode for a rechargeable lithium battery, the electrode comprising: a current collector; an electrode active material layer on the current collector; and a coating layer on the electrode active material layer, wherein the coating layer comprises nanofibers and a curable polymer distributed in an island shape between the nanofibers.

[0006] Some example embodiments provide a method for manufacturing an electrode for a rechargeable lithium battery, the method comprising the steps of: preparing a fiber spinning solution; preparing a spray solution comprising a curable polymer; electrospinning the fiber spinning solution into nanofibers on the surface of an electrode active material layer, and simultaneously or concurrently electrospraying the spray solution; and curing the curable polymer to form a coating layer on the surface of the electrode active material layer.

[0007] Some example embodiments provide a rechargeable lithium battery that includes: the electrode; and an electrolyte.

[0008] The electrodes according to some example embodiments have desired or improved strength, adhesion, and permeability, and the rechargeable lithium battery including the electrodes exhibits desired or improved safety because gas generation is reduced or suppressed during operation. Attached Figure Description

[0009] Figure 1This is a schematic cross-sectional view of an electrode assembly according to some example embodiments.

[0010] Figure 2 This is a schematic cross-sectional view of a negative electrode according to some example embodiments.

[0011] Figures 3 to 6 This is a schematic view of a rechargeable lithium battery according to some example embodiments.

[0012] Figure 7 This is an SEM image of the surface of the coating layer manufactured in Example 1.

[0013] Figure 8 This is a flowchart illustrating a method for manufacturing an electrode for a rechargeable lithium battery according to an example embodiment. Detailed Implementation

[0014] Example embodiments are described in detail below. However, these embodiments are given by way of example, and this disclosure is not limited thereto, and is defined by the scope of the claims described above.

[0015] As used herein, unless otherwise specifically defined, it is understood that when an element such as a layer, film, region, or substrate is referred to as being “on” another element, it may be directly on said other element, or there may be an intervening element.

[0016] Unless otherwise stated in this specification, a singular expression may also include a plural expression. Furthermore, unless otherwise stated, “A or B” may mean “including A, including B, or including both A and B”.

[0017] As used herein, “combination of them” means mixtures, laminates, complexes, copolymers, alloys, blends, reaction products, etc. of the components.

[0018] As used herein, unless otherwise defined, particle size can be the average particle size. Alternatively, particle size can refer to the average particle size (D50) of the diameter of particles having a cumulative volume of 50% in a particle size distribution. The average particle size (D50) can be measured by methods known to those skilled in the art, for example, by a particle size analyzer or by transmission electron microscopy or scanning electron microscopy images. Optionally, data analysis is performed using a dynamic light scattering measurement device, and the number of particles in each particle size range is counted. Thus, the average particle size (D50) value can be readily obtained by calculation. Optionally, it can be measured using laser diffraction. When measured by laser diffraction, for example, the particles to be measured are dispersed in a dispersion medium and then introduced into a commercially available laser diffraction particle size measurement device (e.g., Microtrac MT3000), and irradiated with ultrasound at an output of 60W at approximately 28kHz to calculate the average particle size (D50) based on a 50% particle size distribution in the measurement device.

[0019] When the terms “about” or “substantially” are used in conjunction with numerical values ​​in this specification, it means that the relevant numerical value includes a tolerance of ±10% around the stated value. When a range is specified, the range includes all values ​​within that range, such as increments of 0.1%.

[0020] electrode An electrode for a rechargeable lithium battery according to some example embodiments includes: a current collector; an electrode active material layer on the current collector; and a coating layer on the electrode active material layer.

[0021] The coating layer can be applied to the electrode active material layer and can be integrated with the electrode active material layer.

[0022] The coating layer can form a separator between the positive and negative electrodes to reduce or prevent short circuits; therefore, rechargeable lithium batteries according to some example embodiments may not require a separate separator. Consequently, because rechargeable lithium batteries according to some example embodiments do not require a separate separator, the separator can be omitted during manufacturing. Furthermore, because a lamination process to combine the separator and electrodes is not required, the battery can be manufactured economically, and energy density can be increased while reducing battery size.

[0023] In some example embodiments, a battery can be manufactured by stacking electrodes and counter electrodes so that the active material layer of the counter electrode contacts the coating layer to create an electrode assembly, inserting the electrode assembly into a battery housing, and then injecting an electrolyte.

[0024] As another example, a battery can be manufactured by forming both a positive electrode and a negative electrode, including coatings according to some example embodiments, stacking the positive and negative electrodes such that the respective coatings come into contact with each other to form an electrode assembly, inserting the positive and negative electrodes into a housing and then injecting an electrolyte.

[0025] As another example, all-solid-state rechargeable batteries can be manufactured by stacking (e.g., sequentially stacking) a solid electrolyte layer and a counter electrode on a coating layer.

[0026] Meanwhile, when using electrodes according to some example embodiments, the diaphragm can be placed separately between the positive and negative electrodes, depending on the required specifications.

[0027] In various example embodiments, the coating can integrate with the electrodes to achieve strong adhesion strength while achieving desired or improved permeability and physical strength between the positive and negative electrodes, and can effectively perform the function of isolating the two electrodes even with a thin thickness, and can improve the cycle life characteristics of the battery by reducing or preventing the growth of lithium dendrites formed during charging and discharging.

[0028] In addition, the fact that the coating layer is integrated with the electrode active material layer can refer to the state in which the coating layer is directly formed on the electrode active material layer by means of electrospinning and electrospraying, and a portion of the coating layer components permeate the electrode active material layer, and can refer to the region in which the electrode active material layer components and the coating layer components are mixed with each other at the interface between the electrode active material layer and the coating layer.

[0029] According to some example embodiments, compared to forming a coating layer on the electrode active material layer using a general coating method or fabricating the coating layer separately in film form and then stacking it on the electrode active material layer, this electrode can make the electrode active material layer and the coating layer more firmly bonded and exhibit higher adhesive strength.

[0030] Therefore, when a cross-section of an electrode assembly is photographed using a scanning electron microscope (SEM), the fact that the coating layer and the electrode active material layer are integrated can be clearly seen. Although the electrode active material layer and the coating layer are distinguishable, the interface (boundary portion) between the electrode active material layer and the coating layer may appear uneven (uneven), or there may be areas of a certain thickness at the interface between the electrode active material layer and the coating layer where the components of the electrode active material layer and the components of the coating layer are mixed.

[0031] In addition, because the electrode active material layer and the coating layer are integrated, the electrode active material layer and the coating layer are in close contact with each other, so that the interface between the electrode active material layer and the coating layer can be formed into a dense structure without pores.

[0032] Therefore, because the coating layer is integrated with the electrode active material layer, the coating layer can be in a more robust bond with the electrode active material layer. This improves the physical strength and durability of the battery, and also improves processability because there are virtually no challenges of layer separation or slippage during battery manufacturing.

[0033] In addition, polymer membranes (such as polypropylene) that are commonly used as separators may undergo dimensional changes due to thermal shrinkage during repeated charging and discharging, which may reduce the separation function of the positive and negative electrodes and potentially cause challenges such as short circuits.

[0034] However, because the coating layer constituting the separator is integrated with the electrode active material layer, rechargeable lithium batteries including electrodes according to some example embodiments do not have challenges such as thermal shrinkage.

[0035] Furthermore, integrating the coating layer with the electrode active material layer can improve heat resistance and insulation while reducing resistance. If the coating layer is not integrated with the electrode active material layer but is formed as a separate layer and then bonded to the electrode active material layer (when the coating layer is not integrated with the electrode active material layer but is formed as a separate layer and then bonded to the electrode active material layer), there may be a disadvantage of increased lithium migration resistance due to the lack of integration between the coating layer and the electrode active material layer, and additional processes may be required for integration.

[0036] The coating layer included in the electrode according to some example embodiments comprises nanofibers and a curable polymer distributed in an island shape between the nanofibers.

[0037] According to some example embodiments, the coating layer may be or include a layer formed by simultaneously or concurrently performing electrospinning of nanofibers and electrospraying of curable polymers.

[0038] For example, nanofibers formed by electrospinning can have a three-dimensional network structure (e.g., a woven or non-woven structure). Therefore, when nanofibers have a three-dimensional network structure (e.g., a woven or non-woven structure), they can have the advantage of reducing or minimizing the resistance to Li ion migration.

[0039] The presence of nanofibers with a three-dimensional network structure can refer to the formation of a porous structure. For example, the average diameter of the pores included in the nanofibers can be in the range of about 10 nm to about 200 nm (e.g., about 10 nm to about 150 nm, about 50 nm to about 150 nm, or about 50 nm to about 100 nm). When the average diameter of the pores meets the above range, the coating can exhibit desired or improved permeability, adhesive strength, and mechanical strength.

[0040] The diameter of a pore refers to the diameter of a single pore contained in a nanofiber having a three-dimensional network structure, and the longest axis of the cross section that runs through the pore can be defined as the diameter.

[0041] The average diameter of the holes can be referred to as the value obtained by measuring the cross-sectional diameter of approximately 20 holes in an SEM image of the surface of the coating and calculating their arithmetic mean.

[0042] For example, curable polymers formed by electrospraying can be distributed in an island shape between the nanofibers of the aforementioned three-dimensional network structure. Therefore, by distributing the curable polymer in an island shape on the surface of the nanofibers having the aforementioned three-dimensional network structure and at the connection points between the nanofibers, the mechanical strength of the nanofibers themselves can be improved, and the strength of the coating layer can also be improved by improving the bonding force between the nanofibers.

[0043] Furthermore, because the curable polymer forms like protrusions on the surface of the nanofibers, it improves the permeability of the coating, thereby enhancing battery safety. Additionally, this structure has the advantage of improving the adhesion strength between the coating and the electrode active material layer, thus reducing or preventing coating delamination (or peeling) and reducing or preventing gas generation during battery operation.

[0044] For example, according to some example embodiments, the electrode can be a negative electrode, a positive electrode, or both; in the example, the electrode can be a negative electrode. The coating layer will be described below primarily based on the case where the electrode is a negative electrode, but the same applies to a positive electrode.

[0045] Figure 1 This is a schematic cross-sectional view of an electrode assembly 1 including a negative electrode 20 when the electrode is a negative electrode, according to some example embodiments.

[0046] Reference Figure 1 According to some example embodiments, the electrode assembly 1 includes: a negative electrode 20, including a current collector 21, a negative electrode active material layer 22 on the current collector 21 and a coating layer 23 on the negative electrode active material layer 22; and a positive electrode 10.

[0047] exist Figure 1 In the diagram, the negative electrode active material layer 22 and the coating layer 23 are shown as being formed as separate layers, but this description is provided only to represent the negative electrode active material layer and the coating layer, and the dashed line indicates that the negative electrode active material layer 22 and the coating layer 23 are integrated.

[0048] Because the electrode assembly 1 according to some example embodiments has an integrated negative electrode active material layer 22 and coating layer 23, the dimensions of the negative electrode active material layer 22 and coating layer 23 in the width direction can be substantially the same.

[0049] For example, because the coating layer 23 is integrated with the negative electrode active material layer 22, at least a portion of the nanofibers and curable polymers can penetrate into the interior of the negative electrode active material layer 22.

[0050] Figure 2 This is a schematic cross-sectional view of the negative electrode 20 according to some example embodiments.

[0051] Reference Figure 2 The negative electrode 20 includes a current collector 21, a negative electrode active material layer 22 on the current collector 21, and a coating layer 23 on the negative electrode active material layer 22. The coating layer includes nanofibers 231 and a curable polymer 232 distributed in an island shape between the nanofibers 231.

[0052] The curable polymer 232 can serve as an adhesive that bonds nanofibers 231 together or bonds nanofibers 231 to the negative electrode active material layer 22 within the coating layer 23.

[0053] For example, when describing the curable polymer 232 as distributed in an island shape between the nanofibers 231, this can mean that the curable polymer 232 exists in the form of particles or dots between the nanofibers 231. In another example, it can be understood as a case where multiple curable polymers in the form of particles or dots aggregate together to form an island shape.

[0054] Reference Figure 2 The curable polymer 232 within the coating layer 23 can be in the form of protrusions on the surface of the nanofibers 231, or at the junctions of the nanofibers 231. Alternatively, the curable polymer 232 can be disposed in the space between the plurality of nanofibers 231, and can be disposed at the junction of the negative electrode active material layer 22 and the nanofibers 231.

[0055] For example, the curable polymer 232 is in the form of protrusions on the surface of the nanofiber 231, which can improve the mechanical strength of the nanofiber itself and improve the air permeability of the coating.

[0056] For example, the curable polymer 232 is present at the junction of the nanofibers 231, thereby improving the mechanical strength of the nanofibers themselves and the bonding force between the nanofibers, and thus also improving the strength of the coating.

[0057] For example, a curable polymer 232 is disposed at the junction of the negative electrode active material layer 22 and the nanofiber 231 of the negative electrode 20, thereby improving the adhesion strength between the coating layer 23 and the negative electrode active material layer 22, thereby reducing or preventing delamination of the coating layer and reducing or preventing gas generation during battery operation.

[0058] For example, by observing scanning electron microscopy (SEM) images of the surface of the coating, the shape of the nanofibers and curable polymers within the coating can be confirmed.

[0059] In the SEM image of the coating, the curable polymer is located at the junctions between the nanofibers and appears as a protrusion on the surface of the nanofibers, thus allowing it to be distinguished within the image.

[0060] For example, nanofibers can be formed by electrospinning a heat-resistant polymer, which may include the heat-resistant polymer. There are no restrictions on the type of heat-resistant polymer that can be used, as long as it is electrospinnable.

[0061] For example, heat-resistant polymers may include polymers of at least one of the following: polyimide (PI), polyethylene (PE), polypropylene (PP), polyester, polyamide, polyamic acid, polyamide-imide (PAI), polyetherimide, polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polycarbonate (PC), polyvinyl chloride (PVC), polyvinylidene chloride, polyethylene glycol derivatives, polyoxides, polyvinyl acetate, polystyrene (PS), polyvinylpyrrolidone (PVP), copolymers thereof, and combinations thereof.

[0062] For example, the average diameter (nm) of the nanofibers can be in the range of about 10 nm to about 200 nm (e.g., about 10 nm to about 150 nm, about 50 nm to about 150 nm, or about 50 nm to about 100 nm). For example, because the coating layer according to some example embodiments is manufactured by electrospinning, the average diameter value of the nanofibers can be in a range similar to the average diameter value of the pores included in the aforementioned nanofibers.

[0063] If the average diameter (nm) of the nanofibers meets the above range (when the average diameter (nm) of the nanofibers meets the above range), the coating can exhibit the desired or improved air permeability, adhesive strength and mechanical strength.

[0064] The diameter of a nanofiber can refer to the widest diameter among the fiber diameters measured based on the cross-section of each nanofiber, and can be measured in a direction perpendicular to the length direction of the nanofiber.

[0065] The average diameter of the nanofibers can be calculated by randomly measuring the cross-sectional diameter of about 20 nanofibers in a scanning electron microscope image of the surface of the coating and then calculating their arithmetic mean.

[0066] For example, curable polymers can be used without restriction, as long as the curable polymer is a material that can be sprayed into island shapes by an electrospray process, and conductive materials cannot be used.

[0067] For example, curable polymers may include thermosetting polymers, photocurable polymers, or combinations thereof.

[0068] Thermosetting polymers may include at least one of epoxy polymers, phenolic polymers, amino polymers, polyester polymers, polyurethane polymers, and combinations thereof. As an example, thermosetting polymers may include epoxy polymers having desired or improved adhesive strength, heat resistance, chemical resistance, and mechanical strength.

[0069] For example, epoxy polymers may include at least one of bisphenol A type epoxy polymers, bisphenol F type epoxy polymers, novolac type epoxy polymers, aliphatic epoxy polymers, alicyclic epoxy polymers, glycidylamine epoxy polymers, modified epoxy polymers, and combinations thereof.

[0070] Phenolic polymers may include at least one of novolac-type phenolic polymers, resol-type phenolic polymers, modified phenolic polymers, and combinations thereof.

[0071] Photocurable polymers may include at least one of acrylate polymers, epoxy acrylate polymers, urethane acrylate polymers, polyester acrylate polymers, silicone acrylate polymers, silicone photocurable polymers, and combinations thereof.

[0072] For example, the average diameter (nm) of the curable polymer can be in the range of about 50 nm to about 500 nm (e.g., about 50 nm to about 400 nm, about 100 nm to about 400 nm, or about 100 nm to about 300 nm). When the average diameter of the curable polymer meets the above range, the coating can exhibit desired or improved mechanical strength, breathability, and adhesive strength.

[0073] The diameter of a curable polymer can refer to the widest diameter among the diameters of polymers measured based on a single island polymer.

[0074] The average diameter of the curable polymer can be calculated by measuring the size (diameter or length of the longest axis) of approximately 20 randomly selected particles (or islands) of the curable polymer in a scanning electron microscope image of the surface of the coating and calculating their arithmetic mean.

[0075] For example, based on 100 parts by weight of nanofibers, the curable polymer may be included in an amount ranging from about 1 part by weight to about 50 parts by weight (e.g., about 1 part by weight to about 40 parts by weight, about 5 parts by weight to about 40 parts by weight, about 5 parts by weight to about 30 parts by weight, or about 5 parts by weight to about 20 parts by weight).

[0076] If a curable polymer is included in an amount less than about 1 part by weight based on 100 parts by weight of nanofibers, the physical properties of the coating (such as strength, adhesive strength, and air permeability) may be degraded; if a curable polymer is included in an amount greater than about 50 parts by weight, the electrospinning properties of the nanofibers may be degraded, and the heat resistance of the coating may be reduced.

[0077] For example, the weight ratio of nanofibers included in the coating to the weight of the curable polymer can be in the range of about 1:0.01 to about 1:0.5 (e.g., about 1:0.01 to about 1:0.4, about 1:0.05 to about 1:0.4, about 1:0.05 to about 1:0.3, or about 1:0.05 to about 1:0.2). When this weight ratio is met, electrodes with desired or improved strength, adhesive strength, and permeability, as well as rechargeable lithium batteries with desired or improved stability, can be achieved.

[0078] For example, the thickness of the coating can be in the range of about 1 μm to about 25 μm (e.g., greater than or equal to about 5 μm or greater than or equal to about 10 μm and less than or equal to about 20 μm or less than or equal to about 15 μm).

[0079] If the thickness of the coating is within the above range (when the thickness of the coating is within the above range), it can exhibit a reasonably high density, thus more effectively reducing or suppressing the formation of Li dendrites during charging and discharging.

[0080] For example, the peel strength of the coating can be greater than about 0.21 gf / mm, for example, in the range of about 0.25 gf / mm to about 3 gf / mm, about 0.25 gf / mm to about 2 gf / mm, about 0.25 gf / mm to about 1 gf / mm, about 0.25 gf / mm to about 0.7 gf / mm, about 0.28 gf / mm to about 0.7 gf / mm, or about 0.28 gf / mm to about 0.62 gf / mm. The peel strength of the coating represents the adhesive strength between the electrode active material layer and the coating layer, and as shown by the above values, the coating layer can be substantially firmly adhered to the electrode active material layer.

[0081] For example, the peel strength of the coating can be measured by attaching a 1.5cm wide strip of tape (3M Celotape, registered trademark) to a negative electrode fixed to a stainless steel plate and using a peel tester (manufacturer: KIPAE E).

[0082] For example, peel strength can be measured using a 180° peel strength test under conditions of a 1kg load sensor and a peel speed of 100mm / min.

[0083] For example, the permeability (sec / 100cc) of the coating layer can be in the range of about 60 sec / 100cc to about 400 sec / 100cc (e.g., about 60 sec / 100cc to about 300 sec / 100cc, about 60 sec / 100cc to about 200 sec / 100cc, about 70 sec / 100cc to about 200 sec / 100cc, or about 70 sec / 100cc to about 180 sec / 100cc). If the permeability of the coating layer meets the above-mentioned numerical range (when the permeability of the coating layer meets the above-mentioned numerical range), the safety of the battery can be improved by reducing or preventing gas generation during battery operation.

[0084] For example, the air permeability of a coating can be obtained by measuring the time (in seconds) required for 100cc of air to permeate using an air permeability measuring device (e.g., Asahi Seiko, EG01-55-1MR).

[0085] The electrode according to some example embodiments may also include an inorganic layer (not shown) on the coating layer. The inorganic layer may be in the form of a dense layer and may be formed, for example, by electrospraying. However, the method for forming the inorganic layer is not limited to electrospraying; as long as the inorganic layer can be formed as a dense layer, the method can be performed using a general coating process such as a doctor blade. If the inorganic layer is in the form of a dense layer (when the inorganic layer is dense), the formation of Li dendrites can be reduced or suppressed more effectively; if the inorganic layer is a porous layer (when the inorganic layer is porous), undesirable short circuits may occur during charging and discharging.

[0086] The inorganic layer may include an inorganic material comprising at least one or a combination thereof, of alumina (Al2O3), boehmite (alumina hydroxide), zirconium oxide, titanium dioxide (TiO2), and silicon dioxide (SiO2). When the inorganic layer is further included on a coating layer, some of the inorganic material may be embedded in the coating layer.

[0087] In addition to the aforementioned coating layer, if an inorganic layer is further included (when an inorganic layer is further included), a heat-resistant synergistic effect can be imparted. Specifically, by including a heat-resistant polymer, challenges of damaging the negative electrode during the battery manufacturing process can be reduced or inhibited. Additionally, the heat-resistant synergistic effect is effective in reducing or inhibiting the occurrence of lithium dendrites during charging and discharging, and the effects of improving heat resistance and puncture strength can be further obtained by including an inorganic material. When a heat-resistant polymer and an inorganic material are mixed to form a single layer, it is difficult to obtain such an effect, so this is not appropriate.

[0088] negative electrode The negative electrode for a rechargeable lithium battery includes a current collector and a negative electrode active material layer on the current collector. The negative electrode active material layer includes a negative electrode active material, and may also include a binder and / or a conductive material.

[0089] For example, the negative electrode active material may include at least one of a material that reversibly embeds / extracts lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / dedoping lithium, and a transition metal oxide.

[0090] The material that reversibly embeds / extracts lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. The crystalline carbon may be graphite such as natural graphite or artificial graphite in the form of amorphous, flaky, lamellar, spherical, or fibrous, and the amorphous carbon may be or include at least one of soft carbon, hard carbon, mesophase pitch carbonization products, calcined coke, etc.

[0091] The lithium metal alloy includes an alloy of lithium and a metal (such as or including at least one of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn).

[0092] The material capable of doping / dedoping lithium may be or include a Si-based negative electrode active material or a Sn-based negative electrode active material. The Si-based negative electrode active material may include silicon, a silicon-carbon composite, SiO x (0 < x ≤ 2), a Si-Q alloy (where Q is or includes at least one of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element (except Si), a Group 15 element, a Group 16 element, a transition metal, a rare earth element, and a combination thereof), and a combination thereof. The Sn-based negative electrode active material may include at least one of Sn, SnO2, Sn-based alloys, and a combination thereof.

[0093] Silicon-carbon composites can be or include composites of silicon and amorphous carbon. According to some example embodiments, the silicon-carbon composite can be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, the silicon-carbon composite can include secondary particles (cores) assembled with primary silicon particles and an amorphous carbon coating (shell) on the surface of the secondary particles. Amorphous carbon can also be present between the primary silicon particles; for example, the primary silicon particles can be coated with amorphous carbon. The secondary particles can be dispersed within an amorphous carbon matrix.

[0094] Silicon-carbon composites may also include crystalline carbon. For example, a silicon-carbon composite may include a core comprising crystalline carbon and silicon particles, and an amorphous carbon coating layer on the surface of the core.

[0095] Si-based or Sn-based negative electrode active materials can be mixed with carbon-based negative electrode active materials.

[0096] For example, the negative electrode active material layer may include about 90 wt% to about 99 wt% of negative electrode active material, about 0.5 wt% to about 5 wt% of binder, and about 0 wt% to about 5 wt% of conductive material.

[0097] The binder causes the negative electrode active material particles to adhere to each other and to adhere the negative electrode active material to the current collector. The binder can be or includes non-aqueous binders, aqueous binders, dry binders, or combinations thereof.

[0098] Non-aqueous adhesives may include at least one of polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide, and combinations thereof.

[0099] The waterborne adhesive may be or include at least one of styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polyepoxygenated alcohol, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0100] When an aqueous binder is used as the negative electrode binder, it may further include a cellulose compound capable of imparting viscosity. The cellulose compound may include at least one of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and their alkali metal salts. The alkali metal may include at least one of Na, K, and Li.

[0101] The dry adhesive may be or include a fibrous polymer material, and may be or include at least one of, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, and combinations thereof.

[0102] Conductive materials are included to provide electrode conductivity, and any electrically conductive material can be used as a conductive material unless it causes an adverse chemical change. Examples of conductive materials include: carbon-based materials, such as at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.; metallic materials such as metal powders or metal fibers, including at least one of copper, nickel, aluminum, silver, etc.; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0103] The negative electrode current collector may include at least one of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with a conductive metal, and combinations thereof.

[0104] Methods for manufacturing electrode assemblies A method for manufacturing an electrode according to some example embodiments includes: preparing a fiber spinning solution; preparing a spray solution comprising a curable polymer; electrospinning the fiber spinning solution into nanofibers on the surface of an electrode active material layer, and simultaneously or concurrently electrospraying the spray solution to form a coating mixture; and curing the electrosprayed curable polymer to form a coating layer on the surface of the electrode active material layer.

[0105] According to a method for manufacturing electrodes based on some example embodiments, a coating layer comprising nanofibers as described above and a curable polymer distributed in an island shape between the nanofibers can be formed by electrospinning a fiber spinning solution and simultaneously or concurrently electrospraying a spray solution.

[0106] First, a fiber spinning solution is prepared. The fiber spinning solution may include polymers and solvents.

[0107] For example, the polymer can be or includes a heat-resistant polymer, and the heat-resistant polymer is the same as described above.

[0108] For example, the solvent may include at least one of dimethylacetamide, dimethyl acetate, dimethylformamide, dimethyl sulfoxide, acetone, and combinations thereof.

[0109] For example, based on a 100 wt% fiber spinning solution, the amount of polymer can be in the range of about 5 wt% to about 30 wt% (e.g., about 10 wt% to about 30 wt% or about 10 wt% to about 20 wt%). If the amount of polymer meets the above range (when the amount of polymer meets the above range), the electrospinning properties of the spun nanofibers can be improved, and the mechanical strength of the manufactured coating can be improved.

[0110] Next, a spray solution is prepared. The spray solution may include a curable polymer, a solvent, and a binder. The curable polymer may be the same as described above.

[0111] For example, the solvent may include at least one of dimethyl acetate, N-methylpyrrolidone, dimethylformamide, acetone, and combinations thereof.

[0112] For example, the adhesive may include at least one of polyvinylidene fluoride, polyamide-imide, polyvinylpyrrolidone, polyacrylonitrile, copolymers thereof, and combinations thereof.

[0113] For example, based on a 100 wt% spray solution, the amount of curable polymer can be in the range of about 5 wt% to about 30 wt% (e.g., about 10 wt% to about 30 wt% or about 10 wt% to about 20 wt%). When the amount of curable polymer meets the above range, the resulting coating has the advantage of desired or improved heat resistance.

[0114] Next, the fiber spinning solution is electrospun into nanofibers on the surface of the electrode active material layer, and the spray solution is electrosprayed.

[0115] Electrospinning can be performed by the following steps: setting up a nozzle assembly at predetermined or desired intervals, the nozzle assembly consisting of a tip with an orifice size in the range of about 23G (gauge) to about 30G and a collecting roller; adding a fiber spinning solution to the tip; setting the target substrate on the collecting roller; and then applying a voltage in the range of about 35kV to about 100kV to the tip.

[0116] The number of tips can be appropriately adjusted according to the type and amount of polymer included in the fiber spinning solution, and can be in the range of, for example, from about 1 to about 1,000.

[0117] The predetermined or desired distance between the nozzle assembly and the target substrate can be in the range of approximately 10 cm to approximately 20 cm.

[0118] If the aperture size of the tip is in the range of about 25G to about 30G (when the aperture size of the tip is in the range of about 25G to about 30G), then the aperture size of the tip can be suitable because a coating layer of the desired shape can be formed.

[0119] According to the electrospinning process, a polymer solution is spun into a fiber shape and stretched, then spun onto a target substrate as nanofibers to form a coating layer. To explain this in more detail, the fiber spinning solution is suspended as droplets at a tip due to surface tension. When a voltage is applied, charges accumulate on the surface of the fiber spinning solution droplets, generating repulsive forces between the charges. Therefore, the repulsive force between the charges points in the opposite direction to the surface tension of the solution. When the voltage reaches a threshold point, a Taylor cone is formed, from which the polymer solution is ejected and subjected to multiaxial stretching in a churning zone. The nanofibers are collected by a collecting roller into a non-woven fabric to form an organic coating layer.

[0120] For example, the electrospinning process can be performed at a temperature ranging from about 20°C to about 30°C and a relative humidity ranging from about 0% to about 60%. If the electrospinning process is performed under the above-mentioned temperature and relative humidity conditions, it has the advantage of maintaining the fiber with a predetermined or desired thickness while spinning.

[0121] Additionally, the rolling speed of the collecting roller can be adjusted (e.g., in the range of about 0.1 m / min to about 3 m / min) to ensure an appropriate thickness of the coating. Furthermore, the fiber spinning solution can be adjusted to be discharged from the tip at a flow rate in the range of about 1 mL / min to about 100 mL / min.

[0122] Additionally, interference between tips can be reduced or minimized by properly controlling the tip air, thus ensuring substantially uniform electrospinning. Tip air can be controlled by flowing compressed air at a pressure ranging from about 0.01 MPa to about 0.5 MPa.

[0123] For example, the electrospinning process can be performed approximately two or more times.

[0124] Since nanofibers are formed through electrospinning, the resulting nanofibers can have a three-dimensional network structure. Because the coating layer is formed through electrospinning, the solvent can easily evaporate, thus better reducing or suppressing the rebound phenomenon of the electrode caused by solvent damage, making this suitable.

[0125] Simultaneously or concurrently with the electrospinning process, the spray solution is electrospinned to form a coating mixture.

[0126] For example, the voltage applied during electrospraying can be in the range of about 15 kV to about 80 kV (e.g., about 15 kV to about 60 kV, about 15 kV to about 40 kV, about 15 kV to about 30 kV, or about 20 kV to about 30 kV). For example, the spray distance during electrospraying can be in the range of about 10 cm to about 30 cm (e.g., about 10 cm to about 25 cm, or about 10 cm to about 20 cm). For example, the spray rate during electrospraying can be in the range of about 0.5 mL / min to about 1.5 mL / min (e.g., about 1.0 mL / min to about 1.5 mL / min, or about 0.5 mL / min to about 1.0 mL / min).

[0127] For example, two or more electrospray processes can be performed.

[0128] Some example embodiments include curing the electrospun curable polymer after the electrospinning and electrospraying processes to form a coating on the surface of the electrode active material layer.

[0129] Depending on the type of curable polymer, curing can be performed using either a thermosetting process or a photocuring process.

[0130] For example, when the curable polymer is a thermosetting polymer (e.g., an epoxy polymer), the thermosetting process can be performed by hot air drying or heat treatment at a temperature ranging from about 70°C to about 120°C. For example, the thermosetting process can be performed at temperatures ranging from about 70°C to about 110°C, about 80°C to about 120°C, about 80°C to about 110°C, about 80°C to about 100°C, or about 90°C to about 100°C.

[0131] For example, when the curable polymer is the aforementioned photocurable polymer, the photocuring process can be performed by irradiation with ultraviolet light or visible light. In this case, the spray solution may also include a photoinitiator.

[0132] The above steps cure the curable polymer, thereby achieving an electrode with desired or improved strength and adhesive strength.

[0133] After the coating layer is formed, rolling can be further performed. The rolling process can be performed at a temperature ranging from about 25°C to about 110°C. If the rolling process is further performed (when the rolling process is further performed), the coating layer is compressed, which can have the advantage of shortening the Li ion migration path and improving the movement of lithium ions during charging and discharging. In addition, by additionally performing the rolling process, the coating layer and the electrode active material layer can be more effectively integrated.

[0134] When the electrode formed by the method for manufacturing an electrode according to some example embodiments is a negative electrode, the electrode assembly can be manufactured by setting the formed negative electrode and positive electrode in contact with each other. Here, the positive electrode is set in contact with the negative electrode, and a coating layer is placed between the positive electrode and the negative electrode.

[0135] positive electrode The positive electrode for a rechargeable lithium battery may include a current collector and a layer of positive electrode active material formed on the current collector. The positive electrode active material layer includes positive electrode active material and may also include a binder and / or a conductive material.

[0136] For example, the positive electrode may also include additives that can constitute a sacrificial positive electrode.

[0137] The positive electrode active material can be or includes compounds capable of intercalating and deintercalating lithium (lithiation intercalation compounds). For example, a composite oxide of lithium with at least one metal (such as or including at least one of cobalt, manganese, nickel and combinations thereof) can be used.

[0138] The composite oxide can be or includes lithium transition metal composite oxides, and examples include at least one of lithium nickel oxides, lithium cobalt oxides, lithium manganese oxides, lithium iron phosphate compounds, cobalt-free lithium nickel manganese oxides, and combinations thereof.

[0139] As an example, a compound represented by any of the following chemical formulas can be used. Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b- c Mn b X c O 2-α D α(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni b Co c L 1 d G e O2 (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4 (0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3 (0≤f≤2); Li a FePO4 (0.90≤a≤1.8).

[0140] In the above chemical formulas, A is or includes at least one of Ni, Co, Mn, and combinations thereof; X is or includes at least one of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, and combinations thereof; D is or includes at least one of O, F, S, P, and combinations thereof; G is or includes at least one of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and combinations thereof; and L 1 It is or includes at least one of Mn, Al and combinations thereof.

[0141] For example, the positive electrode active material can be or includes a high-nickel positive electrode active material. Based on 100 mol% of metals other than lithium in the lithium transition metal complex oxide, the high-nickel positive electrode active material has a nickel content of greater than or equal to about 80 mol%, greater than or equal to about 85 mol%, greater than or equal to about 90 mol%, greater than or equal to about 91 mol%, or greater than or equal to about 94 mol% and less than or equal to about 99 mol%. High-nickel positive electrode active materials can achieve high capacity and can be applied to high-capacity, high-density rechargeable lithium batteries.

[0142] Based on a 100wt% positive electrode active material layer, the amount of positive electrode active material can be in the range of about 90wt% to about 99.5wt%, and based on a 100wt% positive electrode active material layer, the amounts of binder and conductive material can be in the range of about 0.5wt% to about 5wt%, respectively.

[0143] The binder adheres the positive electrode active material particles to each other and to the current collector.

[0144] Examples of adhesives may include, but are not limited to, at least one of the following: polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylate resin, polyester resin, nylon, etc.

[0145] Conductive materials can impart conductivity to electrodes and can be used in batteries as any material that does not cause adverse chemical changes and conducts electrons. Examples of conductive materials can include: carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials, including at least one of copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fibers; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0146] The current collector can be or includes Al, but the current collector is not limited to this.

[0147] Rechargeable lithium batteries Some example embodiments include rechargeable lithium batteries comprising electrodes and an electrolyte. By including the electrodes described above, rechargeable lithium batteries offer the advantage of desired or improved battery safety.

[0148] Electrolytes may include liquid electrolytes, solid electrolytes, or combinations thereof, and as an example, liquid electrolytes for rechargeable lithium batteries may include non-aqueous organic solvents and lithium salts.

[0149] Non-aqueous organic solvents constitute the medium for transporting ions that participate in the electrochemical reactions of the battery.

[0150] Non-aqueous organic solvents may be or include at least one of carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, aprotic solvents, and combinations thereof.

[0151] Carbonate solvents may include at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), and butyl carbonate (BC). Esters may include at least one of methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanolactone, mevalonolactone, valproic acid lactone, and caprolactone. Ether solvents may include at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and tetrahydrofuran. Ketone solvents may include cyclohexanone. Alcohol solvents may include ethanol and isopropanol. Aprotic solvents may include at least one of the following: nitriles, such as R-CN (wherein R is a C2 to C20 straight-chain, branched or cyclic hydrocarbon group, and may include double bonds, aromatic rings or ether bonds, etc.); amides, such as dimethylformamide; dioxolane, such as 1,3-dioxolane, 1,4-dioxolane, etc.; sulfolane, etc.

[0152] Non-aqueous organic solvents can be used alone or in mixtures of two or more types of solvents.

[0153] In addition, when using carbonate solvents, cyclic carbonates and chain carbonates can be mixed, and the cyclic carbonates and chain carbonates can be mixed in a volume ratio ranging from about 1:1 to about 1:9.

[0154] Lithium salts dissolved in organic solvents supply lithium ions in batteries, enabling rechargeable lithium batteries to operate and improving lithium ion transport between the positive and negative electrodes. Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide, LiFSI), LiC4F9SO3, and LiN(C x F 2x+1 SO2)(C y F 2y+1 At least one of the following: (SO2) (x and y are integers in the range of 1 to 20), lithium trifluoromethane sulfonate, lithium tetrafluoroethane sulfonate, lithium difluoro(oxalate)borate (LiDFOB), lithium difluorobis(oxalate)phosphate (LiDFBOP), and lithium bis(oxalate)borate (LiBOB).

[0155] Depending on the type of rechargeable lithium battery, a separator may be present between the positive and negative electrodes. The separator may include at least one of polyethylene, polypropylene, polyvinylidene fluoride, and multilayer films of the same two or more layers, and may include mixed multilayer films (such as polyethylene / polypropylene bilayer separators, polyethylene / polypropylene / polyethylene trilayer separators, and polypropylene / polyethylene / polypropylene trilayer separators).

[0156] Rechargeable lithium batteries can be classified according to their shape, such as cylindrical, prismatic, pouch-shaped, and coin-shaped. Figures 3 to 6 This is a schematic diagram illustrating a rechargeable lithium battery according to some example embodiments. Figure 3 A cylindrical battery is shown. Figure 4 A prismatic battery is shown. Figure 5 and Figure 6 A pouch-type battery is shown. (See reference) Figures 3 to 6 The rechargeable lithium battery 100 includes an electrode stack structure 40 and a housing 50. The electrode stack structure 40 includes a separator 30 between a positive electrode 10 and a negative electrode 20, and the electrode stack structure 40 is housed within the housing 50. The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with an electrolyte (not shown). Figure 3 As shown, the rechargeable lithium battery 100 may include a sealing member 60 of the sealed housing 50. Figure 4 In this context, the rechargeable lithium battery 100 may include a positive electrode lead connector 11, a positive electrode terminal 12 connected to the positive electrode lead connector 11, a negative electrode lead connector 31, and a negative electrode terminal 32 connected to the negative electrode lead connector 31. For example... Figure 5 and Figure 6 As shown, the rechargeable lithium battery 100 includes Figure 6 The electrode terminals 70 shown in the figure or Figure 5 The positive electrode terminal 71 and negative electrode terminal 72 shown in the figure form an electrical path for guiding the current formed in the electrode stack structure 40 to the outside of the rechargeable lithium battery 100.

[0157] The rechargeable lithium batteries according to some example embodiments can be used in, for example, automobiles, mobile phones and / or various types of electrical devices, but this disclosure is not limited thereto.

[0158] Figure 8 This is a flowchart illustrating a method for manufacturing electrodes for a rechargeable lithium battery according to an example embodiment. Figure 8In the method (800), the steps include: operation (810), including preparing a fiber spinning solution; operation (820), including preparing a spray solution comprising a curable polymer; operation (830), including electrospinning the fiber spinning solution into nanofibers on the surface of the electrode active material layer, and simultaneously electrospraying the spray solution to form a coating mixture; and operation (840), including curing the electrosprayed curable polymer to form a coating layer on the surface of the electrode active material layer. In the example, curing is performed by one of a thermal curing process and a photocuring process. For example, a thermal curing process is performed by one of hot air drying and heat treatment at a temperature in the range of about 70°C to about 120°C.

[0159] Examples and comparative examples of this disclosure are described below. However, the following examples are merely examples of this disclosure, and this disclosure is not limited to these examples.

[0160] Example: Example 1 First, 97.5 wt% artificial graphite, 1.0 wt% carboxymethyl cellulose, and 1.5 wt% styrene-butadiene rubber (SBR) were mixed in an aqueous solvent to prepare a negative electrode active material slurry. The negative electrode active material slurry was coated onto a copper current collector, then dried and rolled to form a negative electrode active material layer.

[0161] Subsequently, a fiber spinning solution comprising polyimide and dimethyl acetate solvent and a spray solution comprising bisphenol A epoxy polymer, dimethyl acetate solvent and polyvinylidene fluoride binder are prepared.

[0162] Here, based on 100 wt% of the fiber spinning solution, which includes 20 wt% of polyimide, and based on 100 wt% of the spray solution, which includes 20 wt% of bisphenol A epoxy polymer.

[0163] On the surface of the negative electrode active material layer, the fiber spinning solution is electrospun into nanofibers, and simultaneously or concurrently, the spray solution is electrosprayed to form a coating mixture.

[0164] Electrospinning is performed under the following conditions.

[0165] After positioning a nozzle assembly consisting of 52 tips with a 25G orifice size and a collecting roller at 15cm intervals, a fiber spinning solution is added to the tips, and electrospinning is then performed at 26°C with 50% relative humidity by applying a voltage of 40kV to 50kV. Here, the collecting roller rotates at 1m / min to 3m / min, and the fiber spinning solution discharged from the tips is adjusted to have a solids content of 150μL / min. Furthermore, electrospinning is performed by flowing compressed air at a pressure of 0.1MPa.

[0166] Electrospraying was performed at an applied voltage of 20 kV, a spraying distance of 10 cm, and a spraying rate of 1 mL / min.

[0167] The coating mixture formed by electrospinning and electrospraying is dried with hot air at 90°C to cure the bisphenol A epoxy polymer, and thus a negative electrode with a coating layer on the surface of the negative electrode active material layer is manufactured.

[0168] The coating layer comprises 100 parts by weight of polyimide nanofibers, including 5 parts by weight of bisphenol A epoxy polymer, and the thickness of the coating layer is 10 μm.

[0169] Furthermore, SEM image analysis of the coating surface revealed that the nanofibers formed within the coating possess a three-dimensional network structure comprising multiple pores with an average diameter of 100 nm. Additionally, the nanofibers have an average diameter of 100 nm, while the bisphenol A epoxy polymer has an average diameter of 300 nm.

[0170] Subsequently, 96 wt% LiCoO2, 2 wt% Ketjen black, and 2 wt% polyvinylidene fluoride were mixed in N-methylpyrrolidone solvent to prepare a positive electrode active material slurry. The positive electrode active material slurry was coated onto an Al current collector, then dried and compressed to fabricate the positive electrode.

[0171] The fabricated negative and positive electrodes are stacked on top of each other to create an electrode assembly. Here, the coating layer of the negative electrode is positioned to contact the positive electrode. The electrode assembly is used with an electrolyte to create a rechargeable lithium-ion battery cell (approximately 40 mAh pouch cell).

[0172] Electrolytes were prepared by dissolving LiPF6 in a mixed solvent of ethylene carbonate and methyl ethyl carbonate (volume ratio 50:50).

[0173] Examples 2 to 4 The negative electrodes and rechargeable lithium battery cells according to Examples 2 to 4 were manufactured in the same manner as in Example 1, except that the amount of bisphenol A epoxy polymer based on 100 parts by weight of polyimide nanofibers in the coating layer was changed as shown in Table 1 below.

[0174] Comparison Example 1 The negative electrode and rechargeable lithium battery cell according to Comparative Example 1 are manufactured in the same manner as in Example 1, except that the coating layer is formed only by an electrospinning process that includes a fiber spinning solution and not by an electrospraying process that includes a spray solution.

[0175] Comparison Example 2 The negative electrode and rechargeable lithium battery cell according to Comparative Example 2 are manufactured in the same manner as in Example 1, except that instead of forming a coating layer, a polyethylene / polypropylene bilayer separator is applied between the positive and negative electrodes.

[0176] Evaluation example: Evaluation Example 1: SEM Image SEM images of the surface of the coating layer manufactured in Example 1 are shown below. Figure 7 In. Figure 7 In the middle, the relatively darker areas represent curable polymers, see reference. Figure 7 The study confirmed the presence of nanofibers and island-like curable polymers between the nanofibers.

[0177] Evaluation Example 2: Evaluation of Peel Strength The peel strength between the coating layer and the active material layer of the negative electrode in Examples 1 to 4 and Comparative Examples 1 to 2 was measured. The peel strength between the active material layer and the separator of the negative electrode in Comparative Example 2, where a separator was used but no coating layer was applied, was measured.

[0178] Specifically, after attaching a 1.5cm wide strip of tape (3M Celotape, registered trademark) to the negative electrode fixed to the stainless steel plate, the peel strength was measured using a peel tester (model: KP-M1T-s, manufacturer: KIPAE E&T Ltd.). Specifically, the peel strength was measured by performing a 180° peel strength test and using a 1kg load sensor at a peel speed of 100mm / min.

[0179] The measurement results are shown in Table 1 below.

[0180] Evaluation Example 3: Evaluation of breathability The air permeability of the coatings of Examples 1 to 4 and the diaphragm of Comparative Example 1 was measured by measuring the time (seconds) required for 100cc of air to permeate using an air permeability measuring device (EG01-55-1MR, Asahi Seiko Co., Ltd.). The results are shown in Table 1 below.

[0181] Evaluation Example 4: Evaluation of DC-IR The DC internal resistance (DC-IR) of the rechargeable lithium battery cells of Examples 1 to 4 and Comparative Examples 1 to 2 was measured at 25°C, and the results are shown in Table 1 below.

[0182] Specifically, the battery cells whose discharge capacity is checked are charged at 0.5C using a CC-CV (constant current-constant voltage) method, cut off at 0.025C, and discharged at 0.1C. Here, the DC internal resistance (DC-IR) is measured by applying a 1C current for 10 seconds at SOC 50 (based on the battery's total charge capacity of 100%, which is based on the state of discharge of 50%) while simultaneously measuring the voltage drop (V).

[0183] Table 1:

[0184] Referring to Table 1, the negative electrodes of Examples 1 to 4 exhibited higher peel strength than those of Comparative Example 1 and Comparative Example 2.

[0185] In addition, it was confirmed that the negative electrode of Comparative Example 1, which does not include island-shaped curable polymers, exhibits low air permeability.

[0186] In addition, the rechargeable lithium battery cells of Examples 1 to 4 have DC-IR comparable to those of the rechargeable lithium battery cells of Comparative Examples 1 and 2, which confirms that the nanofibers and curable polymers do not act as resistors, but rather achieve the desired or improved peel strength and permeability.

[0187] While this disclosure has been described in conjunction with exemplary embodiments now considered to be practical, it will be understood that the disclosure is not limited to the disclosed embodiments. Rather, the disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0188] Description of reference numerals in the attached figures: 1: Electrode assembly 10: Positive electrode 20: Negative electrode; 21: Current collector 22: Negative electrode active material layer 23: Coating layer 231: Nanofibers; 232: Curable polymers 100: Rechargeable lithium battery; 11: Positive electrode lead connector. 12: Positive electrode terminal; 31: Negative electrode lead connector. 32: Negative electrode terminal; 30: Diaphragm 40: Electrode stacking structure; 50: Housing 60: Sealing component; 70: Electrode terminal piece 71: Positive electrode connector; 72: Negative electrode connector.

Claims

1. An electrode for a rechargeable lithium battery, the electrode comprising: current collector; An electrode active material layer is placed on the current collector; as well as A coating layer is applied to the electrode active material layer. The coating layer comprises nanofibers and a curable polymer distributed in an island shape between the nanofibers.

2. The electrode for a rechargeable lithium battery according to claim 1, wherein, The nanofibers have a three-dimensional network structure including pores.

3. The electrode for a rechargeable lithium battery according to claim 2, wherein, The average diameter of the pore is in the range of 10 nm to 200 nm.

4. The electrode for a rechargeable lithium battery according to claim 1, wherein, The coating layer is integrated with the electrode active material layer.

5. The electrode for a rechargeable lithium battery according to claim 1, wherein, At least a portion of the nanofibers and the curable polymer penetrate into the interior of the electrode active material layer.

6. The electrode for a rechargeable lithium battery according to claim 1, wherein, The nanofibers comprise polymers, including at least one of polyimide, polyethylene, polypropylene, polyester, polyamide, polyamic acid, polyamide-imide, polyether-imide, polyacrylonitrile, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polycarbonate, polyvinyl chloride, polyvinylidene chloride, polyethylene glycol derivatives, polyoxides, polyvinyl acetate, polystyrene, polyvinylpyrrolidone, copolymers thereof, and combinations thereof.

7. The electrode for a rechargeable lithium battery according to claim 1, wherein, The average diameter of the nanofibers is in the range of 10 nm to 200 nm.

8. The electrode for a rechargeable lithium battery according to claim 1, wherein, The curable polymer includes at least one of thermosetting polymers, photocurable polymers, and combinations thereof.

9. The electrode for a rechargeable lithium battery according to claim 8, wherein, The thermosetting polymer includes at least one of epoxy polymers, phenolic polymers, amino polymers, polyester polymers, polyurethane polymers, and combinations thereof.

10. The electrode for a rechargeable lithium battery according to claim 9, wherein, The epoxy polymers include at least one of bisphenol A type epoxy polymers, bisphenol F type epoxy polymers, novolac type epoxy polymers, aliphatic epoxy polymers, alicyclic epoxy polymers, glycidylamine epoxy polymers, modified epoxy polymers, and combinations thereof.

11. The electrode for a rechargeable lithium battery according to claim 1, wherein, The average diameter of the curable polymer is in the range of 100 nm to 300 nm.

12. The electrode for a rechargeable lithium battery according to claim 1, wherein, Based on 100 parts by weight of the nanofibers, the curable polymer is included in an amount ranging from 1 part by weight to 50 parts by weight.

13. The electrode for a rechargeable lithium battery according to claim 1, wherein, The weight ratio of the nanofibers included in the coating to the weight of the curable polymer is in the range of 1:0.01 to 1:0.

5.

14. The electrode for a rechargeable lithium battery according to claim 1, wherein, The thickness of the coating layer is in the range of 1 μm to 25 μm.

15. The electrode for a rechargeable lithium battery according to claim 1, wherein, The electrode also includes an inorganic layer on the coating layer.

16. The electrode for a rechargeable lithium battery according to claim 1, wherein, The electrode is a negative electrode.

17. A method for manufacturing an electrode for a rechargeable lithium battery, the method comprising the steps of: Preparation of fiber spinning solution; Preparation of a spray solution comprising a curable polymer; The fiber spinning solution is electrospun into nanofibers on the surface of the electrode active material layer, and the spray solution is electrosprayed simultaneously to form a coating mixture; as well as The curable polymer, which is electrosprayed, is cured to form a coating layer on the surface of the electrode active material layer.

18. The method according to claim 17, wherein, The curing is performed by either a thermosetting process or a photocuring process.

19. The method according to claim 18, wherein, The thermosetting process is performed by either hot air drying or heat treatment at a temperature ranging from 70°C to 120°C.

20. A rechargeable lithium battery, said rechargeable lithium battery comprising: Electrodes according to any one of claims 1 to 16; as well as Electrolytes.

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