Negative electrode for lithium secondary battery and method for manufacturing same

Abstract

The present disclosure provides a negative electrode for a lithium secondary battery and a method for manufacturing the negative electrode for a lithium secondary battery. A negative electrode for a lithium secondary battery according to the present disclosure comprises a current collector and a porous structure disposed on the current collector, wherein the porous structure includes a semiconductor inorganic material, and the band gap of the semiconductor inorganic material may decrease due to the insertion of lithium into the crystal of the semiconductor inorganic material.

Description

Negative electrode for lithium secondary battery and method for manufacturing the same

[0001] The present disclosure relates to a negative electrode for a lithium secondary battery and a method for manufacturing the same.

[0002] Recently, accompanied by the rapid proliferation of battery-powered electronic devices such as mobile phones, laptop computers, and electric vehicles, the demand for high-energy-density, high-capacity rechargeable batteries is rapidly increasing. Accordingly, research and development to improve the performance of lithium-ion batteries is actively underway.

[0003] A lithium secondary battery is a battery comprising a positive electrode and a negative electrode containing an active material capable of lithium ion intercalation and deintercalation, and an electrolyte, and produces electrical energy through oxidation and reduction reactions when lithium ions are intercalated / deintercalated from the positive electrode and the negative electrode.

[0004] Currently commercially available lithium secondary batteries mainly use carbon-based negative electrode active materials such as graphite. Carbon-based negative electrode active materials do not change in volume during charging and discharging, so the stability of lithium secondary batteries is high. The theoretical electric capacity of graphite is small, about 372 mAh / g.

[0005] Lithium metal can be used as a negative electrode active material. Lithium metal has a very large theoretical electric capacity of approximately 3,860 mAh / g. During charging and discharging, dendrites can form on the surface of lithium metal due to side reactions with the electrolyte, and as these dendrites grow, they can cause a short circuit between the positive and negative electrodes. Consequently, the lifespan characteristics and thermal stability of lithium metal batteries containing lithium metal are degraded.

[0006] A method is required to improve the lifespan characteristics and thermal stability of lithium metal batteries containing lithium metal.

[0007] In addition, numerous studies are being conducted on lithium metal batteries without a negative electrode active material coating on the negative electrode current collector to achieve higher energy density compared to conventional lithium secondary batteries. However, it has been reported that lithium metal batteries without a negative electrode active material coating on the current collector inevitably experience volume changes due to the direct deposition of lithium on the current collector during repeated charging and discharging cycles.

[0008] The information described above disclosed in the background technology of this invention is intended only to enhance understanding of the background of the present invention and may therefore include information that does not constitute prior art.

[0009] One embodiment provides a negative electrode for a lithium secondary battery and a method for manufacturing the same to solve the above technical problem.

[0010] Another embodiment provides a lithium secondary battery comprising a negative electrode for a lithium secondary battery to solve the above technical problem.

[0011] A negative electrode for a lithium secondary battery according to one embodiment of the present invention for solving the above technical problem comprises a current collector and a porous structure disposed on the current collector, wherein the porous structure comprises a semiconductor inorganic material, and the band gap of the semiconductor inorganic material can be reduced due to the insertion of lithium into the crystal of the semiconductor inorganic material.

[0012] A lithium secondary battery according to one embodiment of the present invention for solving the above technical problem may include a positive electrode, a negative electrode for a lithium secondary battery according to one embodiment, and an electrolyte disposed between the positive electrode and the negative electrode.

[0013] A method for manufacturing a negative electrode for a lithium secondary battery according to one embodiment of the present invention for solving the above technical problem comprises the steps of preparing a current collector and placing a porous structure on the current collector, wherein the porous structure comprises a semiconductor inorganic material, and the band gap of the semiconductor inorganic material can be reduced due to the insertion of lithium into the crystal of the semiconductor inorganic material.

[0014] According to some embodiments of the present disclosure, lithium is captured in a porous structure disposed on a current collector during charging and discharging, thereby minimizing volume change of the lithium metal battery.

[0015] According to some embodiments of the present disclosure, as the band gap of the interlayer compound formed by the bonding of the semiconductor inorganic material constituting the porous structure with lithium is reduced, lithium can be electrodeposited from the bottom of the porous structure and captured throughout the entire porous structure without any empty spaces.

[0016] According to some embodiments of the present disclosure, crystalline titanium oxide (TiO2) constituting a porous structure undergoes only a small amount of lithium intercalation reaction (Li x Since TiO2 exhibits electrical conductivity, it conducts electrical conductivity starting from the bottom of the porous structure, thereby enabling the electrodeposition of lithium across the entire porous structure.

[0017] According to some embodiments of the present disclosure, dendrite formation is suppressed during the charging and discharging process, thereby enabling the manufacture of a lithium metal battery with improved capacity retention rate, lifespan characteristics, and thermal stability.

[0018] However, the effects obtainable through the present invention are not limited to those described above, and other unmentioned technical effects will be clearly understood by those skilled in the art from the description of the invention below.

[0019] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings.

[0020] FIG. 1 schematically shows the structure of a negative electrode for a lithium secondary battery according to one embodiment.

[0021] Figure 2 shows lithium being captured in the negative electrode of a lithium secondary battery according to one embodiment depending on charging and discharging.

[0022] Figure 3 shows a cross-sectional SEM image of a porous structure before filling according to one embodiment.

[0023] Figure 4 shows a cross-sectional SEM image of a porous structure after filling according to one embodiment.

[0024] Figure 5 shows the appearance of a lithium secondary battery without a negative electrode active material layer before charging.

[0025] Figure 6 shows the appearance of a lithium secondary battery after charging, without a negative electrode active material layer.

[0026] FIG. 7 schematically shows the structure of a lithium secondary battery according to one embodiment.

[0027] Figure 8 shows the appearance of a lithium secondary battery after voltage has been applied according to one embodiment.

[0028] FIG. 9 is a flowchart illustrating an example of a method for manufacturing a negative electrode for a lithium secondary battery according to the present disclosure.

[0029] FIG. 10 is a schematic diagram illustrating a lithium secondary battery according to one embodiment.

[0030] FIG. 11 is a schematic diagram illustrating a lithium secondary battery according to one embodiment.

[0031] FIG. 12 is a schematic diagram illustrating a lithium secondary battery according to one embodiment.

[0032] FIG. 13 is a schematic diagram illustrating a lithium secondary battery according to one embodiment.

[0033] FIG. 14 shows a cross-sectional SEM image of lithium that was not filled inside the porous structure after charging and was electrodeposited outside the surface according to one embodiment.

[0034] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below.

[0035] Unless otherwise specifically stated in this specification, when a part such as a layer, film, region, plate, etc. is described as being "on" another part, this includes not only cases where it is "immediately on" another part, but also cases where there is another part in between.

[0036] Unless otherwise specified in this specification, a singular form may also include a plural form. Additionally, unless otherwise specified, "A or B" may mean "including A, including B, or including A and B."

[0037] In this specification, "combination of these" may mean a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, and a reaction product, etc.

[0038] Unless otherwise defined in this specification, the particle size may be the average particle size. Additionally, the particle size refers to the average particle size (D50), which means the diameter of the particle whose cumulative volume in the particle size distribution is 50% by volume. The average particle size (D50) may be measured by methods widely known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope (TEM) image or a scanning electron microscope (SEM) image. Alternatively, the average particle size (D50) value may be obtained by measuring using a measuring device utilizing dynamic light scattering, performing data analysis to count the number of particles for each particle size range, and then calculating from this. Alternatively, it may be measured using a laser diffraction method. When measuring by laser diffraction, more specifically, after dispersing the particles to be measured in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), and ultrasound of about 28 kHz is irradiated at an output of 60 W, and then the average particle size (D50) at 50% of the particle size distribution in the measuring device can be calculated.

[0039] Methods and materials similar or equivalent to those described herein may be used in the practice or testing of the present invention, but suitable methods and materials are described herein. The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0040] In this specification, terms such as “comprising” or “having” are intended to indicate the existence of the features, numbers, steps, actions, components, parts, components, materials, or combinations thereof described in the specification, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, components, materials, or combinations thereof.

[0041] In this specification, the term “combination of these” means a mixture or combination with one or more of the described components, and may mean a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, and a reaction product, etc.

[0042] In this specification, the term “and / or” means any combination of one or more items described in relation and all combinations thereof. In this specification, the term “or” means “and / or”.

[0043] In this specification, when a part such as a layer, film, region, plate, etc. is described as being "on" another part, this includes not only cases where it is directly above the other part, but also cases where there is another part in between.

[0044] In this specification, terms such as "first," "second," etc., may be used to describe various components, but the components should not be limited by these terms. The terms are used solely for the purpose of distinguishing one component from another.

[0045] In this specification, “metal” includes both metals and metalloids such as silicon and germanium in an elemental or ionic state.

[0046] In this specification, "alloy" means a mixture of two or more metals.

[0047] In this specification, "anode active material" refers to an anode material capable of undergoing lithiation and delithiation.

[0048] In this specification, "anode active material" refers to an anode material capable of undergoing lithiation and delithiation.

[0049] In this specification, "lithiation" and "to lithiate" refer to the process of adding lithium to a specific substance or compound.

[0050] In this specification, "delithiation" and "to delithiate" refer to the process of removing lithium from a specific substance or compound.

[0051] In this specification, "charge" and "to charge" refer to the process of providing electrochemical energy to a battery.

[0052] In this specification, "discharge" and "discharge" refer to the process of removing electrochemical energy from a battery.

[0053] In this specification, "anode" and "cathode" refer to electrodes where electrochemical reduction and lithiation occur during the discharge process.

[0054] In this specification, "cathode" and "anode" refer to electrodes where electrochemical oxidation and delithiation occur during the discharge process.

[0055] Exemplary embodiments will be described in more detail below with reference to the attached drawings.

[0056]

[0057] cathode

[0058] FIG. 1 schematically shows the structure of a negative electrode for a lithium secondary battery according to one embodiment. FIG. 2 also shows lithium being captured in the negative electrode for a lithium secondary battery according to one embodiment during charging and discharging.

[0059] Referring to FIG. 1, a negative electrode (100) for a lithium secondary battery according to one embodiment of the present invention may include a current collector (110) and a porous structure (120) disposed on the current collector (110). For example, the porous structure (120) may be disposed to be in direct contact with the current collector (110). The porous structure (120) may be disposed to be in direct contact with the current collector (110) even after lithium has been captured. The porous structure (120) may include a plurality of pores for capturing lithium (or lithium ions). For example, in terms of volume, the porosity of the porous structure (120) may be 20% to 70%. The porosity may be calculated through the mercury intrusion method or the density calculation method.

[0060] In one embodiment, the porous structure (120) can completely cover the surface of the current collector (110).

[0061] According to some embodiments of the present disclosure, lithium is captured in a porous structure (120) disposed on a current collector (110) during the charging and discharging of a lithium secondary battery, thereby minimizing volume change of the lithium metal battery. Specifically, as the lithium secondary battery is charged, lithium ions contained in the electrolyte can be electrodeposited on the porous structure (120).

[0062] The thickness of the porous structure (120) may be, for example, 0.1 μm to 100 μm, 0.1 μm to 80 μm, 1 μm to 80 μm, or 10 μm to 80 μm, but is not necessarily limited to these ranges and can be adjusted according to the required shape, capacity, etc. of the lithium secondary battery. If the thickness of the porous structure (120) increases excessively, the energy density of the lithium secondary battery may decrease.

[0063] In one embodiment, the porous structure (120) may include a semiconductor inorganic material for capturing lithium. Specifically, the porous structure (120) may be formed by coating the surface of a current collector (110) with a powder containing the semiconductor inorganic material. For example, the semiconductor inorganic material forming the porous structure (120) may include any one of TiO2, MoS2, VO2, V2O5, MoO2, TiS2, or any combination thereof.

[0064] The band gap of a semiconductor inorganic material can be reduced due to bonding with lithium. For example, the band gap of a semiconductor inorganic material can be reduced due to the insertion of lithium into the crystal of the semiconductor inorganic material. Through this, the semiconductor inorganic material bonded with lithium can have superior electrical conductivity compared to the semiconductor inorganic material not bonded with lithium. Here, the band gap of the semiconductor inorganic material before bonding with lithium can be 0.1 eV to 4 eV.

[0065] That is, the porous structure (120) has low electrical conductivity during the initial charging of the lithium secondary battery. Therefore, the combination of lithium and semiconductor inorganic material occurs in the porous structure (120) closest to the current collector (110) which has high electrical conductivity. The combination of lithium and semiconductor inorganic material may correspond, for example, to lithiation.

[0066] Specifically, referring to FIG. 2, in a voltage range of 0.1 V to 2.5 V, the semiconductor inorganic material can create an interlayer compound (220) by capturing lithium ions from the bottom of a porous structure (120) close to a current collector (110) through an intercalation reaction. In one embodiment, the band gap of the semiconductor inorganic material is 0.1 eV to 4 eV, and the band gap of the interlayer compound (220) may be smaller than the band gap of the semiconductor inorganic material.

[0067] Since the interlayer compound (220) has higher electrical conductivity than the semiconductor inorganic material, the combination of lithium and the semiconductor inorganic material occurs in the porous structure (120) near the interlayer compound (220) during the subsequent charging process of the lithium secondary battery. Through this, lithium can be electrodeposited from the bottom of the porous structure (120) so that lithium can be collected throughout the entire porous structure (120) without any empty spaces. Specifically, at the beginning of charging (101a) of the lithium secondary battery, the interlayer compound (220) may exist only in the bottom of the porous structure (120), but at the end of charging (101b) of the lithium secondary battery, the interlayer compound (220) can be electrodeposited sequentially so that it also exists in the upper part of the porous structure (120).

[0068] Finally, the maximum proportion of lithium captured in the interlayer compound (220) may be 0.1 wt% to 30 wt%, 0.1 wt% to 20 wt%, or 0.1 wt% to 10 wt% relative to the total weight of the porous structure (120).

[0069] According to one embodiment comprising TiO2 as a semiconductor inorganic material forming a porous structure (120), the TiO2 contained in the porous structure (120) in contact with the current collector (110) at the beginning of the lithium secondary battery charging process undergoes a lithium intercalation reaction together with electrons received from the current collector (110), and then forms an interlayer compound (220) with excellent electrical conductivity Li x TiO2 can be formed. The Li formed in this way x TiO2 transfers electrons again, making lithium Li x Lithium is captured on a porous structure (120) in contact with TiO2, and Li x Additional TiO2 can be formed. The additionally formed Li x TiO2 consists of Li that was formed first. xCompared to TiO2, it can be formed at a location further away from the current collector. In other embodiments, the semiconductor inorganic material forming the porous structure (120) may include MoS2, VO2, V2O5, MoO2, TiS2, or any combination thereof, and may also undergo a corresponding lithium insertion reaction to form an interlayer compound (220) with excellent electrical conductivity.

[0070] Accordingly, during the charging process of a lithium secondary battery, lithium metal begins to form sequentially on the entire surface of the porous structure (120) starting from a position close to the current collector and is uniformly electrodeposited throughout until a position separated from the current collector, so that the formation of lithium dendrites can be effectively suppressed.

[0071] According to one embodiment, a cross-sectional SEM image of a porous structure (120) containing TiO2 before charging is shown in FIG. 3. Also, according to one embodiment, a blade-cut cross-sectional SEM image of a porous structure (120) containing TiO2 after charging is shown in FIG. 4. According to one embodiment, the particle size of the powder containing semiconductor inorganic material included in the porous structure (120) may be, for example, 0.5 μm to 2 μm, 2 μm to 4 μm, or 4 μm to 8 μm, 8 μm to 20 μm, or 10 μm to 50 μm. By having the powder have a thickness within this range, the lifespan characteristics of the lithium secondary battery can be further improved.

[0072] On the other hand, when the porous structure (120) contains a large amount of a conductive material that already possesses conductivity rather than a semiconductor inorganic material, the electric field is strongest at the top of the porous structure (120) closest to the positive electrode, which is the opposite electrode, so lithium electrodeposition occurs starting from the top of the porous structure (120). During the charging process of the lithium secondary battery, lithium metal may begin to form on the entire surface of the porous structure (120) starting from a position spaced apart from the current collector. That is, lithium ions cannot be captured at the bottom of the porous structure (120), where the electric field is relatively weak.

[0073] For example, when a porous structure (120) is formed by coating the surface of a current collector (110) with a powder containing carbon black, which is used as a commercial conductive material, lithium electrodeposition occurs locally only on the upper part of the porous structure (120) or the surface layer of the porous structure (120) close to the anode, so lithium dendrites may occur.

[0074] In one embodiment, the porous structure (120) may further include a polymer binder. For example, the porous structure (120) may include a binding layer containing a binder. Here, the polymer binder may include a conductive binder or a non-conductive binder. For example, the binder may be a fluorine-based binder such as polyvinylidene fluoride (PVDF).

[0075] Conductive binders are, for example, ion-conducting binders and / or electronic-conducting binders. Binders that possess both ion conductivity and electronic conductivity may belong to both ion-conducting binders and electronic-conducting binders.

[0076] Ion-conducting binders are, for example, polystyrene sulfonate (PSS), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), poly(methylmethacrylate) (PMMA), polyethylene oxide (PEO), polyethylene glycol (PEG), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), polyethylenedioxythiophene (PEDOT), polypyrrole (PPY), polyacrylonitrile (PAN), polyaniline, and polyacetylene. Ion-conducting binders may include polar functional groups. Ion-conducting binders containing polar functional groups are, for example, Nafion, Aquivion, These include Flemion, Gore, Aciplex, Morgane ADP, sulfonated poly(ether ether ketone) (SPEEK), sulfonated poly(arylene ether ketone sulfone) (SPAEKKS), sulfonated poly(aryl ether ketone) (SPAEK), poly[bis(benzimidazobenzisoquinolinones)] (SPBIBI), poly(styrene sulfonate) (PSS), and lithium 9,10-diphenylanthracene-2-sulfonate (DPASLi+).Electronically conductive binders include, for example, polyacetylene, polythiophene, polypyrrole, poly(p-phenylene), poly(phenylenevinylene), poly(phenylenesulfide), and polyaniline.

[0077] In one embodiment, the porous structure (120) may further include a conductive material. However, in the porous structure (120) according to one embodiment, the conductive material may be included in a specific ratio or less so that the electrical conductivity of the porous structure (120) is not too high. Specifically, the ratio of the conductive material in the porous structure (120) may be 0.01 wt% to 0.5 wt%, or 0.01 wt% to 0.2 wt%. Here, the conductive material is used to impart conductivity to the electrode, and any electronically conductive material that does not cause chemical changes may be used in the battery being constructed. An embodiment in which the ratio of the conductive material in the porous structure (120) is 0.5 wt% or more is described later in FIG. 14.

[0078] FIG. 5 shows the appearance (501) of a lithium secondary battery without a negative electrode active material layer before charging. FIG. 6 also shows the appearance (502) of a lithium secondary battery without a negative electrode active material layer after charging.

[0079] Referring to FIGS. 5 and 6, in a lithium secondary battery without a negative electrode active material layer, lithium ions can be reversibly electrodeposited or desorbed on the surface of a negative electrode current collector (510) during the charging and discharging process.

[0080] A lithium secondary battery without a negative active material layer has the advantage of having a significantly higher energy density per unit weight compared to a conventional lithium-ion battery in which a thick negative active material layer is coated on a negative current collector. However, a lithium secondary battery without a negative active material layer may inevitably undergo a change in volume as lithium metal (540) is directly deposited on the negative current collector (510) during repeated charging and discharging. Specifically, while charging of a lithium secondary battery without a negative active material layer is in progress, the volume of the positive electrode (530) and the separator (520) are the same, so the total volume of the lithium secondary battery may increase as the lithium metal (540) deposited on the negative current collector (510) is newly formed.

[0081]

[0082]

[0083] Method for manufacturing a cathode

[0084] FIG. 9 is a flowchart illustrating an example of a method for manufacturing a negative electrode for a lithium secondary battery according to the present disclosure.

[0085] A method (900) for manufacturing a negative electrode for a lithium secondary battery according to one embodiment of the present invention may be initiated by preparing a current collector (S910).

[0086] Afterwards, a porous structure can be placed on the current collector (S920). Here, the porous structure includes a semiconductor inorganic material, and the band gap of the semiconductor inorganic material can be reduced due to bonding with lithium.

[0087] In one embodiment, the step of placing a porous structure (S920) may include the step of coating the surface of a current collector with a powder containing semiconductor inorganic material using slurry casting. Specifically, a slurry in which semiconductor inorganic material and a binder are mixed in an organic solvent or water at a ratio of 80:20 to 99.5:0.5 with a solid content of 30% to 80% and dissolved and dispersed is applied onto a metal substrate through a doctor blade, and a cathode with a porous structure placed thereon can be manufactured by drying it in a vacuum of 80°C or higher for at least 2 hours.

[0088] In this case, the organic solvent may be N-methylpyrrolidone, tetrahydrofuran, dimethyl sulfoxide, dimethyl acetamide, etc., and when using such organic solvents, the binder may be polyvinylidene difluoride (PVDF), PVDF-HFP, etc. When water is used as the slurry solvent, the binder may be carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), polyacrylate (PAA), lithium polyacrylate (Li-PAA), polyethylene oxide (PEO), etc. Here, the semiconductor inorganic material may include any one of TiO2, MoS2, VO2, V2O5, MoO2, TiS2, or any combination thereof, and the band gap of the semiconductor inorganic material may be 0.1 eV to 4 eV.

[0089] In one embodiment, the porous structure arranged may include an interlayer compound formed by capturing lithium ions through an intercalation reaction of semiconductor inorganic materials at a voltage range of 0.1 V to 2.5 V.

[0090]

[0091] lithium secondary battery

[0092] FIG. 7 schematically illustrates the structure of a lithium secondary battery according to one embodiment. FIG. 8 also illustrates the appearance of a lithium secondary battery after charging according to one embodiment. Specifically, FIG. 7 and FIG. 8 illustrate the lithium secondary battery according to one embodiment by omitting the configuration other than the battery structure.

[0093] Referring to FIG. 7, a lithium secondary battery (701) before charging according to one embodiment of the present invention may include a negative electrode (700) for a lithium secondary battery comprising a positive electrode (730), a negative electrode current collector (710), and a porous structure (740) disposed on the negative electrode current collector (710), and an electrolyte (720) disposed between the positive electrode (730) and the negative electrode (700).

[0094] According to one embodiment, the electrolyte (720) may have a solid, liquid, or gel form.

[0095] In one embodiment, before charging, the negative electrode (700) in the lithium secondary battery (701) may include a negative electrode current collector (710) in which the negative electrode active material layer is free. The positive electrode (730) may include a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector.

[0096] Referring to FIG. 8, a lithium secondary battery (702) after charging according to one embodiment of the present invention may further include an interlayer compound (750) formed inside a porous structure (740). In this case, the negative electrode (700) may include a negative electrode current collector (710), a porous structure (740) disposed on the negative electrode current collector (710), and an interlayer compound (750) formed inside the porous structure (740). During the discharge process, lithium ions dissociate from the interlayer compound (750), so that the thickness of the interlayer compound (750) within the porous structure (740) may decrease. Conversely, during the charging process, lithium ions are formed by electrodeposition, so that the thickness of the interlayer compound (750) within the porous structure (740) may increase.

[0097] In one embodiment, the anode (730) may have a charging capacity 1.5 to 20 times greater than the intercalation capacity of the semiconductor inorganic material of the cathode (700). When the charging capacity of the anode far exceeds the intercalation capacity of the semiconductor inorganic material of the cathode, the lithium charged after the intercalation capacity of the semiconductor inorganic material of the cathode may be electrodeposited between the pores of the porous active material layer.

[0098] According to some embodiments of the present disclosure, dendrite formation is suppressed during the charging and discharging process, thereby enabling the manufacture of a lithium metal battery with improved capacity retention rate, lifespan characteristics, and thermal stability.

[0099] FIGS. 10 to 13 are schematic diagrams illustrating a lithium secondary battery according to one embodiment, where FIG. 10 is cylindrical, FIG. 11 is prismatic, and FIGS. 12 and 13 are pouch-type batteries. Referring to FIGS. 10 to 13, the lithium secondary battery (1) includes a battery structure (7, electrode assembly) having a separator (4, separator) interposed between a positive electrode (3) and a negative electrode (2), and a case (5) in which the battery structure (7) is housed. The positive electrode (3), the negative electrode (2), and the separator (4) may be impregnated with an electrolyte (not shown). The lithium secondary battery (1) may include an assembly (6, sealing member) that seals the case (5) as in FIG. 10. Additionally, in FIG. 11, the lithium secondary battery (1) may include a positive lead tab (3') and a positive terminal (3"), a negative lead tab (2') and a negative terminal (2"). As shown in FIGS. 12 and 13, the lithium secondary battery (1) may include electrode tabs (70), namely a positive electrode tab (71) and a negative electrode tab (72), which serve as electrical passages for inducing current formed in the battery structure (7) to the outside.

[0100] Referring to FIG. 10, a lithium secondary battery (1) according to one embodiment includes the anode (3), the cathode (2), and the separator (4) described above. The anode (3), the cathode (2), and the separator (4) are wound or folded to form a battery structure (7). The formed battery structure (7) is housed in a case (5). An electrolyte is injected into the case (5) and sealed with a cap assembly (6) to complete the lithium secondary battery (1). The case (5) is cylindrical but is not necessarily limited to this shape and may be, for example, prismatic, thin film, etc.

[0101] Referring to FIG. 11, a lithium secondary battery (1) according to one embodiment includes a positive electrode (3), the aforementioned negative electrode (2), and a separator (4). The positive electrode (3), the negative electrode (2), and the separator (4) are wound, folded, or stacked to form a battery structure (7). The formed battery structure (7) is housed in a case (5). An electrolyte is injected into the case (5), cross-linked, and sealed to complete the lithium secondary battery (1). The case (5) is prismatic, but is not necessarily limited to this shape and may be, for example, cylindrical, thin film, etc. A positive lead tab (3') and a positive terminal (3") are electrically connected to the positive electrode (3). A negative lead tab (2') and a negative terminal (2") are electrically connected to the negative electrode (2).

[0102] Referring to FIG. 12, a lithium secondary battery (1) according to one embodiment includes a positive electrode (3), the aforementioned negative electrode (2), and a separator (4). A separator (4) is disposed between the positive electrode (3) and the negative electrode (2), and the positive electrode (3), the negative electrode (2), and the separator (4) are wound or folded to form a battery structure (7). The formed battery structure (7) is housed in a case (5). It may include an electrode tab (70) that serves as an electrical path for inducing the current formed in the battery structure (7) to the outside. An electrolyte is injected into the case (5) and sealed to complete the lithium secondary battery (1). The case (5) is prismatic but is not necessarily limited to this shape and may be, for example, cylindrical, thin film, etc.

[0103] Referring to FIG. 13, a lithium secondary battery (1) according to one embodiment includes a positive electrode (3), the aforementioned negative electrode (2), and a separator (4). An electrolyte containing the separator (4) is disposed between the positive electrode (3) and the negative electrode (2) to form a battery structure. For example, the battery structure (7) is stacked in a bicell structure and then housed in a case (5). It may include a positive electrode tab (71) and a negative electrode tab (72) that serve as electrical pathways for inducing the current formed in the battery structure (7) to the outside. The electrolyte is injected into the case (5) and sealed to complete the lithium secondary battery (1). The case (5) is prismatic but is not necessarily limited to this shape and may be, for example, cylindrical, thin film, etc.

[0104] However, the present invention is not limited to this, and the case (5) may be configured in various shapes such as circular or pouch type. For example, the pouch-type lithium secondary battery corresponds to the lithium secondary battery (1) of FIGS. 10 to 13 in which a pouch is used as the case (5). The pouch-type lithium secondary battery includes one or more battery structures (7). A separator (4) is disposed between the positive electrode (3) and the negative electrode (2) to form the battery structure (7). The battery structure (7) is stacked in a bicell structure, then impregnated with an electrolyte, and then housed and sealed in a pouch to complete the pouch-type lithium secondary battery.

[0105] Specifically, the battery structure (7) including the aforementioned positive electrode (3), negative electrode (2), and separator (4) is simply stacked and contained in a pouch, or wound into a jelly roll shape or folded and contained in a pouch. Subsequently, an electrolyte is injected into the pouch and sealed to complete the lithium secondary battery (1).

[0106] The case (5) may be made of metal such as aluminum, aluminum alloy, nickel-plated steel, or a laminate film or plastic that constitutes the pouch.

[0107] Lithium secondary battery (1) has excellent lifespan characteristics and high rate characteristics, so it is used in, for example, electric vehicles (EV). For example, it is used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEV). In addition, it is used in fields where a large amount of power storage is required. For example, it is used in electric bicycles, power tools, etc.

[0108] A plurality of lithium secondary batteries (1) are stacked to form a battery module, and a plurality of battery modules form a battery pack. Such a battery pack can be used in any device requiring high capacity and high output. For example, it can be used in laptops, smartphones, electric vehicles, etc. A battery module includes, for example, a plurality of batteries and a frame that holds them.

[0109] A battery pack includes, for example, a plurality of battery modules and a bus bar connecting them. The battery modules and / or battery pack may further include a cooling device. A plurality of battery packs are controlled by a battery management system. The battery management system includes a battery pack and a battery control device connected to the battery pack.

[0110] Figure 14 shows an SEM image of a lithium secondary battery according to one embodiment in which lithium is not electrodeposited in the internal pores of a porous structure after charging, and metallic lithium is electrodeposited on the surface of the negative electrode.

[0111] Specifically, referring to FIG. 14, according to Example 16, metallic lithium can be electrodeposited on the surface of a cathode in which the ratio of CNT conductive material in a porous structure is 0.5 wt%.

[0112] According to some embodiments of the present disclosure, if a certain amount or more of an electrically conductive material is included to impart high electrical conductivity to the porous structure from the beginning, it can be confirmed that lithium is not electrodeposited in the internal pores, and metallic lithium is electrodeposited on the outermost surface of the negative electrode, thereby suppressing volume change and improving battery life.

[0113] According to some embodiments of the present disclosure, crystalline titanium oxide (TiO2) constituting a porous structure undergoes only a small amount of lithium intercalation reaction (Li x Since TiO2 exhibits electrical conductivity, it conducts electrical conductivity starting from the bottom of the porous structure, thereby enabling the electrodeposition of lithium across the entire porous structure.

[0114]

[0115] cathode current collector

[0116] The negative electrode current collector may not include a negative electrode active material layer. In a negative electrode current collector that does not include a negative electrode active material layer, lithium metal may be plated onto the negative electrode current collector by charging. The plated metal layer may comprise plated lithium, lithium metal foil, lithium metal powder, lithium alloy foil, lithium alloy powder, an organic compound containing lithium, or a combination thereof. The metal layer may comprise non-fibrous lithium, non-needle lithium, plate lithium, or any combination thereof. The lithium alloy contains lithium and a first metal, and the first metal may include indium (In), silicon (Si), gallium (Ga), tin (Sn), aluminum (Al), titanium (Ti), zirconium (Zr), niobium (Nb), germanium (Ge), antimony (Sb), bismuth (Bi), gold (Au), platinum (Pt), palladium (Pd), magnesium (Mg), silver (Ag), zinc (Zn), nickel, iron, cobalt, chromium, cesium, sodium, potassium, calcium, yttrium, bismuth, tantalum, hafnium, barium, vanadium, strontium, lanthanum, or a combination thereof.

[0117] The material constituting the negative electrode current collector can be any material that does not react with lithium, that is, a material that does not form an alloy or compound with lithium and has conductivity. The metal substrate is, for example, a metal or an alloy. The metal substrate may be, for example, made of indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. The electrode current collector (200) may have a shape selected from, for example, a sheet, foil, film, plate, porous body, mesoporous body, through-hole containing body, polygonal ring body, mesh body, foam, and nonwoven body, but is not necessarily limited to these shapes and any shape used in the relevant technical field is possible.

[0118] The negative electrode current collector comprises, for example, a first metal substrate. The first metal substrate comprises the first metal as a main component or is composed of the first metal. The first metal substrate comprises the first metal as a main component or is composed of the first metal. The content of the first metal included in the first metal substrate is, for example, 90 weight% or more, 95 weight% or more, 99 weight% or more, or 99.9 weight% or more with respect to the total weight of the first metal substrate. The first metal substrate may be composed of, for example, a material that does not react with lithium, that is, does not form an alloy and / or compound with lithium.

[0119] The first metal may be, for example, copper (Cu), nickel (Ni), stainless steel (SUS), iron (Fe), and cobalt (Co), but is not necessarily limited to these; any metal used as a current collector in the relevant technical field may be used. The first metal substrate may be composed of, for example, one of the metals described above, or may be composed of an alloy of two or more metals. The first metal substrate is, for example, in the form of a sheet or foil.

[0120] The negative current collector may further include a coating layer (not shown) containing a second metal on a first metal substrate.

[0121] The cathode current collector may include, for example, a first metal substrate and a coating layer disposed on the first metal substrate and comprising a second metal. The second metal has a higher Mohs hardness than the first metal. That is, since the coating layer comprising the second metal is harder than the substrate comprising the first metal, deterioration of the first metal substrate can be prevented. The Mohs hardness of the material constituting the first metal substrate is, for example, 5.5 or less. The Mohs hardness of the first metal is, for example, 5.5 or less, 5.0 or less, 4.5 or less, 4.0 or less, 3.5 or less, or 3.0 or less. The Mohs hardness of the first metal may be, for example, 2.0 to 6.0. The coating layer comprises the second metal. The coating layer may, for example, comprise the second metal as a main component or be composed of the second metal. The content of the second metal included in the coating layer is, for example, 90% by weight or more, 95% by weight or more, 99% by weight or more, or 99.9% by weight or more with respect to the total weight of the coating layer. The coating layer may be composed of, for example, a material that does not react with lithium, that is, does not form an alloy and / or compound with lithium. The Mohs hardness of the material constituting the coating layer is, for example, 6.0 or more. For example, the Mohs hardness of the second metal is 6.0 or more, 6.5 or more, 7.0 or more, 7.5 or more, 8.0 or more, 8.5 or more, or 9.0 or more. The Mohs hardness of the second metal may be, for example, 6.0 to 12. If the Mohs hardness of the second metal is excessively low, it may be difficult to suppress the deterioration of the negative electrode current collector. If the Mohs hardness of the second metal is excessively high, processing may not be easy. The second metal is one or more selected from, for example, titanium (Ti), manganese (Mn), niobium (Nb), tantalum (Ta), iridium (Ir), vanadium (V), rhenium (Re), osmium (Os), tungsten (W), chromium (Cr), boron (B), ruthenium (Ru), and rhodium (Rh).The coating layer may be composed of, for example, one of the metals described above, or an alloy of two or more metals. The difference in Mohs hardness between the first metal included in the first metal substrate and the second metal included in the coating layer may be, for example, 2 or more, 2.5 or more, 3 or more, 3.5 or more, or 4 or more. By having such a difference in Mohs hardness between the first metal and the second metal, the deterioration of the negative current collector can be suppressed more effectively. The coating layer may have a single-layer structure or a multilayer structure of two or more layers. The coating layer may have a two-layer structure including, for example, a first coating layer and a second coating layer. The coating layer may have a three-layer structure including, for example, a first coating layer, a second coating layer, and a third coating layer. The thickness of the coating layer may be, for example, 10 nm to 1 μm, 50 nm to 500 nm, 50 nm to 200 nm, or 50 nm to 150 nm. The coating layer may be deposited on the first metal substrate by, for example, vacuum deposition, sputtering, plating, etc., but is not necessarily limited to these methods; any method capable of forming a coating layer in the relevant technical field is possible.

[0122] For example, the cathode current collector may have a reduced thickness compared to a conventional cathode current collector. Accordingly, the cathode according to the present disclosure is distinguished from a conventional electrode comprising a thick film current collector by including, for example, a thin film current collector.

[0123] As a result, the energy density of a lithium metal battery employing such an electrode is increased. The thickness of the negative electrode current collector may be, for example, less than 15 μm, 14.5 μm or less, or 14 μm or less. The thickness of the negative electrode current collector may be, for example, 0.1 μm to less than 15 μm, 1 μm to 14.5 μm, 2 μm to 14 μm, 3 μm to 14 μm, 5 μm to 14 μm, or 10 μm to 14 μm.

[0124] The cathode current collector may have a form selected from, for example, a sheet, foil, film, plate, porous body, mesoporous body, through-hole containing body, polygonal ring body, mesh body, foam, and nonwoven body, but is not necessarily limited to these forms, and any form used in the relevant technical field is possible.

[0125] The negative current collector may include, for example, a base film and a metal substrate layer disposed on one or both sides of the base film. The negative current collector may have a structure comprising a substrate, wherein the substrate may include, for example, a base film and a metal substrate layer disposed on one or both sides of the base film. An intermediate layer may be additionally disposed on the metal substrate layer.

[0126] For example, the base film may include, for example, a polymer. The polymer may be, for example, a thermoplastic polymer. The polymer may include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. By including a thermoplastic polymer in the base film, the base film may melt upon the occurrence of a short circuit, thereby suppressing a sudden increase in current. The base film may be, for example, an insulator.

[0127] The metal substrate layer may include, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), or alloys thereof. The metal substrate layer can act as an electrochemical fuse and cut off upon overcurrent to perform a short-circuit prevention function. The limit current and maximum current can be controlled by adjusting the thickness of the metal substrate layer. The metal substrate layer may be plated or deposited on a base film. As the thickness of the metal substrate layer decreases, the limit current and / or maximum current of the negative electrode current collector decreases, thereby improving the stability of the lithium metal battery during a short circuit.

[0128] A lead tab may be added to the metal substrate layer for external connection. The lead tab may be welded to the metal substrate layer or the metal substrate layer / base film laminate by means of ultrasonic welding, laser welding, spot welding, etc. During welding, the base film and / or the metal substrate layer may melt, thereby electrically connecting the metal substrate layer to the lead tab. To make the weld between the metal substrate layer and the lead tab more robust, a metal chip may be added between the metal substrate layer and the lead tab. The metal chip may be a thin sheet of the same material as the metal of the metal substrate layer. The metal chip may be, for example, metal foil, metal mesh, etc. The metal chip may be, for example, aluminum foil, copper foil, SUS foil, etc. The lead tab may be welded to the metal chip / metal substrate layer laminate or the metal chip / metal substrate layer / base film laminate by placing the metal chip on the metal substrate layer and then welding it to the lead tab. During welding, the base film, metal layer, and / or metal chip may melt, allowing the metal layer or the metal layer / metal chip laminate to be electrically connected to the lead tab. A metal chip and / or lead tab may be added to a portion of the metal substrate layer. The thickness of the base film may be, for example, 1 μm to 50 μm, 1.5 μm to 50 μm, 1.5 μm to 40 μm, or 1 μm to 30 μm. By having the base film within this thickness range, the weight of the cathode assembly can be reduced more effectively. The melting point of the base film may be, for example, 100 to 300 °C, 100 to 250 °C or lower, or 100 to 200 °C. By having the base film within this melting point range, the base film can melt during the welding process of the lead tab and be easily bonded to the lead tab. To improve the adhesion between the base film and the metal substrate layer, a surface treatment such as corona treatment may be performed on the base film. The thickness of the metal substrate layer is, for example, 0.The thickness may be 0.1 μm to 3 μm, 0.1 μm to 3 μm, 0.1 μm to 2 μm, or 0.1 μm to 1 μm. By having the metal substrate layer have a thickness within this range, the stability of the cathode can be ensured while maintaining conductivity. The thickness of the metal piece may be, for example, 2 μm to 10 μm, 2 μm to 7 μm, or 4 μm to 6 μm. By having the metal piece have a thickness within this range, the connection between the metal layer and the lead tab can be performed more easily. By having the cathode current collector have this structure, the weight of the electrode can be reduced and, consequently, the energy density can be improved.

[0129] According to one embodiment, a negative electrode active material layer may be free on the negative electrode current collector before charging and discharging. For example, a lithium metal layer may be free on the negative electrode current collector before charging and discharging.

[0130] According to one embodiment, a lithium metal layer including a plate-shaped lithium metal thin film may be disposed on a negative electrode current collector before performing charging and discharging.

[0131]

[0132] electrolytes

[0133] The electrolyte may be, for example, a liquid electrolyte, a solid electrolyte, a gel electrolyte, or a combination thereof.

[0134] The electrolyte is, for example, an organic electrolyte. The organic electrolyte is prepared, for example, by dissolving a lithium salt in an organic solvent. Any organic solvent used as an organic solvent in the relevant technical field may be used. Organic solvents are, for example, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether, or mixtures thereof.

[0135] Any lithium salt used as a lithium salt in the relevant technical field is also acceptable. Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, and LiN(C x F 2x+1 SO2)(C y F 2y+1 The lithium salts are SO2)(1≤x≤20, 1≤y≤20), LiCl, LiI, or mixtures thereof. The concentration of the lithium salt is, for example, 0.1 M to 5.0 M.

[0136] Solid electrolytes are, for example, oxide-based solid electrolytes, sulfide-based solid electrolytes, polymeric solid electrolytes, or combinations thereof.

[0137] Solid electrolytes are, for example, oxide-based solid electrolytes. Oxide-based solid electrolytes are Li 1+x+y Al x Ti 2-x Si y P 3-y O 12(0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(O≤x<1, O≤y<1), PB(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Li3PO4, Li x Ti y (PO4)3(0 <x<2, 0<y<3), Li x Al y Ti z (PO4)3(0 <x<2, 0<y<1, 0<z<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1 0≤y≤1), Li x La y TiO3(0 <x<2, 0<y<3), Li2O, LiOH, Li2CO3, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2, Li 3+x La3M2O 12 It is one or more selected from (M = Te, Nb, or Zr, where x is an integer from 1 to 10). Solid electrolytes are produced by sintering methods, etc. For example, oxide-based solid electrolytes include Li7La3Zr2O 12 (LLZO) and Li 3+x La3Zr 2-a MaO 12 It is a garnet-type solid electrolyte selected from (M doped LLZO, M=Ga, W, Nb, Ta, or Al, x is an integer from 1 to 10).

[0138] Sulfide-based solid electrolytes may comprise, for example, lithium sulfide, silicon sulfide, phosphorus sulfide, boron sulfide, or combinations thereof. Sulfide-based solid electrolyte particles may comprise Li2S, P2S5, SiS2, GeS2, B2S3, or combinations thereof. Sulfide-based solid electrolyte particles may be Li2S or P2S5. Sulfide-based solid electrolyte particles are known to have high lithium ion conductivity compared to other inorganic compounds. For example, sulfide-based solid electrolytes comprise Li2S and P2S5. When the sulfide solid electrolyte material constituting the sulfide-based solid electrolyte comprises Li2S-P2S5, the mixed molar ratio of Li2S to P2S5 may be, for example, in the range of about 50:50 to about 90:10. Additionally, Li3PO4, halogens, halogen compounds, Li 2+2x Zn 1-x GeO4("LISICON", 0≤x<1), Li 3+y PO 4-x N x ("LIPON", 0 <x<4, 0<y<3), Li 3.25 Ge 0.25 P 0.75An inorganic solid electrolyte prepared by adding S4 ("ThioLISICON"), Li2O-Al2O3-TiO2-P2O5 ("LATP"), etc., to an inorganic solid electrolyte of Li2S-P2S5, SiS2, GeS2, B2S3, or a combination thereof can be used as a sulfide solid electrolyte. Non-limiting examples of sulfide solid electrolyte materials include Li2S-P2S5, Li2S-P2S5-LiX (X = halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-ZmSn (0 <m<10, 0<n<10, Z=Ge, Zn 또는 Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, 및 Li2S-SiS2-Li p MO q (0 <p<10, 0<q<10, M=P, Si, Ge, B, Al, Ga 또는 In)을 포함한다. 이와 관련하여, 황화물계 고체전해질 재료는 황화물계 고체전해질 물질의 원료 시작 물질(예를 들면, Li2S, P2S5, 등)을 용융 담금질법(melt quenching method), 기계적 밀링법 등에 의해 처리함으로써 제조될 수 있다.

[0139] In addition, a calcination process may be performed after the above treatment. The sulfide-based solid electrolyte may be amorphous, crystalline, or a mixture thereof.

[0140] Polymer solid electrolytes are electrolytes that, for example, contain a mixture of a lithium salt and a polymer, or contain a polymer having ion-conducting functional groups. Polymer solid electrolytes are, for example, polymer electrolytes that do not contain a liquid electrolyte. The polymers included in the polymeric solid electrolyte are, for example, polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyethylene oxide (PEO), poly(styrene-b-ethylene oxide) block copolymer (PS-PEO), poly(styrene-butadiene), poly(styrene-isoprene-styrene), poly(styrene-b-divinylbenzene) block copolymer, poly(styrene-ethylene oxide-styrene) block copolymer, polystyrene sulfonate (PSS), polyvinyl fluoride (PVF), poly(methylmethacrylate) (PMMA), polyethylene glycol (PEG), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), polyethylenedioxythiophene (PEDOT), polypyrrole (PPY), polyacrylonitrile (PAN), Polyaniline, Polyacetylene, Nafion, Aquivion, Flemion, Gore, Aciplex, Morgane ADP, Sulfonated poly, (ether ether ketone)(sulfonated poly(ether ether ketone), SPEEK), Sulfonated poly(arylene ether ketone sulfone)(sulfonated poly(aryl ether ketone, SPAEK), Poly[bis(benzimidazobenzisoquinolinones)](poly[bis(benzimidazobenzisoquinolinones)], SPBIBI), Poly(styrene sulfonate)(Poly(styrene sulfonate), PSS), Lithium 9,It may be 10-diphenylanthracene-2-sulfonate (lithium 9,10-diphenylanthracene-2-sulfonate, DPASLi+) or a combination thereof, but is not limited thereto; any that is used as a polymer electrolyte in the relevant technical field is acceptable. Any lithium salt that can be used as a lithium salt in the relevant technical field is acceptable. Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C, x F 2x+1 SO2)(C y F 2y+1 SO2)(x and y are each 1 to 20), LiCl, LiI, or mixtures thereof, etc.

[0141] A gel electrolyte is, for example, a gel polymer electrolyte. A gel polymer electrolyte is an electrolyte that includes, for example, a liquid electrolyte and a polymer, or includes an organic solvent and a polymer having ion-conducting functional groups. The liquid electrolyte may be, for example, an ionic liquid, a mixture of a lithium salt and an organic solvent, a mixture of an ionic liquid and an organic solvent, or a mixture of a lithium salt, an ionic liquid, and an organic solvent. The polymer may be selected from among the polymers used in solid polymer electrolytes. The organic solvent may be selected from among the organic solvents used in liquid electrolytes. The lithium salt may be selected from among the lithium salts used in solid polymer electrolytes. An ionic liquid refers to a salt in a liquid state at room temperature or a room temperature molten salt that has a melting point below room temperature and consists solely of ions. The ionic liquid comprises, for example, a) one or more cations selected from ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, triazolium, and mixtures thereof, and b) BF4 - , PF6 - , AsF6 -, SbF6 - , AlCl4 - , HSO4 - , ClO4 - , CH3SO3 - , CF3CO2 - , Cl - , Br - , I - , BF4 - , SO4 - , CF3SO3 - , (FSO2)2N - , (C2F5SO2)2N - , (C2F5SO2)(CF3SO2)N - , and (CF3SO2)2N - It may include one or more compounds selected from those containing one or more anions selected from among. A gel polymer electrolyte may be formed by impregnating the polymer solid electrolyte into the electrolyte in a lithium secondary battery. The gel electrolyte may further include inorganic particles.

[0142]

[0143] anode

[0144] A positive active material layer is disposed on a positive current collector to form a positive electrode. A positive active material layer is disposed on an electrolyte, and a positive current collector may be disposed on the positive active material layer.

[0145]

[0146] positive current collector

[0147] The positive electrode includes a positive electrode current collector. For example, a positive electrode can be prepared by forming a layer of positive electrode active material on the positive electrode current collector.

[0148] For example, the positive current collector may include indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof.

[0149] According to one embodiment, the anode current collector may include aluminum (Al).

[0150] For example, the positive current collector may include a base film and a metal substrate layer disposed on one or both sides of the base film, in the same way as the negative current collector described above.

[0151]

[0152] positive active material layer

[0153] The positive active material layer may include a positive active material, a conductive material, and a binder.

[0154] As a positive electrode active material, a compound capable of reversible intercalation and deintercalation of lithium (a lithated intercalation compound) may be used. Specifically, one or more composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof may be used. The composite oxide may be a lithium transition metal composite oxide, and specific examples include a lithium nickel-based oxide, a lithium cobalt-based oxide, a lithium manganese-based oxide, a lithium iron phosphate-based compound, a cobalt-free nickel-manganese-based oxide, or a combination thereof.

[0155] As an example, a compound represented by any one of the following chemical formulas may 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-cMn 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 Mn2GbO4(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).

[0156] In the chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; and L 1 is Mn, Al, or a combination thereof.

[0157] For example, the cathode active material may be a high-nickel cathode active material in which the nickel content relative to 100 mol% of the metal excluding lithium in a lithium transition metal composite oxide is 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more and 99 mol% or less. The high-nickel cathode active material can achieve high capacity and can be applied to high-capacity, high-density lithium secondary batteries.

[0158] For example, the lithium transition metal oxide may be a compound represented by the following chemical formula 1:

[0159]

[0160] <Chemical Formula 1>

[0161] Li a Ni x Co y M z O 2-b A b

[0162]

[0163] In Chemical Formula 1, 1.0≤a≤1.2, 0≤b≤0.2, 0.6≤x<1, 0≤y≤0.3, 0 <z≤0.3, x+y+z=1, M은 망간(Mn), 바나듐(V), 마그네슘(Mg), 갈륨(Ga), 실리콘(Si), 텅스텐(W), 몰리브덴(Mo), 철(Fe), 크롬(Cr), 구리(Cu), 아연(Zn), 티타늄(Ti), 알루미늄(Al) 및 보론(B)으로 이루어진 군으로부터 선택된 하나 이상이고, A는 F, S, Cl, Br 또는 이들의 조합이다.

[0164] In Chemical Formula 1, for example, 0.7≤x<1, 0 <y≤0.3, 0<z≤0.3, 0.8≤x<1, 0<y≤0.2, 0<z≤0.2, 0.83≤x<0.97, 0<y≤0.15, 0<z≤0.15, 또는 0.85≤x<0.95, 0<y≤0.1, 0<z≤0.1일 수 있다.

[0165] For example, the lithium transition metal oxide may be at least one of the compounds represented by the following chemical formulas 2 and 3:

[0166]

[0167] <Chemical Formula 2>

[0168] LiNi x Co y Mn z O2

[0169]

[0170] In Chemical Formula 2, 0.6≤x≤0.95, 0 <y≤0.2, 0<z≤0.1이다. 예를 들어, 0.7≤x≤0.95, 0<y≤0.3, 0<z≤0.3이다.

[0171]

[0172] <Chemical Formula 3>

[0173] LiNi x Co y Al z O2

[0174]

[0175] In Chemical Formula 3, 0.6≤x≤0.95, 0 <y≤0.2, 0<z≤0.1이다. 예를 들어, 0.7≤x≤0.95, 0<y≤0.3, 0<z≤0.3이다. 예를 들어, 0.8≤x≤0.95, 0<y≤0.3, 0<z≤0.3이다. 예를 들어, 0.82≤x≤0.95, 0<y≤0.15, 0<z≤0.15이다. 예를 들어, 0.85≤x≤0.95, 0<y≤0.1, 0<z≤0.1이다.

[0176] For example, lithium transition metal oxides are LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.88 Co 0.08 Mn 0.04O2 , LiNi 0.8 Co 0.15 Mn 0.05O2 , LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.88 Co 0.1 Mn 0.02O2 , LiNi 0.8 Co 0.15 Al 0.05O2 , LiNi 0.8 Co0.1 Mn 0.2O2 or LiNi 0.88 Co 0.1 Al 0.02O2 It could be.

[0177] For example, the positive electrode active material may be one having a coating layer on the surface of a lithium transition metal oxide, or a mixture of a lithium transition metal oxide and a lithium transition metal oxide having a coating layer may be used.

[0178] For example, the coating layer may include a coating element compound of an oxide, hydroxide, oxyhydroxide, oxycarbonate, or hydroxycarbonate of a coating element.

[0179] For example, the compound forming the coating layer may be amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. For the coating layer formation process, any coating method may be used as long as the coating can be applied to the lithium transition metal oxide using the coating elements in a manner that does not adversely affect the physical properties of the cathode active material (e.g., spray coating, immersion method, etc.).

[0180] For example, the anode may additionally include an additive that can serve as a sacrificial anode.

[0181] The content of the positive active material is 90% to 99.5% by weight with respect to 100% by weight of the positive active material layer, and the content of the binder and the conductive material may each be 0.5% to 5% by weight with respect to 100% by weight of the positive active material layer.

[0182] The binder serves to adhere the positive active material particles well to each other and also to adhere the positive active material well to the current collector. Representative examples of binders include, but are not limited to, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride (PVDF), polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, nylon, etc.

[0183] A conductive material is used to impart conductivity to an electrode, and any electronically conductive material that does not cause chemical changes can be used in the battery being constructed. Examples of conductive materials include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and carbon nanotube; metal-based materials in the form of metal powder or metal fibers containing copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0184]

[0185] separator

[0186] A lithium secondary battery according to one embodiment may further include a separator.

[0187] As a separator, polyethylene, polypropylene, polyvinylidene fluoride, or multilayer films of two or more layers thereof may be used, and of course, mixed multilayer films such as polyethylene / polypropylene two-layer separator, polyethylene / polypropylene / polyethylene three-layer separator, polypropylene / polyethylene / polypropylene three-layer separator may be used.

[0188] The separator may include a porous substrate and a coating layer comprising an organic material, an inorganic material, or a combination thereof located on one or both sides of the porous substrate.

[0189] The porous substrate may be a polymer membrane formed from any one of the following: polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyacetal; polyamide; polyimide; polycarbonate; polyetherketone; polyaryletherketone; polyetherimide; polyamideimide; polybenzimidazole; polyethersulfone; polyphenylene oxide; cyclic olefin copolymer; polyphenylene sulfide; polyethylene naphthalate; glass fiber; Teflon; and polytetrafluoroethylene, or a copolymer or mixture of two or more of these.

[0190] The organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.

[0191] The inorganic material may include, but is not limited to, inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0192] Organic and inorganic materials may exist mixed in a single coating layer, or may exist in a stacked form with a coating layer containing organic materials and a coating layer containing inorganic materials.

[0193] This will be explained in more detail through the following examples and comparative examples. However, the examples are for illustrative purposes only and are not limited thereto.

[0194]

[0195] Example 1: Preparation of a negative electrode for a lithium secondary battery

[0196] A copper foil was prepared as a current collector. A cathode was manufactured by coating rutile-phase TiO2 with a particle size (D50) of 1 μm in powder form with a PVDF binder onto the copper foil. Specifically, rutile-phase TiO2 and a PVDF binder were mixed in an NMP solvent at a mass ratio of 98:2 with a solid content of 57.1%, and zirconia balls were added for uniform dispersion. A slurry was prepared by mixing in a Thinky Mixer at 1000 rpm for 10 minutes. The slurry was applied onto a 10 μm copper substrate and dried in a vacuum oven at 130°C for 3 hours, after which a cathode coated with a TiO2 semiconductor inorganic layer to a thickness of 40 μm was manufactured.

[0197]

[0198] Example 2: Preparation of a negative electrode for a lithium secondary battery

[0199] A cathode was prepared in the same manner as in Example 1, except that MoS2 powder was used as the semiconductor inorganic material.

[0200]

[0201] Example 3: Preparation of a negative electrode for a lithium secondary battery

[0202] A cathode was prepared in the same manner as in Example 1, except that VO2 was used in powder form as a semiconductor inorganic material.

[0203]

[0204] Example 4: Preparation of a negative electrode for a lithium secondary battery

[0205] A cathode was prepared in the same manner as in Example 1, except that V2O5 was used in powder form as the semiconductor inorganic material.

[0206]

[0207] Example 5: Preparation of a negative electrode for a lithium secondary battery

[0208] A cathode was prepared in the same manner as in Example 1, except that MoO2 was used in powder form as the semiconductor inorganic material.

[0209]

[0210] Example 6: Preparation of a negative electrode for a lithium secondary battery

[0211] A cathode was prepared in the same manner as in Example 1, except that TiS2 was used in powder form as the semiconductor inorganic material.

[0212]

[0213] Example 7: Preparation of a negative electrode for a lithium secondary battery

[0214] A cathode was prepared in the same manner as in Example 1, except that rutile-phase TiO2 with a particle size of 10 μm was used as a semiconductor inorganic in powder form.

[0215]

[0216] Example 8: Preparation of a negative electrode for a lithium secondary battery

[0217] A cathode was prepared in the same manner as in Example 1, except that anatase-phase TiO2 with a particle size of 10 μm was used in powder form as a semiconductor inorganic.

[0218]

[0219] Example 9: Preparation of a negative electrode for a lithium secondary battery

[0220] A copper foil was prepared as a current collector. A cathode was fabricated by coating 0.2 wt% of CNT conductive material and TiO2 with an average particle size of 1 μm in powder form with a PVDF binder onto the copper foil. Specifically, rutile-phase TiO2, CNT conductive material, and PVDF binder were mixed in an NMP solvent at a mass ratio of 98:0.2:1.8 with a solid content of 55%, and zirconia balls were added for uniform dispersion. A slurry was prepared by mixing in a Thinky Mixer at 1000 rpm for 10 minutes. The slurry was applied onto a 10 μm copper substrate and dried in a vacuum oven at 130°C for 6 hours to fabricate a cathode coated with a porous active material layer to a thickness of 40 μm.

[0221]

[0222] Example 10: Preparation of a negative electrode for a lithium secondary battery

[0223] A cathode was prepared in the same manner as in Example 9, except that MoS2 was used in powder form as the semiconductor inorganic material.

[0224]

[0225] Example 11: Preparation of a negative electrode for a lithium secondary battery

[0226] A cathode was prepared in the same manner as in Example 9, except that VO2 was used in powder form as a semiconductor inorganic material.

[0227]

[0228] Example 12: Preparation of a negative electrode for a lithium secondary battery

[0229] A cathode was prepared in the same manner as in Example 9, except that V2O5 was used in powder form as the semiconductor inorganic material.

[0230]

[0231] Example 13: Preparation of a negative electrode for a lithium secondary battery

[0232] A cathode was prepared in the same manner as in Example 9, except that MoO2 was used in powder form as the semiconductor inorganic material.

[0233]

[0234] Example 14: Preparation of a negative electrode for a lithium secondary battery

[0235] A cathode was prepared in the same manner as in Example 9, except that TiS2 was used in powder form as the semiconductor inorganic material.

[0236]

[0237] Example 15: Preparation of a negative electrode for a lithium secondary battery

[0238] A cathode was manufactured in the same manner as in Example 1, except that rutile-phase TiO2 with a particle size of 1 μm was used as a semiconductor inorganic in powder form, and the thickness of the porous active material layer was manufactured to 35 μm by drying in a vacuum oven and then rolling.

[0239]

[0240] Example 16: Preparation of a negative electrode for a lithium secondary battery

[0241] A copper foil was prepared as a current collector. A cathode was fabricated by coating 0.5 wt% of CNT conductive material and TiO2 in powder form with an average particle size of 1 μm together with a PVDF binder onto the copper foil. Specifically, rutile-phase TiO2, CNT conductive material, and PVDF binder were mixed in an NMP solvent at a mass ratio of 98:0.5:1.5 with a solid content of 55%, and zirconia balls were added for uniform dispersion. A slurry was prepared by mixing in a Thinky Mixer at 1000 rpm for 10 minutes. The slurry was applied onto a 10 μm copper substrate and dried in a vacuum oven at 130°C for 6 hours to fabricate a cathode coated with a porous active material layer to a thickness of 40 μm.

[0242]

[0243] Comparative Example 1: Preparation of a negative electrode for a lithium secondary battery

[0244] Copper foil was prepared as the entire current collector. A cathode was fabricated on the copper foil without a coating.

[0245]

[0246] Comparative Example 2: Preparation of a negative electrode for a lithium secondary battery

[0247] A copper foil was prepared as a current collector. A cathode was manufactured by mixing CNT powder and a PVDF binder and coating the mixture onto the copper foil. Specifically, CNT and PVDF were mixed in an NMP solvent at a mass ratio of 90:10 with a solid content of 10%, and zirconia balls were added for uniform dispersion. A slurry was prepared by mixing in a Thinky Mixer at 1000 rpm for 10 minutes. The slurry was applied onto the copper foil and dried in a vacuum oven at 130°C for 6 hours to produce a cathode coated with a carbon layer 40 µm thick.

[0248]

[0249] Classification Current Collector Semiconductor Inorganic Conductive Material Binder Active Material Thickness (㎛) Porosity (%) Comparative Example 1 Copper Foil -- 00 Comparative Example 2 Copper Foil - CNT 90wt% PVDF 10wt% 4057.08 Example 1 Copper Foil (D50) 1㎛ Rutile TiO2 98wt% - PVDF 2.0wt% 4052.78 Example 2 Copper Foil MoS 298wt% - PVDF 2.0wt% 4049.87 Example 3 Copper Foil VO2 98wt% - PVDF 2.0wt% 4055.40 Example 4 Copper Foil V2O 598wt% - PVDF 2.0wt% 4056.72 Example 5 Copper Foil MoO2 98wt% - PVDF 2.0wt% 4055.64 Example 6 Copper foil TiS298wt%-PVDF2.0wt% 4047.25 Example 7 Copper foil (D50) 10㎛ Rutile TiO298wt%-PVDF2.0wt% 4055.62 Example 8 Copper foil (D50) 10㎛ Anatase TiO298wt%-PVDF2.0wt% 4054.11 Example 9 Copper foil (D50) 1㎛ Rutile TiO298wt%CNT0.2wt%PVDF1.8wt% 4056.13 Example 10 Copper foil MoS298wt%CNT0.2wt%PVDF1.8wt% 4050.36 Example 11 Copper Example 12 Copper foil V298wt%CNT0.2wt%PVDF1.8wt%4056.29 Example 12 Copper foil V2O598wt%CNT0.2wt%PVDF1.8wt%4058.07 Example 13 Copper foil MoO298wt%CNT0.2wt%PVDF1.8wt%4057.88 Example 14 Copper foil TiS298wt%CNT0.2wt%PVDF1.8wt%4051.46 Example 15 Copper foil (D50)1㎛ Rutile TiO298wt%-PVDF2.0wt%35 (rolled)42.77 Example 16 Copper foil (D50)1㎛ Rutile TiO298wt%CNT0.5wt%PVDF1.5wt%4058.92

[0250] Evaluation Example 1: Measurement of capacity retention rate when charging and discharging n times. A lithium secondary battery composed of each negative electrode, positive electrode, separator, and electrolyte prepared according to Examples 1 to 16 and Comparative Examples 1 to 2 was manufactured, and a charge-discharge evaluation was performed.

[0251] Manufacturing of anodes

[0252] First, in the case of the anode, Li 1.04 Ni 0.8 Co 0.1 Al 0.1 An anode slurry was prepared by dispersing an O2 anode active material and a PVDF binder together with a carbon black conductive material in an NMP solvent at a mass ratio of 97:1.5:1.5. The anode was prepared by coating the slurry onto a 12㎛ aluminum substrate and then drying and rolling it in a vacuum oven at 120°C for 8 hours.

[0253] Separator

[0254] The separator used for the above battery evaluation was a polypropylene separator with a thickness of 10㎛ and an air permeability (JIS Gurley) value of 120 sec / 100ml.

[0255] Electrolyte manufacturing

[0256] The electrolyte used for the evaluation of the above secondary battery was a gel electrolyte (GPE) prepared by adding 4 wt% of dipentaerythritol pentaacrylate (DPHA) monomer and 1200 ppm of the polymerization initiator tert-butyl peroxypivalate to a liquid electrolyte. The liquid electrolyte has a composition in which lithium tetrafluoroborate (LiBF4) and lithium difluorooxalate borate (LiDFOB) are dissolved at 0.6 M and 0.6 M, respectively, in a mixed solvent containing fluoroethylene carbonate (FEC), diethyl carbonate (DEC), and butyronitrile in a volume ratio of 31:55:14.

[0257] Manufacturing of charge / discharge evaluation cells

[0258] A single-plate pouch cell was fabricated to perform the above charge-discharge evaluation. A single-plate pouch cell was fabricated by sequentially stacking a separator and an anode on top of the respective cathodes corresponding to Examples 1 to 16 and Comparative Examples 1 to 2 inside an aluminum pouch, injecting the gel electrolyte (GPE), and then vacuum sealing the aluminum pouch. The cathode and anode were configured to be connected to tabs made of nickel and aluminum, respectively, so as to be connected to external wires. In addition, the pouch cell, sealed with the injected gel electrolyte (GPE), was left at room temperature for 12 hours to allow the electrolyte to fully impregnate the anode pores, and subsequently, it was left in an 80°C oven for 3 hours to cure the gel electrolyte (GPE) impregnated in all the pores inside the pouch cell.

[0259] Charge / Discharge Evaluation in Progress

[0260] The pouch cell manufactured through the above process was charged with a constant current at a rate of 0.1C at 45℃ until the voltage reached 4.30V (vs. Li), and then cut off at a current rate of 0.05C while maintaining 4.30V in constant voltage mode. Subsequently, it was discharged with a constant current rate of 0.1C until the voltage reached 3.6V (vs. Li) during discharge (Formation Stage 1).

[0261] A lithium secondary battery that has undergone the first stage of formation was charged at 45°C at a constant current of 0.2C in a voltage range of 3.6 to 4.3 V relative to lithium metal, and then cut off at a current rate of 0.05C while maintaining 4.3V in constant voltage mode. Subsequently, constant current discharge was performed at 0.2C until a cut-off voltage of 3.6V was reached (second stage of formation).

[0262] The Mars stage was completed by going through the above Mars 1 and 2 stages one cycle each.

[0263] A lithium secondary battery with a completed formation stage was charged at 45°C at a constant current of 0.33C in a voltage range of 3.6 to 4.3 V relative to lithium metal, and then cut off at a current rate of 0.05C while maintaining 4.3V in constant voltage mode. Subsequently, constant current discharge was performed at 1.0C until a cut-off voltage of 3.6V was reached.

[0264] The aforementioned charge / discharge process was repeated a total of 100 times. In all charge / discharge cycles, a 5-minute pause was observed after each charge / discharge cycle. Here, the capacity retention rate in the Nth cycle is defined by the following formula.

[0265] Capacity Retention Rate (%) = (Discharge Capacity at Nth Cycle / Discharge Capacity at 1st Cycle) × 100

[0266]

[0267] Evaluation Example 2: Confirmation of the volume change rate of a lithium secondary battery after n charge-discharge cycles

[0268] Using the same manufacturing and evaluation method as described in Evaluation Example 1 above, for lithium secondary batteries containing negative electrodes manufactured according to Examples 1 to 16 and Comparative Examples 1 to 2, the thickness of the pouch cell before and after 50 cycles of charge-discharge operation was measured using a digital micrometer, and the volume change rate of the lithium secondary battery was confirmed according to the following equation.

[0269] Volume change rate (%) = (Thickness of pouch cell after 50 cycles - Thickness of pouch cell before charge / discharge) / (Thickness of pouch cell before charge / discharge) × 100

[0270]

[0271] According to Evaluation Example 1 above, the cycles reaching a capacity retention rate of 80% were measured and listed in Table 2 below.

[0272] According to Evaluation Example 2 above, the volume change rate of the lithium secondary battery after 50 cycles was measured and listed in Table 2 below.

[0273]

[0274] Classification Capacity Retention Rate After Reaching 80% Cycles (50 Cycles) Volume Change Rate (%) of Lithium Secondary Battery Comparative Example 1191 12.1 Comparative Example 214 38.8 Example 127 11.3 Example 225 42.6 Example 323 32.1 Example 426 03.0 Example 524 22.4 Example 6226 2.4 Example 727 43.3 Example 828 33.7 Example 927 71.3 Example 1024 52.7 Example 1122 22.6 Example 1224 82.7 Example 1323 72.7 Example 1421 53.4 Example 1526 90.8 Example 1619 77.1

[0275] Referring to Table 2, Examples 1 to 16 each had lithium metal uniformly electrodeposited inside the porous structure compared to Comparative Examples 1 to 2, thereby suppressing volume change and resulting in excellent capacity retention rate characteristics corresponding to battery life. Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto and can be implemented with various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and it is obvious that such modifications also fall within the scope of the present invention.

Claims

1. The entire house; and It includes a porous structure disposed over the entire house, and The above porous structure comprises a semiconductor inorganic material, and A negative electrode for a lithium secondary battery, wherein the band gap of the above semiconductor inorganic material is reduced due to the insertion of lithium into the crystal of the semiconductor inorganic material.

2. In Paragraph 1, The above semiconductor inorganic material comprises any one of TiO2, MoS2, VO2, V2O5, MoO2, TiS2, or any combination thereof, for a negative electrode for a lithium secondary battery.

3. In Paragraph 1, A negative electrode for a lithium secondary battery, wherein the band gap of the semiconductor inorganic material is 0.1 eV to 4 eV.

4. In Paragraph 1, A negative electrode for a lithium secondary battery, wherein, in a voltage range of 0.1 V to 2.5 V, the semiconductor inorganic material captures lithium ions within the porous structure through an intercalation reaction to form an interlayer compound.

5. In Paragraph 4, A negative electrode for a lithium secondary battery, wherein the band gap of the above interlayer compound is smaller than the band gap of the above semiconductor inorganic material.

6. In Paragraph 4, A negative electrode for a lithium secondary battery, wherein the proportion of lithium captured in the interlayer compound is 0.1 wt% to 30 wt% relative to the total weight of the porous structure.

7. In Paragraph 1, The above current collector comprises a foil structure layer containing copper (Cu) or a sheet structure layer containing copper, a negative electrode for a lithium secondary battery.

8. In Paragraph 1, The above porous structure completely covers the surface of the above current collector, a negative electrode for a lithium secondary battery.

9. In Paragraph 8, The above porous structure is a negative electrode for a lithium secondary battery formed by coating the surface of the above current collector with a powder containing the semiconductor inorganic material.

10. In Paragraph 1, The above porous structure is a negative electrode for a lithium secondary battery, further comprising a polymer binder.

11. In Paragraph 1, A negative electrode for a lithium secondary battery, wherein the porosity of the above porous structure is 20% to 70% based on volume.

12. In Paragraph 1, The above porous structure further comprises a conductive material, and A negative electrode for a lithium secondary battery, wherein the ratio of the conductive material in the porous structure is 0.01 wt% to 0.5 wt%.

13. Anode; A negative electrode for a lithium secondary battery according to claim 1; and A lithium secondary battery comprising an electrolyte disposed between the anode and the cathode.

14. In Paragraph 13, A lithium secondary battery in which the anode has a charging capacity 1.5 to 20 times greater than the intercalation capacity of the semiconductor inorganic material of the cathode.

15. In Paragraph 13, A lithium secondary battery in which a lithium metal layer is absent on the negative current collector of the above-mentioned negative electrode before charging.

16. Steps for preparing the entire house; and The method includes the step of placing a porous structure on the above-mentioned current collector, The above porous structure comprises a semiconductor inorganic material, and A method for manufacturing a negative electrode for a lithium secondary battery, wherein the band gap of the semiconductor inorganic material is reduced due to the insertion of lithium into the crystal of the semiconductor inorganic material.

17. In Paragraph 16, The step of arranging the above porous structure A method for manufacturing a negative electrode for a lithium secondary battery, comprising the step of coating the surface of the above-mentioned current collector with a powder containing the semiconductor inorganic material.

18. In Paragraph 16, A method for manufacturing a negative electrode for a lithium secondary battery, wherein the semiconductor inorganic material comprises any one of TiO2, MoS2, VO2, V2O5, MoO2, TiS2, or any combination thereof.

19. In Paragraph 16, A method for manufacturing a negative electrode for a lithium secondary battery, wherein the band gap of the semiconductor inorganic material is 0.1 eV to 4 eV.

20. In Paragraph 16, A method for manufacturing a negative electrode for a lithium secondary battery, wherein, in a voltage range of 0.1 V to 2.5 V, the porous structure comprises an interlayer compound formed by capturing lithium ions through an intercalation reaction of the semiconductor inorganic material.

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