Positive electrode for lithium secondary battery and lithium secondary battery comprising same

Abstract

The present disclosure provides a positive electrode for a lithium secondary battery and a lithium secondary battery comprising same. The positive electrode for a lithium secondary battery according to the present disclosure comprises: a positive electrode current collector; a first positive electrode mixture layer disposed on the positive electrode current collector and including a first positive electrode active material and a first sacrificial positive electrode active material; and a second positive electrode mixture layer disposed on the first positive electrode mixture layer and including a second positive electrode active material and a second sacrificial positive electrode active material, wherein the particle size (D50) of the first sacrificial positive electrode active material may be different from the particle size of the second sacrificial positive electrode active material.

Description

Anode for a lithium secondary battery and a lithium secondary battery including the same

[0001] The present disclosure relates to a positive electrode for a lithium secondary battery and a lithium secondary battery including the same.

[0002]

[0003] 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.

[0004] 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.

[0005] 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.

[0006] In contrast, recently, numerous studies have been conducted on lithium metal batteries using lithium metal instead of carbon-based negative electrode active material on the negative electrode current collector to increase energy density. Lithium metal has a very large theoretical electric capacity of approximately 3860 mAh / g. Therefore, lithium metal batteries without a negative electrode active material layer have the advantage of having a significantly higher energy density per unit weight compared to conventional lithium-ion batteries coated with a thick layer of carbon-based negative electrode active material on the negative electrode current collector.

[0007] However, since such lithium metal batteries lack a source of extra lithium, their lifespan characteristics may deteriorate due to the continuous consumption of lithium during charging and discharging and the progression of irreversible reactions. Therefore, in order to drastically improve lifespan characteristics while maintaining the structure of a lithium metal battery without a negative electrode active material layer, a means to supply additional lithium within the cell is required.

[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]

[0010] One embodiment provides a positive electrode for a lithium secondary battery to solve the above technical problem.

[0011] Another embodiment provides a lithium secondary battery comprising a positive electrode for a lithium secondary battery to solve the above technical problem.

[0012]

[0013] A positive electrode for a lithium secondary battery according to an embodiment of the present invention for solving the above technical problem comprises a positive electrode current collector, a first positive electrode composite layer disposed on the positive electrode current collector and comprising a first positive electrode active material and a first sacrificial positive electrode active material, and a second positive electrode composite layer disposed on the first positive electrode composite layer and comprising a second positive electrode active material and a second sacrificial positive electrode active material, wherein the particle size (D50) of the first sacrificial positive electrode active material may be different from the particle size of the second sacrificial positive electrode active material.

[0014] A lithium secondary battery according to an embodiment of the present invention for solving the above technical problem comprises a positive electrode for a lithium secondary battery, a negative electrode including a negative electrode current collector, a separator interposed between the positive electrode and the negative electrode, and an electrolyte disposed between the positive electrode and the negative electrode. The positive electrode for a lithium secondary battery comprises a positive electrode current collector, a first positive electrode composite layer disposed on the positive electrode current collector and comprising a first positive electrode active material and a first sacrificial positive electrode active material, and a second positive electrode composite layer disposed on the first positive electrode composite layer and comprising a second positive electrode active material and a second sacrificial positive electrode active material. The average particle size of the first sacrificial positive electrode active material may be different from the average particle size of the second sacrificial positive electrode active material.

[0015]

[0016] A cathode for a lithium secondary battery according to some embodiments of the present disclosure uses a sacrificial cathode, thereby compensating for lithium consumption caused by the formation of Solid Electrolyte Interphase (SEI) or other side reactions during charging and discharging, while suppressing the phenomenon of localized lithium growth during the formation stage, and thus improving the uniformity of lithium electrodeposition.

[0017] A lithium secondary battery according to some embodiments of the present disclosure introduces a double-layer electrode (DLE) composed of an optimally designed double layer, thereby solving the problem of increased resistance caused by increased side reactions on the electrode surface due to reduced particle size, and increasing capacity retention rate and lifespan characteristics.

[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]

[0020] 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.

[0021] FIG. 1 schematically shows a positive electrode for a lithium secondary battery according to one embodiment.

[0022] Figure 2 shows a surface SEM image of a lithium secondary battery negative electrode according to one embodiment.

[0023] Figure 3 shows a surface SEM image of a lithium secondary battery negative electrode according to one embodiment.

[0024] Figure 4 shows a surface SEM image of a lithium secondary battery negative electrode according to one embodiment.

[0025] Figure 5 shows a surface SEM image of a lithium secondary battery negative electrode according to one embodiment.

[0026] Figure 6 shows a surface SEM image of a lithium secondary battery negative electrode according to one embodiment.

[0027] Figure 7 shows a surface SEM image of a lithium secondary battery negative electrode according to one embodiment.

[0028] FIG. 8 schematically shows the stacked structure of a lithium secondary battery according to one embodiment.

[0029] Figure 9 is a diagram showing the stacked structure after charging of the lithium secondary battery of Figure 8.

[0030] FIG. 10 is a diagram showing a stacked structure of a lithium secondary battery according to another embodiment.

[0031] FIG. 11 is a perspective view illustrating a lithium secondary battery according to one embodiment.

[0032] FIG. 12 is a perspective view illustrating a lithium secondary battery according to one embodiment.

[0033] FIG. 13 is a perspective view illustrating a lithium secondary battery according to one embodiment.

[0034] FIG. 14 is a perspective view illustrating a lithium secondary battery according to one embodiment.

[0035] 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.

[0036] 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.

[0037] 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."

[0038] 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.

[0039] Unless otherwise defined in this specification, particle size or particle size distribution may be the average particle size. Additionally, particle size or particle size distribution refers to the average particle size (D50), which is the diameter of a particle whose cumulative volume is 50% of the particle size distribution. 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 irradiated with ultrasound of about 28 kHz 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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”.

[0044] 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.

[0045] 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.

[0046] In this specification, “metal” includes both metals and metalloids such as silicon and germanium in an elemental or ionic state.

[0047] In this specification, "alloy" means a mixture of two or more metals.

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

[0049] In this specification, "anode active material" refers to an anode material capable of undergoing lithiation and delithiation.

[0050] In this specification, "lithiation" and "to lithiate" refer to the process of adding lithium to a positive electrode active material or a negative electrode active material.

[0051] In this specification, "delithiation" and "to delithiate" refer to the process of removing lithium from a positive electrode active material or a negative electrode active material.

[0052] In this specification, "charge" and "to charge" refer to the process of providing electrochemical energy to a battery.

[0053] In this specification, "discharge" and "discharge" refer to the process of removing electrochemical energy from a battery.

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

[0055] In this specification, "cathode" and "anode" refer to electrodes where electrochemical oxidation and delithiation occur during the discharge process.

[0056] Exemplary embodiments will be described in more detail below.

[0057]

[0058] anode

[0059] FIG. 1 schematically shows a positive electrode (130) for a lithium secondary battery according to one embodiment.

[0060] Referring to FIG. 1, a positive electrode (130) for a lithium secondary battery according to one embodiment of the present invention may include a positive electrode current collector (132), a first positive electrode composite layer (110), and a second positive electrode composite layer (120).

[0061] The first positive composite layer (110) may be disposed on the positive current collector (132). Additionally, the second positive composite layer (120) may be disposed on the first positive composite layer (110). That is, the positive (130) for a lithium secondary battery may have a multilayer structure in which the positive current collector (132), the first positive composite layer (110), and the second positive composite layer (120) are sequentially stacked.

[0062] In one embodiment, the positive current collector (132) 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.

[0063] As illustrated in FIG. 1, the thickness of the first anode composite layer (110) may be thicker than the thickness of the second anode composite layer (120). For example, the thickness of the first anode composite layer (110) and the thickness of the second anode composite layer (120) may have a ratio of 95:5 to 80:20, 90:10 to 70:30, or 80:20 to 50:50.

[0064] In one embodiment, the anode composite part may include a first anode composite layer (110) and a second anode composite layer (120). Specifically, the anode composite part may be a double layer structure in which the first anode composite layer (110) and the second anode composite layer (120) are stacked.

[0065] In the anode composite section, the thickness (d1) of the first anode composite layer (110) may be 50% to 95% of the thickness (d3) of the anode composite section. That is, the thickness (d1) of the first anode composite layer (110) may be 50% to 95% of the thickness of the first anode composite layer (110) and the second anode composite layer (120). In contrast, the thickness (d2) of the second anode composite layer (120) may be 5% to 50% of the thickness (d3) of the anode composite section.

[0066] Conversely, unlike as illustrated in FIG. 1, in one embodiment, the thickness of the second anode composite layer (120) may be thicker than the thickness of the first anode composite layer (110). For example, the thickness of the first anode composite layer (110) and the thickness of the second anode composite layer (120) may have a ratio of 5:95 to 20:80, 10:90 to 30:70, or 20:80 to 50:50.

[0067] In one embodiment, the first anode composite layer (110) may include a first anode active material (112) and a first sacrificial anode active material (114). For example, the first anode composite layer (110) may be formed by mixing the first anode active material (112), the first sacrificial anode active material (114), a conductive material, and a binder.

[0068] In one embodiment, the second anode composite layer (120) may include a second anode active material (122) and a second sacrificial anode active material (124). For example, the second anode composite layer (120) may be formed by mixing the second anode active material (122), the second sacrificial anode active material (124), a conductive material, and a binder.

[0069] Here, the particle size (D50) of the first sacrificial positive active material (114) may be different from the particle size of the second sacrificial positive active material (124).

[0070] In one embodiment, the particle size of the first sacrificial positive active material (114) may be larger than the particle size of the second sacrificial positive active material (124).

[0071] For example, the particle size of the first sacrificial cathode active material (114) may be 1.3 to 10 times, 2 to 6 times, or 3 to 4 times the particle size of the second sacrificial cathode active material (124). Specifically, the particle size of the first sacrificial cathode active material (114) may be 4 μm to 10 μm, 4 μm to 5 μm, or 9 μm to 10 μm, and the particle size of the second sacrificial cathode active material (124) may be 1 μm to 3 μm, 1.5 μm to 2.5 μm, or 1.8 μm to 2.2 μm.

[0072] In one embodiment, the particle size of the second sacrificial cathode active material (124) may be larger than the particle size of the first sacrificial cathode active material (114). For example, the particle size of the second sacrificial cathode active material (124) may be 1.3 to 10 times, 2 to 6 times, or 3 to 4 times the particle size of the first sacrificial cathode active material (114). Specifically, the particle size of the second sacrificial cathode active material (124) may be 4 μm to 10 μm, 4 μm to 5 μm, or 9 μm to 10 μm, and the particle size of the first sacrificial cathode active material (114) may be 1 μm to 3 μm, 1.5 μm to 2.5 μm, or 1.8 μm to 2.2 μm.

[0073] The first sacrificial cathode active material (114) may include Li5FeO4, Li2MoO3, Li6CoO4, Li2O, Li3N, Li3P, or a combination thereof. Additionally, the second sacrificial cathode active material (124) may include Li5FeO4, Li2MoO3, Li6CoO4, Li2O, Li3N, Li3P, or a combination thereof. In one embodiment, the first sacrificial cathode active material (114) and the second sacrificial cathode active material (124) may have the same chemical composition. That is, the first sacrificial cathode active material (114) and the second sacrificial cathode active material (124) may be compounds that differ only in particle size.

[0074] The first positive active material may include LiMO2 (M is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or a combination thereof), LFP, LiM2O4 (M is Ti, V, Mn or a combination thereof), or a combination thereof. Additionally, the second positive active material may include LiMO2 (M is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or a combination thereof), LFP, LiM2O4 (M is Ti, V, Mn or a combination thereof), or a combination thereof. In one embodiment, the first positive active material (112) and the second positive active material (114) may have the same chemical composition. That is, the first positive active material (112) and the second positive active material (114) may be the same compound.

[0075] According to one embodiment, the first sacrificial cathode active material (114) or the second sacrificial cathode active material (124) included in the positive electrode (130) for a lithium secondary battery can form a lithium metal layer on a negative electrode substrate during the formation step in the manufacturing process of the lithium secondary battery. Through this process, the lifespan characteristics of the secondary battery can be significantly improved by compensating for irreversible lithium consumption caused by SEI generation or other side reactions while the charging and discharging of the lithium secondary battery is in progress.

[0076] FIGS. 2 to 7 show surface SEM images of a lithium secondary battery negative electrode according to one embodiment.

[0077] Figures 2 and 3 show the surface of the negative electrode after charging and discharging a lithium secondary battery containing a positive electrode for a lithium secondary battery having a particle size of 1.7 μm of sacrificial positive electrode active material.

[0078] Figures 4 and 5 show the surface of the negative electrode after charging and discharging a lithium secondary battery containing a positive electrode for a lithium secondary battery having a particle size of 4.1 μm of sacrificial positive electrode active material.

[0079] Figures 6 and 7 show the surface of the negative electrode after charging and discharging a lithium secondary battery containing a positive electrode for a lithium secondary battery having a particle size of 9.3 μm of sacrificial positive active material.

[0080] Referring to FIGS. 2 to 7, as described above, a phenomenon in which lithium grows locally is observed during the process of electrodepositing the sacrificial anode active material onto the cathode substrate. This non-uniform electrodeposition phenomenon may decrease as the particle size of the sacrificial anode active material decreases. That is, it can be confirmed that the lithium electrodeposition occurred most uniformly in FIGS. 2 and 3, and that the lithium electrodeposition occurred most non-uniformly in FIGS. 6 and 7.

[0081] In addition, as the particle size of the sacrificial cathode active material decreases, the composite density of the cathode containing the sacrificial cathode active material may increase. However, as the particle size of the sacrificial cathode active material decreases, the internal resistance (or DC-IR) of the battery may increase due to an increase in the specific surface area (BET) and side reactions on the cathode surface.

[0082] Accordingly, in a positive electrode for a lithium secondary battery according to one embodiment of the present disclosure (e.g., 130 of FIG. 1), a first sacrificial positive active material (114) having medium particle size with low resistance is placed in a first positive composite layer (110) close to the positive current collector (132) to lower the resistance, and a second sacrificial positive active material (124) having small particle size is placed in a second positive composite layer (120) close to the negative electrode to improve the uniformity of lithium electrodeposition.

[0083] A cathode for a lithium secondary battery according to some embodiments of the present disclosure uses a sacrificial cathode, thereby compensating for lithium consumption caused by the formation of Solid Electrolyte Interphase (SEI) or other side reactions during charging and discharging, while suppressing the phenomenon of localized lithium growth during the formation stage, and thus improving the uniformity of lithium electrodeposition.

[0084] A lithium secondary battery according to some embodiments of the present disclosure introduces a double-layer electrode (DLE) composed of an optimally designed double layer, thereby solving the problem of increased resistance caused by increased side reactions on the electrode surface due to reduced particle size, and increasing capacity retention rate and lifespan characteristics.

[0085] A lithium secondary battery comprising a sacrificial cathode according to some embodiments of the present disclosure can have improved lifespan characteristics even with a lower composite density than a cathode using only a cathode active material (such as LiCoO2) by optimizing the particle size distribution and ratio of the sacrificial cathode active material. Through this, a cathode for a lithium secondary battery with a novel structure that deviates from the existing correlation between composite density and lifespan characteristics can be provided.

[0086]

[0087] lithium secondary battery

[0088] FIG. 8 is a diagram showing a stacked structure of a lithium secondary battery according to one embodiment. FIG. 9 is a diagram showing the stacked structure of the lithium secondary battery of FIG. 8 after charging. FIG. 10 is a diagram showing a stacked structure of a lithium secondary battery according to another embodiment.

[0089] FIG. 8 is a drawing showing a stacked structure of a non-anode lithium secondary battery (800), and FIG. 9 may correspond to a drawing showing a lithium secondary battery (802) in which lithium metal is deposited on a negative electrode current collector (840) as the non-anode lithium secondary battery (800) of FIG. 8 is charged. FIG. 10 may correspond to a drawing showing a lithium metal secondary battery (1000) in which lithium metal (1050) is used as a negative electrode active material layer. The thickness of each layer shown in FIG. 8 to FIG. 10 is shown as an arbitrary size and is not necessarily limited thereto.

[0090] A lithium secondary battery (800, 802, 1000) according to one embodiment includes a positive electrode, a negative electrode, and an electrolyte (860, 1060) disposed between the positive electrode and the negative electrode. The electrolyte (860, 1060) may have a solid, liquid, or gel form. Although the present disclosure describes lithium metal secondary batteries primarily, it is not limited thereto and may be, for example, a lithium primary battery, and may also be applied to lithium-sulfur batteries, lithium-air batteries, etc.

[0091] Referring to FIGS. 8 and 9, a lithium secondary battery (800, 802) according to one embodiment of the present invention may include a positive electrode (830) for a lithium secondary battery according to one embodiment of the present invention described above, a negative electrode including a negative electrode current collector (840), an electrolyte (860) disposed between the positive electrode (830) and the negative electrode, and a separator interposed between the positive electrode (830) and the negative electrode.

[0092] That is, the lithium secondary battery according to one embodiment comprises a positive electrode (830) having a positive electrode current collector (832), a first positive electrode composite layer (810) disposed on the positive electrode current collector (832) and including a first positive electrode active material and a first sacrificial positive electrode active material, and a second positive electrode composite layer (820) disposed on the first positive electrode composite layer (810) and including a second positive electrode active material and a second sacrificial positive electrode active material, and the particle size of the first sacrificial positive electrode active material may be different from the particle size of the second sacrificial positive electrode active material.

[0093] Here, the negative current collector (840) may include a foil structure layer containing copper (Cu) or a sheet structure layer containing copper, as described below.

[0094] Referring to FIG. 8, in one embodiment, a lithium secondary battery (800) may be free of a negative electrode active material layer on the negative electrode before charging is performed. That is, the negative electrode current collector (840) may be exposed to the electrolyte (860).

[0095] Referring to FIG. 9, in a lithium secondary battery (802) according to one embodiment, a lithium metal layer (850) may be formed on a negative electrode current collector (840) after charging. Specifically, the lithium metal layer (850) may be disposed between the negative electrode current collector (840) and the electrolyte (860). For example, the lithium metal layer (850) may be a lithium electrodeposited layer. For example, the lithium metal layer (850) may include a lithium alloy and a lithium metal. For example, the lithium alloy included in the lithium metal layer (850) may weaken the reactivity of the lithium metal, thereby effectively preventing side reactions between the lithium metal layer (850) and the polymer electrolyte. Additionally, the lithium metal layer (850) has excellent electrical conductivity, which may reduce the internal resistance of the lithium secondary battery containing it. Accordingly, the lithium secondary battery (802) containing the lithium metal layer (850) may have improved lifespan characteristics as well as charge / discharge efficiency.

[0096] Here, the lithium constituting the lithium metal layer (850) may originate from the first sacrificial positive active material or the second sacrificial positive active material contained in the first positive composite layer (810) or the second positive composite layer (820). For example, the lithium metal layer (850) may be formed as lithium ions contained in the electrolyte (860), originating from the first sacrificial positive active material or the second sacrificial positive active material, are electrodeposited onto the negative current collector (840) as the lithium secondary battery is charged and discharged.

[0097] In particular, in conventional lithium-ion batteries, only the irreversible reaction at the beginning of charging and discharging is compensated for, so a small proportion of sacrificial cathode active material is sufficient; however, in a lithium metal secondary battery according to one embodiment, lithium derived from the sacrificial cathode is continuously utilized during charging and discharging, so a large amount of sacrificial cathode active material may be required compared to a lithium-ion battery of the same capacity. Therefore, in a secondary battery (800, 802) according to one embodiment, the electrical capacity of the negative electrode relative to the electrical capacity of the positive electrode (830) may be less than 100%.

[0098] Referring to FIG. 10, a lithium secondary battery (1000) according to one embodiment may further include a lithium metal layer (1050) disposed between a negative electrode current collector (1040) and an electrolyte (1060). In this case, the negative electrode may include a lithium metal layer (1050) disposed between the negative electrode current collector (1040) and the electrolyte (1060). For example, the lithium secondary battery (1000) may include a negative electrode current collector (1040), a lithium metal layer (1050) disposed above the negative electrode current collector (1040), an electrolyte (1060) disposed above the lithium metal layer (1050), and a positive electrode (1030) disposed above the electrolyte (1060).

[0099] The positive electrode (1030) may include a positive electrode current collector (1032) and a first positive electrode composite layer (1010) or a second positive electrode composite layer (1020) disposed on the positive electrode current collector (1032). Accordingly, an electrolyte (1060) may be disposed between the positive electrode (1030) and the lithium metal layer (1050).

[0100] For example, the lithium metal layer (1050) may include lithium metal or a lithium alloy. For example, the lithium metal layer (1050) may be reduced in thickness by dissociating into lithium ions and metal cations during the discharge process. Conversely, the lithium metal layer (1050) may be increased in thickness by electrodepositing lithium ions during the charging process.

[0101] According to one embodiment, the lithium metal layer (1050) may include, for example, lithium foil, lithium powder, plated lithium, a carbon-based material, or a combination thereof. For example, the lithium metal layer (1050) may include lithium foil. In this case, the lithium metal layer (1050) may be a negative electrode active material layer. For example, the lithium metal layer (1050) may be introduced by coating a slurry containing lithium powder and a binder, etc., onto a negative electrode current collector. For example, the binder may be a fluorine-based binder such as polyvinylidene fluoride (PVDF).

[0102] For example, the thickness of the lithium metal layer (1050) 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 lithium metal layer (1050) increases excessively, the structural stability of the lithium secondary battery may decrease, and side reactions may increase. If the thickness of the lithium metal layer (1050) is excessively small, the energy density of the lithium metal battery may decrease.

[0103] According to one embodiment, the thickness of the lithium foil included in the lithium metal layer (1050) may be, for example, 1 μm to 50 μm, 1 μm to 30 μm, or 10 μm to 30 μm, or 10 μm to 80 μm. By having the lithium foil have a thickness within this range, the lifespan characteristics of the lithium metal secondary battery may be further improved.

[0104] According to one embodiment, the particle size of the lithium powder included in the lithium metal layer (1050) may be, for example, 0.1 μm to 3 μm, 0.1 μm to 2 μm, or 0.1 μm to 1 μm. By having the lithium powder have a thickness within this range, the lifespan characteristics of the lithium secondary battery (800, 802, 1000) can be further improved.

[0105] According to one embodiment, a lithium secondary battery (800, 802, 1000) comprising an electrolyte (860, 1060) may further include a protective layer (not shown) disposed between a negative electrode and the electrolyte. For example, the protective layer may be formed between a negative electrode current collector (840, 1040) and the electrolyte (860, 1060). Alternatively, the protective layer may be formed between a lithium metal layer (850, 1050) and the electrolyte (860, 1060). According to one embodiment, the protective layer of the lithium secondary battery (800, 802, 1000) comprises an inorganic oxide, and the electrolyte (860, 1060) may be disposed between the protective layer and the positive electrode (830, 1030). The protective layer is formed on the negative electrode current collector and may be formed by the reaction of an inductive layer comprising a silane compound and a crosslinking agent contained in the electrolyte. Electrolytes will be discussed later.

[0106] According to one embodiment, one or more stacked structures of the lithium secondary battery (800, 802, 1000) as described above may be stacked or wound and accommodated in a case, and the case may be classified into cylindrical, prismatic, thin film, coin, pin type, etc.

[0107] FIGS. 11 to 14 are schematic diagrams illustrating a lithium secondary battery according to one embodiment, where FIG. 11 is cylindrical, FIG. 12 is prismatic, and FIGS. 13 and 14 are pouch-type batteries. Referring to FIGS. 11 to 14, 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. 11. Additionally, in FIG. 12, 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. 13 and 14, 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.

[0108] Referring to FIG. 11, 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.

[0109] 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). 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).

[0110] 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). 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.

[0111] Referring to FIG. 14, a lithium secondary battery (1) according to one embodiment includes a positive electrode (3), a negative electrode (2) and a separator (4) as described above. An electrolyte as described above, including a 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 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.

[0112] 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. 11 to 14 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.

[0113] 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).

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118]

[0119] positive electrode active material

[0120] Referring to FIGS. 1 to 10, the first positive active material included in the first positive composite layer (110, 810, 1010) or the second positive active material included in the second positive composite layer (120, 820, 1020) in the present invention may be a positive active material described later. For example, the first positive active material or the second positive active material may include LiMO2 (M is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or a combination thereof), LFP, LiM2O4 (M is Ti, V, Mn or a combination thereof), or a combination thereof. The first positive active material and the second positive active material may be the same or different materials.

[0121] 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.

[0122] 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-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 bO2(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).

[0123] 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.

[0124] 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.

[0125] For example, the lithium transition metal oxide may be a compound represented by the following chemical formula 1:

[0126]

[0127] <Chemical Formula 1>

[0128] Li a Ni x Coy M z O 2-b A b

[0129]

[0130] 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.

[0131] 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.

[0132] For example, the lithium transition metal oxide may be at least one of the compounds represented by the following chemical formulas 2 and 3:

[0133]

[0134] <Chemical Formula 2>

[0135] LiNi x Co y Mn z O2

[0136]

[0137] 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.

[0138]

[0139] <Chemical Formula 3>

[0140] LiNi x Co y Al z O2

[0141]

[0142] 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.

[0143] 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 Co 0.1 Mn 0.2O2 or LiNi 0.88 Co 0.1 Al 0.02O2 It could be.

[0144] 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.

[0145] For example, the coating layer may include a coating element compound of an oxide, hydroxide, oxyhydroxide, oxycarbonate, or hydroxycarbonate of a coating element.

[0146] 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.).

[0147] For example, the anode may additionally include an additive that can serve as a sacrificial anode.

[0148] 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.

[0149] 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.

[0150] 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.

[0151]

[0152] Cathode: Cathode current collector

[0153] The negative current collector may not include a negative active material layer. In a negative current collector that does not include a negative active material layer, lithium metal may be plated onto the negative 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.

[0154] 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 possesses conductivity. The metal substrate is, for example, a metal or an alloy. The metal substrate may be composed of, for example, 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 alloys thereof. The electrode 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.

[0155] The negative 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.

[0156] 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.

[0157] The negative current collector may further include a coating layer (not shown) containing a second metal on a first metal substrate.

[0158] 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.

[0159] 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.

[0160] As a result, the energy density of a lithium metal secondary 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 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] 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 secondary battery during a short circuit.

[0165] 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 melt, allowing the metal substrate layer to be electrically connected 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° (Celsius), 100° to 250° (Celsius) or lower, or 100° to 200° (Celsius). 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 may be, for example, 0.01 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 within this thickness 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 within this thickness range, the connection between the metal layer and the lead tab can be performed more easily. By having the cathode current collector with this structure, the weight of the electrode can be reduced and, consequently, the energy density can be improved.

[0166] 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.

[0167] 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.

[0168] According to one embodiment, the cathode may further include an interlayer disposed between the cathode current collector and the lithium metal layer.

[0169] According to one embodiment, the interlayer may be placed directly on, for example, one or both sides of the negative current collector. Therefore, no other layer may be placed between the negative current collector and the interlayer. By placing the interlayer directly on one or both sides of the negative current collector, the bonding strength between the negative current collector and the lithium metal layer may be further improved.

[0170] The thickness of the intermediate layer (not shown) may be, for example, 30% or less of the thickness of the cathode current collector. The thickness of the intermediate layer (not shown) is, for example, 0.01% to 30%, 0.1% to 30%, 0.5% to 30%, 1% to 25%, 1% to 20%, 1% to 15%, 1% to 10%, 1% to 5%, or 1% to 3% of the thickness of the cathode current collector. The thickness of the intermediate layer is, for example, 10 nm to 5 µm, 50 nm to 5 µm, 200 nm to 4 µm, 500 nm to 3 µm, 500 nm to 2 µm, 500 nm to 1.5 µm, or 700 nm to 1.3 µm.

[0171] By having the intermediate layer have a thickness within this range, the bonding strength between the cathode current collector and the metal layer is further improved, and the increase in interfacial resistance can be suppressed.

[0172] For example, the intermediate layer may include a binder. By including a binder in the intermediate layer, the bonding strength between the negative current collector and the lithium metal layer can be further improved. The binder included in the intermediate layer is, for example, a conductive binder or a non-conductive binder.

[0173] 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.

[0174] 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, Flemion, Gore, Aciplex, Morgane ADP, sulfonated poly(ether ether ketone) (SPEEK), sulfonated poly(arylene ether ketone ketone sulfone) (SPAEKKS), sulfonated poly(aryl ether ketone) (SPAEK), poly[bis(benzimidazobenzisoquinolinones)] (SPBIBI), poly(styrene sulfonate) (PSS), lithium 9,10-diphenylanthracene-2-sulfonate, DPASLi+ etc.The electronically conductive binder is, for example, polyacetylene, polythiophene, polypyrrole, poly(p-phenylene), poly(phenylenevinylene), poly(phenylenesulfide), polyaniline, etc. The intermediate layer may be, for example, a conductive layer containing a conductive polymer.

[0175] The binder included in the intermediate layer may be, for example, a fluorine-based binder. The fluorine-based binder included in the intermediate layer may be, for example, polyvinylidene fluoride (PVDF). The intermediate layer may be disposed on the cathode current collector, for example, dry or wet. The intermediate layer may be, for example, a binding layer containing a binder.

[0176] The intermediate layer may additionally include, for example, a carbon-based conductive material. By including the carbon-based conductive material, the intermediate layer may be, for example, a conductive layer. The intermediate layer may be, for example, a conductive layer including a binder and a carbon-based conductive material.

[0177] The intermediate layer can be disposed on the cathode current collector in a dry manner by deposition, for example, CVD, PVD, etc. The intermediate layer can be disposed on the cathode current collector in a wet manner by, for example, spin coating, dip coating, etc. The intermediate layer can be disposed on the cathode current collector by, for example, depositing a carbon-based conductive material on the cathode current collector by deposition. The dry-coated intermediate layer consists of a carbon-based conductive material and may not contain a binder. Alternatively, the intermediate layer can be disposed on the cathode current collector by, for example, coating a composition comprising a carbon-based conductive material, a binder, and a solvent onto the surface of the cathode current collector and drying it. The intermediate layer may have a single-layer structure or a multilayer structure comprising multiple layers.

[0178]

[0179] electrolytes

[0180] The electrolyte may be, for example, a liquid electrolyte, a solid electrolyte, a gel electrolyte, or a combination thereof.

[0181] 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.

[0182] 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.

[0183] Solid electrolytes are, for example, oxide-based solid electrolytes, sulfide-based solid electrolytes, polymeric solid electrolytes, or combinations thereof.

[0184] Solid electrolytes are, for example, oxide-based solid electrolytes. Oxide-based solid electrolytes are Li1+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).

[0185] 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 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, halogen, halogen compound, 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.

[0186] 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.

[0187] A polymeric solid electrolyte is an electrolyte that, for example, contains a mixture of a lithium salt and a polymer, or contains a polymer having ion-conducting functional groups. A polymeric solid electrolyte is, for example, a polymeric electrolyte that does 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 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.

[0188] 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.

[0189]

[0190] Positive: Positive current collector

[0191] 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.

[0192] 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.

[0193] According to one embodiment, the anode current collector may include aluminum (Al).

[0194] 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.

[0195]

[0196] separator

[0197] A lithium battery according to one embodiment may further include a separator (not shown).

[0198] 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.

[0199] 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.

[0200] 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.

[0201] The organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.

[0202] 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.

[0203] 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.

[0204] 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.

[0205]

[0206] Example 1

[0207] Aluminum foil was prepared as an anode current collector. A first anode composite layer slurry containing an anode active material (LiCoO2, LCO) and a sacrificial anode active material (Li5FeO4) with a particle size (D50) of 1.7 was applied onto the aluminum foil and then lightly dried. Subsequently, a second anode composite layer slurry containing an anode active material (LiCoO2, LCO) and a sacrificial anode active material (Li5FeO4) with a particle size (D50) of 4.1 was applied and then dried to manufacture an anode. In the completed anode, the thickness ratio of the first anode composite layer to the second anode composite layer is 2:8.

[0208] As electrolytes, lithium salts of 0.6M LiDFOB and 0.6M LiBF4 were dissolved in a solvent mixed with FEC (Fluoroethylene carbonate), DEC (Diethyl carbonate), and BN (Butyronitrile) in a volume ratio of 42:28:10. Subsequently, an in-situ crosslinking reaction was induced using 4 wt% of DPHA (Dipentaerythritol hexaacrylate) as a crosslinking agent to form a gel polymer electrolyte.

[0209] A copper foil without an active material layer was used as the cathode.

[0210]

[0211] Examples 2 to 8

[0212] The anode composite part was prepared as indicated in Table 1, and the rest of the composition was manufactured in the same manner as in Example 1.

[0213]

[0214] Comparative Example 1

[0215] An aluminum foil was prepared as an anode current collector. An anode was manufactured by applying an anode composite layer slurry containing an anode active material (LiCoO2, LCO) and a sacrificial anode active material (LiCoO2) with a particle size (D50) of 15.8 onto the aluminum foil and then drying it briefly. The rest of the composition was manufactured in the same manner as in Example 1.

[0216]

[0217] Comparative Example 2

[0218] An aluminum foil was prepared as the positive current collector. A positive composite layer slurry containing a positive active material (LiCoO2, LCO) and a sacrificial positive active material (Li5FeO4) with a particle size (D50) of 1.7 was coated onto the aluminum foil, and then the positive was prepared by abbreviated drying. The rest of the composition was prepared in the same manner as in Example 1.

[0219]

[0220] Comparative Examples 3 to 4

[0221] The anode composite part was prepared as indicated in Table 1, and the rest of the composition was manufactured in the same manner as Comparative Example 2.

[0222]

[0223] Classification Sacrificial Anode Active Material Particle Size (D50) (㎛) Thickness (%) Composition Density (g / cc) 1st Anode Composition Layer 2nd Anode Composition Layer 1st Anode Composition Layer 2nd Anode Composition Layer Example 1 Li5FeO4 1.7 4.1 20 80 3.62 Example 2 ↑ 4.1 1.7 20 80 4.08 Example 3 ↑ 1.7 4.1 50 50 3.75 Example 4 ↑ 1.7 4.1 80 20 3.86 Example 5 ↑ 4.1 1.7 80 20 4.04 Example 6 ↑ 1.7 9.3 80 20 3.71 Example 7 ↑ 9.3 1.7 80 20 3.58 Example 8 ↑ 4.1 1.7 50 50 4.05 Comparative Example 1 LiCoO2 15.8 -100 -4.16 Comparative Example 2Li5FeO4 1.7 -100 -4.10 Comparative Example 3 ↑ <1 -100 -4.12 Comparative Example 4 ↑ 9.3 -100 -3.56

[0224] Evaluation Example 1: Measurement of DC-IR (mΩ) Resistance of a Lithium Secondary Battery

[0225] For the lithium secondary battery prepared according to the examples and comparative examples, the formation process is carried out by charging at a current of 0.1C rate, and then fully charged at a current of 0.2C rate (SOC 100%). For the discharge process, first, it is discharged at a current of 3C rate for 10 seconds, then discharged at a current of 0.2C rate for 10 seconds, and then discharged at a current of 3C rate for 10 seconds. Finally, DC-IR is calculated from the voltage drop (IR Drop) that occurs when a current of 3C rate is applied after being fully discharged at a rate of 0.2C. The results are shown in the table below.

[0226]

[0227] Evaluation Example 2: Measurement of capacity retention rate (%, @100cy) of a lithium secondary battery

[0228] For the lithium secondary batteries prepared according to the examples and comparative examples, a formation process is carried out by charging at a current rate of 0.1C. Subsequently, during the charging process, the secondary battery cell is charged at a constant current rate of 0.33C until the voltage reaches 4.5V (vs. Li), and then cut-off is performed at a current rate of 0.05C while maintaining a constant voltage of 4.5V in constant voltage mode. Subsequently, during discharge, a constant current discharge at a rate of 1.0C is performed until the voltage reaches 3.0V (vs. Li). The above-described charge-discharge process was repeated, and the charge-discharge process was repeated a total of 100 times. In all charge-discharge cycles, a 5-minute pause was allowed after each charge / discharge cycle. Here, the capacity retention rate in the Nth cycle is defined by the following formula.

[0229] [ceremony]

[0230] Capacity retention rate (%) = (Discharge capacity at the Nth cycle / 1 st Discharge capacity per cycle) × 100

[0231] The capacity retention rate at the 100th cycle for each is listed in the table below.

[0232]

[0233]

[0234] Classification DC-IR (mΩ) Lifespan Retention Rate (%, @100CYC) Example 1 17.4 17.5.30 Example 2 25.8 38.0.10 Example 3 21.0 17.7.40 Example 4 24.9 77.97 Example 5 18.6 18.88 Example 6 24.0 87.8.10 Example 7 16.8 87.6.40 Example 8 22.2 28.4.65 Comparative Example 1 12.30 39.90 Comparative Example 2 42.00 0 (Not Driven) Comparative Example 3 33.2 47.2.60 Comparative Example 4 15.4 66 3.00

[0235] Referring to Table 2, the examples exhibited superior life retention rate characteristics compared to each comparative example. Additionally, referring to Table 2, the examples exhibited lower resistance and superior life retention rate characteristics compared to Comparative Examples 2 and 3. According to the examples of the present disclosure, DC-IR values ​​and life characteristics can be improved through a combination of the particle size of the sacrificial cathode active material, composite density, and the content of the sacrificial cathode active material. Furthermore, this has the effect of improving life characteristics in secondary batteries using GPE (Gel Polymer Electrolyte). Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and it is possible to implement 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. Positive current collector; A first positive composite layer disposed on the above positive current collector and comprising a first positive active material and a first sacrificial positive active material; and A second anode composite layer disposed on the first anode composite layer and comprising a second anode active material and a second sacrificial anode active material, and A lithium secondary battery positive electrode, wherein the particle size (D50) of the first sacrificial positive electrode active material is different from the particle size of the second sacrificial positive electrode active material.

2. In Paragraph 1, The particle size of the first sacrificial positive electrode active material is larger than the particle size of the second sacrificial positive electrode active material. Cathode for lithium secondary batteries.

3. In Paragraph 2, The particle size of the first sacrificial positive electrode active material is 1.3 to 10 times the particle size of the second sacrificial positive electrode active material, Cathode for lithium secondary batteries.

4. In Paragraph 2, The particle size of the first sacrificial cathode active material is 4 μm to 10 μm, Cathode for lithium secondary batteries.

5. In Paragraph 2, The particle size of the second sacrificial cathode active material is 1 μm to 3 μm, Cathode for lithium secondary batteries.

6. In Paragraph 1, The first sacrificial positive electrode active material and the second sacrificial positive electrode active material have the same chemical composition. Cathode for lithium secondary batteries.

7. In Paragraph 1, The particle size of the second sacrificial positive electrode active material is larger than the particle size of the first sacrificial positive electrode active material. Cathode for lithium secondary batteries.

8. In Paragraph 1, The first sacrificial cathode active material or the second sacrificial cathode active material comprises Li5FeO4, Li2MoO3, Li6CoO4, Li2O, Li3N, Li3P, or a combination thereof. Cathode for lithium secondary batteries.

9. In Paragraph 1, The thickness of the first anode composite layer is 50% to 95% of the thickness of the first anode composite layer and the second anode composite layer. Cathode for lithium secondary batteries.

10. In Paragraph 1, The first positive active material and the second positive active material have the same chemical composition. Cathode for lithium secondary batteries.

11. In Paragraph 1, The first positive electrode active material or the second positive electrode active material comprises LiMO2 (M is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or a combination thereof), LFP, LiM2O4 (M is Ti, V, Mn or a combination thereof), or a combination thereof. Cathode for lithium secondary batteries.

12. Cathode for lithium secondary battery; A cathode including a cathode current collector; A separator interposed between the anode and the cathode; and Electrolyte placed between the anode and the cathode Includes, The above-mentioned positive electrode for a lithium secondary battery is, Positive current collector; A first positive composite layer disposed on the above positive current collector and comprising a first positive active material and a first sacrificial positive active material; and A second anode composite layer disposed on the first anode composite layer and comprising a second anode active material and a second sacrificial anode active material, and The particle size of the first sacrificial positive electrode active material is different from the particle size of the second sacrificial positive electrode active material. Lithium secondary battery.

13. In Paragraph 12, The electrical capacitance of the cathode relative to the electrical capacitance of the anode is less than 100%, Lithium secondary battery.

14. In Paragraph 12, A lithium metal layer further comprising a lithium metal layer disposed between the above-mentioned negative current collector and the above-mentioned electrolyte, Lithium secondary battery.

15. In Paragraph 12, The particle size of the first sacrificial positive electrode active material is larger than the particle size of the second sacrificial positive electrode active material. Lithium secondary battery.

16. In Paragraph 12, The particle size of the first sacrificial positive electrode active material is 1.3 to 10 times the particle size of the second sacrificial positive electrode active material, Lithium secondary battery.

17. In Paragraph 12, The particle size of the first sacrificial cathode active material is 4 μm to 10 μm, Lithium secondary battery.

18. In Paragraph 12, The particle size of the second sacrificial cathode active material is 1 μm to 3 μm, Lithium secondary battery.

19. In Paragraph 12, The first sacrificial positive electrode active material and the second sacrificial positive electrode active material have the same chemical composition. Lithium secondary battery.

20. In Paragraph 12, The thickness of the first anode composite layer is 50% to 95% of the thickness of the first anode composite layer and the second anode composite layer. Lithium secondary battery.

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