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 includes a positive electrode current collector, and a positive electrode mixture part disposed on the positive electrode current collector, wherein the positive electrode mixture part may include a positive electrode active material, a first sacrificial positive electrode coated on the surface of the positive electrode active material, and a second sacrificial positive electrode mixed with the 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] 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] 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 3,860 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.

[0006] 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.

[0007] 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.

[0008] One embodiment provides a positive electrode for a lithium secondary battery to solve the above technical problem.

[0009] Another embodiment provides a lithium secondary battery comprising a positive electrode for a lithium secondary battery to solve the above technical problem.

[0010] According to some embodiments of the present disclosure for solving the above technical problem, a positive electrode for a lithium secondary battery comprises a positive electrode current collector and a positive electrode composite portion disposed on the positive electrode current collector, and the positive electrode composite portion may include a positive electrode active material having a first sacrificial electrode coated on its surface and a second sacrificial electrode mixed with the positive electrode active material.

[0011] According to some embodiments of the present disclosure for solving the above technical problem, a lithium secondary battery comprises a positive electrode, a negative electrode including a negative electrode current collector, and an intermediate layer disposed between the negative electrode and the positive electrode. The positive electrode comprises a positive electrode current collector and a positive electrode composite portion disposed on the positive electrode current collector. The positive electrode composite portion may include a positive electrode active material coated on the surface of a first sacrificial positive electrode, and a second sacrificial positive electrode mixed with the positive electrode active material.

[0012] According to some embodiments of the present disclosure, the anode composite may further include a first sacrificial anode coated on the surface of the anode active material described above. With this configuration, lithium consumption caused by the formation of Solid Electrolyte Interphase (SEI) or other side reactions during charging and discharging can be compensated for, while suppressing the phenomenon of localized lithium growth during the formation stage, thereby improving the uniformity of lithium electrodeposition.

[0013] The positive electrode composite may further include a second sacrificial electrode mixed with the positive electrode active material described above. By including a sacrificial electrode (or sacrificial electrode active material) that forms a lithium metal layer on the negative electrode substrate during the formation stage through this configuration, the lifespan characteristics of the secondary battery can be significantly improved by compensating for lithium consumption caused by SEI generation or other side reactions during charging and discharging.

[0014] According to some embodiments of the present disclosure, the first sacrificial anode may include a nano-sized sacrificial anode (e.g., Li2O, Li2O2, Li3N, Li3P). With this configuration, the surface area of ​​the first sacrificial anode is increased, thereby expanding the surface active area where the lithium ion extraction reaction takes place. Additionally, the ion diffusion distance is shortened, improving the reaction rate, and the contact area with the anode active material is increased, which reduces electrical resistance and improves electrical conductivity.

[0015] A lithium secondary battery according to some embodiments of the present disclosure can improve DC-IR values ​​and lifespan characteristics.

[0016] 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.

[0017] 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.

[0018] FIG. 1 is a diagram showing a stacked structure of a lithium secondary battery according to one embodiment.

[0019] Figure 2 is a diagram showing the stacked structure of the lithium secondary battery of Figure 1 after charging.

[0020] FIG. 3 is a diagram showing a stacked structure of a lithium secondary battery according to one embodiment.

[0021] FIG. 4 is a perspective view illustrating a lithium secondary battery according to one embodiment.

[0022] FIG. 5 is a perspective view illustrating a lithium secondary battery according to one embodiment.

[0023] FIG. 6 is a perspective view illustrating a lithium secondary battery according to one embodiment.

[0024] FIG. 7 is a perspective view illustrating a lithium secondary battery according to one embodiment.

[0025] 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.

[0026] 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.

[0027] 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."

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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”.

[0034] 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.

[0035] 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.

[0036] In this specification, “metal” includes both metals and metalloids such as silicon and germanium in an elemental or ionic state.

[0037] In this specification, "alloy" means a mixture of two or more metals.

[0038] In this specification, "anode active material" refers to an anode material capable of undergoing lithiation and delithiation.

[0039] In this specification, "anode active material" refers to an anode material capable of undergoing lithiation and delithiation.

[0040] 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.

[0041] 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.

[0042] In this specification, "charge" and "to charge" refer to the process of providing electrochemical energy to a battery.

[0043] In this specification, "discharge" and "discharge" refer to the process of removing electrochemical energy from a battery.

[0044] In this specification, "anode" and "cathode" refer to electrodes where electrochemical reduction and lithiation occur during the discharge process.

[0045] In this specification, "cathode" and "anode" refer to electrodes where electrochemical oxidation and delithiation occur during the discharge process.

[0046] Exemplary embodiments will be described in more detail below.

[0047] Stacked structure of a lithium secondary battery

[0048] FIG. 1 is a diagram showing a stacked structure of a lithium secondary battery according to one embodiment. FIG. 2 is a diagram showing the stacked structure of the lithium secondary battery of FIG. 1 after charging. FIG. 3 is a diagram showing a stacked structure of a lithium secondary battery according to one embodiment.

[0049] FIG. 1 is a drawing showing a stacked structure of a non-anode lithium secondary battery (100), and FIG. 2 may correspond to a drawing showing lithium metal precipitated on a negative current collector as the non-anode lithium secondary battery (100) is charged. FIG. 3 may correspond to a drawing showing a lithium metal secondary battery (300) in which lithium metal is used as a negative active material. The thickness of each layer shown in FIG. 1 to FIG. 3 is shown as an arbitrary size and is not necessarily limited thereto.

[0050] Referring to FIG. 1, a lithium secondary battery (100) according to one embodiment may include a positive electrode (130), a negative electrode or negative current collector (140), and an intermediate layer (180) disposed between the positive electrode (130) and the negative electrode or negative current collector (140).

[0051] A lithium secondary battery (100) according to one embodiment may include a negative electrode current collector (140), an intermediate layer (180) disposed on top of the negative electrode current collector (140), and a positive electrode (130) disposed on top of the intermediate layer (180), as shown in FIG. 1. The negative electrode may include a negative electrode current collector (140) in which the negative electrode active material layer is free, and the positive electrode (130) may include a positive electrode current collector (110) and a positive electrode composite part (120) disposed on the positive electrode current collector (110). The intermediate layer (180) may include at least one of an electrolyte (160) or a separator (170).

[0052] Referring to FIG. 2, a lithium secondary battery (100) according to one embodiment may have a lithium metal layer (150) formed on a negative electrode current collector (140) after charging. Specifically, the lithium metal layer (150) may be disposed between the negative electrode current collector (140) and the electrolyte (160). For example, the lithium metal layer (150) may be a lithium electrodeposited layer. For example, the lithium metal layer (150) may include a lithium alloy and a lithium metal. For example, the lithium alloy included in the lithium metal layer (150) weakens the reactivity of the lithium metal, thereby effectively preventing side reactions between the lithium metal layer (150) and the polymer electrolyte. In addition, the lithium metal layer (150) has excellent electrical conductivity, which can reduce the internal resistance of the lithium secondary battery containing it. Accordingly, the lithium secondary battery (100) containing the lithium metal layer (150) may have improved lifespan characteristics as well as charge / discharge efficiency.

[0053] The lithium constituting the lithium metal layer (150) may originate from the sacrificial anode included in the positive electrode composite part (120). For example, the lithium metal layer (150) may be formed as lithium ions included in the electrolyte (160) originating from the sacrificial anode are electrodeposited on the negative electrode current collector (140) as the lithium secondary battery is charged and discharged.

[0054] A lithium secondary battery (300) according to one embodiment may further include a lithium metal layer (350) disposed between a negative electrode current collector (340) and an intermediate layer (380), as shown in FIG. 3. The negative electrode may include a lithium metal layer (350) disposed between the negative electrode current collector (340) and the intermediate layer (380). For example, the lithium secondary battery (300) may include a negative electrode current collector (340), a lithium metal layer (350) disposed above the negative electrode current collector (340), an intermediate layer (380) disposed above the lithium metal layer (350), and a positive electrode (330) disposed above the intermediate layer (380). The positive electrode (330) may include a positive electrode current collector (310) and a positive electrode composite portion (320) disposed on the positive electrode current collector (310). Accordingly, the intermediate layer (380) may be disposed between the positive composite portion (320) and the lithium metal layer (350). The intermediate layer (380) may include at least one of an electrolyte (360) or a separator (370).

[0055] For example, the lithium metal layer (350) may include lithium metal or a lithium alloy. For example, the lithium metal layer (350) may be reduced in thickness by dissociating into lithium ions and metal cations during the discharge process. Conversely, the lithium metal layer (350) may be increased in thickness by electrodepositing lithium ions during the charging process.

[0056] According to one embodiment, a lithium secondary battery (100, 300) comprising an electrolyte (160, 360) 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 (140) and the electrolyte (160). Alternatively, the protective layer may be formed between a lithium metal layer (350) and the electrolyte (360). According to one embodiment, the protective layer of the lithium secondary battery (100, 300) comprises an inorganic oxide, and the electrolyte (160, 360) may be disposed between the protective layer and the positive electrode (130, 330).

[0057] According to one embodiment, one or more stacked structures of the lithium secondary battery (100, 300) 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.

[0058] A lithium secondary battery according to one embodiment includes a positive electrode, a negative electrode, and an electrolyte (160, 360) disposed between the positive electrode and the negative electrode. The electrolyte (160, 360) 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.

[0059] anode

[0060] Referring to FIG. 1, a positive electrode (130) for a lithium secondary battery according to one embodiment of the present disclosure may include a positive electrode current collector (110) and a positive electrode composite part (120) disposed on the positive electrode current collector (110) and comprising a positive electrode active material, a first sacrificial electrode coated on the surface of the positive electrode active material, and a second sacrificial electrode mixed with the positive electrode active material. For example, the positive electrode active material may be included in a range of 80 wt% or more of the total weight of the positive electrode composite part.

[0061] Positive: Positive current collector

[0062] The positive electrode (130) includes a positive electrode current collector (110). For example, the positive electrode can be prepared by forming a positive electrode composite part (120) on the positive electrode current collector (110).

[0063] For example, the positive current collector (110) 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.

[0064] According to one embodiment, the positive current collector (110) may include aluminum (Al).

[0065] For example, the positive current collector (110) 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 (140) described above.

[0066] Anode: Anode composite part

[0067] A positive electrode composite member (120) according to one embodiment of the present disclosure is disposed on a positive electrode current collector (110) and may include a positive electrode active material, a first sacrificial electrode, and a second sacrificial electrode. The active material may be a positive electrode active material. In the present disclosure, "positive electrode active material" refers to a material that enables charging and discharging of a battery through a process in which lithium ions are extracted from the positive electrode of a lithium secondary battery or lithium ions are inserted into the positive electrode. The positive electrode active material can drive the battery in a reversible manner in which lithium ions move to the negative electrode during charging and return to the positive electrode during discharging.

[0068] A positive electrode composite according to one embodiment may include a positive electrode active material, a conductive material, and a binder.

[0069] 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, examples of which 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.

[0070] In one embodiment, the positive active material may be an active material having a layered structure. In another example, the positive active material may have an olivine structure or a spinel structure. For example, the 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, LMFP, LiM2O4 (M is Ti, V, Mn or a combination thereof) or a combination thereof.

[0071] 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 (0.90a≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05), Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05), Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2), Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2), Li a Ni b Co c L 1 d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1), Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1), Li a CoG bO2(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).

[0072] 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.

[0073] 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.

[0074] For example, the lithium transition metal oxide may be a compound represented by the following chemical formula 3:

[0075] <Chemical Formula 1>

[0076] Li a Ni x Co y M z O 2-b A b

[0077] 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.

[0078] In Chemical Formula 1, for example, 0.7≤x<1, 0 <y≤0.3, 0<z≤0.3, 0.8≤x<1, 0<y≤0.3, 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.

[0079] For example, the lithium transition metal oxide may be at least one of the compounds represented by the following chemical formulas 2 and 3:

[0080] <Chemical Formula 2>

[0081] LiNi x Co y Mn z O2

[0082] 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.

[0083] <Chemical Formula 3>

[0084] LiNi x Co y Al z O2

[0085] 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.

[0086] 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.

[0087] The positive electrode composite section (120) may include a first sacrificial positive electrode coated on the surface of the positive active material described above. By using a sacrificial positive electrode, lithium consumption caused by the generation of Solid Electrolyte Interphase (SEI) or other side reactions during charging and discharging can be compensated for, while suppressing the phenomenon of localized lithium growth during the formation stage, thereby improving the uniformity of lithium electrodeposition.

[0088] The specific form in which the first sacrificial anode is coated on the surface of the positive active material particles is not particularly limited. The surface of the positive active material to which the first sacrificial anode is attached may include the surface of the primary particles of the positive active material and / or the surface of secondary particles formed by the aggregation of the primary particles. The first sacrificial anode may be formed in the form of a thin film on at least a portion of the surface of the particles. For example, it may be formed on the surface of the positive active material particles by 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. The first sacrificial anode may include an active material different from the second sacrificial anode. In one embodiment, the first sacrificial anode may include a lithium-nonmetal compound. For example, the lithium-nonmetal compound may include Li2O (Lithium Oxide), Li2O2 (Lithium Peroxide), Li3N (Lithium Nitride), Li3P (Lithium Phosphide), Li2S (Lithium Sulfide), or a combination thereof.

[0089] The first sacrificial anode may comprise a nanoscaled lithium-nonmetallic compound. For example, the first sacrificial anode may comprise nanoscaled Li2O. The average particle size (D50) of the first sacrificial anode may be 1 nm to 1000 nm, 1 nm to 900 nm, 1 nm to 800 nm, 1 nm to 700 nm, 1 nm to 600 nm, 1 nm to 500 nm, 10 nm to 1000 nm, 10 nm to 900 nm, 10 nm to 800 nm, 10 nm to 700 nm, 10 nm to 600 nm, 10 nm to 500 nm, 20 nm to 1000 nm, 20 nm to 900 nm, 20 nm to 800 nm, 20 nm to 700 nm, 20 nm to 600 nm, or 20 nm to 500 nm. With this configuration, the surface area of ​​the first sacrificial anode is increased, and the surface active area where the lithium ion extraction reaction takes place can be expanded. In addition, the reaction rate is improved by shortening the ion diffusion distance, and electrical resistance is reduced and electrical conductivity can be improved by increasing the contact area with the positive electrode active material.

[0090] The first sacrificial anode can be manufactured to a nanoscale size using a milling process including a high-energy ball mill, a planetary mill, a stirred ball mill, or a vibrating mill. However, it is not limited to the processes described above and can be carried out by various nanoscale processes. The nanoscaled first sacrificial anode can be uniformly coated on the surface of the anode active material using a dry coating method. For example, the dry coating method may include vacuum deposition, sputtering, or plasma deposition, but is not limited to the processes described above and can be carried out by various dry coating methods.

[0091] The anode composite section (120) may further include a second sacrificial anode mixed with the anode active material described above. The second sacrificial anode may include Li5FeO4 (Lithium Iron Oxide), Li2MoO3 (Lithium Molybdenum Oxide), Li6CoO4 (Lithium Cobalt Oxide), Li2NiO2 (Lithium Nickel Oxide), Li8ZrO6 (Lithium Zirconium Oxide), or a combination thereof.

[0092] However, the second sacrificial anode is not limited to the materials described above, and may be selected from materials that can be blended with the positive electrode active material. In one embodiment, the second sacrificial anode may be a material that has a particle size similar to that of the positive electrode active material and can be uniformly distributed within the electrode. Generally, if the difference in particle size is large, aggregation may occur during slurry preparation or density imbalance may occur in the electrode after coating. Accordingly, the difference in particle size between the positive active material and the second sacrificial positive can be set to within 20% of the D50 standard, and for example, the average particle size (D50) of the second sacrificial positive can be controlled within the range of 5 μm to 15 μm, 5 μm to 10 μm, 10 μm to 15 μm, 10 μm to 13 μm, 0.8 μm to 18 μm, 0.8 μm to 12 μm, 0.8 μm to 9.6 μm, 0.4 μm to 12 μm, 0.4 μm to 9.6 μm, or 0.4 μm to 6 μm.

[0093] In one embodiment, the second sacrificial anode may be a material that is chemically compatible with the positive electrode active material, so that no unnecessary side reactions occur during the electrode manufacturing and driving process. The second sacrificial anode may not react directly with the aforementioned positive electrode active material or induce unexpected chemical changes within the electrode. Accordingly, the second sacrificial anode maintains chemical stability with the positive electrode active material during the electrode manufacturing process and long-term use, and may have low reactivity to moisture and oxygen.

[0094] In one embodiment, the second sacrificial cathode may be a material that is electrochemically harmonized with the positive electrode active material and can serve as a uniform lithium source during the charging and discharging process. If the active material performs the role of releasing or storing lithium during charging and discharging, battery performance may be degraded if the second sacrificial cathode decomposes at an excessively low potential or has a structure that inhibits lithium ion diffusion. Therefore, the second sacrificial cathode may be a material that possesses high ionic conductivity without obstructing the lithium ion diffusion pathway within the electrode, and can minimize local lithium concentration changes by being uniformly dispersed with the positive electrode active material.

[0095] In one embodiment, the second sacrificial anode may be a material capable of maintaining stability during the electrode manufacturing process while mixed with the positive electrode active material. By including the second sacrificial anode, aggregation can be minimized even when appropriate solvents and dispersants are not applied during the slurry manufacturing process, and the positive electrode active material can be uniformly distributed within the electrode. Additionally, by including the second sacrificial anode, the composition and density within the electrode can be uniformly formed during the slurry coating process, and non-uniform aggregation of the positive electrode active material and the second sacrificial anode can be prevented even after drying. For example, the second sacrificial anode may be configured to have excellent dispersibility in NMP (N-Methyl-2-pyrrolidone) or other suitable solvents, thereby enabling a uniform electrochemical reaction within the electrode.

[0096] According to some embodiments of the present disclosure, a positive electrode (130) for a lithium secondary battery includes a sacrificial positive electrode (or sacrificial positive electrode active material) that forms a lithium metal layer on a negative electrode substrate during the formation step, thereby compensating for lithium consumption caused by SEI generation or other side reactions during charging and discharging, and can significantly improve the lifespan characteristics of the secondary battery.

[0097] In one embodiment, the positive active material may be included in a range of 80 wt% or more of the total weight of the positive composite part (120). Alternatively, the positive active material may be included in a range of 90 wt% to 95 wt% of the total weight of the positive composite part (120).

[0098] In one embodiment, the first sacrificial anode may be included in a range of greater than 0 wt% and less than or equal to 10 wt% of the total weight of the anode composite part (120). The first sacrificial anode may be included in a range of 2.5 wt% to 5 wt% of the total weight of the anode composite part (120). The second sacrificial anode may be included in a range of greater than 0 wt% and less than or equal to 10 wt% of the total weight of the anode composite part (120). The second sacrificial anode may be included in a range of 2.5 wt% to 5 wt% of the total weight of the anode composite part (120). However, it is not limited thereto, and the sum of the weights of the first sacrificial anode and the second sacrificial anode may be greater than 0 wt% and less than or equal to 20 wt% of the total weight of the anode composite part (120). The secondary battery corresponding to the above-described range may have improved DC-IR values ​​and lifespan characteristics.

[0099] The positive electrode composite (120) may further include a conductive material and a binder. For example, 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 electrode active material.

[0100] 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.

[0101] 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.

[0102] Cathode: Cathode current collector

[0103] Referring to FIGS. 1 and 2, the negative current collector (140) may not include a negative active material layer. In the negative current collector (140) that does not include a negative active material layer, lithium metal may be plated onto the negative current collector by charging. As shown in FIG. 2, the plated lithium metal layer (150) may include plated lithium, lithium metal foil, lithium metal powder, lithium alloy foil, lithium alloy powder, an organic compound containing lithium, or a combination thereof. The lithium metal layer (150) may include 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.

[0104] Referring to FIGS. 1 to 3, the material constituting the negative electrode current collector (140, 340) 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 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 an alloy thereof. The electrode current collector 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.

[0105] The negative current collector (140, 340) includes, for example, a first metal substrate. The first metal substrate includes the first metal as a main component or is made of the first metal. The first metal substrate includes the first metal as a main component or is made 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.

[0106] 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.

[0107] The negative current collector (140, 340) may further include a coating layer (not shown) containing a second metal on a first metal substrate.

[0108] The negative current collector (140, 340) 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.

[0109] For example, the negative current collector (140, 340) may have a reduced thickness compared to a conventional negative current collector. Accordingly, the negative 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.

[0110] As a result, the energy density of the lithium metal secondary battery employing such electrodes is increased. The thickness of the negative electrode current collector (140, 340) 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 (140, 340) 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.

[0111] The negative current collector (140, 340) may have a shape selected from, for example, a sheet, a foil, a film, a plate, a porous body, a mesoporous body, a through-hole containing body, a polygonal ring body, a mesh body, a foam, and a nonwoven body, but is not necessarily limited to these shapes and any shape used in the relevant technical field is possible.

[0112] The negative current collector (140, 340) 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.

[0113] 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.

[0114] 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.

[0115] 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° (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 range of thickness, 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 range of thickness, the connection between the metal layer and the lead tab can be performed more easily. By having the cathode current collector (140, 340) having this structure, the weight of the electrode can be reduced and, consequently, the energy density can be improved.

[0116] Referring to FIG. 1, the negative active material layer may be free on the negative current collector (140) before charging and discharging. For example, the lithium metal layer may be free on the negative current collector (140) before charging and discharging.

[0117] Referring to FIG. 3, a lithium metal layer (350) including a plate-shaped lithium metal thin film can be disposed on a negative electrode current collector (340) before charging and discharging.

[0118] According to one embodiment, the cathode may further include an interlayer disposed between the cathode current collector (340) and the lithium metal layer (350).

[0119] According to one embodiment, the interlayer may be placed directly on, for example, one or both sides of the negative current collector (340). Thus, no other layer may be placed between the negative current collector (340) and the interlayer. By placing the interlayer directly on one or both sides of the negative current collector (340), the bonding strength between the negative current collector (340) and the lithium metal layer (350) may be further improved.

[0120] The thickness of the intermediate layer (not shown) may be, for example, 30% or less of the thickness of the negative current collector (340). 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 negative current collector (340). 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.

[0121] By having the intermediate layer have a thickness within this range, the bonding strength between the negative current collector (340) and the lithium metal layer (350) is further improved, and the increase in interfacial resistance can be suppressed.

[0122] 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 (340) and the lithium metal layer (350) can be further improved. The binder included in the intermediate layer is, for example, a conductive binder or a non-conductive binder.

[0123] 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.

[0124] 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), polytetrafluoroethylene (PTFE), polyethylenedioxythiophene (PEDOT), polypyrrole (PPY), polyacrylonitrile (PAN), polyaniline, and polyacetylene, etc. Ion-conducting binders may include polar functional groups. Ion-conducting binders containing polar functional groups are, for example, Nafion, Aquivion, Flemion, These include 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+).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.

[0125] 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 negative current collector (340) in a dry or wet manner, for example. The intermediate layer may be, for example, a binding layer including a binder.

[0126] 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.

[0127] The intermediate layer may be disposed on the cathode current collector in a dry manner by deposition, for example, CVD, PVD, etc. The intermediate layer may be disposed on the cathode current collector (340) in a wet manner by, for example, spin coating, dip coating, etc. The intermediate layer may be disposed on the cathode current collector (340) by, for example, depositing a carbon-based conductive material on the cathode current collector (340) by deposition. The dry-coated intermediate layer may be composed of a carbon-based conductive material and may not contain a binder. Alternatively, the intermediate layer may be disposed on the cathode current collector (340) by, for example, coating a composition comprising a carbon-based conductive material, a binder, and a solvent on the surface of the cathode current collector (340) and drying it. The intermediate layer may have a single-layer structure or a multi-layer structure including multiple layers.

[0128] Cathode: Lithium metal layer

[0129] Referring to FIG. 3, the lithium secondary battery (300) may further include a lithium metal layer (350) disposed between a negative electrode current collector (340) and an electrolyte (360). For example, the lithium metal layer (350) may include lithium metal or a lithium alloy. For example, the lithium metal layer (350) may be a negative electrode active material layer. For example, the lithium metal layer (350) may be a lithium electrodeposited layer.

[0130] For example, the lithium metal layer (350) can be formed by electrodepositing lithium ions contained in the electrolyte (360) onto the negative current collector (340) as the lithium secondary battery is charged. For example, the lithium metal layer (350) may include a lithium alloy and a lithium metal. For example, the lithium alloy included in the lithium metal layer (350) weakens the reactivity of the lithium metal, thereby effectively preventing side reactions between the lithium metal layer (350) and the electrolyte (360). Additionally, the lithium metal layer (350) has excellent electrical conductivity, which can reduce the internal resistance of the lithium secondary battery (300) containing it. Accordingly, the lithium secondary battery (300) containing the lithium metal layer (350) can have improved lifespan characteristics as well as charge / discharge efficiency.

[0131] According to one embodiment, the lithium metal layer (350) may include, for example, lithium foil, lithium powder, plated lithium, a carbon-based material, or a combination thereof. For example, the lithium metal layer (350) may include lithium foil. In this case, the lithium metal layer (350) may be a negative electrode active material layer. For example, the lithium metal layer (350) 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).

[0132] According to one embodiment, the lithium metal layer (350) may comprise only electrodeposited lithium metal or lithium alloy. In this case, the lithium metal layer (350) may be a lithium electrodeposited layer.

[0133] According to one embodiment, the lithium metal layer (350) may not include a carbon-based negative electrode active material. Accordingly, the lithium metal layer (350) may be made of a metal-based negative electrode active material.

[0134] For example, the thickness of the lithium metal layer (350) 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 (350) 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 (350) is excessively small, the energy density of the lithium metal secondary battery (300) may decrease.

[0135] According to one embodiment, the thickness of the lithium foil included in the lithium metal layer (350) 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 (300) can be further improved.

[0136] According to one embodiment, the particle size of the lithium powder included in the lithium metal layer (350) 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 (100, 300) can be further improved.

[0137] Intermediate layer: Electrolyte

[0138] Referring to FIGS. 1 to 3, the intermediate layer (180, 380) may include an electrolyte (160, 360). The lithium secondary battery may further include an electrolyte (160, 360), and the electrolyte (160, 360) may be injected into a case to impregnate the laminated structure. Alternatively, the electrolyte (160, 360) may be placed between the positive electrode composite part (120, 320) and the separator (170, 370). Alternatively, the electrolyte (160, 360) may be placed between the negative electrode and the separator (170, 370).

[0139] The electrolyte (160, 360) may be, for example, a liquid electrolyte, a solid electrolyte, a gel electrolyte, or a combination thereof.

[0140] The electrolyte (160, 360) is, for example, an organic electrolyte. The organic electrolyte is, for example, prepared by dissolving a lithium salt in an organic solvent. 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, gamma-butyrolactone, dioxolane, 4-methyldioxolane, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether, butyronitrile, or mixtures thereof.

[0141] Any lithium salt used as a lithium salt in the relevant technical field is also acceptable. Examples of lithium salts include LiDFOB, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, and LiN(C x F 2x+1 SO2)(C y F2y+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.

[0142] Solid electrolytes are, for example, oxide-based solid electrolytes, sulfide-based solid electrolytes, polymeric solid electrolytes, or combinations thereof.

[0143] 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, 0혏<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 12It 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).

[0144] 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<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.

[0145] 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.

[0146] 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), 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, polyvinyl fluoride (PVF), poly(methylmethacrylate) (PMMA), polyethylene glycol (PEG), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), polyethylenedioxythiophene (PEDOT), polypyrrole (PPY), polyaniline, polyacetylene, Nafion, Aquivion, Flemion, Gore, Aciplex, Morgane ADP, sulfonated poly(ether ketone), SPEEK, sulfonated poly(arylene ether ketone sulfone), SPAEKKS), sulfonated poly(aryl ether ketone, SPAEK), poly[bis(benzimidazobenzisoquinolinones)], SPBIBI), polystyrene sulfonate (Poly(styrene sulfonate), PSS), lithium 9,10-diphenylanthracene-2-sulfonate (lithium 9,10-diphenylanthracene-2-sulfonate, DPASLi。+ It may be ) or a combination thereof, but is not limited thereto, and any that are used as polymer electrolytes in the relevant technical field are permitted. Any lithium salt that can be used as a lithium salt in the relevant technical field is permitted. 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.

[0147] 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.

[0148] The electrolyte (160, 360) may correspond to the gel polymer electrolyte described above. In one embodiment, the gel polymer electrolyte may include a first gel polymer electrolyte disposed between the cathode and the separator and / or a second gel polymer electrolyte disposed between the anode and the separator.

[0149] The gel polymer electrolyte may include an organic solvent, a lithium salt, and a crosslinking agent for forming a polymer matrix. Specifically, a liquid electrolyte containing an organic solvent and a lithium salt may be impregnated into a polymer matrix formed by a crosslinking agent to form a gel polymer electrolyte.

[0150] The crosslinking agent may include a polyfunctional crosslinking agent having three or more crosslinkable functional groups. The crosslinkable functional groups are, for example, 3 to 10, or 3 to 6. These crosslinking agents may include pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, propoxylate (3) trimethylolpropane triacrylate (PO(3)TMPTA), propoxylated (6) trimethylolpropane triacrylate (PO(6)TMPTA), ethoxylated trimethylolpropane triacrylate, di(trimethylolpropane) tetraacrylate, pentaerythritol triacrylate (PETA), propoxylated glyceryl triacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate (THEICTA), dipentaerythritol pentaacrylate (DPEPA), or a combination thereof.

[0151] According to one embodiment, the crosslinking agent may include an acrylate-based and / or methacrylate-based monomer. For example, the acrylate and / or methacrylate monomer capable of forming a polymer matrix may include PETTA (Pentaerythritol Tetraacrylate), DPHA (dipentaerythritol hexacrylate), TMPTMA (trimethylolpropane trimethacrylate), PETA (Pentaerythritol Triacrylate), DPEPA (Dipentaerythritol Pentaacrylate), DTMPTTA (Dipentaerythritol Tetramethacrylate), ETPTA (Ethoxylated Trimethylolpropane Triacrylate), TMPTA (Trimethylolpropane Triacrylate), TTEGDA (Triethylene Glycol Diacrylate), or any combination thereof.

[0152] However, the monomers are not limited to those described above, and acrylate and / or methacrylate monomers capable of forming a polymer matrix include, specifically, diethylene glycol diacrylate (DEGDA), diethylene glycol dimethacrylate (DEGDMA), triethylene glycol diacrylate (TEGDA), triethylene glycol dimethacrylate (TEGDMA), tetraethylene glycol diacrylate (TTEGDA), glycidyl methacrylate, polyethylene glycol diacrylate (PEGDA), polyethylene glycol dimethacrylate (PEGDMA), polypropylene glycol diacrylate (PPGDA), dipropylene glycol diacrylate (DPGDA), tripropylene glycol diacrylate (TPGDA), dianol diacrylate (DDA), dianol dimethacrylate (DDMA), ethoxylated trimethylolpropane triacrylate (ETPTA), acrylate-functionalized ethylene oxide, and butanediol It may be formed from dimethacrylate, ethoxylated neopentyl glycol diacrylate (NPEOGDA), propoxylated neopentyl glycol diacrylate (NPPOGDA), trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate (TMPTMA), pentaerythritol triacrylate (PETA), ethoxylated propoxylated trimethylolpropane triacrylate (TMPEOTA / TMPPOTA), propoxylated glyceryl triacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate (THEICTA), pentaerythritol tetraacrylate (PETTA), dipentaerythritol pentaacrylate (DPEPA), ditrimethylolpropane tetraacrylate (DTMPTTA), or any combination thereof.

[0153] For example, the crosslinking agent may be included in a range of 2 wt% to 20 wt% of the total weight of the electrolyte. For example, the gel polymer electrolyte may contain 80 wt% to 98 wt% of the liquid electrolyte and 2 wt% to 20 wt% of the crosslinking agent. When the content of the liquid electrolyte and the crosslinking agent in the gel polymer electrolyte is within the ranges described above, the ionic conductivity may be improved.

[0154] An electrolyte (160, 360) according to one embodiment of the present disclosure may further include a liquid electrolyte. The liquid electrolyte may be a mixture of a flame-retardant additive, a lithium salt, and an organic solvent. The organic solvent may be selected from organic solvents used in liquid electrolytes. The lithium salt may be selected from lithium salts used in gel polymer electrolytes. A gel polymer electrolyte may be formed by impregnating a crosslinking agent into the liquid electrolyte within a lithium secondary battery.

[0155] Lithium salts are dissolved in organic solvents and can act as a source of lithium ions within the battery, enabling the operation of basic lithium secondary batteries. Lithium salts can facilitate the movement of lithium ions between the anode and the cathode. Examples of lithium salts include LiPF6, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N, lithium bis(fluorosulfonyl)imide (LiFSI), LiC4F9SO3, and LiN(C x F2 x+1 SO2)(C y F 2y+1 It may further include one or more selected from SO2)(x and y are integers from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, and lithium bis(oxalate)borate (LiBOB).

[0156] A lithium salt according to one embodiment may include lithium hexafluorophosphate (LiPF6), lithium difluoro(oxalato)borate (LiDFOB), lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), or any combination thereof.

[0157] Organic solvents serve as a medium through which ions involved in the electrochemical reaction of a cell can move. Organic solvents may be carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvents, aprotic solvents, or a combination thereof.

[0158] Carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and fluoroethylene carbonate (FEC) may be used.

[0159] Ester-based solvents such as methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methylpropionate, ethylpropionate, decanolide, mevalonolactone, valerolactone, and caprolactone may be used.

[0160] Dibutyl ether, tetraglame, diglame, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. can be used as ether-based solvents. In a negative electrode lithium secondary battery or a lithium metal battery with lithium metal as the negative electrode active material layer, ether-based solvents with relatively high reduction safety can be used.

[0161] In addition, cyclohexanone and the like may be used as ketone-based solvents. Ethyl alcohol and isopropyl alcohol and the like may be used as alcohol-based solvents, and as aprotic solvents, nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond, an aromatic ring, or an ether group); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane and 1,4-dioxolane; and sulfolanes may be used.

[0162] The above-described organic solvents can be used alone or in a mixture of two or more types.

[0163] Intermediate layer: Separator

[0164] The intermediate layer (180, 380) may include a separator (170, 370). The separator (170, 370) may be placed between the anode and the cathode. The separator (170, 370) may be placed between the anode composite part (120, 320) and the cathode. As the separator (170, 370) according to one embodiment, polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof may be used, and of course, a mixed multilayer film such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, a polypropylene / polyethylene / polypropylene three-layer separator, etc. may be used.

[0165] The separator (170, 370) 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.

[0166] 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.

[0167] The organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.

[0168] 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.

[0169] 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.

[0170] lithium secondary battery

[0171] FIGS. 4 to 7 are schematic diagrams illustrating a lithium secondary battery according to one embodiment, where FIG. 4 is cylindrical, FIG. 5 is prismatic, and FIGS. 6 and 7 are pouch-type batteries. Referring to FIGS. 4 to 7, 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. 4. Additionally, in FIG. 5, 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. 6 and 7, 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.

[0172] Referring to FIG. 4, 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.

[0173] Referring to FIG. 5, 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).

[0174] Referring to FIG. 6, 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.

[0175] Referring to FIG. 7, 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.

[0176] 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. 6 and 7 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.

[0177] 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).

[0178] 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.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] Example 1

[0184] (Anode manufacturing)

[0185] Aluminum foil was prepared as an anode current collector. A first sacrificial anode (Li2O) with an average particle size (D50) of 500 nm was coated on the surface of anode active material (LCO) particles. To this end, the anode active material (LCO), the first sacrificial anode (Li2O), and the second sacrificial anode (Li5FeO4) were prepared in a weight ratio of 95:2.5:2.5. The anode active material and the first sacrificial anode were fed into a dry milling machine, and silica balls were added at a weight ratio of 20 times the anode active material, followed by milling for 12 hours. Subsequently, the anode active material coated with the first sacrificial anode and the second sacrificial anode were fed into an NMP-based solvent in which a conductive material and a binder were pre-dispersed, and then blended using a PD mixer or an HD mixer. The anode composite slurry thus prepared was applied onto the aluminum foil and then lightly dried.

[0186] (Electrolytes)

[0187] 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 42:48:10. Subsequently, 4 wt% of DPHA (Dipentaerythritol hexaacrylate) was added as a crosslinking agent, and a gel polymer electrolyte was formed by inducing a crosslinking reaction in-situ at 70°C.

[0188] (Cathode manufacturing)

[0189] A copper (Cu) foil with a thickness of 10 μm and no active material layer was used as the cathode.

[0190] (Lithium secondary battery manufacturing)

[0191] An electrode assembly was prepared by sequentially stacking a negative electrode current collector, a separator, and a positive electrode, and the gel polymer electrolyte described above was injected into the electrode assembly. Then, a lithium secondary battery was prepared by thermally crosslinking in an oven at 70 degrees (Celsius) for 1 hour and 30 minutes.

[0192] Example 2

[0193] A lithium secondary battery was prepared in the same manner as in Example 1, except that the weight ratio of the positive active material, the first sacrificial cathode, and the second sacrificial cathode in the positive composite part was varied to 92.5:5:2.5 as indicated in Table 1.

[0194] Example 3

[0195] A lithium secondary battery was prepared in the same manner as in Example 1, except that the weight ratio of the positive active material, the first sacrificial cathode, and the second sacrificial cathode in the positive composite part was changed to 90:5:5 as indicated in Table 1.

[0196] Example 4

[0197] A lithium secondary battery was prepared in the same manner as in Example 1, except that the average particle size of the first sacrificial anode in the anode composite part was changed to 20 nm and the weight ratio was changed to 90:5:5 as indicated in Table 1.

[0198] Example 5

[0199] A lithium secondary battery was prepared in the same manner as in Example 1, except that the average particle size of the first sacrificial anode in the anode composite part was changed to 200 nm and the weight ratio was changed to 90:5:5 as indicated in Table 1.

[0200] Example 6

[0201] A lithium secondary battery was prepared in the same manner as in Example 1, except that the average particle size of the first sacrificial anode in the anode composite part was changed to 650 nm and the weight ratio was changed to 90:5:5 as indicated in Table 1.

[0202] Example 7

[0203] A lithium secondary battery was prepared in the same manner as in Example 1, except that the average particle size of the first sacrificial cathode was changed to 800 nm and the weight ratio was changed to 90:5:5 for the cathode composite part as indicated in Table 1.

[0204] Comparative Example 1

[0205] A lithium secondary battery was prepared in the same manner as in Example 1, except that the first sacrificial anode and the second sacrificial anode were absent from the anode composite part as indicated in Table 1, and the anode active material was used alone.

[0206] Comparative Example 2

[0207] A lithium secondary battery was prepared in the same manner as in Example 1, except that the second sacrificial cathode was absent from the cathode composite portion as indicated in Table 1, and the weight ratio of the cathode active material to the first sacrificial cathode was changed to 90:10.

[0208] Comparative Example 3

[0209] A lithium secondary battery was prepared in the same manner as in Example 1, except that the first sacrificial cathode was absent from the cathode composite part as indicated in Table 1, and the weight ratio of the cathode active material to the second sacrificial cathode was changed to 90:10.

[0210] Cathode Active Material 1 Sacrificial Cathode 2 Sacrificial Cathode Weight Ratio (%) Average Particle Size of Active Material Example 1 LOCOL i2O 500 nm Li5FeO 495:2.5:2.5 Example 2 LOCOL i2O 500 nm Li5FeO 492.5:5:2.5 Example 3 LOCOL i2O 500 nm Li5FeO 490:5:5 Example 4 LOCOL i2O 20 nm Li5FeO 490:5:5 Example 5 LOCOL i2O 200 nm Li5FeO 490:5:5 Example 6 LOCOL i2O 650 nm Li5FeO 490:5:5 Example 7 LOCOL i2O 800 nm Li5FeO 490:5:5 Comparative Example 1 LCO --- 100:0:0 Comparative Example 2 LOCOL i2O 500 nm - 90:10:0 Comparative Example 3LCO--Li5FeO490:0:10

[0211] Evaluation Example 1: Measurement of DC-IR (mΩ) Resistance of a Lithium Secondary Battery For the lithium secondary battery prepared according to the above-described examples and comparative examples, the formation process is carried out by charging with a current of 0.1C rate, and then fully charged with a current of 0.2C rate (SOC 100%). In the discharge process, first, it is discharged for 10 seconds at a current of 3C rate, then discharged for 10 seconds at a current of 0.2C rate, and then discharged for 10 seconds at a current of 3C rate. Finally, after fully discharging at a rate of 0.2C, the DC-IR is calculated from the voltage drop (IR Drop) that occurs when a current of 3C rate is applied. The results are shown in Table 2 below.

[0212] Evaluation Example 2: Lifespan Characteristics Test of Lithium Secondary Battery

[0213] The lithium secondary battery prepared according to the above-described examples and comparative examples was charged to 4.5 V at a rate of 0.1 C. Subsequently, the first cycle was carried out by discharging to 3 V at a rate of 0.1 C. From the subsequent cycles, it was charged to 4.5 V at a rate of 0.33 C and discharged to 3 V at a rate of 1 C. In all charge / discharge cycles, a 10-minute pause was taken after each charge / discharge cycle, and the temperature during charging and discharging was maintained at 45 degrees (Celsius).

[0214] The method used to calculate SOH in this evaluation involved directly measuring the discharge capacity of the lithium secondary battery and calculating it using Equation 2 below. In this case, the initial discharge capacity refers to the initial rated discharge capacity (designed nominal capacity) of the battery, and the discharge capacity at the Nth cycle refers to the maximum discharge capacity that the battery can provide at the Nth cycle.

[0215] [Equation 2]

[0216] SOH [%] = [Discharge capacity at the Nth cycle / Initial discharge capacity] × 100

[0217] The number of cycles (N) at which SOH decreases to about 80% is shown in Table 2 below.

[0218] Classification DC-IR (mΩ) Lifespan (Cycles) Example 1 7.17 168 Example 2 8.83 173 Example 39.25 181 Example 4 6.22 190 Example 5 8.54 185 Example 6 9.59 174 Example 7 10.61 170 Comparative Example 15.94 113 Comparative Example 2 22.75 75 Comparative Example 39.52 136

[0219] Referring to Table 2, the examples exhibited superior resistance and life retention rate characteristics compared to the comparative examples. According to the examples of the present disclosure, life characteristics can be improved while maintaining a constant DC-IR value through a combination of the composition, average particle size, and 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 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. Positive current collector; and Anode composite portion disposed on the anode current collector above Includes, The above-mentioned anode composite part is, A positive active material with a first sacrificial anode coated on its surface; and A second sacrificial anode mixed with the above positive active material A positive electrode for a lithium secondary battery comprising 2. In Paragraph 1, A positive electrode for a lithium secondary battery, wherein the positive electrode active material is included in a range of 80 wt% or more of the total weight of the positive electrode composite.

3. In Paragraph 1, The above-mentioned positive active material comprises a spinel-based positive active material, an olivine-based positive active material, a layered positive active material, or a combination thereof, for a lithium secondary battery.

4. In Paragraph 1, The above-mentioned positive active material comprises any one of LiMO2 (M is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or a combination thereof), LFP, LMFP, LiM2O4 (M is Ti, V, Mn or a combination thereof) or a combination thereof, for a lithium secondary battery.

5. In Paragraph 1, The first sacrificial anode is a positive electrode for a lithium secondary battery, comprising an active material different from the second sacrificial anode.

6. In Paragraph 1, The first sacrificial anode is a lithium-nonmetallic compound, and The above lithium-nonmetal compound comprises Li2O, Li2O2, Li3N, Li3P, Li2S, or a combination thereof, a positive electrode for a lithium secondary battery.

7. In Paragraph 1, A positive electrode for a lithium secondary battery, wherein the average particle size (D50) of the first sacrificial positive electrode is 1 nm to 1000 nm.

8. In Paragraph 1, A lithium secondary battery anode, wherein the first sacrificial anode is included in a range of more than 0 wt% and less than or equal to 10 wt% of the total weight of the anode composite.

9. In Paragraph 1, The above second sacrificial anode is a cathode for a lithium secondary battery comprising Li5FeO4, Li2MoO3, Li6CoO4, Li2NiO2, Li8ZrO6, or a combination thereof.

10. In Paragraph 1, A positive electrode for a lithium secondary battery, wherein the sum of the weights of each of the first sacrificial positive electrode and the second sacrificial positive electrode is greater than 0 wt% and less than or equal to 20 wt% of the total weight of the positive electrode mixture.

11. Anode; A cathode including a cathode current collector; An intermediate layer disposed between the above cathode and the above anode Includes, The above anode is, positive current collector; and Anode composite portion disposed on the anode current collector above Includes, The above-mentioned anode composite part is, A positive active material with a first sacrificial anode coated on its surface; and A second sacrificial anode mixed with the above positive active material A lithium secondary battery including 12. In Paragraph 11, The above intermediate layer comprises at least one of a separator or an electrolyte, and The above electrolyte is a lithium secondary battery comprising a gel polymer electrolyte.

13. In Paragraph 12, The above electrolyte is Organic solvent; lithium salt; and It includes a crosslinking agent for forming a polymer matrix, The above-mentioned crosslinking agent is a lithium secondary battery having three or more reactive functional groups.

14. In Paragraph 13, A lithium secondary battery comprising the above-mentioned crosslinking agent in a range of 2 wt% to 20 wt% of the total weight of the electrolyte.

15. In Paragraph 11, A lithium secondary battery in which the above positive active material is included in a range of 80 wt% or more of the total weight of the above positive composite.

16. In Paragraph 11, A lithium secondary battery comprising a positive electrode active material, a spinel-based positive electrode active material, an olivine-based positive electrode active material, a layered positive electrode active material, or a combination thereof.

17. In Paragraph 11, A lithium secondary battery comprising any one of the above positive active material, LiMO2 (M is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or a combination thereof), LFP, LMFP, LiM2O4 (M is Ti, V, Mn or a combination thereof), or a combination thereof.

18. In Paragraph 11, The first sacrificial anode is a lithium-nonmetallic compound, and A lithium secondary battery comprising the above lithium-nonmetal compound, Li2O, Li2O2, Li3N, Li3P, Li2S, or a combination thereof.

19. In Paragraph 11, A lithium secondary battery having an average particle size (D50) of the first sacrificial anode of 1 nm to 1000 nm.

20. In Paragraph 11, The above second sacrificial anode comprises Li5FeO4, Li2MoO3, Li6CoO4, Li2NiO2, Li8ZrO6, or a combination thereof, in a lithium secondary battery.

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