A negative electrode, a positive electrode, or a current collector having the characteristics of both a negative and positive electrode, and a secondary battery containing the same.

Abstract

The present invention relates to a current collector that exhibits excellent corrosion resistance when a lithium metal anode or sulfide-based solid electrolyte is applied, and that possesses all the characteristics of a negative electrode, a positive electrode, or both a negative electrode and a positive electrode, and to a secondary battery containing the same. The current collector according to the present invention is characterized by comprising a current collector substrate made of an alloy containing iron (Fe) and nickel (Ni), and a positive electrode characteristic material layer formed on one surface of the current collector substrate.

Description

Detailed description of the invention

[0001] [Technical Field] This invention was supported by a national research and development project.

[0002] <Project-Specific Number>141588492 <Project Number>20024818 Ministry of Industry and Energy <Name of the specialized organization for project management> Korea Institute of Industrial Technology Planning and Evaluation <Research Project Name> Development of Materials and Components Technology <Research Project Title> Development of High-Strength, Corrosion-Resistant, Lightweight Current Collector Material Technology for Sulfide-Based All-Solid-State Batteries The present invention relates to a current collector that exhibits excellent corrosion resistance when a lithium metal anode or sulfide-based solid electrolyte is applied, and that possesses all the characteristics of a negative electrode, a positive electrode, or both a negative and a positive electrode, and to a secondary battery containing the same.

[0003] [Background technology] Lithium-ion batteries offer the best energy density and power characteristics among various types of secondary batteries and are widely used commercially. Furthermore, as demand for electric vehicles and large-capacity energy storage devices increases, there is a need for the development of high-energy batteries to meet these needs.

[0004] To achieve high energy densities of 400 Wh / kg or more, the technology of applying lithium metal anodes to secondary batteries is being actively developed. However, recently, there have been a series of reports that when lithium metal is used as the anode, corrosion occurs in the copper foil (Cu foil) used as the anode current collector, reducing the battery life.

[0005] On the other hand, carbonate-based organic solvents contained in the liquid electrolytes currently widely used in lithium-ion batteries have the problem of low thermal stability and high flammability. To solve this, all-solid-state battery technology using solid electrolytes is being actively researched, but a problem has emerged with sulfide-based all-solid-state batteries, which are the most actively researched and developed, in that the sulfide-based solid electrolyte corrodes the copper foil that serves as the current collector.

[0006] In secondary batteries, the current collector acts as a connecting medium for supplying electrons or holes from the external conductor to the electrode active material, or conversely, as a transmitter that collects electrons or holes generated as a result of electrode reactions and carries them to the external conductor. The current collector also functions as an important support in realizing the actual shape of the electrode plates, and it is important that the metal constituting the current collector does not oxidize in the low potential region for the negative electrode current collector and in the high potential region for the positive electrode current collector. Generally, considering electrical conductivity, electrochemical stability, and suitability for the electrode plate manufacturing process, copper (Cu) is used for the negative electrode and aluminum (Al) or platinum (Pt) for the positive electrode, and the electrodes are manufactured by coating the active material slurry on top of it and then drying it.

[0007] However, as mentioned earlier, copper foil (Cu foil) has the fatal problem of corrosion occurring in lithium metal batteries and sulfide-based all-solid-state batteries. Aluminum (Al) cannot be used as a negative electrode, so it is impossible to use aluminum (Al) alone as a current collector that possesses all the characteristics of both a negative and positive electrode. Furthermore, platinum (Pt) has the problem of increasing battery prices due to its excessively high price, and has limitations in terms of low economic efficiency in battery application and mass production.

[0008] [Summary of the Invention] [Problems the invention aims to solve] One objective of the present invention is to provide a current collector that not only exhibits low corrosion even when used with lithium metal negative electrodes or sulfide-based all-solid-state batteries, but can also be used as both a positive and negative electrode current collector.

[0009] Another object of the present invention is to provide a secondary battery that can achieve high energy density by including the current collector. [Means for solving the problem] For the purposes described above, the present invention provides the following current collectors (1) to (20) and secondary batteries (21) and (22).

[0010] (1) A current collector comprising a current collector substrate made of an alloy containing iron (Fe) and nickel (Ni), and a positive electrode characteristic material layer formed on one surface of the current collector substrate.

[0011] (2) A current collector comprising a current collector substrate made of an alloy containing iron (Fe) and nickel (Ni), and a negative electrode characteristic material layer formed on one surface of the current collector substrate.

[0012] (3) A current collector comprising a current collector substrate made of an alloy containing iron (Fe) and nickel (Ni), a positive electrode characteristic material layer formed on one surface of the current collector substrate, and a negative electrode characteristic material layer formed on the other surface of the current collector substrate.

[0013] (4) In any one of (1) to (3), the alloy containing iron (Fe) and nickel (Ni) consists of 3 to 32% or 40 to 90% by weight of nickel (Ni), with the remainder being iron (Fe) and unavoidable impurities, as a current collector.

[0014] (5) A current collector in which, in any one of (1) to (4), the thickness of the current collector substrate is 3.5 μm to 20 μm.

[0015] (6)(1) or (3), the current collector wherein the positive electrode characteristic material layer comprises at least one selected from the group consisting of aluminum (Al), nickel (Ni), titanium (Ti), and alloys thereof.

[0016] (7)(2) or (3), the current collector wherein the negative electrode characteristic material layer contains at least one selected from the group consisting of titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), silver (Ag), tantalum (Ta), tungsten (W), cobalt (Co), gold (Au), ruthenium (Ru), platinum (Pt), iridium (Ir), and alloys thereof.

[0017] (8)(1) or (3), the thickness of the positive electrode characteristic material layer is 0.09 to 2 μm, the current collector.

[0018] (9) In (2) or (3), the thickness of the negative electrode characteristic substance layer is 10 nm to 1 μm, the current collector.

[0019] (10) In any one of (1) to (9), the current collector has a specific resistance value of 20 × 10 -8 Ωm or less, the current collector.

[0020] (11) In any one of (1) to (10), the average crystal grain size of the current collector base material is 15 nm or less (excluding 0 nm), the tensile strength of the current collector base material is 800 MPa or more, and the elongation rate is 2% or more, the current collector.

[0021] (12) In any one of (1) to (11), the current collector base material is manufactured by the electroforming method, the current collector.

[0022] (13) In (1) or (3), the positive electrode characteristic substance layer includes a metal oxide layer, and the metal oxide layer has a gradient composition in which the oxygen concentration continuously or intermittently increases from the current collector base material side toward the surface, the current collector.

[0023] (14) In (2) or (3), the negative electrode characteristic substance layer includes a metal oxide layer, and the metal oxide layer has a gradient composition in which the oxygen concentration continuously or intermittently increases from the current collector base material side toward the surface, the current collector.

[0024] (15) In (3), the positive electrode characteristic substance layer includes a metal oxide layer, the negative electrode characteristic substance layer includes a metal oxide layer, and the metal oxide layers included in the positive electrode characteristic substance layer and the negative electrode characteristic substance layer have a gradient composition in which the oxygen concentration continuously or intermittently increases from the current collector base material side toward the surface, the current collector.

[0025] (16) In any one of (13) to (15), the current collector further includes a metal layer located between the current collector base material and the metal oxide layer, the current collector.

[0026] A current collector in which, in any one of (17)(13) to (15), the metal oxide layer and the metal constituting the metal layer are the same.

[0027] (18)(16) The current collector wherein the thickness of the metal oxide layer is 4.5 nm to 1 μm.

[0028] In any one of (19), (13), to (15), the metal oxide layer has a composition represented by the following chemical formula 1 as a whole, as a current collector.

[0029] [Cation 1] TiO x (0 <x<2) A current collector in which, in any one of (20)(13) to (15), the metal oxide layer is formed by vapor deposition (PVD).

[0030] (21) A secondary battery comprising a first current collector, a first positive electrode active material layer formed on the first current collector, a first electrolyte layer formed on the first positive electrode active material layer, a first negative electrode active material layer formed on the first electrolyte layer, a second current collector formed on the first negative electrode active material layer, a second positive electrode active material layer formed on the second current collector, a second electrolyte layer formed on the second positive electrode active material layer, a second negative electrode active material layer formed on the second electrolyte layer, and a third current collector formed on the second negative electrode active material layer, wherein the second current collector is a current collector having all of the negative electrode and positive electrode characteristics described in (3) or (15).

[0031] (22)(21) A secondary battery in which the first electrolyte layer and the second electrolyte layer contain a solid electrolyte.

[0032] [Effects of the invention] The current collector according to the present invention has excellent corrosion resistance when used as a current collector in secondary batteries to which lithium metal anodes or sulfide-based solid electrolytes are applied, because the current collector base material is made of an alloy containing iron (Fe) and nickel (Ni). Through this, lithium metal batteries and all-solid-state batteries can be realized that can improve capacity and output characteristics and enhance battery stability.

[0033] Furthermore, since the current collector according to one embodiment of the present invention includes a metal oxide layer on one side of the current collector substrate in which the oxygen concentration increases from the substrate side toward the surface side, when used as a current collector in a secondary battery to which lithium ions and lithium metal negative electrodes or sulfide-based solid electrolytes are applied, it can improve battery characteristics and further enhance corrosion resistance.

[0034] Furthermore, the current collector according to one embodiment of the present invention includes a current collector substrate manufactured by electroforming plating, and this current collector substrate, through electroforming plating, consists of ultrafine grains and has excellent corrosion resistance and high strength, thereby enabling a reduction in the amount of current collector used and weight reduction and increased capacity through improvement of the active material.

[0035] Furthermore, in the secondary battery according to one embodiment of the present invention, a positive electrode active material layer is formed on one surface of the current collector and a negative electrode active material layer is formed on the other surface, thereby realizing a lightweight and high-capacity secondary battery by reducing the amount of current collector used.

[0036] Furthermore, the secondary battery according to one embodiment of the present invention can have its corrosion resistance further improved by applying a current collector on which a metal oxide layer is formed.

[0037] [Brief explanation of the drawing] Figure 1 is a diagram showing the cross-sectional structure of a current collector according to the first embodiment of the present invention.

[0038] Figure 2 shows a cross-sectional structure of a current collector according to a second embodiment of the present invention.

[0039] Figure 3 shows a cross-sectional structure of a current collector according to a third embodiment of the present invention.

[0040] Figure 4 shows a cross-sectional structure of a current collector according to the fourth embodiment of the present invention.

[0041] Figure 5 shows a cross-sectional structure of a secondary battery according to a fifth embodiment of the present invention.

[0042] Figure 6 shows a cross-sectional structure of a secondary battery according to the sixth embodiment of the present invention.

[0043] Figure 7 shows a cross-sectional structure of a secondary battery according to the seventh embodiment of the present invention.

[0044] Figure 8 shows a cross-sectional structure of a secondary battery according to the eighth embodiment of the present invention.

[0045] Figure 9 is a schematic diagram of the process and manufacturing apparatus for manufacturing a current collector according to the first to fourth embodiments of the present invention.

[0046] [Best mode for carrying out the invention] Hereinafter, embodiments of the present application will be described in detail with reference to the attached drawings so that they can be easily implemented by a person with ordinary skill in the art to which the present application pertains. However, the present application can be embodied in a variety of different forms and is not limited to the embodiments described herein.

[0047] Furthermore, in order to clearly illustrate the present application with drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification have been given similar reference numerals.

[0048] Throughout this specification, when it is stated that one part is "connected" to another part, this includes not only cases where they are "directly connected" but also cases where they are "electrically connected" with other elements in between.

[0049] Throughout this specification, when it is stated that a member is located "on top of," "at the top," "at the top end," "below," "at the bottom," or "at the bottom end" of another member, this includes not only cases where one member is in contact with another member, but also cases where yet another member exists between the two members.

[0050] Whenever the specification as a whole states that a part "includes" a certain component, this means, unless otherwise stated, that it may include other components rather than excluding them.

[0051] Throughout this specification, the term “these alloys” as used in the Marcush expression means one or more mixtures or combinations selected from the group of components described in the Marcush expression, and means an alloy containing one or more selected from the group of components.

[0052] Throughout this specification, the phrase "A and / or B" means "A or B, or A and B."

[0053] Current collectors and all-solid-state batteries <First Embodiment> Figure 1 is a diagram showing the cross-sectional structure of a current collector according to the first embodiment of the present invention. Referring to Figure 1, the current collector according to the first embodiment consists of a current collector substrate made of an Fe-Ni alloy containing iron (Fe) and nickel (Ni), and a positive electrode characteristic material layer formed on one surface (top and bottom surface in the drawing) of the current collector substrate.

[0054] The Fe-Ni alloy may preferably contain 3 to 90% by weight of nickel (Ni), and more preferably 3 to 32% by weight or 40 to 90% by weight of nickel (Ni).

[0055] If the thickness of the current collector substrate is less than 3.5 μm, it is impossible to form a normal foil, and if it exceeds 20 μm, the volume of the current collector increases and the amount of active material coating decreases significantly. Therefore, a thickness of 3.5 to 20 μm is preferable, and a more preferable current collector thickness is 4 to 12 μm.

[0056] The average crystal grain size of the current collector substrate is preferably 15 nm or less (excluding 0 nm), because excellent strength can be achieved through a fine crystal grain size. The tensile strength of the current collector substrate is preferably 800 MPa or more, and the elongation is preferably 2% or more.

[0057] The current collector substrate may be manufactured by electroforming, which facilitates obtaining a foil with a fine crystal grain size.

[0058] The positive electrode characteristic material layer may contain at least one selected from the group consisting of, for example, aluminum (Al), nickel (Ni), titanium (Ti), and alloys thereof, and preferably aluminum (Al). The thickness of the positive electrode characteristic material layer may be, for example, 0.09 to 2 μm.

[0059] In the current collector according to the first embodiment, the surface on which the positive electrode characteristic material layer is formed has positive electrode characteristics and can be used as a positive electrode current collector, and the surface on which the positive electrode characteristic material layer is not formed has negative electrode characteristics and can be used as a negative electrode current collector.

[0060] The resistivity of the current collector according to the first embodiment is preferably 20 × 10 -8 It can have a value of Ωm or less.

[0061] <Second Embodiment> Figure 2 shows a cross-sectional structure of a current collector according to a second embodiment of the present invention.

[0062] Referring to Figure 2, the current collector according to the second embodiment consists of a current collector substrate made of the same Fe-Ni alloy as in the first embodiment, a positive electrode characteristic material layer formed on one surface (top and bottom surfaces in the drawing) of the current collector substrate, and a negative electrode characteristic material layer formed on the other surface (top surface in the drawing) of the current collector substrate.

[0063] The positive electrode characteristic material layer can be formed in the same manner as in the first embodiment.

[0064] The negative electrode characteristic material layer may contain, for example, at least one selected from the group consisting of titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), silver (Ag), tantalum (Ta), tungsten (W), cobalt (Co), gold (Au), ruthenium (Ru), platinum (Pt), iridium (Ir), and alloys thereof. Preferably, it may be titanium (Ti), nickel (Ni), or silver (Ag), or an alloy thereof. The thickness of the negative electrode characteristic material layer may be 10 nm to 1 μm.

[0065] The resistivity of the current collector according to the second embodiment is preferably 20 × 10 -8 It can have a value of Ωm or less.

[0066] <Third Embodiment> Figure 3 shows a cross-sectional structure of a current collector according to a third embodiment of the present invention.

[0067] Referring to Figure 3, the current collector according to the third embodiment consists of a current collector substrate made of the same Fe-Ni alloy as in the first embodiment, and a metal oxide layer formed on one side of this current collector substrate.

[0068] The metal oxide layer may have a gradient composition in which the oxygen concentration increases continuously or intermittently from the current collector substrate side to the surface. Of these, the gradient composition with intermittently increasing oxygen concentration may have two or more sublayers, such that the oxygen concentration in each sublayer increases from the substrate side sublayer to the surface layer sublayer. Furthermore, each sublayer may consist of a single compound, for example, metal (Me) + metal oxide (MeO). x Mixture layer (low oxygen concentration) → metal oxide (MeO x The oxygen concentration may be adjusted in a mixture form, such as a mixture layer of (low oxygen concentration) + metal oxide (MeO2, high oxygen concentration) → metal oxide (MeO2, high oxygen concentration) layer.

[0069] On the other hand, Figure 3 presents MeO2 as a metal oxide with a high oxygen concentration, but since the number of stoichiometric oxygen atoms differs depending on the metal element to which it is applied, MeO2 should be understood as being presented as an example.

[0070] The metal oxide layer further enhances the current collector's positive or negative electrode characteristics and increases the oxygen concentration towards the surface, thereby improving corrosion resistance.

[0071] The thickness of the metal oxide layer is preferably maintained in the range of 4.5 nm to 1 μm, more preferably in the range of 4.75 nm to 50 nm, and even more preferably in the range of 4.75 nm to 20 nm.

[0072] A metal layer (Me) can be selectively included between the current collector substrate and the metal oxide layer, as shown in Figure 3, thereby further improving the positive or negative electrode characteristics of the metal oxide layer. In this case, it is preferable to maintain the total thickness of the metal layer and the metal oxide layer to be 1 μm or less. When considering corrosion resistance and positive or negative electrode characteristics, the total thickness of the metal layer and the metal oxide layer is preferably in the range of 9.5 nm to 1 μm.

[0073] The metal constituting the metal oxide layer can include at least one selected from the group consisting of titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), silver (Ag), tantalum (Ta), tungsten (W), cobalt (Co), gold (Au), ruthenium (Ru), platinum (Pt), iridium (Ir), and alloys thereof.

[0074] The metal oxide layer can, for example, have a composition represented by the following Chemical Formula 1 as a whole.

[0075] [Chemical Formula 1] TiO x (0 < x < 2) The specific resistance of the current collector according to the third embodiment preferably has a value of 20×10 -8 Ωm or less.

[0076] [Fourth Embodiment] FIG. 4 is a diagram showing a cross-sectional structure of a current collector according to the fourth embodiment of the present invention.

[0077] Referring to FIG. 4, the current collector according to the fourth embodiment is characterized in that it includes a current collector substrate made of the same Fe—Ni-based alloy as in the first embodiment, and metal oxide layers are formed on both sides of the current collector substrate.

[0078] Thus, when metal oxide layers are formed on both sides of the current collector substrate, a battery can be formed by applying a positive electrode active material or a negative electrode active material on both sides of the current collector. At this time, the same substance or different substances can be applied to the metal oxide layers formed on one side and the other side of the current collector substrate, and in this case, it can be selected as a substance that enhances the positive electrode characteristics or the negative electrode characteristics.

[0079] The specific resistance of the current collector according to the fourth embodiment preferably has a value of 20×10 -8 Ωm or less.

[0080] [Fifth Embodiment] Figure 5 shows a cross-sectional structure of a secondary battery according to a fifth embodiment of the present invention.

[0081] Referring to Figure 5, the secondary battery according to the fifth embodiment consists of three current collectors according to the first embodiment, each having a positive electrode characteristic material layer formed on one side, and a structure in which a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer are formed between the current collectors.

[0082] In this configuration, the positive electrode active material layer is formed on the side of the current collector where the positive electrode characteristic material layer is formed, and the negative electrode active material layer is formed on the opposite side where the positive electrode characteristic material layer is not formed.

[0083] The positive electrode active material layer may contain a variety of known positive electrode active materials, and the negative electrode active material layer may also contain a variety of known negative electrode active materials, preferably including lithium metal.

[0084] In all-solid-state batteries with this structure, a positive electrode active material layer can be formed on one side of the central current collector, and a negative electrode material layer on the opposite side. This reduces the amount of current collectors used compared to secondary batteries that use separate current collectors for the positive and negative electrodes, enabling the creation of lightweight, high-capacity batteries.

[0085] <Sixth Embodiment> Figure 6 shows a cross-sectional structure of a secondary battery according to the sixth embodiment of the present invention.

[0086] Referring to Figure 6, the secondary battery according to the sixth embodiment consists of three current collectors, each having a positive electrode characteristic material layer formed on one side and a negative electrode characteristic material layer formed on the other side of a current collector substrate made of Fe-Ni alloy according to the second embodiment, and a structure in which a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer are formed between the current collectors.

[0087] In this configuration, the positive electrode active material layer is formed on the side of the current collector where the positive electrode characteristic material layer is formed, and the negative electrode active material layer is formed on the side where the negative electrode characteristic material layer is not formed.

[0088] In all-solid-state batteries with this structure, a positive electrode active material layer can be formed on one side of the central current collector, and a negative electrode material layer on the opposite side. This reduces the amount of current collectors used compared to secondary batteries that use separate current collectors for the positive and negative electrodes, enabling the creation of lightweight, high-capacity batteries. Furthermore, the battery characteristics can be further improved by incorporating metal oxide layers on the positive and negative electrodes, which can enhance the properties of each electrode.

[0089] <Seventh Embodiment> Figure 7 shows a cross-sectional structure of a secondary battery according to the seventh embodiment of the present invention.

[0090] Referring to Figure 7, the secondary battery according to the seventh embodiment consists of a current collector substrate made of an Fe-Ni alloy, three current collectors on which a metal oxide layer is formed on one surface (top and bottom surfaces in the drawing) of the current collector substrate, and a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer formed between the current collectors.

[0091] In this configuration, the negative electrode active material layer is formed on the side of the current collector where the metal oxide layer is formed, and the positive electrode active material layer is formed on the side where the metal oxide layer is not formed.

[0092] The positive electrode active material layer may contain a variety of known positive electrode active materials, and the negative electrode active material layer may also contain a variety of known negative electrode active materials, preferably including lithium metal.

[0093] In all-solid-state batteries with this structure, a positive electrode active material layer can be formed on one side of the central current collector, and a negative electrode material layer on the opposite side. This reduces the amount of current collectors used compared to secondary batteries that use separate current collectors for the positive and negative electrodes, resulting in a lightweight, high-capacity battery.

[0094] <Eighth Embodiment> Figure 8 shows a cross-sectional structure of a secondary battery according to the eighth embodiment of the present invention.

[0095] Referring to Figure 8, the secondary battery according to the eighth embodiment consists of a current collector substrate made of an Fe-Ni alloy, three current collectors with metal oxide layers formed on both sides of the current collector substrate, and a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer formed between the current collectors.

[0096] In this case, the metal oxide layers formed on both sides of the current collector may be identical, or they may be layers with negative electrode characteristics or positive electrode characteristics. In this case, it is preferable that a negative electrode active material layer is formed on the metal oxide layer with negative electrode characteristics, and a positive electrode oxide layer is formed on the metal oxide layer with positive electrode characteristics.

[0097] In all-solid-state batteries with this structure, a positive electrode active material layer can be formed on one side of the central current collector, and a negative electrode material layer on the opposite side. This reduces the amount of current collectors used compared to secondary batteries that use separate current collectors for the positive and negative electrodes, resulting in a lightweight, high-capacity battery. Furthermore, the battery characteristics can be further improved by incorporating metal oxide layers on the positive and negative electrodes, which can enhance their respective properties.

[0098] Examples <Manufacturing of current collectors> Figure 9 is a schematic diagram of the process and manufacturing apparatus for manufacturing a current collector according to the first to fourth embodiments of the present invention.

[0099] As shown in Figure 9, the process for manufacturing a current collector according to the first to fourth embodiments of the present invention consists of a process for manufacturing a current collector substrate made of an Fe-Ni alloy through electroforming and a process for coating the Fe-Ni alloy substrate with a metal oxide layer (including metal layer formation) through a vapor deposition process.

[0100] There are two methods for manufacturing Fe-Ni alloy metal foil: rolling and electroforming. In the embodiments of this invention, Fe-Ni alloy foil is manufactured by electroforming. However, the present invention is not necessarily limited to this method.

[0101] As an example of manufacturing Fe-Ni alloy foil by electroforming, the composition is as follows: iron concentration of 1-80 g / L, nickel concentration of 5-200 g / L, stress relaxation agent of 1.0-20 g / L, conductivity enhancer of 5-40 g / L, and pH stabilizer of 5-40 g / L, with a pH of 1.0-5.0 and a current density of 1-80 A / dm². 2 Fe-Ni alloy foil can be manufactured under conditions of a plating solution temperature of 40-90°C and a flow rate of 0.2-5 m / sec.

[0102] In this case, the iron can be used in the form of salts such as iron sulfate, iron chloride, or iron sulfamate, or electrolytic iron and iron powder can be supplied dissolved in hydrochloric acid or sulfuric acid. The nickel can be supplied in the form of salts such as nickel chloride, nickel sulfate, or nickel sulfamate, or dissolved in acid. Saccharin can be used as a stress relaxant, sodium chloride can be used as a conduction aid, and boric acid or citric acid can be used as a pH stabilizer.

[0103] The current collector substrate made of Fe-Ni alloy foil manufactured by the electroforming plating method described above, while thin with a thickness of approximately 4 to 20 μm, has a small average crystal grain size of 15 nm or less, and possesses excellent mechanical properties such as a tensile strength of 800 MPa or more and an elongation of 2% or more.

[0104] As shown in Figure 9, on one surface of the current collector substrate manufactured by electroforming, an aluminum (Al) layer is formed as the positive electrode characteristic material layer and a titanium (Ti), nickel (Ni), or copper (Cu) layer is formed as the negative electrode characteristic material layer through a known vacuum deposition method (thermal deposition).

[0105] A current collector according to the first or second embodiment was manufactured using the method described above, and the thickness and composition of the Fe-Ni substrate, negative electrode characteristic material layer, and positive electrode characteristic material layer constituting these current collectors are shown in Table 1 below.

[0106] [Table 1]

[0107] *In the Fe-Ni base material, the content of Fe is the remainder after removing Ni and impurities inevitably contained during the process.

[0108] Next, a titanium (Ti) layer and a titanium oxide layer were formed on one surface of the Fe-24wt%Ni alloy current collector substrate manufactured by electroforming plating method through the aforementioned vacuum evaporation method (electron beam evaporation) with a thickness of about 4 to 10 nm (the total thickness of the titanium and titanium oxide layers).

[0109] The titanium oxide layer is first formed with a titanium (Ti) layer, and then adjusted to the conditions under which titanium oxide (TiO) is formed, so that a "first oxide layer" in which titanium (Ti) and titanium oxide (TiO x , 0 < x ≤ 2) are present in a mixed state is formed, and a "second oxide layer" made of titanium dioxide (TiO2) is formed with a predetermined thickness, so that the oxygen content forms an inclined composition that becomes higher from the current collector substrate to the current collector surface.

[0110] The current collector according to the third embodiment was manufactured by the method as described above. The thickness of the Fe-Ni-based alloy current collector constituting these current collectors, the thickness of the first oxide layer and the second oxide layer are as follows.

[0111]

Table 2

[0112] <Manufacture of all-solid-state battery> When the current collectors according to Examples 1 to 8 and Comparative Examples 1 to 10 were applied to all-solid-state batteries, in order to confirm whether the battery could be driven, all-solid-state batteries were manufactured by the following method. The entire manufacturing process of the all-solid-state battery was manufactured in the following order. <000039​​​​​​(2) A solid electrolyte is coated onto the negative electrode active material layer of a portion of the current collector coated with the negative electrode active material.

[0115] (3) A positive electrode active material layer is coated onto the positive electrode characteristic material layer of another current collector.

[0116] (4) A solid electrolyte is coated onto the negative electrode active material of a current collector, which has the negative electrode active material and positive electrode active material prepared in (3) coated on different surfaces.

[0117] (5) The current collector prepared in (2) above, on one side of which the negative electrode active material and solid electrolyte are coated, the current collector prepared in (4) is coated with the solid electrolyte, and the current collector prepared in (3) is coated with the positive electrode active material are laminated together and pressurized (for example, by pressurizing using hydrostatic pressure) to produce the all-solid-state battery shown in Figure 5 or Figure 6.

[0118] This document provides a detailed explanation of the negative electrode active material layer, positive electrode active material layer, and solid electrolyte used in all-solid-state batteries.

[0119] Negative active material layer A slurry is prepared by mixing the materials constituting the negative electrode active material layer (negative electrode active material, binder, etc.) with a polar or nonpolar solvent. Then, as shown in Figure 5 or Figure 6, the obtained slurry is applied onto the negative electrode characteristic material layer coated on the Fe-Ni alloy metal current collector and dried to produce the negative electrode active material layer.

[0120] The negative electrode active material layer contains at least one of the following: a negative electrode active material that forms an alloy with lithium and a negative electrode active material that forms a compound with lithium. The negative electrode active material layer contains such negative electrode active material and can be configured to allow metallic lithium to be deposited on one or all surfaces of both sides of the negative electrode active material layer, as described below. The negative electrode active material layer may further contain a binder as needed. Such a binder may be, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene (PET), polyvinylidene fluoride, polyethylene oxide, etc. The binder may consist of one of these or two or more. By including a binder in the negative electrode active material layer in this way, the detachment of the negative electrode active material can be suppressed, especially when the negative electrode active material is in particulate form. The binder content in the negative electrode active material layer is 3.0 wt% to 15.0 wt% of the total mass of the negative electrode active material layer. Furthermore, the negative electrode active material layer can be appropriately formulated with additives used in conventional all-solid-state secondary batteries, such as fillers, dispersants, and ion conductors.

[0121] The thickness of the negative electrode active material layer is not particularly limited when the negative electrode active material is in particulate form, but is, for example, 1.0 μm to 20.0 μm, preferably 1.0 μm to 10.0 μm. By having a thickness in this range, the resistance value of the negative electrode active material layer can be sufficiently low while fully obtaining the effects of the negative electrode active material layer described above, and the characteristics of the all-solid-state secondary battery can be sufficiently improved. On the other hand, when the negative electrode active material forms a uniform layer, the thickness of the negative electrode active material layer is, for example, 1.0 nm to 100.0 nm.

[0122] Furthermore, in another exemplary embodiment, not limited to the embodiments described above, the negative electrode active material layer can be made of other materials and configurations that can be used as the negative electrode active material layer of an all-solid-state secondary battery.

[0123] solid electrolyte layer The solid electrolyte layer can be fabricated using a solid electrolyte formed from a sulfide-based solid electrolyte material.

[0124] The solid electrolyte material used in this disclosure may be any suitable solid electrolyte capable of conducting metal ions. As the solid electrolyte, a material containing one or more elements selected from the group consisting of sulfur, silicon, phosphorus, and boron can be used from among the sulfide-based solid electrolyte materials. This improves the lithium conductivity of the solid electrolyte layer and enhances the battery characteristics of the all-solid-state battery. In particular, a solid electrolyte containing at least sulfur (S), phosphorus (P), and lithium (Li) as constituent elements can be used. In particular, a solid electrolyte containing azirodite-based lithium (Li6PS5Cl) can be utilized. The solid electrolyte may include a mixture of any of the listed electrolytes. The solid electrolyte may have a thickness of 1 μm to 50 μm.

[0125] Cathode active material layer A slurry is prepared by mixing the materials constituting the positive electrode active material layer (positive electrode active material, binder, etc.) with a nonpolar solvent. Then, as shown in Figure 5 or Figure 6, the obtained slurry is applied onto a current collector coated with a positive electrode characteristic material layer and dried.

[0126] The positive electrode active material may be a positive electrode active material capable of reversibly intercepting and releasing lithium ions.

[0127] For example, the positive electrode active material may be in powder or particulate form and can be formed using lithium salts such as lithium cobalt oxide (hereinafter referred to as LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (hereinafter referred to as NCA), lithium nickel cobalt manganese oxide (hereinafter referred to as NCM), lithium manganese oxide, lithium iron phosphate, nickel sulfide, copper sulfide, sulfur, iron oxide, or vanadium oxide. Such positive electrode active materials may be used individually or in combination of two or more types.

[0128] <Evaluation of current collectors and all-solid-state batteries> Resistivity evaluation The resistivity of the current collectors manufactured as described above (Examples 1-14 and Comparative Examples 1-16) was measured according to the ASTM D991 (Four-Point-Probe) standard. The measured resistivity was evaluated according to the following criteria, and the results are shown in Tables 3 and 4 below.

[0129] ○: 15×10 -8 Ωm or less △: 15×10 -8 Exceeding Ωm~20×10 -8 Ωm or less X: 20 × 10 -8 Exceeding Ωm Tensile strength evaluation The tensile strength of the current collectors in Examples 1-8 and Comparative Examples 1-10 was measured according to the ASTM D882 standard. The measured tensile strength was evaluated according to the following criteria, and the results are shown in Table 3 below.

[0130] ○: 800 MPa or higher X: Less than 800 MPa Corrosion resistance evaluation The corrosion resistance of current collectors formed in Examples 8-14 and Comparative Examples 11-16, which had metal oxide layers, was measured using cyclic voltammetry (CV). The measurement temperature was 50°C, the applied voltage range was 0-5V, and the scan rate was 5mV / sec. The electrodes used were those of the current collectors from Examples 8-14 and Comparative Examples 11-16, the electrolyte was an argyrodite-based Li6PS5Cl, and the relative electrode was lithium metal. The measured corrosion resistance results were evaluated according to the following criteria, and the results are shown in Table 4 below.

[0131] ○: Current density 50 μA / cm after 30 cycles 2 below X: Current density after 30 cycles: 50 μA / cm² 2 That's all. Battery life evaluation Furthermore, the all-solid-state batteries manufactured using the current collectors described in Examples 1-8 and Comparative Examples 1-10 were charged at 0.1C at 60°C until the voltage reached 4.2V, and then discharged at 0.5C until the voltage reached 2.5V to confirm whether the batteries were operational. The results are shown in Table 3 below.

[0132] [Table 3]

[0133] As can be seen from Table 3 above, in the case of Examples 1 to 8 and Comparative Examples 3, 4, 7, and 8 of the present invention, the resistivity characteristics and mechanical strength characteristics required for the current collector are satisfied, and in particular, Examples 3 to 8 and Comparative Examples 3 and 4 were confirmed to have good characteristics in both resistivity and tensile strength. However, when this is applied to an all-solid-state battery in the form of a bipolar current collector, it can be seen that Comparative Examples 1 to 10 do not operate as a battery.

[0134] In particular, in Comparative Example 9, the nickel content was 36% by weight, resulting in a high resistivity of the material itself, and the thickness of the current collector substrate was thin. Similarly, in Comparative Example 10, the thickness of the current collector substrate was thin. Therefore, even when the positive electrode characteristic material layer and the negative electrode characteristic material layer were formed similarly to those in the examples, it was difficult for the battery to operate normally when applied to a bipolar current collector.

[0135] Through this, when using a current collector that satisfies the thickness range of the current collector substrate and the material layer having negative / positive electrode characteristics according to Examples 1 to 8 of the present invention, it is possible to maintain battery performance by providing the same level of conductivity as conventional copper foil and aluminum foil while ensuring the lightness of the battery, and to confirm the effects of reducing production costs and improving economic efficiency through improved productivity.

[0136] Furthermore, the evaluation results of the resistivity, tensile strength, and corrosion resistance of the current collectors manufactured according to Examples 9-14 and Comparative Examples 11-16 are summarized in Table 4 below.

[0137] [Table 4]

[0138] As can be seen from Table 4 above, in the case of Examples 9 to 14, which have a metal, first oxide layer, and second oxide layer structure, it is possible to maintain battery performance by providing the same level of conductivity as conventional copper foil (Cu foil) while ensuring excellent corrosion resistance of the battery. Furthermore, it is possible to confirm the effects of reducing production costs and improving economic efficiency through increased productivity.

[0139] On the other hand, in the case of Comparative Example 11, evaluation was not performed due to the difficulty in manufacturing. Comparative Examples 12 to 16 showed comparable levels of resistivity and strength compared to the embodiments of the present invention, but were found to be inferior to embodiments 9 to 14 of the present invention in terms of corrosion resistance.

[0140] As described above with reference to examples, a person of ordinary skill in the art will understand that the present invention can be modified and altered in various ways without departing from the spirit and scope of the invention as set forth in the following claims. [Brief explanation of the drawing]

[0141] [Figure 1] This figure shows the cross-sectional structure of a current collector according to the first embodiment of the present invention. [Figure 2] This figure shows a cross-sectional structure of a current collector according to a second embodiment of the present invention. [Figure 3] This figure shows the cross-sectional structure of a current collector according to a third embodiment of the present invention. [Figure 4] This figure shows the cross-sectional structure of a current collector according to the fourth embodiment of the present invention. [Figure 5] This figure shows a cross-sectional structure of a secondary battery according to a fifth embodiment of the present invention. [Figure 6] This figure shows a cross-sectional structure of a secondary battery according to the sixth embodiment of the present invention. [Figure 7] This figure shows a cross-sectional structure of a secondary battery according to the seventh embodiment of the present invention. [Figure 8] This figure shows a cross-sectional structure of a secondary battery according to the eighth embodiment of the present invention. [Figure 9] This is a schematic diagram of the process and manufacturing apparatus for manufacturing a current collector according to the first to fourth embodiments of the present invention.

Claims

1. A current collector comprising a current collector substrate made of an alloy containing iron (Fe) and nickel (Ni), and a positive electrode characteristic material layer formed on one surface of the current collector substrate.

2. A current collector comprising a current collector substrate made of an alloy containing iron (Fe) and nickel (Ni), and a negative electrode characteristic material layer formed on one surface of the current collector substrate.

3. A current collector comprising a current collector substrate made of an alloy containing iron (Fe) and nickel (Ni), a positive electrode characteristic material layer formed on one surface of the current collector substrate, and a negative electrode characteristic material layer formed on the other surface of the current collector substrate.

4. The current collector according to any one of claims 1 to 3, characterized in that the alloy containing iron (Fe) and nickel (Ni) consists of 3 to 32% by weight or 40 to 90% by weight of nickel (Ni), the remainder being iron (Fe) and unavoidable impurities.

5. The current collector according to any one of claims 1 to 3, characterized in that the thickness of the current collector substrate is 3.5 μm to 20 μm.

6. The current collector according to claim 1 or claim 3, characterized in that the positive electrode characteristic material layer includes at least one selected from the group consisting of aluminum (Al), nickel (Ni), titanium (Ti), and alloys thereof.

7. The current collector according to claim 2 or 3, characterized in that the negative electrode characteristic material layer contains at least one selected from the group consisting of titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), silver (Ag), tantalum (Ta), tungsten (W), cobalt (Co), gold (Au), ruthenium (Ru), platinum (Pt), iridium (Ir), and alloys thereof.

8. The current collector according to claim 1 or claim 3, characterized in that the thickness of the positive electrode characteristic material layer is 0.09 to 2 μm.

9. The current collector according to claim 2 or claim 3, characterized in that the thickness of the negative electrode characteristic material layer is 10 nm to 1 μm.

10. The current collector is 20 x 10 －８ A current collector according to any one of claims 1 to 3, characterized by having a resistivity of Ωm or less.

11. The current collector according to any one of claims 1 to 3, characterized in that the average crystal grain size of the current collector substrate is 15 nm or less (excluding 0 nm), the tensile strength of the current collector substrate is 800 MPa or more, and the elongation is 2% or more.

12. The current collector according to any one of claims 1 to 3, characterized in that the current collector substrate is manufactured by electroforming.

13. The positive electrode characteristic material layer includes a metal oxide layer, The current collector according to claim 1, characterized in that the metal oxide layer has a gradient composition in which the oxygen concentration increases continuously or intermittently from the current collector substrate side to the surface.

14. The negative electrode characteristic material layer includes a metal oxide layer. The current collector according to claim 2, characterized in that the metal oxide layer has a gradient composition in which the oxygen concentration increases continuously or intermittently from the current collector substrate side to the surface.

15. The positive electrode characteristic material layer includes a metal oxide layer, The negative electrode characteristic material layer includes a metal oxide layer. The current collector according to claim 3, characterized in that the metal oxide layers contained in the positive electrode characteristic material layer and the negative electrode characteristic material layer have a gradient composition in which the oxygen concentration increases continuously or intermittently from the current collector substrate side to the surface.

16. The current collector according to any one of claims 13 to 15, further comprising a metal layer located between the current collector substrate and the metal oxide layer.

17. The current collector according to any one of claims 13 to 15, characterized in that the metal oxide layer and the metal constituting the metal layer are the same.

18. The current collector according to claim 16, characterized in that the thickness of the metal oxide layer is 4.5 nm to 1 μm.

19. The current collector according to any one of claims 13 to 15, characterized in that the metal oxide layer has an overall composition represented by the following chemical formula 1. [Chemical 1] Uncle ｘ (0<x<2)

20. The current collector according to any one of claims 13 to 15, characterized in that the metal oxide layer is formed by vapor deposition (PVD).

21. The first current collector and, A first positive electrode active material layer formed on the first current collector, A first electrolyte layer formed on the first positive electrode active material layer, A first negative electrode active material layer formed on the first electrolyte layer, A second current collector formed on the first negative electrode active material layer, A second positive electrode active material layer formed on the second current collector, A second electrolyte layer formed on the second positive electrode active material layer, A second negative electrode active material layer formed on the second electrolyte layer, It includes a third current collector formed on the second negative electrode active material layer, A secondary battery characterized in that the second current collector is a current collector having all of the negative electrode and positive electrode characteristics described in claim 3 or claim 15.

22. The secondary battery according to claim 21, characterized in that the first electrolyte layer and the second electrolyte layer contain a solid electrolyte.

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