Fe-ni alloy current collector having low resistance multilayer structure and secondary battery comprising same

Abstract

The present invention relates to a current collector that has a Fe-Ni alloy formed on at least one surface of a core part composed of copper foil and which exhibits low resistance and high strength while improving corrosion resistance when used as a current collector of a secondary battery to which lithium ions and a lithium metal negative electrode or a sulfide-based solid electrolyte are applied.

Description

Low-resistance multilayer FE-NI alloy current collector and secondary battery including the same

[0001] This invention was supported by the following two national research and development projects.

[0002] [Project ID] 1415188492

[0003] [Assignment Number] 20024818

[0004] Ministry of Trade, Industry and Energy

[0005] [Name of Project Management (Specialist) Institution] Korea Institute of Industrial Technology Planning and Evaluation

[0006] [Research Project Name] Material and Components Technology Development

[0007] [Research Project Title] Development of High-Strength, Corrosion-Resistant, and Lightweight Current Collector Materials for Sulfide-Based All-Solid-State Batteries

[0008] [Project ID] 1425179998

[0009] [Assignment Number] 00262524

[0010] [Ministry Name] Ministry of SMEs and Startups

[0011] [Name of Project Management (Specialist) Agency] Small and Medium Business Technology Information Promotion Agency

[0012] [Research Project Name] Startup Growth Technology Development (Small Business Accounting)

[0013] [Research Project Name] Development of Ultra-Thin Fe-Based Alloy Foil Manufacturing and Application Products Based on Roll-to-Roll Continuous Electroplating Technology

[0014] The present invention relates to an Fe-Ni alloy current collector having a low-resistance multilayer structure and a secondary battery including the same.

[0015]

[0016] Lithium secondary batteries offer the highest energy density and output characteristics among all secondary batteries, making them widely commercialized. Furthermore, the growing demand for electric vehicles and large-capacity power storage devices necessitates the development of high-energy batteries to meet these needs.

[0017] In response, technologies for applying lithium metal anodes to secondary batteries are being actively developed to achieve high energy densities of over 400 Wh / kg. However, recent reports have shown that applying lithium metal to the anode can cause corrosion of the copper foil used as the anode current collector, reducing battery life.

[0018] Meanwhile, the carbonate-based organic solvents contained in the liquid electrolytes currently widely used in lithium secondary batteries suffer from low thermal stability and highly flammable properties. To address these issues, all-solid-state battery technology using solid electrolytes is being actively researched. However, the most actively researched and developed sulfide-based all-solid-state batteries are facing a growing problem: the sulfide-based solid electrolyte corrodes the copper foil used as a current collector.

[0019] In secondary batteries, the current collector serves as a connecting medium to supply electrons or holes provided from an external conductor to the electrode active material, or conversely, it serves as a conductor that collects electrons or holes generated as a result of the electrode reaction and channels them to the external conductor. In addition, the current collector functions as an important support in implementing the shape of the actual electrode plate. In addition, 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, the current collector is made of copper (Cu) for the negative electrode and aluminum (Al) or platinum (Pt) for the positive electrode, taking into account electrical conductivity, electrochemical stability, and suitability for the electrode plate manufacturing process. Active material particles are coated on top of the collector and then dried to manufacture the electrode.

[0020] However, as previously mentioned, copper foil has the critical problem of causing corrosion in lithium metal batteries and sulfide-based all-solid-state batteries. Furthermore, aluminum (Al) cannot be used as a cathode, making it impossible to utilize aluminum (Al) alone as a current collector possessing both cathode and anode properties. Furthermore, platinum (Pt) is excessively expensive, driving up battery prices, limiting its economic efficiency in battery application and mass production.

[0021]

[0022] The first object of the present invention is to provide a current collector having low corrosion as well as low resistance and high strength characteristics, even when used in a lithium secondary battery using a negative electrode containing a high content of silicon (Si), a secondary battery using a lithium metal negative electrode, or a sulfide-based all-solid-state battery.

[0023] The second object of the present invention is to provide a current collector having low resistance and high strength characteristics, which not only has less corrosion but also has anode characteristics or bipolar characteristics having both cathode and anode characteristics, even when used in a lithium secondary battery using a cathode containing a high content of silicon (Si), a secondary battery using a lithium metal cathode, or a sulfide-based all-solid-state battery.

[0024] A third object of the present invention is to provide a secondary battery capable of realizing high energy density, including the above-described collector.

[0025] However, the problems to be solved by the present invention are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0026]

[0027] To achieve the above purpose, the present invention provides a low-resistance multilayer Fe-Ni alloy current collector of the following (1) to (14) and a secondary battery of (15) to (16) including the current collector.

[0028] (1) A low-resistance multilayer Fe-Ni alloy current collector comprising a copper foil (Cu coil) and an Fe-Ni alloy layer containing iron (Fe) and nickel (Ni) formed on at least one surface of the copper foil (Cu coil), as a current collector of a battery.

[0029] (2) In (1), a low-resistance multilayer Fe-Ni alloy current collector in which the Fe-Ni alloy layer is formed on both sides of the copper foil (Cu coil).

[0030] (3) A low-resistance multilayer Fe-Ni alloy current collector further comprising a cathode characteristic material layer or a cathode characteristic material layer formed on the Fe-Ni alloy layer in (1) or (2).

[0031] (4) A low-resistance multilayer structure Fe-Ni alloy current collector, further comprising a cathode characteristic material layer formed on the Fe-Ni alloy layer on one of the two surfaces of (2), and a cathode characteristic material layer formed on the Fe-Ni alloy layer on the other of the two surfaces.

[0032] (5) In (3) or (4), the negative electrode characteristic material layer is a low-resistance multilayer Fe-Ni alloy current collector comprising at least one selected from the group consisting of nickel (Ni), titanium (Ti), chromium (Cr), molybdenum (Mo), silver (Ag), cobalt (Co), gold (Au), ruthenium (Ru), platinum (Pt), iridium (Ir), and alloys thereof.

[0033] (6) In (3) or (4), a low-resistance multilayer Fe-Ni alloy current collector, wherein 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.

[0034] (7) A low-resistance multilayer Fe-Ni alloy current collector having a thickness of 4 to 20 μm in any one of (1) to (4).

[0035] (8) A low-resistance multilayer Fe-Ni alloy current collector, wherein the thickness of the copper foil is 3 to 14 μm in any one of (1) to (4).

[0036] (9) A low-resistance multilayer Fe-Ni alloy current collector, wherein the total thickness of the Fe-Ni alloy layers formed on both sides of the copper foil in any one of (1) to (4) is 1 to 6 µm.

[0037] (10) A low-resistance multilayer Fe-Ni alloy current collector in any one of (1) to (4), wherein the Fe-Ni alloy layer is composed of 10 to 90 wt% of nickel (Ni), the remainder being iron (Fe) and unavoidable impurities.

[0038] (11) A low-resistance multilayer Fe-Ni alloy current collector having a thickness of 10 nm to 1 μm, in (3) or (4).

[0039] (12) A low-resistance multilayer Fe-Ni alloy current collector, wherein the thickness of the positive electrode characteristic material layer in (3) or (4) is 0.09 to 2 ㎛.

[0040] (13) In any one of (1) to (4), the total collector is 5×10 -8 A low-resistance multilayer Fe-Ni alloy current collector having a resistivity value of less than Ωm.

[0041] (14) A low-resistance multilayer Fe-Ni alloy current collector, wherein in any one of (1) to (4), the average crystal grain size of the Fe-Ni alloy layer is 15 nm or less (excluding 0 nm), the tensile strength of the current collector is 600 MPa or more, and the elongation is 3% or more.

[0042] (15) A secondary battery comprising a first electrode including a current collector as described in any one of (1) to (4) and a first active material layer formed on the current collector, a second electrode disposed opposite the first electrode and including a second current collector and a second active material layer formed on the second current collector, and an electrolyte disposed between the first electrode and the second electrode to provide an environment in which lithium ions can move.

[0043] (16) In (15), a secondary battery including the electrolyte as a solid electrolyte.

[0044]

[0045] The current collector according to the present invention is composed of an alloy containing iron (Fe) and nickel (Ni), and thus exhibits excellent corrosion resistance when used as a current collector in a secondary battery employing a lithium ion or lithium metal anode or a sulfide-based solid electrolyte. This enables the implementation of lithium ion batteries, lithium metal batteries, and all-solid-state batteries that can improve capacity and output characteristics and enhance battery stability.

[0046] In addition, since the current collector according to the present invention has low resistance and high strength, it is possible to realize weight reduction and / or high capacity of a secondary battery by reducing the amount of current collector used or increasing the amount of active material coated.

[0047] In addition, according to one embodiment of the present invention, it is possible to realize weight reduction and high capacity through a reduction in the amount of current collector used and an increase in the amount of active material by having both negative and positive electrode characteristics, bipolar properties, low resistance and high strength.

[0048]

[0049] Figure 1 shows a laminated structure of a collector according to the first embodiment of the present invention.

[0050] Figure 2 shows a laminated structure of a collector according to a second embodiment of the present invention.

[0051] Figure 3 shows a laminated structure of a collector according to a third embodiment of the present invention.

[0052] Figure 4 shows a laminated structure of a collector according to a fourth embodiment of the present invention.

[0053] Figure 5 illustrates a laminated structure of a secondary battery according to a fifth embodiment of the present invention.

[0054] Figure 6 shows a laminated structure of a secondary battery according to the sixth embodiment of the present invention.

[0055] Figure 7 illustrates a laminated structure of a secondary battery according to the seventh embodiment of the present invention.

[0056] Figure 8 shows a laminated structure of a secondary battery according to the eighth embodiment of the present invention.

[0057] Figure 9 is a schematic diagram of a process and manufacturing device for manufacturing a multilayer structure current collector according to the first embodiment of the present invention.

[0058] Figure 10 is a schematic diagram of a process and manufacturing device for manufacturing a multilayer structure current collector according to the second to eighth embodiments of the present invention.

[0059]

[0060] Below, with reference to the attached drawings, embodiments of the present invention are described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0061] In addition, in order to clearly explain the invention in the drawings, parts unrelated to the explanation were omitted, and similar drawing symbols were assigned to similar parts throughout the specification.

[0062] Throughout this specification, when a part is said to be "connected" to another part, this includes not only cases where it is "directly connected" but also cases where it is "electrically connected" with another element in between.

[0063] Throughout this specification, when it is said that a member is located “on,” “above,” “upper,” “lower,” “lower” or “lower” another member, this includes not only cases where the member is in contact with the other member, but also cases where another member exists between the two members.

[0064] Throughout this specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0065] Throughout this specification, the term "alloys thereof" included in the expressions in the Makushi format means one or more mixtures or combinations selected from the group consisting of the components described in the expressions in the Makushi format, and means an alloy comprising one or more selected from the group consisting of said components.

[0066] Throughout this specification, references to “A and / or B” mean “A or B, or A and B.”

[0067]

[0068] <Collector and solid-state battery>

[0069] [Embodiment 1]

[0070] Figure 1 shows a laminated structure of a collector according to the first embodiment of the present invention.

[0071] Referring to FIG. 1, a multilayer structure current collector according to one embodiment of the present invention is structured such that a copper foil is placed on a current collector core portion, and an Fe-Ni alloy layer containing iron (Fe) and nickel (Ni) is formed on both sides of the copper foil.

[0072] The above copper foil may be made of pure copper (Cu) having a purity of 99.9% or more, or a copper (Cu) alloy containing 50% or less of other elements in copper (Cu). Elements that may be added to the copper (Cu) alloy include, for example, metallic elements such as zinc (Zn), tin (Sn), chromium (Cr), magnesium (Mg), iron (Fe), cobalt (Co), nickel (Ni), silver (Ag), silicon (Si), manganese (Mn), and tungsten (W), or non-metallic elements such as carbon (C), sulfur (S), nitrogen (N), and chlorine (Cl).

[0073] The Fe-Ni alloy layer laminated on both sides of the copper foil is a layer that provides corrosion resistance (rust prevention) to the current collector when used in a lithium secondary battery using an anode containing a high silicon (Si) content, a secondary battery using a lithium metal anode, or a sulfide-based all-solid-state battery. The Fe-Ni alloy layer may preferably contain 10 to 90 wt% of nickel (Ni), and more preferably 10 to 33 wt% or 40 to 90 wt% of nickel (Ni).

[0074] If the thickness of the above multilayer structure current collector is less than 4 ㎛, normal foil formation is difficult, and if it exceeds 20 ㎛, the volume of the current collector increases and the coating amount of the active material is significantly reduced. Therefore, it is preferably 4 to 20 ㎛, and a more preferable thickness of the current collector is 4 to 12 ㎛.

[0075] If the thickness of the copper foil constituting the above-mentioned collector is less than 3 ㎛, normal foil formation is difficult, and if it exceeds 14 ㎛, the volume of the collector increases and the coating amount of the active material is significantly reduced. Therefore, the thickness of the copper foil is preferably 3 to 14 ㎛, and a more preferable thickness of the copper foil is 3 to 11 ㎛.

[0076] If the total thickness of the Fe-Ni alloy layer formed on both sides of the copper foil is less than 1 ㎛, coating cannot be performed over the entire area of ​​the copper foil, resulting in pinholes. If it exceeds 6 ㎛, it is not economical compared to the effect of improving corrosion resistance. Therefore, it is preferably 1 to 6 ㎛, and a more preferable total thickness of the Fe-Ni alloy layer is 1 to 4 ㎛. In addition, an Fe-Ni alloy layer of, for example, 0.5 ㎛ to 5.5 ㎛ can be formed on one side of the copper foil.

[0077]

[0078] [Embodiment 2]

[0079] Figure 2 shows a laminated structure of a collector according to a second embodiment of the present invention.

[0080] Referring to FIG. 2, a current collector according to the second embodiment is characterized in that a negative electrode characteristic material layer is formed on one surface (upper side in the drawing) of the current collector according to the first embodiment.

[0081] The above cathode characteristic material layer may include at least one selected from the group consisting of, for example, copper (Cu), nickel (Ni), titanium (Ti), chromium (Cr), molybdenum (Mo), silver (Ag), cobalt (Co), gold (Au), ruthenium (Ru), platinum (Pt), iridium (Ir) and alloys thereof, and preferably titanium (Ti), nickel (Ni), silver (Ag) or an alloy thereof.

[0082] If the thickness of the above-mentioned negative characteristic material layer is less than 10 nm, coating cannot be performed over the entire area of ​​the film, resulting in pinholes. If it is more than 1 ㎛, the volume of the current collector increases, resulting in a decrease in the coating amount of the active material. Therefore, it is preferable that the thickness be in the range of 10 nm to 1 ㎛.

[0083]

[0084] [Embodiment 3]

[0085] Figure 3 shows a laminated structure of a collector according to a third embodiment of the present invention.

[0086] Referring to FIG. 3, a current collector according to the third embodiment is characterized in that a positive electrode characteristic material layer is formed on one side (lower side in the drawing) of the current collector according to the first embodiment.

[0087] The above-mentioned positive characteristic material layer may include at least one selected from the group consisting of aluminum (Al), nickel (Ni), titanium (Ti) and alloys thereof.

[0088] If the thickness of the above-mentioned positive electrode characteristic material layer is less than 0.09㎛, coating cannot be performed over the entire area of ​​the foil, resulting in pinholes. If it is more than 2㎛, the volume of the current collector increases, resulting in a decrease in the coating amount of the active material. Therefore, it is preferable that the thickness be in the range of 0.09 to 2㎛.

[0089]

[0090] [Embodiment 4]

[0091] Figure 4 shows a laminated structure of a collector according to a fourth embodiment of the present invention.

[0092] Referring to FIG. 4, a current collector according to the fourth embodiment is characterized in that a negative electrode characteristic material layer like the second embodiment is formed on one side (upper side in the drawing) of the current collector according to the first embodiment, and a positive electrode characteristic material layer like the third embodiment is formed on the other side (lower side in the drawing).

[0093] That is, the current collector according to the fourth embodiment is characterized by having bipolar properties through coating of a positive electrode material layer and a negative electrode material layer.

[0094]

[0095] [Embodiment 5]

[0096] Figure 5 illustrates a laminated structure of a secondary battery according to a fifth embodiment of the present invention.

[0097] Referring to FIG. 5, a secondary battery according to the fifth embodiment includes a negative electrode formed of a multilayered current collector according to the first embodiment and a negative electrode active material layer formed on one surface of the current collector, a positive electrode formed of a positive electrode plate and a positive electrode active material layer formed on one surface of the positive electrode plate, and a solid electrolyte layer disposed between the positive electrode and the negative electrode.

[0098] The positive electrode active material layer may include various known positive electrode active materials, and the negative electrode active material layer may also include various known negative electrode active materials. For example, the negative electrode active material may include carbon-based active materials such as graphite and coke-based materials.

[0099] The above solid electrolyte layer may include various known solid electrolyte compositions, and for example, a sulfide-based solid electrolyte may be used. In this case, the Fe-Ni alloy layer suppresses the reaction with the sulfide-based solid electrolyte, thereby enabling the implementation of a long-life all-solid-state battery.

[0100] Meanwhile, in the secondary battery of the fifth embodiment, a structure in which a solid electrolyte is placed between the positive electrode and the negative electrode is exemplified, but a liquid electrolyte or a mixture of solid and liquid electrolytes may also be used, and when a liquid electrolyte is included, a separator is additionally placed between the positive electrode and the negative electrode.

[0101]

[0102] [Embodiment 6]

[0103] Figure 6 shows a laminated structure of a secondary battery according to the sixth embodiment of the present invention.

[0104] Referring to FIG. 6, a secondary battery according to the sixth embodiment includes a negative electrode formed of a multilayer structure current collector according to the second embodiment and a negative electrode active material layer formed on a negative electrode characteristic material layer of the current collector, a positive electrode formed of a multilayer structure current collector according to the second embodiment and a positive electrode active material layer formed on an Fe-Ni alloy layer of the current collector, and a solid electrolyte layer disposed between the positive electrode and the negative electrode.

[0105] That is, it is the same as the fifth embodiment, except that the negative electrode active material layer is formed on the negative electrode characteristic material layer.

[0106]

[0107] [Embodiment 7]

[0108] Figure 7 illustrates a laminated structure of a secondary battery according to the seventh embodiment of the present invention.

[0109] Referring to FIG. 7, a secondary battery according to the seventh embodiment includes a positive electrode formed of a multilayer structure current collector according to the third embodiment and a positive electrode active material layer formed on a positive electrode characteristic material layer of the current collector, a negative electrode formed of a multilayer structure current collector according to the second embodiment and a negative electrode active material layer formed on an Fe-Ni alloy layer of the current collector, and a solid electrolyte layer disposed between the positive electrode and the negative electrode.

[0110] That is, it is the same as the fifth embodiment, except that the positive electrode active material layer is formed on the positive electrode characteristic material layer.

[0111]

[0112] [Embodiment 8]

[0113] Figure 8 shows a laminated structure of a secondary battery according to the eighth embodiment of the present invention.

[0114] Referring to FIG. 8, a secondary battery according to the eighth embodiment includes a positive electrode comprising a multilayer structure current collector according to the fourth embodiment and a positive electrode active material layer formed on a positive electrode characteristic material layer of the current collector, a negative electrode comprising a multilayer structure current collector according to the fourth embodiment and a negative electrode active material layer formed on a negative electrode characteristic material layer of the current collector, and a solid electrolyte layer disposed between the positive electrode and the negative electrode.

[0115] That is, it is the same as the fifth embodiment, except that a positive electrode active material layer is formed on a positive electrode characteristic material layer, and a negative electrode active material layer is formed on a negative electrode characteristic material layer to impart positive electrode characteristics.

[0116]

[0117] [Example]

[0118] <Manufacturing of the entire house>

[0119] FIG. 9 is a schematic diagram of a process and a manufacturing device for manufacturing a multilayer structure current collector according to the first embodiment of the present invention, and FIG. 10 is a schematic diagram of a process and a manufacturing device for manufacturing a multilayer structure current collector according to the second to eighth embodiments of the present invention.

[0120] Referring to FIGS. 9 and 10, a copper foil is formed on a rotating cathode drum by electroforming by energizing a positive electrode plate and a rotating cathode drum, which are spaced apart from each other in an electrolyte solution in an electrolytic cell, and the copper foil thus manufactured is guided into an Fe-Ni alloy plating tank by a guide roll, thereby forming an Fe-Ni alloy layer on both sides of the copper foil.

[0121] Specifically, the electrolyte for forming the copper foil basically contains 75 g / L of copper ions and 100 g / L of sulfuric acid, and may contain organic sulfides, organic nitrides, and conductive additives as organic additives. At this time, the electrolyte is maintained at about 50°C, and the current density is 40 A / dm 2 , the flow rate is 35 m 3 / hr can be adjusted.

[0122] An Fe-Ni alloy layer can be formed on the copper foil manufactured in this manner by various known methods, and for example, it can be formed by electroplating.

[0123] In the case of electroplating, the Fe-Ni alloy layer is formed using a plating solution composed of iron (Fe) concentration of 1 to 80 g / L, nickel (Ni) concentration of 5 to 200 g / L, stress reliever of 1.0 to 20 g / L, conductive aid of 5 to 40 g / L, and pH stabilizer of 5 to 40 g / L, with a pH of 1.0 to 5.0 and a current density of 1 to 80 A / dm. 2 , can be formed under the conditions of plating solution temperature of 40 to 90 ℃ and flow rate of 0.2 to 5 m / sec.

[0124] At this time, the iron (Fe) can be used by dissolving in the form of a salt such as iron sulfate, iron chloride, or iron sulfamate, or supplied by dissolving electrolytic iron and iron powder in hydrochloric acid or sulfuric acid. In addition, the nickel (Ni) can be supplied in the form of a salt such as nickel chloride, nickel sulfate, or nickel sulfamate, or by dissolving ferronickel in acid. For example, saccharin can be used as the stress reliever, sodium chloride can be used as the conduction aid, and boric acid, citric acid, etc. can be used as the pH stabilizer.

[0125] The low-resistance multilayer Fe-Ni alloy current collector substrate manufactured by the above electroplating method is thin, with a thickness of about 4 to 20 ㎛, and has excellent mechanical properties due to the average crystal grain size of the Fe-Ni alloy layer being less than 15 nm, thereby providing the mechanical strength required for an all-solid-state battery current collector.

[0126] Additionally, as illustrated in FIG. 10, a cathode characteristic material layer and / or an anode characteristic material layer can be formed on one surface of the collector using a known deposition method, for example, an electron beam deposition method.

[0127]

[0128] <Manufacturing of all-solid-state batteries>

[0129] In order to verify whether the collector manufactured by the above method can be operated as a battery when applied to an all-solid-state battery, an all-solid-state battery was manufactured through the following processes ① to ④.

[0130] ① A negative electrode active material layer is coated on a current collector substrate (a Fe-Ni alloy layer formed on both sides of a Cu foil, the same applies hereinafter) or a current collector substrate coated with a negative electrode characteristic material layer.

[0131] ② A solid electrolyte is coated on the negative active material layer of a portion of the current collector coated with the negative active material.

[0132] ③ A cathode active material is coated on a current collector substrate coated with a current collector substrate or a cathode characteristic material layer.

[0133] ④ A current collector coated with a negative electrode active material and a solid electrolyte on one surface of the current collector prepared in ② above and a current collector coated with a positive electrode active material prepared in ③ are laminated and packaged and pressurized (for example, pressurized using hydrostatic pressure) to manufacture an all-solid-state battery.

[0134] Steps ① to ③ of the above solid-state battery manufacturing process will be described in more detail.

[0135]

[0136] Coating of negative active material on the entire collector

[0137] Materials constituting the negative electrode active material layer (negative electrode active material, binder, etc.) are mixed with a polar or non-polar solvent to prepare a slurry. The prepared slurry is applied to a current collector and dried to form a negative electrode active material layer. Furthermore, although the wet coating method is exemplified as a method for forming the negative electrode active material layer in the embodiments of the present invention, the application of other methods for forming the active material layer, such as a dry coating method, is not limited.

[0138] The negative electrode active material layer includes, for example, at least one of a negative electrode active material that forms an alloy with lithium and a negative electrode active material that forms a compound with lithium. In addition, the negative electrode active material layer may be configured to deposit metallic lithium on the surface of one or both sides of the negative electrode active material layer by containing such a negative electrode active material. The negative electrode active material layer may further include a binder as needed. The binder may include, for example, one or more kinds of styrene butadiene rubber (SBR), polytetrafluoroethylene (PET), polyvinylidene fluoride, polyethylene oxide, etc. The binder can suppress the detachment of the negative electrode active material, especially when the negative electrode active material is in a particulate form. The binder is preferably included in an amount of 3.0 to 15.0 wt% with respect to the total mass of the negative electrode active material layer. In addition, known additives used in all-solid-state secondary batteries, such as fillers, dispersants, and ion conductors, can be appropriately mixed into the negative active material layer.

[0139] The thickness of the negative electrode active material layer is not particularly limited when the negative electrode active material is in the form of particles, but may be, for example, 1.0 to 20.0 ㎛ or less, and preferably 1.0 to 10.0 ㎛ or less. By having a thickness within this range, the effects of the above-described negative electrode active material layer can be sufficiently obtained while the resistance value of the negative electrode active material layer can be sufficiently reduced, thereby sufficiently improving the characteristics of the all-solid-state secondary battery.

[0140] In addition, in another exemplary embodiment, without being limited to the above-described embodiment, the negative electrode active material layer may apply other materials and configurations that can be used as the negative electrode active material layer of an all-solid-state secondary battery.

[0141]

[0142] Solid electrolyte coating on the negative electrode active material layer

[0143] The solid electrolyte layer can be manufactured using a solid electrolyte formed from a sulfide-based solid electrolyte material. The solid electrolyte material used in the present disclosure can be any suitable solid electrolyte capable of conducting metal ions.

[0144] In addition, among the sulfide-based solid electrolyte materials, a material containing at least one element selected from the group consisting of sulfur (S), silicon (Si), phosphorus (P), and boron (B) can be used. As a result, the lithium conductivity of the solid electrolyte layer is improved, and the battery characteristics of the all-solid-state battery are improved. In addition, a solid electrolyte containing at least sulfur (S), phosphorus (P), and lithium (Li) can be used as a constituent element of the solid electrolyte. In particular, a solid electrolyte containing argyrodite-based lithium (Li6PS5Cl) can be used. In addition, the solid electrolyte layer can be a mixture of the electrolytes listed above.

[0145] The thickness of the solid electrolyte layer may be, for example, 1 to 100 μm. In addition, the solid electrolyte layer may further include a binder. The binder included in the solid electrolyte layer may include, for example, one or two or more types of styrene butadiene rubber (SBR), polytetrafluoroethylene (PET), polyvinylidene fluoride, polyethylene oxide, etc. The binder in the solid electrolyte layer may be the same as or different from the binder in the positive electrode active material layer.

[0146] One method for forming a solid electrolyte layer is to press the solid electrolyte layer during the manufacturing process of an all-solid-state battery. In the present embodiment, the solid electrolyte layer is laminated by pressing the solid electrolyte layer before laminating the positive electrode active material on the negative electrode active material layer.

[0147] In the embodiment of the present invention, a process of coating a solid electrolyte on a negative electrode active material layer is exemplified, but in another exemplary embodiment, an all-solid-state battery may be manufactured by coating a solid electrolyte on a positive electrode active material layer and then laminating it, without being limited to the above-described embodiment.

[0148]

[0149] Coating of positive electrode active material on positive electrode current collector

[0150] The positive electrode current collector (positive electrode plate) can use aluminum foil, and similarly to the negative electrode, the positive electrode active material can be coated by mixing the materials constituting the positive electrode active material layer (positive electrode active material, binder, etc.) with a non-polar solvent to make a slurry, then applying the slurry onto the positive electrode current collector and drying it. In addition, although the wet coating method is exemplified as the method for forming the positive electrode active material layer in the embodiments of the present invention, the application of other methods for forming the active material layer, such as a dry coating method, is not limited.

[0151] The positive electrode active material is not particularly limited as long as it can reversibly absorb and release lithium ions. For example, the positive electrode active material may be in powder or granular form and may be formed using lithium salts such as lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, lithium manganate, and lithium iron phosphate, nickel sulfide, copper sulfide, sulfur, iron oxide, or vanadium oxide. These positive electrode active materials may be used alone or in combination of two or more.

[0152]

[0153] <Examples 1 to 6 and Comparative Examples 1 to 6>

[0154] Through the aforementioned current collector manufacturing process, the thickness and components of the current collector in which an Fe-Ni alloy layer is formed on both sides of a Cu foil and a titanium (Ti) layer is formed as a negative electrode characteristic material layer on one side of the Fe-Ni alloy layer are shown in Table 1 below.

[0155] CompositionCu foil thickness (㎛)Total thickness of Fe-Ni alloy layer (㎛)Cathode characteristic material layer thickness (㎛)RemarksExample 131 - Anode plate: AluminumExample 23 10.1Cathode characteristic material: TiExample 33 40.1Cathode characteristic material: TiExample 46 2 - Example 56 20.1Cathode characteristic material: TiExample 66 40.1Cathode characteristic material: TiComparative Example 130.8 - Comparative Example 230.8 0.1Cathode characteristic material: TiComparative Example 330.8 1Cathode characteristic material: TiComparative Example 42.5 1 - Comparative Example 52.5 10.1Cathode characteristic material: TiComparative Example 62.5 40.1Cathode characteristic material: Ti

[0156]

[0157] <Examples 7 to 13 and Comparative Examples 7 to 12>

[0158] In addition, through the above-described current collector manufacturing process, a positive electrode material layer was formed on one side of a current collector substrate on which an Fe-Ni alloy layer was formed on both sides of a Cu foil, or a positive electrode material layer and a negative electrode material layer were formed on each side of the current collector substrate. At this time, titanium (Ti) was formed as the negative electrode material layer, and aluminum (Al) was formed as the positive electrode material layer. The thickness and components of the formed current collector are shown in Table 2 below.

[0159] Composition Copper (Cu) Thickness (㎛) Fe-Ni coating layer thickness (㎛) Cathode characteristic material layer thickness (㎛) Anode characteristic material layer thickness (㎛) Note Example 732-0.1 Anode characteristic material: Al Example 8320.10.1 Example 9320.11.0 Example 103210.1 Example 11620.10.1 Example 12620.11.0 Example 13630.11.0 Comparative Example 731.6-1 Comparative Example 831.60.11 Comparative Example 931.611 Comparative Example 102.5 Not formable--Comparative Example 112.5 Not formable--Comparative Example 122.5 Not formable--

[0160] The resistivity of the current collectors manufactured as described above according to Examples 1 to 13 and Comparative Examples 1 to 12 was measured according to ASTM D991 (Four-Point-Probe) standards. The measured resistivity was judged according to the evaluation criteria below, and the results are shown in Tables 3 and 4 below.

[0161] Resistivity evaluation criteria

[0162] ○: 5×10 -8 Ωm or less

[0163] △: 5×10 -8 Ωm or more to 15×10 -8 Ωm or less

[0164] ×: 15×10 -8 exceeding Ωm

[0165]

[0166] In addition, the tensile strength of the collectors according to Examples 1 to 13 and Comparative Examples 1 to 12 was measured according to ASTM D882 standards. The measured tensile strength was judged according to the evaluation criteria below, and the results are shown in Tables 3 and 4 below.

[0167] Tensile strength evaluation criteria

[0168] ○: 600 MPa or more

[0169] ×: Less than 600 MPa

[0170]

[0171] In addition, for the all-solid-state batteries manufactured by the above-described all-solid-state battery manufacturing method using the current collectors according to Examples 1 to 13 and Comparative Examples 1 to 12, the batteries were charged at 0.1 C until 4.2 V at 60°C and discharged at 0.5 C until 2.5 V to check whether the batteries were operational. The battery operation evaluation criteria were as follows.

[0172] Battery-powered evaluation criteria

[0173] ◎: More than 92% of the initial capacity after 100 charge / discharge cycles

[0174] ○: More than 90% of the initial capacity after 100 charge / discharge cycles

[0175] △: 80% to 90% of the initial capacity after 100 charge / discharge cycles

[0176] ×: Less than 80% of initial capacity after 100 charge / discharge cycles

[0177]

[0178] Table 3 below shows the results of evaluating the resistivity and strength of the current collectors according to Examples 1 to 6 and Comparative Examples 1 to 6, and the operating performance of the all-solid-state batteries manufactured using these current collectors.

[0179] Composition specific resistance strength All-solid-state battery operation Example 1○○○ Example 2○○◎ Example 3○○◎ Example 4○○○ Example 5○○◎ Example 6○○◎ Comparative Example 1○×× Comparative Example 2○×× Comparative Example 3○×× Comparative Example 4△○△ Comparative Example 5△○△ Comparative Example 6△○△

[0180] As confirmed in Table 3 above, the collectors according to Examples 1 to 6 of the present invention were found to have lower resistivity and superior strength compared to the collectors according to Comparative Examples 1 to 6.

[0181] In addition, in terms of all-solid-state battery driving performance, the collectors using the current collectors according to Examples 1 to 6 of the present invention exhibited superior performance compared to the collectors according to Comparative Examples 1 to 6. In particular, the collectors having an additional negative electrode characteristic material layer formed on the Fe-Ni alloy layer exhibited improved battery driving performance compared to the collectors without such a layer.

[0182] Table 4 below shows the results of evaluating the resistivity and strength of the current collectors according to Examples 7 to 13 and Comparative Examples 7 to 12, and the operating performance of the all-solid-state batteries manufactured using these current collectors.

[0183] Composition specific resistance strength All-solid-state battery operation example 7○○○Example 8○○◎Example 9○○◎Example 10○○◎Example 11○○◎Example 12○○◎Example 13○○◎Comparative example 7○××Comparative example 8○××Comparative example 9○××Comparative example 10×××Comparative example 11×××Comparative example 12×××

[0184] As confirmed in Table 4 above, the collectors according to Examples 7 to 13 of the present invention were found to have lower resistivity and superior strength compared to the collectors according to Comparative Examples 7 to 12.

[0185] In addition, in terms of all-solid-state battery driving performance, the collectors using the current collectors according to Examples 7 to 13 of the present invention exhibited superior performance compared to the collectors according to Comparative Examples 7 to 12. In particular, the collectors having a positive electrode material layer and a negative electrode material layer formed on an Fe-Ni alloy layer exhibited improved battery driving performance compared to collectors without such a layer.

Claims

1. As a battery collector, Copper foil (Cu coil) and, A low-resistance multilayer Fe-Ni alloy current collector comprising an Fe-Ni alloy layer containing iron (Fe) and nickel (Ni) formed on at least one surface of the above copper foil (Cu coil).

2. In paragraph 1, The above Fe-Ni alloy layer is a low-resistance multilayer Fe-Ni alloy current collector formed on both sides of the above copper foil (Cu coil).

3. In paragraph 1, A low-resistance multilayer Fe-Ni alloy current collector further comprising a cathode characteristic material layer or a cathode characteristic material layer formed on the Fe-Ni alloy layer.

4. In paragraph 2, A low-resistance multilayer Fe-Ni alloy current collector further comprising a cathode characteristic material layer formed on the Fe-Ni alloy layer on one of the above two surfaces, and a cathode characteristic material layer formed on the Fe-Ni alloy layer on the other of the above two surfaces.

5. In paragraph 3 or 4, A low-resistance multilayer Fe-Ni alloy current collector, wherein the cathode characteristic material layer includes at least one selected from the group consisting of nickel (Ni), titanium (Ti), chromium (Cr), molybdenum (Mo), silver (Ag), cobalt (Co), gold (Au), ruthenium (Ru), platinum (Pt), iridium (Ir), and alloys thereof.

6. In paragraph 3 or 4, A low-resistance multilayer Fe-Ni alloy current collector, wherein 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. In any one of paragraphs 1 to 4, A low-resistance multilayer Fe-Ni alloy current collector having a thickness of 4 to 20 μm.

8. In any one of paragraphs 1 to 4, A low-resistance multilayer Fe-Ni alloy current collector having a copper foil thickness of 3 to 14 μm.

9. In any one of paragraphs 1 to 4, A low-resistance multilayer Fe-Ni alloy current collector having a total thickness of 1 to 6 μm of Fe-Ni alloy layers formed on both sides of the copper foil.

10. In any one of paragraphs 1 to 4, The above Fe-Ni alloy layer is a low-resistance multilayer Fe-Ni alloy current collector composed of 10 to 90 wt% nickel (Ni), the remainder iron (Fe), and unavoidable impurities.

11. In paragraph 3 or 4, A low-resistance multilayer Fe-Ni alloy current collector having a thickness of the above-mentioned cathode characteristic material layer of 10 nm to 1 μm.

12. In paragraph 3 or 4, A low-resistance multilayer Fe-Ni alloy current collector having a thickness of the above-mentioned positive electrode material layer of 0.09 to 2 μm.

13. In any one of paragraphs 1 to 4, The above total number of collectors is 5×10 -8 A low-resistivity multilayer Fe-Ni alloy current collector having a resistivity value of less than Ωm.

14. In any one of paragraphs 1 to 4, The average grain size of the above Fe-Ni alloy layer is 15 nm or less (excluding 0 nm), A low-resistance multilayer Fe-Ni alloy current collector having a tensile strength of 600 MPa or more and an elongation of 3% or more.

15. A first electrode including a current collector as described in any one of claims 1 to 4 and a first active material layer formed on the current collector, A second electrode disposed opposite to the first electrode and including a second current collector and a second active material layer formed on the second current collector, A secondary battery comprising an electrolyte disposed between the first electrode and the second electrode to provide an environment in which lithium ions can move.

16. In paragraph 15, A secondary battery, wherein the electrolyte comprises a solid electrolyte.

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