Lithium secondary battery and method for manufacturing the same

Abstract

The present invention provides a lithium secondary battery and a method for manufacturing the same that can improve lifespan performance and enhance output and capacity performance. [Solution] A lithium secondary battery is provided in which a separator membrane 50 and a positive electrode plate are arranged between a negative electrode current collector 10 and a positive electrode current collector 20, and an electrolyte is provided between the negative electrode current collector 10 and the positive electrode plate, wherein the positive electrode plate is formed by pressurizing a positive electrode active material powder 30, and a sacrificial material 40 formed from a lithium-containing compound is coated on the positive electrode plate.

Description

Technical Field

[0001] The present invention relates to a lithium secondary battery and a method for manufacturing the same. Specifically, it relates to a non-anode lithium secondary battery capable of improving battery life performance by depositing a sacrificial substance on a positive electrode plate by vapor deposition, and enhancing battery output and capacity performance by improving the electrical conductivity of the positive electrode, and a method for manufacturing the same.

Background Art

[0002] A lithium secondary battery is manufactured by using substances capable of inserting and extracting lithium ions for the negative electrode and the positive electrode, and filling an organic electrolyte or a polymer electrolyte between the positive electrode and the negative electrode, and generating electrical energy by oxidation and reduction reactions when lithium ions are inserted and extracted with respect to the positive electrode and the negative electrode.

[0003] In the development of next-generation lithium secondary batteries with high capacity and high energy density, silicon has attracted attention as a negative electrode active material. However, silicon has a problem of volume expansion, and research is actively being conducted to use lithium metal itself as a negative electrode active material. On the other hand, lithium metal has a SEI (Solid-electrolyte interface) layer formed by reacting with the liquid electrolyte itself due to its high reactivity. Due to the physically or electrochemically inferior characteristics of the SEI layer, side reactions occur during repeated charge and discharge, reducing the efficiency characteristics of the lithium secondary battery and causing surface reactions. For this reason, lithium growth grows in the form of dendrites, and there is a risk of short circuit and explosion of the battery. In addition, due to volume changes caused by the porous deposition of lithium ions on the surface of lithium metal due to non-uniform reactions, there is a problem of reduced stability of the lithium secondary battery system.

[0004] Furthermore, lithium films (lithium layers) are not only prone to oxidation but can also melt at relatively low temperatures, making them difficult to manufacture and maintain performance, and their high cost increases the unit price of the product.

[0005] In lithium metal batteries, the implementation of negative electrode-less technology, which does not use lithium film (lithium layer) in the negative electrode, can solve the aforementioned safety problems and drastically reduce the unit cost of the manufacturing process. However, negative electrode-less technology has the problem of shortening the battery life.

[0006] On the other hand, a conventional method has been disclosed in which particles of a positive electrode active material (e.g., positive electrode active material powder) are pre-coated with a sacrificial substance (e.g., Li2O) that is easily decomposed by high voltage, and the positive electrode active material coated with the sacrificial substance is pressurized to form a positive electrode plate.

[0007] However, in this conventional technique, the positive electrode active material is pre-coated with a non-conductive sacrificial material, and the positive electrode plate is formed by pressurizing the anode active material that has been pre-coated with the sacrificial material. This has the problem that the non-conductive sacrificial material inhibits the electrical conductivity of the positive electrode plate.

[0008] Furthermore, when a positive electrode plate is formed by pressurizing a positive electrode active material that has been pre-coated with a sacrificial material, the positive electrode capacity (positive electrode density or density of positive electrode active material) in the formed positive electrode plate decreases relatively, resulting in a problem of reduced battery capacity. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Korean Published Patent Publication No. 10-2019-0100078 [Overview of the project] [Problems that the invention aims to solve]

[0010] The present invention aims to solve the aforementioned problems and to provide a lithium secondary battery and a method for manufacturing the same that can improve battery life performance by coating a sacrificial substance onto the positive electrode plate by vapor deposition and enhance battery output and capacity performance by improving the electrical conductivity of the positive electrode. [Means for solving the problem]

[0011] The present invention aims to achieve the aforementioned objectives, and a first aspect of the present invention provides a lithium secondary battery in which a separator membrane and a positive electrode plate are disposed between a negative electrode current collector and a positive electrode current collector, and an electrolyte is provided between the negative electrode current collector and the positive electrode plate, wherein the positive electrode plate is formed by pressurizing a positive electrode active material powder, and the positive electrode plate is coated with a sacrificial material formed from a lithium-containing compound.

[0012] Since a sacrificial material is coated onto the positive electrode plate formed by pressurization, the problem of the sacrificial material acting as a resistor and reducing the electrical conductivity of the positive electrode plate can be prevented.

[0013] Furthermore, the sacrificial substance may be formed from at least one of the following, containing lithium: oxides, chalcogenides, halides, nitrides, phosphates, carbonates, borates, silicates, sulfates, carbides, peroxides, amides, imides, and organolithium compounds.

[0014] In other words, the sacrificial substance may be formed such that it contains lithium in oxides, chalcogenides, halides, etc.

[0015] Furthermore, the sacrificial material may be coated onto the positive electrode plate after the positive electrode plate has been formed by the positive electrode active material. That is, since the sacrificial material is coated onto the positive electrode plate after the formation of the positive electrode plate is complete, the sacrificial material is not coated on the contact area of ​​the positive electrode active material powder constituting the positive electrode plate, and therefore, a decrease in the electrical conductivity of the positive electrode plate due to the sacrificial material can be prevented.

[0016] Furthermore, after the formation of the positive electrode plate is completed by pressurizing the positive electrode active material powder, the sacrificial material may be coated on the outer surface of the positive electrode plate and around the pores within the positive electrode plate. Therefore, it is possible to ensure a sufficient amount of sacrificial material is coated on the outer surface of the positive electrode plate and around the pores within the positive electrode plate, while simultaneously preventing a decrease in the electrical conductivity of the positive electrode plate due to the sacrificial material.

[0017] Furthermore, the positive electrode plate may be formed by mixing a binder material and at least one conductive material with the positive electrode active material powder and applying pressure. The binder material may make the positive electrode plate more rigid, and the conductive material may improve the electrical conductivity of the positive electrode plate.

[0018] Furthermore, the sacrificial substance does not need to be coated on the parts where the positive electrode active material powders are in contact with each other under pressure. Therefore, it is possible to prevent the electrical conductivity between the positive electrode active material powders forming the positive electrode plate from being reduced by the sacrificial substance.

[0019] Furthermore, the lithium secondary battery according to the present invention does not necessarily have to include a negative electrode active material and a negative electrode plate. This is because, during battery charging, a negative electrode layer can be formed by lithium ions supplied from the sacrificial material and the positive electrode plate (or positive electrode active material). Therefore, a more stable and lower-cost lithium secondary battery can be provided.

[0020] On the one hand, the second aspect of the present invention provides a method for manufacturing a lithium secondary battery. Specifically, the method for manufacturing a lithium secondary battery according to the present invention may include a first step of forming a positive electrode plate by pressing a positive electrode active material powder, a second step of coating a sacrificial material formed of a lithium-containing compound on the positive electrode plate, and a third step of disposing a separator and the positive electrode plate coated with the sacrificial material between a negative electrode current collector and a positive electrode current collector, and providing an electrolyte between the negative electrode current collector and the positive electrode plate.

[0021] Further, after the positive electrode plate is formed by the positive electrode active material in the first step, the sacrificial material may be coated on the positive electrode plate in the second step.

[0022] After the positive electrode plate is completed by the first step, the sacrificial material is coated on the positive electrode plate by the second step, so that the problem that the sacrificial material, which is an insulator, acts as a resistor and reduces the electrical conductivity of the positive electrode plate can be prevented.

[0023] Further, in the second step, the sacrificial material may be coated on the outer surface of the positive electrode plate and around the pores in the positive electrode plate. Therefore, a sufficient amount of the sacrificial material can be ensured on the surface of the positive electrode plate and around the pores in the positive electrode plate, and at the same time, the problem that the electrical conductivity of the positive electrode plate is reduced by the sacrificial material can be prevented.

[0024] Further, in the first step, at least one of a binder material and a conductive material may be mixed with the positive electrode active material powder, and the positive electrode plate may be formed by pressing.

[0025] Further, in the second step, the sacrificial material does not need to be coated on the portion where the positive electrode active material powders are in pressure contact with each other. Therefore, the electrical conductivity between the positive electrode active material powders forming the positive electrode plate can be prevented from being reduced by the sacrificial material.

[0026] Further, the method for manufacturing a lithium secondary battery according to an embodiment of the present invention may not include a negative electrode active material or a negative electrode plate. That is, the method for manufacturing a lithium secondary battery according to an embodiment of the present invention may not include a step of providing a negative electrode active material or a step of forming or providing a negative electrode plate. This is because, during charging of the battery, a negative electrode layer can be provided by lithium ions provided from a sacrificial material and a positive electrode plate (or, a positive electrode active material). Therefore, it is possible to provide a method for manufacturing a lithium secondary battery that is more stable and has a lower unit cost.

Effects of the Invention

[0027] According to the present invention, it becomes possible to provide a lithium secondary battery and a method for manufacturing the same, which can improve battery life performance by applying a sacrificial material onto a positive electrode plate by a vapor deposition method, and can enhance the output and capacity performance of the battery by improving the electrical conductivity of the positive electrode.

Brief Description of the Drawings

[0028] [Figure 1] It is a diagram showing a lithium secondary battery according to an embodiment of the present invention. [Figure 2] It is a diagram showing a lithium secondary battery according to a comparative example. [Figure 3] It is a diagram showing a lithium secondary battery according to another comparative example. [Figure 4] It is a diagram showing a lithium secondary battery according to still another comparative example. [Figure 5] It is a flowchart showing a method for manufacturing a lithium secondary battery according to an embodiment of the present invention.

Modes for Carrying Out the Invention

[0029] Hereinafter, a lithium secondary battery according to one embodiment of the present invention and a method for manufacturing the same will be described in detail with reference to the accompanying drawings. The accompanying drawings are illustrative embodiments of the present invention and are provided solely for the purpose of illustrating the present invention in more detail, and are not intended to limit the technical scope of the present invention.

[0030] Furthermore, the same reference number shall be assigned to identical or corresponding components regardless of the drawings, and redundant explanations related thereto shall be omitted. Note that the size and shape of each component shown may be exaggerated or reduced for the sake of clarity.

[0031] Furthermore, in explaining the present invention, if it is determined that a specific explanation of related prior art would obscure the gist of the present invention, a detailed explanation of the prior art will be omitted.

[0032] Figure 1 shows a lithium secondary battery according to an embodiment of the present invention.

[0033] Specifically, Figure 1(a) shows a state in which a sacrificial material is coated onto a positive electrode plate that has been pre-formed by pressurizing the positive electrode active material (or positive electrode active material powder). Then, Figure 1(b) shows a state in which, due to charging, the sacrificial material moves toward the negative electrode current collector and a negative electrode layer is formed.

[0034] For example, during charging, lithium ions separated from the sacrificial material and the positive electrode active material (positive electrode plate) may move toward the negative electrode current collector and be reduced on the negative electrode current collector to form a negative electrode layer (i.e., a lithium layer). That is, during charging, lithium ions may first be separated from the sacrificial material and move toward the negative electrode current collector (pre-charging), and then separated from the positive electrode active material and move toward the negative electrode current collector (main charging).

[0035] Furthermore, during discharge, the negative electrode layer oxidizes to generate lithium ions. Some of the generated lithium ions are reduced by the positive electrode active material (positive electrode plate), and the remaining lithium ions may be reduced to sacrificial material on the surface of the positive electrode plate.

[0036] In the following description, the positive electrode active material can mean positive electrode active material powder, and a positive electrode plate may be formed by pressurizing the positive electrode active material. That is, a positive electrode plate may be formed by pressurizing the positive electrode active material powder. Furthermore, in this invention, the negative electrode active material and the negative electrode plate are not provided separately. In other words, this invention relates to a lithium secondary battery without a negative electrode.

[0037] Referring to Figure 1, the lithium secondary battery according to an embodiment of the present invention may include a negative electrode current collector 10, a positive electrode current collector 20, a positive electrode active material 30, and a separator membrane 50. A liquid electrolyte (not shown) may be provided between the negative electrode current collector 10 and the positive electrode active material 30.

[0038] Any material that does not induce chemical changes in the lithium secondary battery and has high conductivity can be used for the negative electrode current collector 10. For example, the material of the negative electrode current collector 10 may be copper, iron, aluminum, nickel, stainless steel, titanium, tantalum, gold, platinum, etc. Preferably, the negative electrode current collector 10 may be made of copper or stainless steel.

[0039] The positive electrode current collector 20 may be made of aluminum, an aluminum polymer composite, or the like. A separator membrane 50 and a positive electrode active material 30 may be placed between the negative electrode current collector 10 and the positive electrode current collector 20.

[0040] The separation membrane 50 is placed between the negative electrode current collector 10 and the positive electrode plate formed by the positive electrode active material 30, separating the negative electrode current collector 10 from the positive electrode active material 30 (or the positive electrode plate). The separation membrane 50 can also provide a passage for lithium ions to move, and any type of separation membrane commonly used in lithium secondary batteries can be used.

[0041] For example, the separation membrane 50 preferably has low resistance to the movement of ions through the electrolyte. For example, the separation membrane 50 may be formed from at least one of polyethylene, polypropylene, or a copolymer of polyethylene and polypropylene, and it is also possible to form a multilayer membrane of two or more layers of these materials.

[0042] The electrolyte may be a liquid electrolyte. The liquid electrolyte may be a non-aqueous electrolyte solution. The non-aqueous electrolyte solution comprises an electrolyte which is a lithium salt and a medium, where the lithium salt may be lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium hexafluoroarsenate (LiAsF6), or lithium trifluoromethanesulfonylimide (Li(CF3SO2)2N). The medium may include ethylene carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, fluoroethylene carbonate, acrylonitrile, γ-caprolactone, or a combination of two or more of these. As an example, the medium may be a combination of dimethyl carbonate and fluoroethylene carbonate. In addition to the lithium salt and medium, the liquid electrolyte may further contain additives. For example, the additive may be LiNO3.

[0043] The positive electrode active material 30 is lithium-containing nickel-cobalt-aluminum oxide (Li(NiCoAl)O2,NCA), lithium-containing nickel-cobalt-manganese oxide (Li(NiCoMn)O2,NCM or NMC), lithium manganese oxide (LiMn2O4,LMO), lithium iron phosphate (LiFePO4,LFP), lithium cobalt oxide (LiCoO2,LCO), lithium-containing manganese-iron phosphate (LiMn x Fe 1-x It may contain at least one of Mn4PO4 (LMFP).

[0044] During charging of a lithium secondary battery, lithium ions may be separated from the positive electrode active material 30, and a negative electrode layer 60 may be formed on the negative electrode current collector 10. The process by which the negative electrode layer 60 is formed by lithium ions separated from the positive electrode active material 30 is called main charging, and this main charging may be performed simultaneously with or after the pre-charging described later.

[0045] For example, if the positive electrode active material 30 is formed of a nickel-cobalt-manganese oxide containing lithium, lithium ions may be separated from the positive electrode active material 30 by the following chemical formula 1. The separated lithium ions can be reduced on the negative electrode current collector 10 (the lower surface of the negative electrode current collector 10 in Figure 1) to form the negative electrode layer 60.

[0046] Chemical formula 1: [ka]

[0047] The lithium ions in the positive electrode active material 30 can be separated at a voltage of approximately 3.6V to 4.3V.

[0048] The positive electrode plate may be formed by pressurizing the positive electrode active material 30. That is, the positive electrode plate may be formed by pressurizing the positive electrode active material powder. The positive electrode active material powder may be pressurized by known methods such as roll pressurization.

[0049] With the positive electrode active material 30 positioned on the positive electrode current collector 20, both the positive electrode active material 30 and the positive electrode current collector 20 may be pressurized. In this case, the positive electrode plate may be formed and simultaneously adhere to the positive electrode current collector 20. Alternatively, the positive electrode plate may be formed as a positive electrode plate by pressurization and then adhere to the positive electrode current collector 20.

[0050] Furthermore, the positive electrode plate may further contain at least one of the binder material 35 and the conductive material. For example, the positive electrode plate may be formed by pressurizing a mixture in which the positive electrode active material 30 is mixed with at least one of the binder material 35 and the conductive material. That is, the mixture and the positive electrode current collector 20 may be pressurized together while the mixture is placed on the positive electrode current collector 20, or the positive electrode plate formed by pressurizing the mixture may adhere to the positive electrode current collector 20.

[0051] For example, the binder material 35 may contain a polymer, and known substances may be used as both the binder material 35 and the conductive material.

[0052] On the other hand, the lithium secondary battery according to the present invention does not necessarily have to include a negative electrode active material and a negative electrode plate. That is, even without a negative electrode active material and a negative electrode plate, the lithium secondary battery according to the present invention can selectively provide a negative electrode layer 60 using the positive electrode plate described above and the sacrificial material 40 described later.

[0053] The lithium secondary battery may further include a sacrificial material 40 coated on the positive electrode plate. That is, the sacrificial material 40 may be coated on the positive electrode plate. The sacrificial material 40 may be coated on the positive electrode plate by known methods such as roll coating, spray coating, slot die coating, or blade coating.

[0054] The sacrificial substance 40 may be formed from a compound containing lithium (Li).

[0055] For example, the sacrificial substance 40 may be formed from at least one of the following, containing lithium: oxides, chalcogenides, halides, nitrides, phosphates, carbonates, borates, silicates, sulfates, carbides, peroxides, amides, imides, and organolithium compounds.

[0056] For example, if the sacrificial material 40 is formed of lithium oxide, lithium ions may be separated from the sacrificial material by the following chemical formula 2. The separated lithium ions can be reduced on the negative electrode current collector 10 (the lower surface of the negative electrode current collector 10 in Figure 1) to form the negative electrode layer 60.

[0057] Chemical formula 2: [ka]

[0058] Lithium ions may be separated from the sacrificial material 40 at a voltage of approximately 3.0V to 3.5V. The process by which lithium ions are separated from the sacrificial material 40 to form the negative electrode layer 60 is called pre-charging.

[0059] The aforementioned pre-charging and main charging may be performed sequentially or simultaneously based on the applied voltage.

[0060] By coating the positive electrode plate with the sacrificial material 40, a lithium-based negative electrode layer in a lithium secondary battery can be selectively and smoothly formed, even without a negative electrode active material and a negative electrode plate.

[0061] Furthermore, the sacrificial material 40 is made of an insulator. Therefore, the sacrificial material 40 may act as a resistor on the positive electrode plate, and there is a risk that the electrical conductivity of the positive electrode plate may decrease due to the sacrificial material 40. However, according to this embodiment, by coating the sacrificial material 40 on a pre-formed positive electrode plate, it is possible to prevent a decrease in the electrical conductivity of the positive electrode plate.

[0062] Specifically, the sacrificial material 40 may be coated onto the positive electrode plate after the positive electrode plate has been formed by the positive electrode active material 30. Therefore, since the sacrificial material 40 is coated onto the outer surface of the positive electrode plate formed under pressure from the powder of the positive electrode active material 30, the problem of the electrical conductivity of the positive electrode plate decreasing due to the sacrificial material 40 can be prevented.

[0063] Furthermore, when the positive electrode active material 30 powder is pressurized to form a positive electrode plate, multiple pores C may be formed within the positive electrode plate. The pores C may be formed between adjacent powders when the positive electrode active material 30 powders are pressurized against each other.

[0064] The sacrificial material 40 may also be coated around the pores C within the positive electrode plate. That is, the sacrificial material 40 may also be coated on the outer surface of the powder of the positive electrode active material 30 that partitions the pores C.

[0065] In other words, after the formation of the positive electrode plate is completed by pressurizing the positive electrode active material 30 powder, the sacrificial material 40 may be coated on the outer surface of the positive electrode plate and around the pores C within the positive electrode plate. Therefore, it is possible to prevent a decrease in the electrical conductivity of the positive electrode plate while ensuring as much of the amount of sacrificial material 40 coated on the positive electrode plate as possible.

[0066] On the other hand, when the powders of the positive electrode active material 30 adhere to each other under pressure, the sacrificial material 40 is not coated on the parts where the powders are in contact under pressure. In other words, since the sacrificial material 40 is coated after the positive electrode plate is formed, the parts where the powders are in contact under pressure do not need to be coated with the sacrificial material 40. Therefore, it is possible to prevent the electrical conductivity of the positive electrode plate from decreasing due to the sacrificial material 40.

[0067] On the other hand, the coating of the sacrificial substance 40 on the positive electrode plate in this embodiment may be distinguished from the mixing or coating of the sacrificial substance with the positive electrode active material 30 (i.e., positive electrode active material powder) before the positive electrode plate is formed.

[0068] When the sacrificial material 40 is coated onto the positive electrode plate, the electrical conductivity, positive electrode capacity (positive electrode density), and battery capacity and lifespan can be improved compared to when the sacrificial material is mixed with or coated onto the positive electrode active material 30 (i.e., positive electrode active material powder).

[0069] The advantages of the lithium secondary battery according to this embodiment will be explained in more detail below, with reference to comparative examples.

[0070] Figure 2 shows a lithium secondary battery related to a comparative example.

[0071] Referring to Figure 2, when forming the positive electrode plate, the positive electrode active material 30 and the sacrificial material 40 are mixed and pressurized. In this case, compared to a positive electrode plate of the same size (or thickness), the amount of positive electrode active material 30 may decrease due to the mixing of sacrificial material 40 (mixing of sacrificial material powder), which can lead to a decrease in positive electrode capacity and, consequently, battery capacity.

[0072] Furthermore, as shown in the comparative example in Figure 2, if the amount of sacrificial material 40 is reduced using a positive electrode plate of the same size as the present invention as a reference, there is a problem that not only does the rate at which the negative electrode layer is formed during charging slow down, but it also becomes impossible to form a sufficient negative electrode layer (lithium layer).

[0073] In contrast, in this embodiment, since the sacrificial material 40 is coated onto a pre-finished positive electrode plate, a larger positive electrode capacity can be secured based on a positive electrode plate of the same size (or thickness), and pre-charging by the sacrificial material 40 (formation of the negative electrode layer) can also be performed at a faster speed.

[0074] Figure 3 shows a lithium secondary battery relating to another comparative example.

[0075] Referring to Figure 3, when forming the positive electrode plate, each of the positive electrode active material 30 powders is coated with a sacrificial material 40, and the positive electrode active material 30 is then pressurized. In this case, since the sacrificial material 40 acts as a resistor, a problem may arise in which the electrical conductivity of the positive electrode plate (i.e., the electrical conductivity between the positive electrode active materials) decreases.

[0076] In contrast, in this embodiment, since the sacrificial material 40 is coated onto the surface of a pre-finished positive electrode plate, the sacrificial material 40 does not act as a resistor on the positive electrode plate, and the electrical conductivity can be improved.

[0077] Figure 4 shows a lithium secondary battery relating to yet another comparative example.

[0078] Referring to Figure 4, a positive electrode plate is formed by applying pressure with a layer of sacrificial material 40 placed on top of a layer of positive electrode active material 30. In this case, the amount of positive electrode active material 30 may decrease depending on the thickness of the sacrificial material 40 layer, relative to a positive electrode plate of the same size (or thickness). This can lead to problems such as a decrease in positive electrode capacity and, consequently, battery capacity.

[0079] In contrast, in this embodiment, since the sacrificial material 40 is coated onto a pre-finished positive electrode plate, a larger positive electrode capacity can be secured based on a positive electrode plate of the same size (or thickness), and furthermore, a larger battery capacity can be secured.

[0080] As described above, according to this embodiment, by preventing the sacrificial material 40 from acting as a resistor in the positive electrode plate, electrical conductivity can be improved while simultaneously ensuring sufficient positive electrode capacitance.

[0081] The method for manufacturing a lithium secondary battery according to an embodiment of this model will be described below with reference to other drawings.

[0082] Figure 5 is a flowchart showing the method for manufacturing a lithium secondary battery according to an embodiment of this embodiment. When describing the method for manufacturing a lithium secondary battery according to an embodiment of this embodiment below, it will be clear that the configuration of the lithium secondary battery described above can also be applied identically to the method for manufacturing the lithium secondary battery.

[0083] Referring to Figure 5, the manufacturing method for a lithium secondary battery according to this embodiment may include a first step (S10) in which a positive electrode plate is formed, a second step (S20) in which a sacrificial material is coated onto the positive electrode plate, and a third step (S30) in which the positive electrode plate is placed between the negative electrode current collector and the positive electrode current collector. The manufacturing method does not necessarily include a step in which the negative electrode plate is manufactured using a negative electrode active material.

[0084] In the first stage (S10), a positive electrode plate may be formed by pressurizing the positive electrode active material powder. In the first stage (S10), the positive electrode plate may be formed by mixing the positive electrode active material powder with at least one of a binder material and a conductive material, and then pressurizing the mixture. That is, a positive electrode plate may be formed by pressurizing a mixture in which the positive electrode active material powder is mixed with at least one of a binder material and a conductive material.

[0085] Alternatively, in the first stage (S10), with the positive electrode active material powder (or mixture) placed on the positive electrode current collector, the positive electrode plate may be formed in a state where it adheres to the positive electrode current collector by pressurizing the positive electrode current collector and the positive electrode active material powder (or mixture).

[0086] Various known pressurization methods may be used; for example, a roll pressurization method may be utilized.

[0087] In the second stage (S20), a sacrificial material formed from a lithium-containing compound may be coated onto the positive electrode plate. For example, in the second stage (S20), the sacrificial material may be coated around the outer surface of the positive electrode plate and around one or more pores formed within the positive electrode plate. Multiple pores may be formed within the positive electrode plate, in which case the sacrificial material may be coated around the multiple pores.

[0088] The sacrificial material may be coated onto the positive electrode plate by known methods such as roll coating, spray coating, slot die coating, or blade coating.

[0089] On the other hand, in the second stage (S20), the parts of the positive electrode active material that are in contact with each other under pressure do not need to be coated with sacrificial material. Specifically, when the positive electrode active material powder is formed into a positive electrode plate by pressure, there may be parts where adjacent positive electrode active material powders are in contact with each other. In this case, the parts of the positive electrode active material powder that are in contact with each other are neither coated with sacrificial material nor can be coated with it.

[0090] In the lithium secondary battery manufacturing method of this embodiment, since the positive electrode plate is pre-formed (pre-completed) and a sacrificial material is coated onto the surface of the positive electrode plate, it is possible to prevent a decrease in electrical conductivity on the positive electrode plate due to the non-conductive sacrificial material.

[0091] Furthermore, according to the lithium secondary battery manufacturing method of this embodiment, since the positive electrode plate is pre-formed (pre-completed) and a sacrificial material is coated onto the surface of the positive electrode plate, it is possible to ensure sufficient positive electrode capacity (positive electrode density) while simultaneously ensuring sufficient battery capacity.

[0092] In the third stage, a separator membrane and a positive electrode plate coated with a sacrificial material may be placed between the negative electrode current collector and the positive electrode current collector. On the other hand, if the positive electrode plate and the positive electrode current collector are formed in an attached state, a separator membrane may be placed between the negative electrode current collector and the positive electrode plate. Also in the third stage, a liquid electrolyte may be provided between the negative electrode current collector and the positive electrode plate.

[0093] The preferred embodiments of the present invention described above are disclosed for illustrative purposes only, and it should be understood that various modifications, changes, and additions are possible within the spirit and scope of the invention for those skilled in the art who have ordinary skill in the invention, and such modifications, changes, and additions fall within the scope of the claims below.

[0094] [National research and development project that supported this invention] [Project-specific number] 1711195872 [Issue Number] 00247245 [Department Name] Department of Science, Technology and ICT [Project Management (Specialized) Institution Name] Korea Research Foundation [Research project name] STEAM research (R&D) [Research Project Title] Development of an Artificial Intelligence Platform for Multi-Angle, Multi-Scale Data Fusion Lithium-ion Secondary Battery Design [Name of organization carrying out the project] BEI Lab Co., Ltd. [Research Period] 2023.04.01~2027.12.31 [National research and development project that supported this invention] [Issue-specific number] 2410000627 [Issue Number] 00410241 [Department Name] Ministry of Trade, Industry and Energy [Name of the specialized organization for project management] Korea Institute of Industrial Technology Planning and Evaluation [Research Project Name] Automotive Industry Technology Development (R&D) [Research Project Title] Development of Next-Generation Lithium Metal Batteries for Electric Vehicles with Ensuring Energy Density and Safety through Lithium Dendrite Growth Suppression [Name of organization carrying out the project] BEI Lab Co., Ltd. [Research Period] 2024.04.01~2026.12.31 [Explanation of symbols]

[0095] 10 Negative electrode current collector 20 Positive electrode current collector 30 Cathode active material 35 Binder 40 Sacrificial substances 50 Separation membrane 60 Negative electrode layer

Claims

1. A lithium secondary battery is provided in which a separator membrane and a positive electrode plate are arranged between a negative electrode current collector and a positive electrode current collector, and an electrolyte is provided between the negative electrode current collector and the positive electrode plate, The positive electrode plate is formed by pressurizing the positive electrode active material powder. A lithium secondary battery characterized in that a sacrificial substance formed from a lithium-containing compound is coated on the positive electrode plate.

2. The lithium secondary battery according to claim 1, characterized in that the sacrificial material is formed of at least one of the following, containing lithium: oxides, chalcogenides, halides, nitrides, phosphates, carbonates, borates, silicates, sulfates, carbides, peroxides, amides, imides, and organolithium compounds.

3. The lithium secondary battery according to claim 1 or claim 2, characterized in that the sacrificial material is coated onto the positive electrode plate after the positive electrode plate has been formed with positive electrode active material powder.

4. The lithium secondary battery according to claim 3, characterized in that, after the formation of the positive electrode plate is completed by pressurizing the positive electrode active material powder, the sacrificial material is coated on the outer surface of the positive electrode plate and around the pores within the positive electrode plate.

5. The lithium secondary battery according to claim 3, characterized in that the positive electrode plate is formed by mixing a positive electrode active material powder with at least one of a binder material and a conductive material and applying pressure.

6. The lithium secondary battery according to claim 3, characterized in that the portion where the positive electrode active material powders are in contact with each other under pressure is not coated with the sacrificial material.

7. A lithium secondary battery according to claim 3, characterized in that it does not include a negative electrode active material and a negative electrode plate.

8. The first step involves the formation of a positive electrode plate by pressurizing the positive electrode active material powder, The second step involves coating the positive electrode plate with a sacrificial substance formed from a lithium-containing compound, A third step is to arrange a separation membrane and the positive electrode plate coated with the sacrificial substance between the negative electrode current collector and the positive electrode current collector, and to provide an electrolyte between the negative electrode current collector and the positive electrode plate. A method for manufacturing lithium secondary batteries, including the battery itself.

9. A method for manufacturing a lithium secondary battery according to claim 8, characterized in that, after the positive electrode plate is formed with positive electrode active material powder in the first step, the sacrificial material is coated onto the positive electrode plate in the second step.

10. The method for manufacturing a lithium secondary battery according to claim 9, characterized in that in the second step, the sacrificial material is coated on the outer surface of the positive electrode plate and around the pores within the positive electrode plate.

11. The method for manufacturing a lithium secondary battery according to claim 9, characterized in that in the first step, at least one of a binder material and a conductive material is mixed with the positive electrode active material powder, and the positive electrode plate is formed by pressurization.

12. The method for manufacturing a lithium secondary battery according to claim 9, characterized in that, in the second step, the portion where the positive electrode active material powders are in contact with each other under pressure is not coated with the sacrificial material.

13. A method for manufacturing a lithium secondary battery according to claim 9, characterized in that it does not contain a negative electrode active material or a negative electrode plate.

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