Lithium secondary battery and method for manufacturing the same

Abstract

Disclosed is a lithium secondary battery and a manufacturing method thereof, the lithium secondary battery being configured such that a separator and a positive electrode plate are provided 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 pressing a positive electrode active material powder, and the positive electrode plate is coated with a sacrificial material formed of a lithium-containing compound.

Description

Technical Field

[0001] This invention relates to a lithium secondary battery and a method for manufacturing the same, and more particularly to a negative electrode-free lithium secondary battery and a method for manufacturing the same, wherein the battery life performance can be improved by coating a sacrificial material onto the positive electrode plate using a deposition process, and the battery output and capacity performance can be improved by increasing the conductivity of the positive electrode. Background Technology

[0002] Lithium-ion batteries use materials capable of lithium-ion insertion and extraction to form the negative and positive electrodes, and place an organic electrolyte or polymer electrolyte between the positive and negative electrodes. Lithium-ion batteries generate electrical energy through the oxidation and reduction reactions that occur when lithium ions are inserted and extracted at the positive and negative electrodes.

[0003] Silicon has attracted attention as a negative electrode active material due to its potential for developing next-generation lithium-ion batteries with high capacity and high energy density. However, silicon suffers from volume expansion, leading to ongoing research into using lithium metal alone as the negative electrode active material. Meanwhile, lithium metal is highly reactive and spontaneously reacts with the liquid electrolyte to form a solid electrolyte interphase (SEI) layer. The SEI layer has poor physical and electrochemical properties, resulting in side reactions during repeated charge / discharge cycles, which reduce the efficiency of the lithium-ion battery and cause surface reactions. Lithium grows in a dendritic shape, leading to short circuits and posing an explosion risk. Furthermore, the porous deposition of lithium ions on the lithium metal surface due to uneven reaction causes volume changes, reducing the stability of the lithium-ion battery system.

[0004] In addition, lithium films (lithium layers) are not only easily oxidized, but may also melt at relatively low temperatures, making their manufacturing and performance maintenance difficult. Furthermore, the high price of lithium films can lead to higher unit prices for products.

[0005] In lithium metal batteries, electrodeless technology eliminates the need for a lithium film (lithium layer) as the negative electrode, thus addressing the aforementioned safety issues and significantly reducing manufacturing costs. However, electrodeless technology also suffers from shortened battery life.

[0006] Meanwhile, the following conventional method for forming a positive electrode plate is disclosed: pre-coating particles of positive electrode active material (e.g., positive electrode active material powder) with a sacrificial material (e.g., Li2O, etc.) that is easily decomposed under high voltage, and then pressing the positive electrode active material coated with the sacrificial material.

[0007] Although this traditional technology can use a sacrificial material, which acts as an insulator, to pre-coat the positive electrode active material, and then press the pre-coated positive electrode active material to form a positive electrode plate, there is a problem of suppressing the conductivity (electrical conductivity) of the positive electrode plate because the sacrificial material is an insulator.

[0008] In addition, when a positive electrode plate is formed by pressing a positive electrode active material pre-coated with a sacrificial material, the problem is that the positive electrode capacity (positive electrode density or density of positive electrode active material) of the formed positive electrode plate is reduced, which ultimately reduces the battery capacity.

[0009] [List of Citations]

[0010] [Patent Literature]

[0011] Korean Patent Application Publication No. 10-2019-0100078. Summary of the Invention

[0012] This invention addresses the problems encountered in related technologies. The purpose of this invention is to provide a lithium secondary battery and its manufacturing method. In this invention, the battery's lifespan performance can be improved by coating a sacrificial material onto the positive electrode plate using a deposition process, and the battery's output and capacity performance can be improved by increasing the conductivity of the positive electrode.

[0013] To achieve the above objectives, the present invention provides a lithium secondary battery, wherein the lithium secondary battery is configured such that a separator and a positive electrode plate are disposed between a negative electrode current collector and a positive electrode current collector, and an electrolyte is disposed between the negative electrode current collector and the positive electrode plate, wherein the positive electrode plate is formed by pressing the positive electrode active material powder, and the positive electrode plate is coated with a sacrificial material formed of a lithium compound.

[0014] Because the positive electrode plate, which is formed by pressing, is coated with a sacrificial material, the conductivity of the positive electrode plate can be prevented from decreasing due to the sacrificial material acting as a resistor.

[0015] Furthermore, the sacrificial material may be formed from at least one of the following: lithium oxides, chalcogenides, halides, nitrides, phosphates, carbonates, borates, silicates, sulfates, carbides, peroxides, amides, imides, and organolithium compounds.

[0016] Examples of sacrificial materials can include oxides, chalcogenides, halides, etc., all of which contain lithium.

[0017] Furthermore, after the positive electrode plate is formed from the positive electrode active material, a sacrificial material is applied to the positive electrode plate. Specifically, since the sacrificial material is coated onto the positive electrode plate after its formation is complete, the contact portion of the positive electrode active material powder particles constituting the positive electrode plate is not covered by the sacrificial material, thus preventing a decrease in the conductivity of the positive electrode plate due to the sacrificial material.

[0018] Furthermore, after forming the positive electrode plate by pressing the positive electrode active material powder, a sacrificial material can be applied to the outer surface of the positive electrode plate and around the pores within the positive electrode plate. Therefore, it can be ensured that a sufficient amount of sacrificial material is coated on the outer surface of the positive electrode plate and around the pores, while preventing a decrease in the conductivity of the positive electrode plate due to the sacrificial material.

[0019] Furthermore, the positive electrode plate is formed by mixing positive electrode active material powder with at least one of a binder material or a conductive material and then pressing it. Here, the binder material is used to form the positive electrode plate more firmly, while the conductive material is used to improve the conductivity of the positive electrode plate.

[0020] Furthermore, since the sacrificial material does not need to be coated on the parts of the positive electrode active material powder particles that are in contact with each other under pressure, the conductivity between the positive electrode active material powder particles forming the positive electrode plate can be prevented from decreasing due to the sacrificial material.

[0021] Furthermore, the lithium secondary battery according to the present invention may not include a negative electrode active material or a negative electrode plate. This is because, during battery charging, a negative electrode layer can be formed by sacrificial materials and lithium ions supplied by the positive electrode plate (or positive electrode active material). Therefore, a more stable and cheaper lithium secondary battery can be provided.

[0022] Furthermore, the present invention also 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 positive electrode active material powder; a second step of coating the positive electrode plate with a sacrificial material formed from a lithium compound; and a third step of providing a separator and a 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.

[0023] Furthermore, after the positive electrode plate is formed from the positive electrode active material in the first step, the sacrificial material can be applied to the positive electrode plate in the second step.

[0024] After completing the positive electrode plate in the first step, the sacrificial material is applied to the positive electrode plate in the second step, which prevents the conductivity of the positive electrode plate from decreasing due to the sacrificial material (which is an insulator) acting as a resistor.

[0025] Furthermore, in the second step, sacrificial material can be applied to the outer surface of the positive electrode plate and around the pores within the positive electrode plate. This ensures a sufficient amount of sacrificial material on the surface of the positive electrode plate and around its pores, while simultaneously preventing a decrease in the conductivity of the positive electrode plate due to the sacrificial material.

[0026] In addition, in the first step, a positive electrode plate can be formed by mixing the positive electrode active material powder with at least one of a binder material or a conductive material and then pressing it.

[0027] Furthermore, in the second step, the sacrificial material can be avoided on the parts of the positive electrode active material powder particles that are under pressure and in contact with each other. Therefore, it is possible to prevent a decrease in the conductivity between the positive electrode active material powder particles forming the positive electrode plate due to the sacrificial material.

[0028] Furthermore, in the method for manufacturing a lithium secondary battery according to an embodiment of the present invention, the lithium secondary battery may not include a negative electrode active material or a negative electrode plate. Specifically, the method for manufacturing a lithium secondary battery according to an embodiment of the present invention may not include providing a negative electrode active material or forming or providing a negative electrode plate. This is because, when the battery is charged, a negative electrode layer can be formed by lithium ions provided by a sacrificial material and a positive electrode plate (or positive electrode active material). Therefore, a method for manufacturing a more stable and inexpensive lithium secondary battery can be provided. Attached Figure Description

[0029] The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein:

[0030] Figure 1 (a) and (b) in the figure show a lithium secondary battery according to an embodiment of the present invention;

[0031] Figure 2 A lithium secondary battery according to a comparative example is shown;

[0032] Figure 3 A lithium secondary battery according to another comparative example is shown;

[0033] Figure 4 A lithium secondary battery according to yet another comparative example is shown; and

[0034] Figure 5 A flowchart illustrating the process of manufacturing a lithium secondary battery according to an embodiment of the present invention is provided. Detailed Implementation

[0035] The following description, in conjunction with the accompanying drawings, details a lithium secondary battery according to an embodiment of the present invention and its manufacturing method. The drawings illustrate exemplary forms of the invention and are used only to explain the invention in more detail, but the scope of the invention is not limited thereto.

[0036] Furthermore, regardless of the reference numerals used, identical or corresponding components are given the same reference numerals and their redundant descriptions are omitted, and for ease of interpretation, the size and shape of each component depicted may be exaggerated or reduced.

[0037] Furthermore, in describing the present invention, detailed descriptions of relevant known technologies are omitted if it is determined that such detailed descriptions may obscure the essence of the present invention.

[0038] Figure 1 (a) and (b) in the figures illustrate a lithium secondary battery according to an embodiment of the present invention.

[0039] Specifically, Figure 1 Image (a) shows the state in which sacrificial material is applied to a positive electrode plate pre-formed by pressing a positive electrode active material (or positive electrode active material powder). Furthermore, Figure 1 (b) shows the state in which the sacrificial material moves toward the negative current collector through charging to form a negative electrode layer.

[0040] For example, during charging, lithium ions separated from the sacrificial material and the positive electrode active material (positive plate) move towards the negative electrode current collector and are reduced on the negative electrode current collector, thus forming a negative electrode layer (i.e., a lithium layer). Specifically, during charging, lithium ions first separate from the sacrificial material and move towards the negative electrode current collector (pre-charging), and then separate from the positive electrode active material and move towards the negative electrode current collector (main charging).

[0041] In addition, during the discharge process, the negative electrode layer is oxidized to generate lithium ions. Some of these generated lithium ions are reduced on the positive electrode active material (positive electrode plate), while the remaining portion of these generated lithium ions are reduced to sacrificial material on the surface of the positive electrode plate.

[0042] In the following description, positive electrode active material may refer to positive electrode active material powder, and positive electrode plate may be formed by pressing positive electrode active material. In short, positive electrode plate may be formed by pressing positive electrode active material powder. Furthermore, in this invention, negative electrode active material and negative electrode plate are not provided separately. Therefore, this invention relates to a negative electrode-free lithium secondary battery.

[0043] See Figure 1In (a) and (b) of the present invention, a lithium secondary battery may include a negative current collector 10, a positive current collector 20, a positive active material 30, and a separator 50. A liquid electrolyte (not shown) may be disposed between the negative current collector 10 and the positive active material 30.

[0044] There are no particular restrictions on the material that can be used for the negative electrode current collector 10, as long as it has high conductivity and will not cause chemical changes in the lithium secondary battery. For example, the material of the negative electrode current collector 10 can be copper, iron, aluminum, nickel, stainless steel, titanium, tantalum, gold, platinum, etc. Preferably, the negative electrode current collector 10 is formed of copper or stainless steel.

[0045] The positive current collector 20 can be formed of aluminum, aluminum polymer composite materials, etc. The separator 50 and the positive active material 30 can be disposed between the negative current collector 10 and the positive current collector 20.

[0046] A separator 50 is disposed between the negative current collector 10 and the positive electrode plate formed of the positive active material 30, thereby separating the negative current collector 10 and the positive active material 30 (or the positive electrode plate) from each other. In addition, the separator 50 can provide a channel for the movement of lithium ions, and can be used without any special restrictions as long as it is generally used as a separator in a lithium secondary battery.

[0047] For example, it is desirable that the membrane 50 has low resistance to the movement of ions through the electrolyte. For example, the membrane 50 may be made of at least one of polyethylene, polypropylene, and copolymers of polyethylene and polypropylene, and the membrane 50 may also be provided in the form of a multilayer membrane with two or more layers.

[0048] The electrolyte can be a liquid electrolyte. A liquid electrolyte can be a non-aqueous electrolyte solution. A non-aqueous electrolyte solution includes both the electrolyte as a lithium salt and the solvent. The lithium salt can include lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium hexafluoroarsenate (LiAsF6), or lithium bis(trifluoromethanesulfonyl)imide (Li(CF3SO2)2N). The medium can include ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, fluoroethylene carbonate, acrylonitrile, γ-butyrolactone, or a combination of two or more of these. As an example, the medium can be a combination of dimethyl carbonate and fluoroethylene carbonate. In addition to the lithium salt and the medium, the liquid electrolyte may also include additives. For example, the additive can be LiNO3.

[0049] The positive electrode active material 30 may include at least one of the following: lithium nickel cobalt aluminum oxide (Li(NiCoAl)O2, NCA), lithium 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), and lithium manganese iron phosphate (LiMn2O4, LMO). x Fe 1-x PO4, LMFP).

[0050] When the lithium secondary battery is charged, lithium ions separate from the positive electrode active material 30 and form a negative electrode layer 60 on the negative electrode current collector 10. The process of lithium ions separating from the positive electrode active material 30 to form the negative electrode layer 60 is called main charging. Main charging can be carried out simultaneously with the pre-charging described below, or it can be carried out after the pre-charging described below.

[0051] For example, when the positive electrode active material 30 is formed of a lithium-containing nickel-cobalt-manganese oxide, lithium ions can be separated from the positive electrode active material 30 as shown in Scheme 1 below. The separated lithium ions will be deposited on the negative electrode current collector 10 ( Figure 1 The lower surface of the negative electrode current collector 10 is reduced, thereby forming the negative electrode layer 60.

[0052] Option 1:

[0053] Li (1-x) N i xCo y Mn z O2→Li (1-x-y) Ni x Co y Mn z O2+yLi + +ye -

[0054] Lithium ions can be separated from the positive electrode active material 30 at a voltage of approximately 3.6V to 4.3V.

[0055] A positive electrode plate can be formed by pressing the positive electrode active material 30. Specifically, the positive electrode plate can be formed by pressing the positive electrode active material powder particles. The pressing of the positive electrode active material powder particles can be carried out by known processes (such as rolling).

[0056] The positive electrode active material 30 can be pressed together with the positive electrode current collector 20, so that the positive electrode active material 30 is disposed on the positive electrode current collector 20. Therefore, the positive electrode plate can be attached to the positive electrode current collector 20 at the same time as forming the positive electrode plate. Alternatively, the positive electrode plate can be attached to the positive electrode current collector 20 after the positive electrode active material 30 is formed by pressing.

[0057] Furthermore, the positive electrode plate may also include at least one of an adhesive material 35 or a conductive material. For example, the positive electrode plate can be formed by pressing a mixture of the positive active material 30 with at least one of the adhesive material 35 or a conductive material. Specifically, the mixture can be placed on the positive current collector 20, the mixture can be pressed together with the positive current collector 20, or the positive electrode plate formed by pressing the mixture can be attached to the positive current collector 20.

[0058] For example, adhesive material 35 may include a polymer, and known materials may be used as both adhesive material 35 and conductive material.

[0059] Meanwhile, the lithium secondary battery according to the present invention may not include a negative electrode active material or a negative electrode plate. Specifically, even if the lithium secondary battery according to the present invention does not include a negative electrode active material and a negative electrode plate, a negative electrode layer 60 may be selectively provided by the positive electrode plate described above and the sacrificial material 40 described below.

[0060] The lithium secondary battery may also include a sacrificial material 40 applied to the positive electrode plate. In short, the positive electrode plate may be coated with sacrificial material 40. The sacrificial material 40 can be applied to the positive electrode plate by known processes, such as roll coating, spray coating, slot coating, blade coating, etc.

[0061] The sacrificial material 40 can be formed from lithium (Li)-containing compounds.

[0062] For example, the sacrificial material 40 may be formed from at least one of the following: lithium oxides, chalcogenides, halides, nitrides, phosphates, carbonates, borates, silicates, sulfates, carbides, peroxides, amides, imides, and organolithium compounds.

[0063] For example, when the sacrificial material 40 is formed of lithium oxide, lithium ions can be separated from the sacrificial material, as shown in Scheme 2 below. The separated lithium ions can be separated at the negative electrode current collector 10 ( Figure 1 The negative electrode layer 60 is reduced on the lower surface of the negative electrode current collector 10.

[0064] Option 2:

[0065]

[0066] Lithium ions can be separated from the sacrificial material 40 at a voltage of approximately 3.0V to 3.5V. The process of lithium ions separating from the sacrificial material 40 to form the negative electrode layer 60 is also called pre-charging.

[0067] The pre-charging and main charging described above can be performed sequentially according to the applied voltage, or they can be performed simultaneously depending on the applied voltage.

[0068] When the sacrificial material 40 is applied to the positive electrode plate, a negative electrode layer formed by lithium can be selectively and effectively formed in a lithium secondary battery, even without a negative electrode active material and a negative electrode plate.

[0069] Furthermore, the sacrificial material 40 is formed as an insulator. Therefore, the sacrificial material 40 can act as a resistor in the positive electrode plate, and there is a concern that the conductivity of the positive electrode plate might decrease due to the sacrificial material 40. However, according to the present invention, since the sacrificial material 40 is applied to the pre-formed positive electrode plate, a decrease in the conductivity of the positive electrode plate can be prevented.

[0070] Specifically, after the positive electrode plate is formed from the positive electrode active material 30, a sacrificial material 40 can be applied to the positive electrode plate. Therefore, since the sacrificial material 40 is applied to the outer surface of the positive electrode plate formed by pressing the powder particles of the positive electrode active material 30, the decrease in the conductivity of the positive electrode plate due to the sacrificial material 40 can be prevented.

[0071] Furthermore, when the positive electrode plate is formed by pressing the powder particles of the positive electrode active material 30, multiple pores C can be formed in the positive electrode plate. Pores C can be formed between adjacent powder particles when the powder particles of the positive electrode active material 30 are pressed together.

[0072] The sacrificial material 40 can also be applied around the pores C of the positive electrode plate. Specifically, the sacrificial material 40 can also be applied to the outer surface of the powder particles of the positive electrode active material 30 that define the pores C.

[0073] Specifically, after forming the positive electrode plate by pressing the powder of the positive electrode active material 30, the sacrificial material 40 can be applied to the outer surface of the positive electrode plate and around the pores C in the positive electrode plate. Therefore, while ensuring that as much sacrificial material 40 as possible is applied to the positive electrode plate, the conductivity of the positive electrode plate can be prevented from decreasing.

[0074] Simultaneously, when the powder particles of the positive electrode active material 30 adhere to each other through pressing, the sacrificial material 40 is not applied to the portions where the powder particles are pressed and in contact with each other. Specifically, since the positive electrode plate is formed and then coated with the sacrificial material 40, the sacrificial material 40 is not applied to the portions where the powder particles are in contact with each other through pressing. Therefore, a decrease in the conductivity of the positive electrode plate due to the sacrificial material 40 can be prevented.

[0075] Meanwhile, coating the positive electrode plate of the present invention with the sacrificial material 40 can be distinguished from mixing the sacrificial material with the positive electrode active material 30 (i.e., the positive electrode active material powder) or applying the sacrificial material to the positive electrode active material 30 before the formation of the positive electrode plate.

[0076] Compared to mixing the sacrificial material with the positive electrode active material 30 (i.e., positive electrode active material powder) or applying the sacrificial material to the positive electrode active material 30, applying the sacrificial material 40 to the positive electrode plate can improve the conductivity, positive electrode capacity (positive electrode density), battery capacity, and lifespan.

[0077] The advantages of the lithium secondary battery according to the present invention will be described in more detail below with reference to comparative examples.

[0078] Figure 2 A lithium secondary battery based on a comparative example is shown.

[0079] See Figure 2 A positive electrode plate can be formed by pressing the mixed positive electrode active material 30 and sacrificial material 40. However, for positive electrode plates of the same size (or thickness), the amount of positive electrode active material 30 may be reduced due to the mixing of sacrificial material 40 (mixing of sacrificial material powder), which may lead to a decrease in positive electrode capacity, particularly a decrease in battery capacity.

[0080] In addition, according to Figure 2 The comparative example shown shows that when the amount of sacrificial material 40 is reduced based on a positive electrode plate of the same size as in the present invention, not only is the rate of formation of the negative electrode layer during charging slower, but there is also a problem that a sufficient negative electrode layer (lithium layer) cannot be formed.

[0081] In contrast, in this invention, since the sacrificial material 40 is applied to the pre-completed positive electrode plate, a larger positive electrode capacity can be obtained based on the positive electrode plate having the same size (or the same thickness), and the pre-charging of the sacrificial material 40 (formation of the negative electrode layer) can also be carried out at a high speed.

[0082] Figure 3 A lithium secondary battery according to another comparative example is shown.

[0083] See Figure 3 A positive electrode plate can be formed by pressing the positive electrode active material 30, wherein each powder particle of the positive electrode active material 30 is coated with a sacrificial material 40. In this way, since the sacrificial material 40 acts as a resistor, the conductivity of the positive electrode plate (i.e., the conductivity of the positive electrode active material) may be reduced.

[0084] In contrast, in this invention, since the sacrificial material 40 is applied to the surface of the pre-finished positive electrode plate, there is no situation where the sacrificial material 40 acts as a resistor in the positive electrode plate, and the conductivity can be improved.

[0085] Figure 4 A lithium secondary battery according to yet another comparative example is shown.

[0086] See Figure 4 A positive electrode plate can be formed by pressing a layer of sacrificial material 40 disposed on a layer of positive electrode active material 30. In this way, based on a positive electrode plate with the same size (or the same thickness), the amount of positive electrode active material 30 may be reduced due to the thickness of the sacrificial material 40 layer, which may lead to a decrease in positive electrode capacity, especially a decrease in battery capacity.

[0087] In contrast, in this invention, since the sacrificial material 40 is applied to the pre-finished positive electrode plate, a larger positive electrode capacity, and in particular a larger battery capacity, can be obtained based on a positive electrode plate of the same size (or the same thickness).

[0088] As described above, according to the present invention, the sacrificial material 40 can be prevented from acting as a resistor in the positive electrode plate, thereby improving the conductivity and obtaining sufficient positive electrode capacity.

[0089] The method for manufacturing a lithium secondary battery according to an embodiment of the present invention will now be described with reference to the accompanying drawings.

[0090] Figure 5 A flowchart illustrating the manufacturing process of a lithium secondary battery according to an embodiment of the present invention is provided. Hereinafter, when describing the manufacturing method of a lithium secondary battery according to an embodiment of the present invention, it will be apparent that the structure of the lithium secondary battery described above can also be applied to the method of manufacturing a lithium secondary battery.

[0091] See Figure 5 A method for manufacturing a lithium secondary battery according to an embodiment of the present invention may include: a first step S10, forming a positive electrode plate; a second step S20, coating the positive electrode plate with a sacrificial material; and a third step S30, disposing the positive electrode plate between a negative electrode current collector and a positive electrode current collector. The manufacturing method according to the present invention may not include manufacturing the negative electrode plate using a negative electrode active material.

[0092] In the first step S10, a positive electrode plate can be formed by pressing the positive electrode active material powder. In the first step S10, a positive electrode plate can be formed by mixing the positive electrode active material powder with at least one of a binder material or a conductive material, and then pressing the mixture. Specifically, a positive electrode plate can be formed by pressing a mixture of the positive electrode active material powder with at least one of a binder material or a conductive material.

[0093] In addition, in the first step S10, the positive current collector and the positive active material powder (or mixture) can be pressed so that the positive active material powder (or mixture) is placed on the positive current collector, thereby forming the positive plate while attaching the positive plate to the positive current collector.

[0094] The pressing process can be carried out in a variety of known ways, such as by using a roll pressing process.

[0095] In the second step S20, the positive electrode plate can be coated with a sacrificial material formed of a lithium-containing compound. For example, in the second step S20, the sacrificial material can be applied to the outer surface of the positive electrode plate and around one or more pores formed in the positive electrode plate. Multiple pores can be formed in the positive electrode plate, in which case the sacrificial material can be applied around the multiple pores.

[0096] Sacrificial materials can be applied to the positive electrode plate using known processes (such as roller coating, spray coating, slot coating, scraper coating, etc.).

[0097] Meanwhile, in the second step S20, sacrificial material may not be applied to the pressed and contacted portions of the positive electrode active material. Specifically, when a positive electrode plate is formed by pressing positive electrode active material powder particles, there may be contact portions between adjacent positive electrode active material powder particles. Therefore, sacrificial material is not applied to the portions where the positive electrode active material powder particles are in contact with each other.

[0098] In the method for manufacturing a lithium secondary battery according to this embodiment, since the surface of the pre-formed (pre-completed) positive electrode plate is coated with a sacrificial material, the decrease in the conductivity of the positive electrode plate due to the sacrificial material acting as an insulator can be prevented.

[0099] Furthermore, in the method for manufacturing a lithium secondary battery according to this embodiment, since the surface of the pre-formed (pre-completed) positive electrode plate is coated with a sacrificial material, not only can sufficient positive electrode capacity (positive electrode density) be obtained, but also sufficient battery capacity can be obtained.

[0100] In the third step, a separator and a positive electrode plate coated with sacrificial material can be placed between the negative current collector and the positive current collector. Additionally, when the positive electrode plate and the positive current collector are formed simultaneously by attaching to each other, a separator can be placed between the negative current collector and the positive electrode plate. Furthermore, in the third step, a liquid electrolyte can be placed between the negative current collector and the positive electrode plate.

[0101] As can be seen from the above, according to the present invention, a lithium secondary battery and a method for manufacturing the same can be provided, wherein the battery life performance can be improved by applying a sacrificial material to the positive electrode plate through a deposition process, and the output and capacity performance of the battery can be increased by improving the conductivity of the positive electrode.

[0102] The preferred embodiments of the present invention described above are disclosed for illustrative purposes only. Those skilled in the art with general knowledge of the present invention will be able to make various modifications, changes and additions within the spirit and scope of the present invention, and such modifications, changes and additions should be considered to fall within the scope of the appended claims.

[0103] [National Supported Invention Research and Development Projects]

[0104] Project Identifier Number: 1711195872

[0105] Project Number: 00247245

[0106] [Department Name] Ministry of Science and ICT

[0107] [Project Management (Professional) Organization Name] National Research Foundation of Korea

[0108] [Research Business Name] STEAM Research (R&D)

[0109] [Research Project Title] Development of an artificial intelligence platform for multi-angle-multi-scale data fusion-type lithium secondary battery design

[0110] [Project Implementing Organization Name] BEI Lab Co., Ltd.

[0111] [Research Period] April 1, 2023 to December 31, 2027

[0112] [National Supported Invention Research and Development Projects]

[0113] Project Identifier Number: 2410000627

[0114] Project Number: 00410241

[0115] [Department Name] Ministry of Trade, Industry and Energy

[0116] [Project Management (Professional) Organization Name] Korea Planning & Evaluation Institute of Industrial Technology

[0117] [Research Business Name] Automobile Industry Technology Development (R&D)

[0118] [Research Project Title] Development of next-generation lithium metal batteries for electric vehicles with high energy density and safety through inhibition of lithium dendrite growth.

[0119] [Project Implementing Organization Name] BEI Lab Co., Ltd.

[0120] [Research Period] April 1, 2024 to December 31, 2026.

Claims

1. A lithium secondary battery, said lithium secondary battery being configured such that a separator and a positive electrode plate are disposed between a negative current collector and a positive current collector, and an electrolyte is disposed between the negative current collector and the positive electrode plate. in, The positive electrode plate is formed by pressing the positive electrode active material powder, and The positive electrode plate is coated with a sacrificial material formed from lithium-containing compounds.

2. The lithium secondary battery according to claim 1, wherein, The sacrificial material is formed from at least one of the following: 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 2, wherein, After the positive electrode plate is formed from the positive electrode active material, the sacrificial material is applied to the positive electrode plate.

4. The lithium secondary battery according to claim 3, wherein, After the positive electrode plate is formed by pressing the positive electrode active material powder, the sacrificial material is applied to the outer surface of the positive electrode plate and around the pores in the positive electrode plate.

5. The lithium secondary battery according to claim 3, wherein, The positive electrode plate is formed by mixing the positive electrode active material powder with at least one of a binder material or a conductive material and then pressing it.

6. The lithium secondary battery according to claim 3, wherein, The sacrificial material was not applied to the portion of the positive electrode active material powder particles that were under pressure and in contact with each other.

7. The lithium secondary battery according to claim 3, wherein the lithium secondary battery does not include a negative electrode active material or a negative electrode plate.

8. A method for manufacturing a lithium secondary battery, the method comprising: The first step is to form a positive electrode plate by pressing the positive electrode active material powder; The second step involves coating the positive electrode plate with a sacrificial material formed from a lithium compound. as well as The third step involves placing a diaphragm and a positive electrode plate coated with the sacrificial material between the negative current collector and the positive current collector, and providing an electrolyte between the negative current collector and the positive electrode plate.

9. The method according to claim 8, wherein, After the positive electrode plate is formed from the positive electrode active material in the first step, the sacrificial material is applied to the positive electrode plate in the second step.

10. The method according to claim 9, wherein, In the second step, the sacrificial material is applied to the outer surface of the positive electrode plate and around the pores in the positive electrode plate.

11. The method according to claim 9, wherein, In the first step, the positive electrode plate is formed by mixing the positive electrode active material powder with at least one of a binder material or a conductive material and then pressing it.

12. The method according to claim 9, wherein, In the second step, the sacrificial material is not applied to the portion of the positive electrode active material powder particles that are under pressure and in contact with each other.

13. The method according to claim 9, wherein, The lithium secondary battery does not include negative electrode active material or negative electrode plate.

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