Anode-free lithium secondary battery and manufacturing method thereof

Abstract

The present invention relates to a lithium secondary battery and a method for manufacturing the same. Specifically, the invention relates to a lithium secondary battery in which a separator and a positive 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 plate, wherein the positive plate is formed by the compression of a positive electrode active material powder, and a sacrificial material formed of a compound containing lithium is coated on the positive plate.

Description

Technology Field

[0001] The present invention relates to a lithium secondary battery and a method for manufacturing the same. Specifically, it relates to a negative electrode-free lithium secondary battery and a method for manufacturing the same, which can improve battery life performance by applying a sacrificial cathode material by a deposition method and increase the output and capacity performance of the battery by improving the electrical conductivity of the positive electrode. Background Technology

[0002] A lithium secondary battery is manufactured by using materials capable of inserting and extracting lithium ions as the negative and positive electrodes, and by filling an organic electrolyte or a polymer electrolyte between the positive and negative electrodes, and generates electrical energy through oxidation and reduction reactions when lithium ions are inserted and extracted from the positive and negative electrodes.

[0003] Silicon has garnered attention as an anode active material for the development of next-generation lithium-ion batteries with high capacity and high energy density. However, due to the volume expansion issues associated with silicon, research is actively underway to utilize lithium metal itself as the anode active material. Meanwhile, due to the high reactivity of lithium metal, a Solid-Electrolyte Interface (SEI) layer exists, formed by spontaneous reactions with the liquid electrolyte. Because the SEI layer exhibits physical or electrochemically inferior characteristics, it causes side reactions during repeated charging and discharging, degrading the efficiency of the lithium-ion battery and triggering surface reactions. Consequently, lithium growth occurs in a dendrite form, leading to battery short circuits and posing a risk of explosion. Furthermore, there is a disadvantage in that the stability of the lithium-ion battery system is compromised due to volume changes caused by the porous deposition of lithium ions on the surface of the lithium metal resulting from non-uniform reactions.

[0004] In addition, since lithium films (lithium layers) are not only prone to oxidation but can also melt at relatively low temperatures, manufacturing and maintaining performance are not easy, and there is a problem of increasing product unit costs due to their high price.

[0005] In lithium metal batteries, the implementation of a cathode-free technology that does not use a lithium film (lithium layer) in the negative electrode can solve the aforementioned safety issues and drastically reduce process costs. However, cathode-free technology has the problem of shortening the battery life.

[0006] Meanwhile, a method has been disclosed in the past in which a sacrificial material (e.g., Li2O, etc.) that is easily decomposed first at high voltage is pre-coated onto particles of a positive electrode active material (e.g., positive electrode active material powder), and the positive electrode active material coated with the sacrificial material is compressed to form a positive electrode plate.

[0007] However, this conventional technology forms an anode plate by pre-coating an insulating sacrificial material onto an anode active material and compressing the anode active material coated with the sacrificial material. This has a problem in that the insulating sacrificial material impairs the conductivity (electrical conductivity) of the anode plate.

[0008] In addition, when a positive plate is formed by compressing a positive active material that has been pre-coated with a sacrificial material, the positive capacity (positive density or density of the positive active material) of the formed positive plate is relatively reduced, which ultimately leads to a problem of reduced battery capacity. Prior art literature

[0009] Republic of Korea Published Patent No. 10-2019-0100078 The problem to be solved

[0010] The present invention aims to solve the aforementioned problems by providing a lithium secondary battery and a method for manufacturing the same, which can improve battery life performance by applying a sacrificial anode material by a deposition method and increase the output and capacity performance of the battery by improving the electrical conductivity of the anode electrode. means of solving the problem

[0011] The present invention provides a lithium secondary battery for achieving the aforementioned objectives, wherein a separator and a positive plate are disposed between a negative current collector and a positive current collector, and an electrolyte is provided between the negative current collector and the positive plate, wherein the positive plate is formed by the compression of a positive active material powder, and a sacrificial material formed of a compound containing lithium is coated on the positive plate.

[0012] Since a sacrificial material is coated on the anode plate formed by compression, the problem of reduced electrical conductivity of the anode plate can be prevented as the sacrificial material acts as a resistor.

[0013] In addition, the sacrificial material may be formed from at least one of oxides, chalcogenides, halides, nitrides, phosphates, carbonates, borates, silicates, sulfates, carbides, peroxides, amides, imides, and organolithium compounds, which contain lithium.

[0014] That is, the sacrificial material can be formed to contain lithium in oxides, chalcogenides, halides, etc.

[0015] In addition, the sacrificial material may be coated onto the anode plate after the anode plate is formed by the anode active material. That is, since the sacrificial material is coated onto the anode plate after the formation of the anode plate is completed, the sacrificial material is not coated on the contact portions of the anode active material powders constituting the anode plate, and thus, a decrease in the electrical conductivity of the anode plate due to the sacrificial material can be prevented.

[0016] In addition, after the formation of the anode plate is completed by compressing the anode active material powder, the sacrificial material can be coated on the outer surface of the anode plate and around the pores within the anode plate. Accordingly, a sufficient amount of sacrificial material coated on the outer surface of the anode plate and around the pores within the anode plate can be secured, while simultaneously preventing a decrease in the electrical conductivity of the anode plate caused by the sacrificial material.

[0017] In addition, the anode plate may be formed by mixing at least one of a binder material and a conductive material with an anode active material powder and by compression. The anode plate may be formed more rigidly by the binder material, and the electrical conductivity of the anode plate may be improved by the conductive material.

[0018] In addition, the sacrificial material may not be coated on the portion where the positive active material powders are compressed and in contact with each other. Therefore, the electrical conductivity between the positive active material powders forming the positive plate can be prevented from being reduced by the sacrificial material.

[0019] In addition, the lithium secondary battery according to the present invention may not include a negative electrode active material and a negative electrode plate. This is because, during the charging of the battery, a negative electrode layer can be formed through lithium ions provided from the sacrificial material and the positive electrode plate (or positive electrode active material). Therefore, a lithium secondary battery that is more stable and has a lower unit cost can be provided.

[0020] Meanwhile, 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 plate by compressing a positive active material powder; a second step of coating a sacrificial material formed of a compound containing lithium onto the positive plate; and a third step of disposing of a separator and the positive plate coated with the sacrificial material between a negative current collector and a positive current collector, and providing an electrolyte between the negative current collector and the positive plate.

[0021] In addition, after the anode plate is formed by the anode active material in the first step, the sacrificial material may be coated on the anode plate in the second step.

[0022] After the anode plate is completed through the first step above, a sacrificial material is coated onto the anode plate through the second step above, so the problem of reduced electrical conductivity of the anode plate can be prevented as the non-conductive sacrificial material acts as a resistor.

[0023] In addition, in the second step, the sacrificial material may be coated on the outer surface of the anode plate and around the voids within the anode plate. Thus, a sufficient amount of sacrificial material can be secured on the surface of the anode plate and around the voids within the anode plate, while simultaneously preventing the problem of reduced electrical conductivity of the anode plate due to the sacrificial material.

[0024] In addition, in the first step, at least one of a binder material and a conductive material is mixed with the positive active material powder, and the positive plate can be formed by compression.

[0025] In addition, in the second step above, the sacrificial material may not be coated on the portion where the positive active material powders are pressed together and in contact. Therefore, the electrical conductivity between the positive active material powders forming the positive plate can be prevented from being reduced by the sacrificial material.

[0026] Furthermore, 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 battery charging, a negative electrode layer can be formed through lithium ions provided from a sacrificial material and a positive electrode plate (or positive electrode active material). Therefore, a method for manufacturing a lithium secondary battery that is more stable and has a lower unit cost can be provided. Effects of the invention

[0027] According to the present invention, by applying a sacrificial anode material by a deposition method, the battery life performance can be improved, and by improving the electrical conductivity of the anode electrode, the output and capacity performance of the battery can be increased, thereby providing a lithium secondary battery and a method for manufacturing the same. Brief explanation of the drawing

[0028] FIG. 1 is a drawing showing a lithium secondary battery according to an embodiment of the present invention. Figure 2 is a drawing showing a lithium secondary battery according to a comparative example. Figure 3 is a drawing showing a lithium secondary battery according to another comparative example. Figure 4 is a drawing showing a lithium secondary battery according to another comparative example. FIG. 5 is a flowchart illustrating a method for manufacturing a lithium secondary battery according to an embodiment of the present invention. Specific details for implementing the invention

[0029] Hereinafter, a lithium secondary battery and a method for manufacturing the same according to an embodiment of the present invention will be described in detail with reference to the attached drawings. The attached drawings illustrate exemplary forms of the present invention and are provided only to explain the present invention in more detail; the technical scope of the present invention is not limited thereby.

[0030] Additionally, identical or corresponding components are assigned the same reference number regardless of drawing symbols, and redundant descriptions thereof are omitted; furthermore, for the convenience of explanation, the size and shape of each illustrated component may be exaggerated or reduced.

[0031] In addition, in describing the present invention, detailed descriptions of related prior art are omitted if it is determined that such descriptions could obscure the essence of the invention.

[0033] FIG. 1 is a drawing showing a lithium secondary battery according to an embodiment of the present invention.

[0034] Specifically, FIG. 1(a) shows a state in which a sacrificial material is coated on a pre-formed positive plate through compression of a positive active material (or positive active material powder). FIG. 1(b) shows a state in which a sacrificial material moves toward the negative current collector side through charging to form a negative electrode layer.

[0035] For example, during charging, lithium ions separated from the sacrificial material and the positive electrode active material (positive plate) move toward the negative electrode current collector and are reduced on the negative electrode current collector to form a negative electrode layer (i.e., a lithium layer). That is, during charging, lithium ions are first separated from the sacrificial material and move toward the negative electrode current collector (pre-charging), and then can be separated from the positive electrode active material and move toward the negative electrode current collector (main charging).

[0036] In addition, during discharge, the negative electrode layer is oxidized to generate lithium ions, some of the generated lithium ions are reduced in the positive electrode active material (positive plate), and the remainder of the generated lithium ions can be reduced as a sacrificial material on the surface of the positive plate.

[0037] In the following description, the positive electrode active material may refer to a positive electrode active material powder, and a positive electrode plate may be formed by compressing the positive electrode active material. That is, a positive electrode plate may be formed by compressing the positive electrode active material powder. Furthermore, in the present invention, the negative electrode active material and the negative electrode plate are not provided separately. In other words, the present invention relates to a negative electrode-free lithium secondary battery.

[0038] Referring to FIG. 1, a 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 (50). A liquid electrolyte (not shown) may be provided between the negative electrode current collector (10) and the positive electrode active material (30).

[0039] The material of the above negative electrode current collector (10) can be used without special restrictions as long as it is a material having high conductivity without causing chemical changes in the lithium secondary battery. 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 formed of copper or stainless steel.

[0040] The above positive current collector (20) may be formed of aluminum, an aluminum polymer composite, etc. A separator (50) and a positive active material (30) may be disposed between the above negative current collector (10) and the above positive current collector (20).

[0041] The separator (50) is disposed between the negative current collector (10) and the positive plate formed by the positive active material (30), thereby separating the negative current collector (10) and the positive active material (30) (or positive plate) from each other. Additionally, the separator (50) can provide a passage for the movement of lithium ions and can be used without special limitations as long as it is typically used as a separator in a lithium secondary battery.

[0042] For example, it is desirable that the separator (50) has low resistance to the movement of ions through the electrolyte. For example, the separator (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 film of two or more layers thereof.

[0043] The above electrolyte may be a liquid electrolyte. The above 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, wherein the lithium salt may be lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium hexafluoroacetate (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. The above liquid electrolyte may further include an additive in addition to the lithium salt and the medium. For example, the additive may be LiNO3.

[0044] The above positive active material (30) is a nickel-cobalt-aluminum oxide containing lithium (Li(NiCoAl)O2, NCA), a nickel-cobalt-manganese oxide containing lithium (Li(NiCoMn)O2, NCM or NMC), a lithium manganese oxide (LiMn2O4, LMO), a lithium iron phosphate (LiFePO4, LFP), a lithium cobalt oxide (LiCoO2, LCO), and a manganese-iron-phosphate containing lithium (LiMn x Fe 1-x It may include at least one of Mn4PO4, LMFP.

[0045] When charging a lithium secondary battery, lithium ions are separated from the positive active material (30), and a negative electrode layer (60) can be formed on the negative electrode current collector (10). The process of forming the negative electrode layer (60) by the lithium ions separated from the positive active material (30) is called the main charging, and the main charging can be performed simultaneously with or after the pre-charging described later.

[0046] For example, if the positive active material (30) is formed of a nickel-cobalt-manganese oxide containing lithium, lithium ions can be separated from the positive active material (30) through the following chemical formula 1. The separated lithium ions can be reduced on the negative current collector (10) (the lower surface of the negative current collector (10) in FIG. 1) to form a negative layer (40).

[0047] Chemical formula 1:

[0048]

[0049] The above positive active material (30) can separate lithium ions at a voltage of approximately 3.6V to 4.3V.

[0050] An anode plate can be formed by compressing the above-mentioned positive active material (30). That is, the anode plate can be formed by compressing the positive active material powders. The compression of the positive active material powders can be performed by a previously known method such as roll compression.

[0051] With the positive active material (30) placed on the positive current collector (20), the positive active material (30) and the positive current collector (20) can be compressed together. In this case, the positive plate can be attached to the positive current collector (20) at the same time as the positive plate is formed. Alternatively, the positive plate may be attached to the positive current collector (20) after the positive active material (30) is formed into a positive plate through compression.

[0052] Additionally, the anode plate may further include at least one of a binder material (30) and a conductive material. For example, the anode plate may be formed by compressing the mixture in the state where at least one of a binder material (35) and a conductive material is mixed with the anode active material (30). That is, while the mixture is placed on the anode current collector (20), the mixture and the anode current collector (20) may be compressed together, or the anode plate formed by the compression of the mixture may be attached to the anode current collector (20).

[0053] For example, the binder material (30) may include a polymer, and known materials may be used as the binder material (30) and the conductive material.

[0054] Meanwhile, the lithium secondary battery according to the present invention may not include a negative electrode active material and a negative electrode plate. That is, even if the lithium secondary battery according to the present invention does not have a negative electrode active material and a negative electrode plate, it can selectively provide a negative electrode layer (60) through the aforementioned positive electrode plate and the sacrificial material (40) to be described later.

[0055] The above lithium secondary battery may further include a sacrificial material (40) coated on the positive plate. That is, the sacrificial material (40) may be coated on the positive plate. The sacrificial material (40) may be coated on the positive plate through known methods such as roll coating, spray coating, slow die coating, blade coating, etc.

[0056] The above sacrificial material (40) can be formed from a compound containing lithium (Li).

[0057] For example, the sacrificial material (40) may be formed from at least one of oxides, chalcogenides, halides, nitrides, phosphates, carbonates, borates, silicates, sulfates, carbides, peroxides, amides, imides, and organolithium compounds, including lithium.

[0058] For example, if the sacrificial material (40) is formed of lithium oxide, lithium ions can be separated from the sacrificial material through 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 FIG. 1) to form a negative electrode layer (40).

[0059] Chemical formula 2:

[0060]

[0061] The above sacrificial material (40) can separate lithium ions at a voltage of approximately 3.0V to 3.5V. The process of separating lithium ions from the above sacrificial material (40) to form a negative electrode layer (40) is also called pre-charging.

[0062] The aforementioned pre-charging and main charging can be performed sequentially or simultaneously based on the applied voltage.

[0063] As the sacrificial material (40) is coated on the positive plate, a negative electrode layer formed of lithium in a lithium secondary battery can be selectively and smoothly formed even without a negative electrode active material and a negative electrode plate.

[0064] In addition, the sacrificial material (40) is formed as an insulator. Therefore, the sacrificial material (40) can act as a resistor in the anode plate, and there is a concern that the electrical conductivity of the anode plate may be reduced by the sacrificial material (40). However, according to the present invention, the sacrificial material (40) is coated on a pre-formed anode plate, thereby preventing a decrease in electrical conductivity in the anode plate.

[0065] Specifically, the sacrificial material (40) can be coated on the anode plate after the anode plate is formed by the anode active material (30). Therefore, since the sacrificial material (40) is coated on the outer surface of the anode plate formed in a compressed state with the powders of the anode active material (30), the problem of the electrical conductivity of the anode plate being reduced by the sacrificial material (40) can be prevented.

[0066] Additionally, when the positive electrode active material (30) powders are compressed to form a positive electrode plate, a plurality of voids (C) may be formed within the positive electrode plate. The voids (C) may be formed between adjacent powders when the positive electrode active material (30) powders are compressed together.

[0067] The sacrificial material (40) may also be coated around the void (C) within the anode plate. That is, the sacrificial material (40) may also be coated on the outer surface of the anode active material (30) powders that partition the void (C).

[0068] In other words, after the formation of the anode plate is completed by compressing the anode active material (30) powder, the sacrificial material (40) can be coated on the outer surface of the anode plate and around the void (C) inside the anode plate. Thus, it is possible to prevent a decrease in the electrical conductivity of the anode plate while securing as much of the sacrificial material (40) coated on the anode plate as possible.

[0069] Meanwhile, when the positive active material (30) powders are attached to each other by compression, the sacrificial material (40) is not coated on the part where the powders are in contact by compression. That is, since the sacrificial material (40) is coated after the positive plate is formed, the sacrificial material (40) cannot be coated on the part where the powders are in contact by compression. Therefore, it is possible to prevent the electrical conductivity of the positive plate from being reduced by the sacrificial material (40).

[0070] Meanwhile, the fact that a sacrificial material (40) is coated on the anode plate of the present invention can be distinguished from the fact that a sacrificial material is mixed or coated on the anode active material (30) (i.e., anode active material powder) prior to the formation of the anode plate.

[0071] When a sacrificial material (40) is coated on the positive plate, the electrical conductivity, positive capacity (positive density), and battery capacity and lifespan can be improved compared to when the sacrificial material is mixed or coated on the positive active material (30) (i.e., positive active material powder).

[0072] Hereinafter, the advantages of the lithium secondary battery according to the present invention will be explained in more detail with reference to comparative examples.

[0074] Figure 2 is a drawing showing a lithium secondary battery according to a comparative example.

[0075] Referring to FIG. 2, when forming a positive plate, the positive active material (30) and the sacrificial material (40) can be compressed while mixed. In this case, when compared to a positive plate of the same size (or same thickness), the amount of the positive active material (30) may be reduced due to the mixing of the sacrificial material (40) (mixing of sacrificial material powder), which may cause a problem of reducing the positive capacity, and furthermore the battery capacity.

[0076] In addition, according to the comparative example shown in Fig. 2, when the amount of sacrificial material (40) is reduced based on an anode plate of the same size as the present invention, not only is the speed at which the negative electrode layer is formed slowed down during charging, but there is also a problem in that a sufficient negative electrode layer (lithium layer) cannot be formed.

[0077] In contrast, in the case of the present invention, since a sacrificial material (40) is coated on a pre-completed anode plate, a larger anode capacity can be secured based on an anode plate of the same size (or same thickness), and pre-charging (formation of the negative electrode layer) by the sacrificial material (40) can also be performed at a faster speed.

[0078] Figure 3 is a drawing showing a lithium secondary battery according to another comparative example.

[0079] Referring to FIG. 3, when forming a positive plate, the positive active material (30) can be compressed while the sacrificial material (40) is coated on each of the positive active material (30) powders. In this case, since the sacrificial material (40) acts as a resistor, a problem may arise in which the electrical conductivity of the positive plate (i.e., the electrical conductivity between the positive active materials) is reduced.

[0080] In contrast, in the case of the present invention, since the sacrificial material (40) is coated on the surface of the pre-finished anode plate, the sacrificial material (40) does not act as a resistor in the anode plate, and the electrical conductivity can be improved.

[0081] Figure 4 is a drawing showing a lithium secondary battery according to another comparative example.

[0082] Referring to FIG. 4, a positive plate can be formed by compression with a layer of sacrificial material (40) placed on a layer of positive active material (30). In this case, when compared to a positive plate of the same size (or same thickness), the amount of the positive active material (30) may be reduced due to the thickness of the layer of sacrificial material (40), which may cause a problem of reducing the positive capacity, and furthermore the battery capacity.

[0083] In contrast, in the case of the present invention, since a sacrificial material (40) is coated on a pre-completed anode plate, a larger anode capacity can be secured based on an anode plate of the same size (or same thickness), and furthermore, a larger battery capacity can be secured.

[0084] As described above, according to the present invention, the sacrificial material (40) in the anode plate is prevented from acting as a resistor, thereby improving electrical conductivity and securing sufficient anode capacity.

[0085] Hereinafter, a method for manufacturing a lithium secondary battery according to an embodiment of the present invention will be described with reference to other drawings.

[0087] FIG. 5 is a flowchart illustrating a method for manufacturing a lithium secondary battery according to an embodiment of the present invention. Hereinafter, in describing the method for manufacturing a lithium secondary battery according to an embodiment of the present invention, it is obvious that the configuration of the lithium secondary battery described above can be applied in the same way to the method for manufacturing a lithium secondary battery.

[0088] Referring to FIG. 5, a method for manufacturing a lithium secondary battery according to an embodiment of the present invention may include a first step (S10) in which a positive plate is formed, a second step (S20) in which a sacrificial material is coated on the positive plate, and a third step (S30) in which the positive plate is disposed between a negative current collector and a positive current collector. The manufacturing method may not include a step of manufacturing a negative plate using a negative active material.

[0089] In the first step (S10) above, an anode plate can be formed by compressing the anode active material powder. In the first step (S10), at least one of a binder material and a conductive material is mixed with the anode active material powder, and the anode plate can be formed by compression. That is, the anode plate can be formed by compressing a mixture in which at least one of a binder material and a conductive material is mixed with the anode active material powder.

[0090] In addition, in the first step (S10), with the positive active material powder (or the mixture) disposed on the positive current collector, the positive plate may be formed attached to the positive current collector by compressing the positive active material powder (or the mixture) with the positive current collector.

[0091] Various previously disclosed methods may be utilized for the above-mentioned compression method, for example, a roll compression method may be utilized.

[0092] In the second step (S20) above, a sacrificial material formed of a lithium-containing compound may be coated on the anode plate. For example, in the second step (S20), the sacrificial material may be coated on the outer surface of the anode plate and around one or more voids formed within the anode plate. Multiple voids may be formed within the anode plate, and in this case, the sacrificial material may be coated around the multiple voids.

[0093] The above sacrificial material can be coated on the anode plate through previously known methods such as roll coating, spray coating, slow die coating, blade coating, etc.

[0094] Meanwhile, in the second step (S20) above, the sacrificial material may not be coated on the portion where the positive active materials are pressed together and in contact. Specifically, when the positive plate is formed by the compression of the positive active material powders, there may be a contact portion between adjacent positive active material powders. At this time, the sacrificial material is not coated on the portion where the positive active material powders are in contact with each other, nor can it be coated.

[0095] According to the method for manufacturing a lithium secondary battery of the present embodiment, since a sacrificial material is coated on the surface of the positive plate while the positive plate is in a pre-formed (pre-completed) state, a decrease in electrical conductivity in the positive plate due to the non-conductive sacrificial material can be prevented.

[0096] In addition, according to the method for manufacturing a lithium secondary battery of the present embodiment, since a sacrificial material is coated on the surface of the positive plate while the positive plate is in a pre-formed (pre-completed) state, it is possible to secure sufficient positive capacity (positive density) and simultaneously secure sufficient battery capacity.

[0097] In the third step above, a separator and the anode plate coated with the sacrificial material may be disposed between the negative current collector and the positive current collector. Meanwhile, if the anode plate and the positive current collector are formed in a state where they are attached to each other, the separator may be disposed between the negative current collector and the anode plate. Additionally, in the third step above, a liquid electrolyte may be provided between the negative current collector and the anode plate.

[0099] The preferred embodiments of the present invention described above are disclosed for illustrative purposes only, and those skilled in the art with ordinary 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 following claims. Explanation of the symbols

[0100] 10 Cathode Current Collector 20 positive current collector 30 positive electrode active material 35 binders 40 sacrificial material 50 separators 60 cathode layers

Claims

Claim 1 A lithium secondary battery wherein a separator and a positive plate are disposed between a negative current collector and a positive current collector, and an electrolyte is provided between the negative current collector and the positive plate, wherein the positive plate is formed by the compression of a positive active material powder, and a sacrificial material formed of a compound containing lithium is coated on the positive plate, and wherein the sacrificial material is coated on the positive plate after the positive plate is formed by the positive active material. Claim 2 A lithium secondary battery according to claim 1, wherein the sacrificial material is formed from at least one of Oxides, Chalcogenides, Halides, Nitrides, Phosphates, Carbonates, Borates, Silicates, Sulfates, Carbides, Peroxides, Amides, Imides, and Organolithium Compounds, which includes lithium. Claim 3 delete Claim 4 A lithium secondary battery according to claim 1 or 2, characterized in that, after the formation of the positive plate is completed by compressing the positive active material powder, the sacrificial material is coated on the outer surface of the positive plate and around the voids within the positive plate. Claim 5 A lithium secondary battery according to claim 1 or 2, wherein the positive plate is formed by mixing at least one of a binder material and a conductive material with a positive active material powder and by compression. Claim 6 A lithium secondary battery according to claim 1 or 2, characterized in that the sacrificial material is not coated on the portion where the positive active material powders are pressed together and in contact with each other. Claim 7 A lithium secondary battery characterized by not including a negative electrode active material and a negative electrode plate in claim 1 or 2. Claim 8 A method for manufacturing a lithium secondary battery comprising: a first step of forming a positive plate by compressing a positive active material powder; a second step of coating a sacrificial material formed of a lithium-containing compound onto the positive plate; and a third step of arranging a separator and the positive plate coated with the sacrificial material between a negative current collector and a positive current collector, and providing an electrolyte between the negative current collector and the positive plate. Claim 9 A method for manufacturing a lithium secondary battery according to claim 8, characterized in that, after the positive plate is formed by the positive active material in the first step, the sacrificial material is coated on the positive plate in the second step. Claim 10 A method for manufacturing a lithium secondary battery according to claim 9, wherein in the second step, the sacrificial material is coated on the outer surface of the positive plate and around the void within the positive plate. Claim 11 A method for manufacturing a lithium secondary battery according to claim 9, wherein in the first step, at least one of a binder material and a conductive material is mixed with the positive active material powder, and the positive plate is formed by compression. Claim 12 A method for manufacturing a lithium secondary battery according to claim 9, characterized in that, in the second step above, the sacrificial material is not coated on the portion where the positive active material powders are pressed together and in contact with each other. Claim 13 A method for manufacturing a lithium secondary battery according to claim 9, characterized by not including a negative electrode active material or a negative electrode plate.

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