Electrode for lithium secondary battery, and lithium secondary battery including the same

Abstract

The present invention relates to an electrode for a lithium secondary battery, the electrode including a current collector, an electrode layer formed on the current collector, and an insulating layer formed on the electrode layer, the electrode including a coating member including a first coating region in contact with a side surface of the electrode portion, and a second coating region that is continuous with the first coating region and in contact with a portion of the insulating layer, and a lithium secondary battery including the electrode.

Description

Technical Field

[0001] Cross-reference to related applications This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0063560 filed on May 24, 2022, and Korean Patent Application No. 10-2023-0062526 filed on May 15, 2023, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference in their entirety.

[0002] The present invention relates to an electrode for a lithium secondary battery that can prevent defects due to short circuits during cell assembly by ensuring insulation at the electrode periphery, and a lithium secondary battery including the same.

Background Art

[0003] Recently, with the development of technologies and the increasing demand for mobile devices, the demand for rechargeable secondary batteries as an energy source has been rapidly increasing, and thus many studies have been conducted on secondary batteries that can meet various requirements. In addition, secondary batteries are attracting attention as power sources for electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (Plug-in HEVs), etc., which are proposed as measures to solve air pollution problems of existing gasoline vehicles and diesel vehicles that use fossil fuels.

[0004] When a short circuit occurs due to contact between the positive electrode and the negative electrode in a lithium secondary battery, an explosion occurs along with severe heat generation. The porous separator of the secondary battery has a problem of causing a short circuit between the positive electrode and the negative electrode by showing severe heat shrinkage behavior at a temperature of about 100 °C or higher due to material characteristics and manufacturing process characteristics including stretching. In order to solve such a problem of battery safety, when providing a porous coating layer formed of a mixture of insulating filler particles and a binder polymer on a porous substrate, a separator in which a substance having a shut-down function is added to the porous coating layer has been proposed.

[0005] However, in the case of a conventional separator in which a porous coating layer having inorganic particles is formed on a porous substrate, there is no separate adhesive layer, the interfacial adhesive force with the counter electrode is weak, the battery assembly processability is reduced, and interfacial peeling occurs due to insufficient adhesive force caused by the expansion and contraction of the electrode, resulting in a problem of reduced battery life characteristics.

[0006] In addition, when punching out an electrode portion coated with an insulating layer based on a high heat-resistant material, a peeling phenomenon occurs at the peripheral portion, and there is a problem of a high possibility of short circuit.

[0007] Therefore, there is a need for research on a lithium secondary battery that can achieve excellent insulation properties and prevent the problem of cell short circuit.

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] The present invention provides an electrode for a lithium secondary battery that realizes high insulation characteristics and low resistance characteristics.

[0009] The present invention also provides a method for manufacturing the electrode for a lithium secondary battery.

[0010] Furthermore, the present invention provides a lithium secondary battery including the electrode for a lithium secondary battery.

MEANS FOR SOLVING THE PROBLEM

[0011] The present invention provides an electrode for a lithium secondary battery including an electrode portion including a current collector, an electrode layer formed on the current collector, and an insulating layer formed on the electrode layer, and a coating member including a first coating region in contact with a side surface of the electrode portion and a second coating region continuous with the first coating region and in contact with a part of the insulating layer.

[0012] The present invention also provides a lithium secondary battery including the electrode for a lithium secondary battery; and a second electrode portion formed on the electrode for a lithium secondary battery.

[0013] Hereinafter, the electrode for a lithium secondary battery according to an embodiment of the invention, the lithium secondary battery including the same, and the like will be specifically described.

[0014] The terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings. In accordance with the principle that the inventor can appropriately define the concept of the terms in order to explain his or her invention in the best way, they must be construed in a meaning and concept that conforms to the technical idea of the invention.

[0015] Unless otherwise defined herein, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used in the description of the present invention are merely for the purpose of effectively describing specific examples and are not intended to limit the present invention.

[0016] As used in this specification, the singular forms also include the plural forms unless the context clearly dictates otherwise.

[0017] As used in this specification, the meaning of "comprising" embodies a specific characteristic, region, integer, step, operation, element, and / or component, and does not exclude the existence or addition of other specific characteristics, regions, integers, steps, operations, elements, components, and / or groups.

[0018] Although the present invention can be modified in various ways and can have various forms, specific examples will be illustrated and described in detail below. However, this is not intended to limit the present invention to a specific disclosed form, and it should be understood that all modifications, equivalents, or alternatives included within the above-mentioned idea and technical scope are included.

[0019] In this specification, for example, when the positional relationship between two parts is described such as "on ~", "above ~", "below ~", "on the side of ~", etc., unless the expressions "directly" or "immediately" are used, one or more other parts can be located between the two parts.

[0020] In this specification, for example, when temporal precedence relationships such as "after ~", "subsequent to ~", "next to ~", "before ~" are described, as long as the expressions "directly" or "immediately" are not used, cases that are not continuous can also be included.

[0021] In this specification, the term "at least one" should be understood to include all combinations that can be presented from one or more related items.

[0022] According to one embodiment of the invention, there is provided an electrode for a lithium secondary battery, including an electrode part including a current collector, an electrode layer formed on the current collector, and an insulating layer formed on the electrode layer, and a coating member including a first coating region in contact with a side surface of the electrode part and a second coating region continuous with the first coating region and in contact with a part of the insulating layer.

[0023] In a conventional lithium secondary battery, a separator interposed between a positive electrode and a negative electrode includes a porous base material and a coating layer formed on the porous base material, resulting in a problem that there is no separate adhesive layer, the interfacial adhesive force with the counter electrode is weak, the battery assembly processability is reduced, interfacial peeling occurs due to insufficient adhesive force caused by expansion and contraction of the electrodes, the life characteristics of the battery are reduced, and defects occur due to short circuits during cell assembly.

[0024] Therefore, the inventors of the present invention confirmed through experiments that when a separator used in a lithium secondary battery is directly formed on a negative electrode or a positive electrode without a porous base material, excellent battery life characteristics can be realized because the adhesive force is maintained even when the electrodes expand and contract. It was confirmed that by directly coating the electrodes with high heat-resistant inorganic fine particles to form an insulating layer having the function of a separator, short circuits of the electrodes can be prevented without deformation and shrinkage even at high temperatures.

[0025] In addition, the inventors of the present invention have confirmed through experiments that the electrode for a lithium secondary battery of the present invention includes a protective layer formed on the periphery of the electrode portion, and can prevent the problem of cell short circuit even if there is a slight deviation during cell assembly, and thus completed the invention. Further, the inventors of the present invention have confirmed through experiments that the electrode for a lithium secondary battery of the present invention includes a protective layer formed on the periphery of the electrode portion, and can minimize the side reaction between the anode unevenly exposed on the side surface and the electrolyte, and realize excellent Coulomb efficiency, thereby preventing the loss of discharge capacity, and thus completed the invention.

[0026] Specifically, the electrode for a lithium secondary battery according to the above embodiment includes an electrode portion 100 including a current collector 101, an electrode layer 102 formed on the current collector, and an insulating layer 103 formed on the electrode layer, and a coating member including a first coating region 10 in contact with the side surface of the electrode portion and a second coating region 20 continuous with the first coating region and in contact with a part of the insulating layer can be included.

[0027] As described above, the electrode for a lithium secondary battery includes a coating member formed on the periphery of the electrode portion, and can prevent the problem of cell short circuit even if there is a slight deviation during cell assembly.

[0028] Specifically, the coating member can include a first coating region in contact with the side surface of the electrode portion and a second coating region continuous with the first coating region and in contact with a part of the insulating layer.

[0029] The first coating region can be in contact with a part of the side surface of the electrode portion or the entire area.

[0030] The specific shape and structure of the coating member are not greatly limited, and may vary depending on the specific shape and structure of the electrode portion.

[0031] For example, the coating member may be shaped to surround a side surface of the electrode portion including one surface of the current collector, the electrode layer, and the insulating layer and a part of the upper surface of the insulating layer by including a first coating region in contact with the side surface of the electrode portion and a second coating region continuous with the first coating region and in contact with a part of the insulating layer.

[0032] When the coating member is shaped to surround a side surface of the electrode portion including one surface of the current collector, the electrode layer, and the insulating layer and a part of the upper surface of the insulating layer, in a cross-section of the coating member, the direction of the first coating region in contact with the side surface of the electrode portion and the direction of the second coating region in contact with a part of the insulating layer can form an angle of 60° or more and 120° or less, 80° or more and 100° or less, preferably 90°.

[0033] When the direction of the first coating region in contact with the side surface of the electrode portion and the direction of the second coating region in contact with a part of the insulating layer form an angle of 60° in a cross-section of the coating member, it is shown as in FIG. 3.

[0034] When the direction of the first coating region in contact with the side surface of the electrode portion and the direction of the second coating region in contact with a part of the insulating layer form an angle of 90° in a cross-section of the coating member, it is shown as in FIG. 4.

[0035] When the direction of the first coating region in contact with the side surface of the electrode portion and the direction of the second coating region in contact with a part of the insulating layer form an angle of 120° in a cross-section of the coating member, it is shown as in FIG. 5.

[0036] In the electrode for a lithium secondary battery, the thickness of the first coating region measured from the side surface of the electrode portion may be 1 μm or more and 100 μm or less.

[0037] In the electrode for a lithium secondary battery, the thickness of the first coating region measured from the side surface of the electrode portion means 11 in FIG. 1.

[0038] Specifically, in the electrode for the lithium secondary battery, the thickness of the first coating region measured from the side surface of the electrode portion is 1 μm or more, 5 μm or more, 10 μm or more, 14 μm or more, or 100 μm or less, 80 μm or less, 75 μm or less, 50 μm or less, 30 μm or less, 20 μm or less, or 1 μm or more and 100 μm or less, 1 μm or more and 80 μm or less, 1 μm or more and 75 μm or less, 1 μm or more and 50 μm or less, 1 μm or more and 30 μm or less, 1 μm or more and 20 μm or less, 5 μm or more and 100 μm or less, 5 μm or more and 80 μm or less, 5 μm or more and 75 μm or less, 5 μm or more and 50 μm or less, 5 μm or more and 30 μm or less, 5 μm or more and 20 μm or less, 10 μm or more and 100 μm or less, 10 μm or more and 80 μm or less, 10 μm or more and 75 μm or less, 10 μm or more and 50 μm or less, 10 μm or more and 30 μm or less, 10 μm or more and 20 μm or less, 14 μm or more and 100 μm or less, 14 μm or more and 80 μm or less, 14 μm or more and 75 μm or less, 14 μm or more and 50 μm or less, 14 μm or more and 30 μm or less, 14 μm or more and 20 μm or less may be sufficient.

[0039] When the thickness of the first coating region measured from the side surface of the electrode portion is less than 1 μm, the insulation characteristics decrease and the risk of short circuit increases. When it exceeds 100 μm, technical problems may occur such as a decrease in energy density due to an increase in volume during stack cell manufacturing.

[0040] Also, in the above embodiment, the thickness of the second coating region measured from the interface with the insulating layer may be 1 μm or more and less than or equal to the thickness of the second electrode portion.

[0041] In the electrode for the lithium secondary battery, the thickness of the second coating region measured from the interface with the insulating layer means 21 in FIG. 1.

[0042] For example, the thickness of the second coating region measured from the interface with the insulating layer may be 1 μm or more and 500 μm or less.

[0043] Specifically, in the electrode for the lithium secondary battery, the thickness of the second coating region measured from the interface with the insulating layer may be 1 μm or more, 5 μm or more, 10 μm or more, 15 μm or more, or 500 μm or less, 100 μm or less, 80 μm or less, 75 μm or less, 50 μm or less, 30 μm or less, 20 μm or less, or 1 μm or more and 500 μm or less, 1 μm or more and 100 μm or less, 1 μm or more and 80 μm or less, 1 μm or more and 75 μm or less, 1 μm or more and 50 μm or less, 1 μm or more and 30 μm or less, 1 μm or more and 20 μm or less, 5 μm or more and 500 μm or less, 5 μm or more and 100 μm or less, 5 μm or more and 80 μm or less, 5 μm or more and 75 μm or less, 5 μm or more and 50 μm or less, 5 μm or more and 30 μm or less, 5 μm or more and 20 μm or less, 10 μm or more and 500 μm or less, 10 μm or more and 100 μm or less, 10 μm or more and 80 μm or less, 10 μm or more and 75 μm or less, 10 μm or more and 50 μm or less, 10 μm or more and 30 μm or less, 10 μm or more and 20 μm or less, 15 μm or more and 500 μm or less, 15 μm or more and 100 μm or less, 15 μm or more and 80 μm or less, 15 μm or more and 75 μm or less, 15 μm or more and 50 μm or less, 15 μm or more and 30 μm or less, 15 μm or more and 20 μm or less.

[0044] When the thickness of the second coating region measured from the interface with the insulating layer is less than 1 μm, the insulation property decreases and the risk of short circuit increases. When the thickness exceeds that of the second electrode part or exceeds 500 μm, the surface in contact with other cells may not be uniformly maintained during the manufacture of the stacked cell, and technical problems may occur, such as inferior charge and discharge characteristics of the battery.

[0045] Further, in the above embodiment, the length of the second coating region measured from the tangent line of the first coating region and the second coating region may be 50 μm or more and 2 mm or less.

[0046] Specifically, the length of the second coating region measured from the tangent line of the first coating region and the second coating region may be 50 μm or more, 100 μm or more, 200 μm or more, 300 μm or more, 2 mm or less, 1.5 mm or less, 1 mm or less, 900 μm or less, 800 μm or less, 750 μm or less, 500 μm or less, 400 μm or less, or may be 50 μm or more and 2 mm or less, 100 μm or more and 2 mm or less, 200 μm or more and 2 mm or less, 300 μm or more and 2 mm or less, 50 μm or more and 1.5 mm or less, 100 μm or more and 1.5 mm or less, 200 μm or more and 1.5 mm or less, 300 μm or more and 1.5 mm or less, 50 μm or more and 1 mm or less, 100 μm or more and 1 mm or less, 200 μm or more and 1 mm or less, 300 μm or more and 1 mm or less, 50 μm or more and 900 μm or less, 100 μm or more and 900 μm or less, 200 μm or more and 900 μm or less, 300 μm or more and 900 μm or less, 50 μm or more and 800 μm or less, 100 μm or more and 800 μm or less, 200 μm or more and 800 μm or less, 300 μm or more and 800 μm or less, 50 μm or more and 750 μm or less, 100 μm or more and 750 μm or less, 200 μm or more and 750 μm or less, 300 μm or more and 750 μm or less, 50 μm or more and 500 μm or less, 100 μm or more and 500 μm or less, 200 μm or more and 500 μm or less, 300 μm or more and 500 μm or less, 50 μm or more and 400 μm or less, 100 μm or more and 400 μm or less, 200 μm or more and 400 μm or less, 300 μm or more and 400 μm or less.

[0047] The length of the second coating region measured from the tangent line of the first coating region and the second coating region can mean the length of the second coating region measured in the extension direction of the electrode portion from the tangent line of the first coating region and the second coating region.

[0048] The tangent line of the first coating region and the second coating region means the boundary line where the first coating region and the second coating region are in contact. Based on the cross-section, it means the line connecting the points at the outermost corner where the first coating region and the second coating region are in contact, and can mean the portion indicated by 40 in FIG. 1. Specifically, in the electrode for the lithium secondary battery, the length of the second coating region measured from the tangent line of the first coating region and the second coating region means the length of 20 in FIG. 1.

[0049] The extension direction can mean the direction in which the tab extends in the electrode portion.

[0050] When the length of the second coating region measured from the tangent line of the first coating region and the second coating region is less than 50 μm, the insulation property decreases and the risk of short circuit increases. When it exceeds 2 mm, the area of the electrode portion may decrease and the cell capacity may decrease.

[0051] Also, the ratio of the thickness of the second coating region measured from the interface with the insulating layer to the length of the second coating region measured from the tangent line of the first coating region and the second coating region may be 0.001 or more and 1.0 or less.

[0052] Specifically, the ratio of the thickness of the second coating region measured from the interface with the insulating layer to the length of the second coating region measured from the tangent line of the first coating region and the second coating region may be 0.001 or more, 0.01 or more, 0.025 or more, 0.03 or more, 0.05 or more, and may also be 1.0 or less, 0.99 or less, 0.9 or less, 0.8 or less, 0.5 or less, 0.2 or less, 0.1 or less, 0.001 or more and 1.0 or less, 0.001 or more and 0.99 or less, 0.001 or more and 0.9 or less, 0.001 or more and 0.8 or less, 0.001 or more and 0.5 or less, 0.001 or more and 0.2 or less, 0.001 or more and 0.1 or less, 0.01 or more and 1.0 or less, 0.01 or more and 0.99 or less, 0.01 or more and 0.9 or less, 0.01 or more and 0.8 or less, 0.01 or more and 0.5 or less, 0.01 or more and 0.2 or less, 0.01 or more and 0.1 or less, 0.025 or more and 1.0 or less, 0.025 or more and 0.99 or less, 0.025 or more and 0.9 or less, 0.025 or more and 0.8 or less, 0.025 or more and 0.5 or less, 0.025 or more and 0.2 or less, 0.025 or more and 0.1 or less, 0.03 or more and 1.0 or less, 0.03 or more and 0.99 or less, 0.03 or more and 0.9 or less, 0.03 or more and 0.8 or less, 0.03 or more and 0.5 or less, 0.03 or more and 0.2 or less, 0.03 or more and 0.1 or less, 0.05 or more and 1.0 or less, 0.05 or more and 0.99 or less, 0.05 or more and 0.9 or less, 0.05 or more and 0.8 or less, 0.05 or more and 0.5 or less, 0.05 or more and 0.2 or less, 0.05 or more and 0.1 or less.

[0053] When the ratio of the thickness of the second coating region measured from the interface with the insulating layer to the length of the second coating region measured from the tangent line of the first coating region and the second coating region is less than 0.001, the area of the electrode portion may decrease, the cell capacitance may decrease, or the insulation characteristics may decrease and the risk of short - circuit may increase.

[0054] Also, when the ratio of the thickness of the second coating region measured from the interface with the insulating layer to the length of the second coating region measured from the tangent line of the first coating region and the second coating region exceeds 1.0, the insulation characteristics may decrease and the risk of short - circuit may increase.

[0055] In the electrode for the lithium secondary battery, the coating member may have a porosity of 10% or more and 50% or less.

[0056] Specifically, in the electrode for the lithium secondary battery, the coating member may have a porosity of 10% or more, 15% or more, or 50% or less, 40% or less, 25% or less, and may be 10% or more and 50% or less, 10% or more and 40% or less, 10% or more and 25% or less, 15% or more and 50% or less, 15% or more and 40% or less, 15% or more and 25% or less.

[0057] That is, each of the first coating region and the second coating region may have a porosity of 10% or more, 15% or more, or 50% or less, 40% or less, 25% or less, and may be 10% or more and 50% or less, 10% or more and 40% or less, 10% or more and 25% or less, 15% or more and 50% or less, 15% or more and 40% or less, 15% or more and 25% or less.

[0058] The porosity of the coating member can be realized by the composition of the coating layer described later. By the porosity of the coating member being 10% or more and 50% or less, the insulating physical properties and mechanical physical properties can be stably maintained, and the technical effect of preventing the risk of short circuit due to electrode displacement can be realized.

[0059] When the porosity of the coating member exceeds 50%, the mechanical physical properties become weak, and when external pressure is applied, it is easily damaged, so there may occur a technical problem of causing a short circuit in the battery.

[0060] The porosity is obtained by measuring the coating volume and mass to obtain the measured density, then calculating the theoretical density of the solid content of the coating composition, and is obtained by the following formula.

[0061] Porosity (%) = (1 - measured density / theoretical density) × 100

[0062] On the other hand, in the electrode for a lithium secondary battery according to the above embodiment, each of the first coating region and the second coating region can contain inorganic fine particles and a binder resin.

[0063] By adjusting the size of the inorganic fine particles, the content of the inorganic fine particles, and the content of the binder resin in the first coating region and the second coating region, pores in the micro or nano unit can be formed, and the pore size and porosity can be adjusted. That is, when each of the first coating region and the second coating region contains a binder resin and inorganic fine particles, the porosity of the coating member, the first coating region, and the second coating region can satisfy 10% or more and 50% or less.

[0064] Also, as described above, when the coating member has a shape surrounding a part of the upper surface of the insulating layer and the side surface of the electrode portion including one surface of the current collector, the electrode layer, and the insulating layer, and each of the first coating region and the second coating region contains inorganic fine particles and a binder resin, even if there is a fine deviation during cell assembly, the problem of cell short circuit can be prevented, and at the same time, a uniform coating layer can be formed to realize excellent mechanical physical properties.

[0065] The inorganic fine particles are the main components forming the first coating region and the second coating region, and play a role in forming fine pores with empty spaces between the inorganic fine particles, and also serve as a kind of spacer that can maintain the physical form of the coating layer.

[0066] The inorganic fine particles can include inorganic fine particles having a particle size of 10 nm or more and 1 μm or less. The particle size of the inorganic fine particles can be confirmed through a scanning electron microscope image (SEM) or a transmission electron microscope image (TEM) taken of the cross section of the first coating region and the second coating region.

[0067] Specifically, the inorganic fine particles may have a particle size of 10 nm or more, 100 nm or more, 1 μm or less, 900 nm or less, 800 nm or less, 700 nm or less, or 500 nm or less, and may contain inorganic fine particles having a particle size of 10 nm or more and 1 μm or less, 100 nm or more and 1 μm or less, 100 nm or more and 900 nm or less, 100 nm or more and 800 nm or less, 100 nm or more and 700 nm or less, or 100 nm or more and 500 nm or less.

[0068] When the particle size of the inorganic fine particles is less than 10 nm, the dispersibility decreases and it is not easy to adjust the physical properties of the coating layer. When it exceeds 1 μm, the thickness of the first coating region and the second coating region may increase and the mechanical properties may decrease. Also, due to an overly large pore size, the insulation property may decrease, increasing the probability of internal short circuit during charge and discharge of the battery.

[0069] Also, the inorganic fine particles may have a D50 of 10 nm or more and 1 μm or less. The D50 can mean the particle size at which 50% of the particles are accumulated by mass from the smaller side among the particle sizes measured using a laser diffraction scattering type particle size distribution measuring device.

[0070] Specifically, the inorganic fine particles may have a D50 of 10 nm or more, 1 μm or less, 900 nm or less, 800 nm or less, 700 nm or less, or 500 nm or less, and may also have a D50 of 10 nm or more and 1 μm or less, 100 nm or more and 1 μm or less, 100 nm or more and 900 nm or less, 100 nm or more and 800 nm or less, 100 nm or more and 700 nm or less, or 100 nm or more and 500 nm or less.

[0071] When the D50 of the inorganic fine particles is less than 10 nm, the dispersibility decreases and it is not easy to adjust the physical properties of the first coating region and the second coating region. When it exceeds 1 μm, the thickness control of the first coating region and the second coating region is not uniform, and also, due to an overly large pore size, the probability of internal short circuit during charge and discharge of the battery increases.

[0072] In the above-described embodiment, the inorganic fine particles are not particularly limited as long as they are electrochemically stable. Specifically, the inorganic fine particles are not particularly limited as long as no oxidation and / or reduction reaction occurs within the operating voltage range of the applied battery. In particular, when using inorganic fine particles having ion transfer ability, the ion conductivity in the lithium secondary battery can be increased to improve the performance. Also, when using inorganic particles having a high dielectric constant as the inorganic fine particles, it is possible to contribute to an increase in the dissociation degree of an electrolyte salt, for example, a lithium salt, in the liquid electrolyte and improve the ion conductivity of the electrolyte solution.

[0073] For example, the inorganic fine particles are alumina (Al 2 O 3 ), boehmite (AlOOH), aluminum hydroxide (Al(OH) 3 ), silica (SiO 2 ), titania (TiO 2 ), zirconia (ZrO 2 ), zirconium titanate (ZrTiO 4 ), La 2 O 3 , Y 2 O 3 , SrTiO 3 , BaTiO 3 , magnesia (MgO), magnesium hydroxide (Mg(OH) 2 ), aluminosilicate (Al 2 O 5 Si), zeolite, LLZO (Li 7 La 3 Zr 2 O 12 ), LATP (Li 1+x Al x Ti 2-x (PO 4 ) 3 , 0 < x < 2), PZT (Pb[Zr x Ti 1-x O 3 , 0 ≦ x ≦ 1) and may include one or more inorganic fine particles selected from the group consisting of.

[0074] Further, each of the first coating region and the second coating region can contain 1 to 100 parts by weight of the inorganic fine particles with respect to 100 parts by weight of the binder resin.

[0075] Specifically, each of the first coating region and the second coating region can contain 1 to 100 parts by weight, 10 to 100 parts by weight, 20 to 100 parts by weight, 25 to 100 parts by weight, 30 to 100 parts by weight, 50 to 100 parts by weight, or 80 to 100 parts by weight of the inorganic fine particles with respect to 100 parts by weight of the binder resin.

[0076] Each of the first coating region and the second coating region can form pores in the unit of several tens to several hundreds of nanometers by adjusting the size of the inorganic fine particles, the content of the inorganic fine particles, and the content of the binder resin, and can also adjust the pore size and the porosity. That is, each of the first coating region and the second coating region can satisfy that the porosity of the first coating region and the second coating region is 10% or more and 70% or less by containing 1 to 100 parts by weight of the inorganic fine particles with respect to 100 parts by weight of the binder resin.

[0077] When the first coating region and the second coating region contain less than 1 part by weight of the inorganic fine particles with respect to 100 parts by weight of the binder resin, the content of the binder resin may be excessively high, resulting in poor heat resistance of the coating and a decrease in the stability of the final battery. Further, when the first coating region and the second coating region contain more than 100 parts by weight of the inorganic fine particles with respect to 100 parts by weight of the binder resin, the content of the binder resin may be excessively low, resulting in weak adhesion between the inorganic fine particles, weak peel resistance, and a decrease in the mechanical properties of the coating layer.

[0078] In the above-described embodiment, the binder resin is located on all or part of the inorganic fine particles and functions to connect and fix the inorganic fine particles to each other.

[0079] On the other hand, the binder resin may include one or more binder resins selected from the group consisting of polyvinylidene fluoride, polyvinylidene fluoride - hexafluoropropylene, polyvinylidene fluoride - trichloroethylene, polyvinylidene fluoride - chlorotrifluoroethylene, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, ethylene vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, acrylonitrile - styrene - butadiene copolymer, polyurethane, polyacrylic acid, polyetherimide, polyimide, silicone, polyvinyl alcohol, and styrene butadiene rubber.

[0080] In the electrode for the lithium secondary battery, the porosity of the insulating layer may be 30% or more, 30% or more and 90% or less, 40% or more and 90% or less, 40% or more and 80% or less, or 40% or more and 70% or less.

[0081] The porosity of the insulating layer can be realized by the composition of the insulating layer described later. By the porosity of the insulating layer being 40% or more and 90% or less, while preventing direct contact between the positive electrode and the negative electrode and smoothing the movement of lithium ions in the electrolyte, a technical effect of realizing the charge and discharge performance of the secondary battery can be achieved.

[0082] When the porosity of the insulating layer is less than 30%, a technical problem occurs in that the resistance to the electrolyte increases, the ionic conductivity decreases, and the charge and discharge performance of the battery deteriorates. When the porosity of the insulating layer exceeds 90%, the possibility of internal short circuit increases, and technical problems regarding the charge and discharge failure and safety of the battery may occur.

[0083] The porosity can be measured in the same process as the method for obtaining the porosity of the first coating layer and the second coating layer for the electrode sample coated with the insulating layer.

[0084] On the other hand, the insulating layer may contain a binder resin and inorganic fine particles.

[0085] The content regarding the binder resin and the inorganic fine particles includes all of the above-described content.

[0086] The insulating layer can form pores in the unit of several tens to several hundreds of nanometers by adjusting the size of the inorganic fine particles, the content of the inorganic fine particles, and the content of the binder resin, and can also adjust the pore size and the porosity. That is, by including the binder resin and the inorganic fine particles, the insulating layer can satisfy that the porosity of the coating layer is 10% or more and 70% or less.

[0087] In the above-described embodiment, the thickness of the insulating layer has no particular limitation, and in consideration of the performance of the battery, it can be adjusted to, for example, 0.01 to 100 μm.

[0088] For example, the insulating layer may have a thickness of 10 μm or more and 30 μm or less.

[0089] When the thickness of the insulating layer is less than 10 μm, it does not play a role in protecting the electrode and the insulation property deteriorates. When it exceeds 30 μm, the ionic conductivity deteriorates, the overall size becomes large, and the output characteristics, energy density, etc. may deteriorate.

[0090] On the other hand, according to another embodiment of the present invention, there is provided a lithium secondary battery including the electrode for a lithium secondary battery; and a second electrode portion formed on the electrode for a lithium secondary battery.

[0091] Regarding the electrode for a lithium secondary battery, it includes all the above-described contents.

[0092] Specifically, the lithium secondary battery of the embodiment may include an electrode assembly wound with a separator interposed between a positive electrode and a negative electrode, and a case in which the electrode assembly is incorporated. And the positive electrode, the negative electrode, and the separator may be impregnated with an electrolyte.

[0093] As described above, the lithium secondary battery of the embodiment includes an insulating layer included in the electrode for a lithium secondary battery of the embodiment in place of a porous polymer separator including a porous base material and a coating layer formed on the porous base material, so that even when the electrode expands and contracts, the adhesive force is maintained and excellent battery life characteristics can be realized.

[0094] The electrode for a lithium secondary battery may be a negative electrode for a lithium secondary battery or a positive electrode for a lithium secondary battery. When the electrode for a lithium secondary battery is a negative electrode for a lithium secondary battery, the second electrode portion may be a positive electrode, and when the electrode for a lithium secondary battery is a positive electrode for a lithium secondary battery, the second electrode portion may be a negative electrode.

[0095] As described above, the electrode portion may include a current collector; an electrode layer formed on the current collector; and an insulating layer formed on the electrode layer.

[0096] In addition, the second electrode portion may include a second electrode layer; and a second current collector formed on the second electrode layer.

[0097] That is, the lithium secondary battery of the above embodiment can have a structure in which a first electrode part including a current collector, an electrode layer formed on the current collector, and an insulating layer formed on the electrode layer, and a second electrode part including a second electrode layer and a second current collector formed on the second electrode layer are laminated in this order.

[0098] The electrode part can include a tab extending from the current collector, and the second electrode part can include a tab extending from the second current collector.

[0099] In the lithium secondary battery of the above embodiment, the electrode part can have a site that is larger in size and exposed on all four surfaces compared to the second electrode part. That is, the lithium secondary battery of the above embodiment can include a site where the electrode part and the second electrode part are not facing each other and exposed, and the above-described coating layer is formed on the site where the electrode part and the second electrode part are not facing each other and exposed.

[0100] Specifically, in the lithium secondary battery of the above embodiment, the lengths in the extending direction of the electrode part and the second electrode part may be different. More specifically, in the lithium secondary battery of the above embodiment, the length in the extending direction of the electrode part is 0.2 mm or more and 5 mm or less longer than the length in the extending direction of the second electrode part.

[0101] Specifically, in the lithium secondary battery of the above embodiment, the length in the extending direction of the electrode part is 0.2 mm or more, 0.5 mm or more, 5 mm or less, 2 mm or less, 0.2 mm or more and 5 mm or less, 0.5 mm or more and 5 mm or less, 0.2 mm or more and 2 mm or less, 0.5 mm or more and 2 mm or less longer than the length in the extending direction of the second electrode part.

[0102] In the electrode for the lithium secondary battery, the difference between the length in the extending direction of the electrode part and the length in the extending direction of the second electrode part may be twice the length corresponding to 30 in FIG. 1.

[0103] The length in the extending direction can mean the length in the direction in which the tab extends in the electrode part and the second electrode part.

[0104] In the lithium secondary battery of the above embodiment, when the length of the electrode portion in the extending direction is less than 0.2 mm longer than the length of the second electrode portion in the extending direction, it is difficult to realize unless it is manufactured with an initial overlap. When the length of the electrode portion in the extending direction is more than 5 mm longer than the length of the second electrode portion in the extending direction, it is not suitable due to the increase in material cost.

[0105] The electrode for the lithium secondary battery may be a negative electrode for a lithium secondary battery or a positive electrode for a lithium secondary battery. When the electrode for the lithium secondary battery is a negative electrode for a lithium secondary battery, the second electrode portion may be a positive electrode. When the electrode for the lithium secondary battery is a positive electrode for a lithium secondary battery, the second electrode portion may be a negative electrode.

[0106] Specifically, the negative electrode for the lithium secondary battery may include a negative electrode material including a negative electrode active material, a conductive material, and a binder; and a current collector that supports the negative electrode material.

[0107] The negative electrode material can correspond to the electrode layer in the electrode for the lithium secondary battery of the above embodiment.

[0108] The negative electrode active material can include a material capable of reversibly inserting (intercalating) and desorbing (deintercalating) lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and undoping lithium, and a transition metal oxide.

[0109] Examples of substances capable of reversibly inserting and extracting lithium ions include, as carbonaceous substances, crystalline carbon, amorphous carbon, or mixtures thereof. Specifically, the carbonaceous substance may be natural graphite, artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitches, mesophase pitch based carbon fiber, meso-carbon microbeads, petroleum or coal tar pitch derived cokes, soft carbon, hard carbon, and the like.

[0110] The alloy of the lithium metal may be an alloy of lithium and one or more metals selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, Sn, Bi, Ga, and Cd.

[0111] Substances capable of doping and undoping lithium include Si, Si-C composites, SiO x (0 < x < 2), Si-Q alloys (where Q is an element containing one or more selected from the group consisting of alkali metals, alkaline earth metals, group 13 elements, group 14 elements, group 15 elements, group 16 elements, transition metals, rare earth elements, and combinations thereof; provided that Si is excluded), Sn, SnO 2 , Sn-R alloys (where R is an element containing one or more selected from the group consisting of alkali metals, alkaline earth metals, group 13 elements, group 14 elements, group 15 elements, group 16 elements, transition metals, rare earth elements, and combinations thereof; provided that Sn is excluded), and the like. And as substances capable of doping and undoping lithium, at least one of the above examples and SiO 2They can be used in mixture. Said Q and R may be Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, etc.

[0112] And the transition metal oxide may be vanadium oxide, lithium vanadium oxide, lithium titanate, etc.

[0113] The negative electrode current collector is generally made to have a thickness of 3 to 500 μm. Such a negative electrode current collector is not particularly limited as long as it has conductivity without inducing chemical changes in the battery. For example, copper, stainless steel, aluminum, nickel, titanium, fired carbon, those surface-treated with carbon, nickel, titanium, silver, etc. on the surface of copper or stainless steel, aluminum-cadmium alloy, etc. can be used. Also, similar to the positive electrode current collector, fine irregularities can be formed on the surface to strengthen the bonding force of the negative electrode active material, and it can be used in various forms such as film, sheet, foil, net, porous body, foam, non-woven fabric body, etc.

[0114] Preferably, the negative electrode can contain a negative electrode active material containing at least one selected from the group consisting of carbonaceous substances and silicon compounds.

[0115] Here, the carbonaceous substance is a substance containing at least one selected from the group consisting of natural graphite, artificial graphite, kish graphite, pyrolytic carbon, mesophase pitch, mesophase pitch-based carbon fiber, carbon microspheres, petroleum or coal-based coke, softened carbon, and hardened carbon exemplified above. And the silicon compound is a compound containing Si exemplified above, that is, Si, Si-C composite, SiO x (0 < x < 2), said Si-Q alloy, mixtures thereof, or mixtures of at least one of these with SiO 2 may also be used.

[0116] Further, the negative electrode can contain micro-silicon. When the negative electrode contains micro-silicon, it can achieve an excellent capacity compared to the case where a carbonaceous material is used as the negative electrode active material. Specifically, when using a specific micro-silicon in the silicon compound, it can maintain a residual capacity of 80% or more even after 500 or more charge and discharge cycles, and can achieve a significantly excellent energy density compared to conventional lithium secondary batteries. Also, when the negative electrode contains micro-silicon, the charge and discharge life of a solid battery using a solid electrolyte can be greatly increased, and the charging speed can also be significantly improved at room temperature.

[0117] The size of the micro-silicon is not greatly limited. For example, the micro-silicon can have a diameter of 100 μm or less, or a diameter of 1 to 100 μm, or a diameter of 1 to 20 μm.

[0118] According to one embodiment, the negative electrode active material is contained in an amount of 85% to 98% by weight based on the total weight of the negative electrode material.

[0119] Specifically, the content of the negative electrode active material may be 85% by weight or more, or 87% by weight or more, or 90% by weight or more based on the total weight of the negative electrode material; and may be 98% by weight or less, or 97% by weight or less, or 95% by weight or less.

[0120] Preferably, the content of the negative electrode active material may be 85% to 97% by weight, or 87% to 97% by weight, or 87% to 95% by weight, or 90% to 95% by weight based on the total weight of the negative electrode material.

[0121] The conductive material is used to impart conductivity to the electrode.

[0122] As the conductive material, any material having electronic conductivity without causing chemical changes in the battery can be used without particular limitation. As non-limiting examples, the conductive material may be a carbon-based material such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber; graphite such as natural graphite and artificial graphite; metal powders or metal fibers such as copper, nickel, aluminum, silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives. As the conductive material, one kind or a mixture of two or more kinds of the above-mentioned examples can be used.

[0123] The content of the conductive material can be adjusted within a range that does not induce a decrease in the battery capacity while exhibiting an appropriate level of conductivity. Preferably, the content of the conductive material may be 0.5 wt% to 10 wt%, or 1 wt% to 10 wt%, or 1 wt% to 5 wt% based on the total weight of the negative electrode material.

[0124] The binder is used to adhere the negative electrode material well to the current collector.

[0125] As non-limiting examples, the binder may be polyvinylidene fluoride (PVdF), vinylidene fluoride-hexafluoropropylene copolymer (PVdF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber (SBR), fluororubber, etc. As the binder, one kind or a mixture of two or more kinds of the above-mentioned examples can be used.

[0126] The content of the binder can be adjusted within a range that does not induce a decrease in the battery capacity while exhibiting an appropriate level of adhesiveness. Preferably, the content of the binder may be 0.5% by weight to 10% by weight, or 1% by weight to 10% by weight, or 1% by weight to 5% by weight based on the total weight of the negative electrode material.

[0127] As the current collector, materials known to be applicable to the negative electrode of a lithium secondary battery in the technical field to which the present invention pertains can be used without particular limitation.

[0128] As non-limiting examples, as the current collector, stainless steel; aluminum; nickel; titanium; fired carbon; or those obtained by surface-treating the surface of aluminum or stainless steel with carbon, nickel, titanium, silver, etc. can be used.

[0129] Preferably, the current collector can have a thickness of 3 μm to 500 μm. In order to enhance the adhesion of the negative electrode material, the current collector may have fine irregularities formed on its surface. The current collector can have various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric body, etc.

[0130] The separator separates the positive electrode and the negative electrode and provides a migration path for lithium ions. In the one embodiment, the insulating layer can act as the separator. In the one embodiment, by directly forming the insulating layer on the electrode substrate, the lithium secondary battery of the one embodiment can include a separator that does not contain a porous polymer substrate.

[0131] The lithium secondary battery of the above embodiment can selectively include a porous polymer substrate. The type of the porous polymer substrate is not greatly restricted. For example, it can be one or more polymers selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenyleneoxide, cyclic olefin copolymer, polyphenylenesulfide, and polyethylene naphthalene, or a polymer substrate formed of a mixture of two or more of these, or their multilayer films, woven fabrics, non-woven fabrics, etc. can be used.

[0132] The porous polymer substrate can be adjusted in terms of the type and thickness of the substrate, the size and number of pores, and especially in the case of non-woven fabrics, the fineness of the ultrafine filaments, etc., considering the melting temperature, manufacturing convenience, porosity, ion movement, insulation, etc.

[0133] In the above embodiment, the thickness of the porous polymer substrate has no special restriction and can be adjusted to, for example, 0.01 - 100 μm considering the battery performance.

[0134] The positive electrode for the lithium secondary battery can include a positive electrode material containing a positive electrode active material, a binder, a conductive material, and a positive electrode additive; and a current collector that supports the positive electrode material.

[0135] The positive electrode material can correspond to the electrode layer in the electrode for the lithium secondary battery of the above embodiment.

[0136] The positive electrode additive for the lithium secondary battery has the property of irreversibly releasing lithium during charge and discharge of the lithium secondary battery. Therefore, the positive electrode additive for the lithium secondary battery can be included in the positive electrode for the lithium secondary battery and serve as sacrificial positive electrode materials for prelithiation.

[0137] Specifically, the positive electrode is manufactured by applying a positive electrode mixture on a positive electrode current collector and then drying it, and if necessary, a filler can be further added to the mixture.

[0138] Preferably, the positive electrode for the lithium secondary battery includes a positive electrode material containing a positive electrode active material, a conductive material, the sacrificial positive electrode material, and a binder; and a current collector that supports the positive electrode material.

[0139] As the battery capacity increases towards a high-capacity battery, the ratio of the negative electrode active material in the negative electrode must be increased, and accordingly, the amount of lithium required for the SEI layer also increases. Therefore, after calculating the amount of lithium required for the SEI layer of the negative electrode, the amount of the sacrificial positive electrode material that must be applied to the positive electrode side can be calculated inversely to determine the design capacity of the battery.

[0140] According to one embodiment, the sacrificial positive electrode material is contained in an amount of more than 0% by weight and 15% by weight or less based on the total weight of the positive electrode material.

[0141] In order to compensate for the irreversible lithium required for the formation of the SEI layer, the content of the sacrificial positive electrode material is preferably more than 0% by weight based on the total weight of the positive electrode material.

[0142] However, when the sacrificial positive electrode material is contained in excess, the content of the positive electrode active material showing a reversible charge-discharge capacity decreases, the capacity of the battery decreases, and residual lithium in the battery may be plated on the negative electrode, inducing a short circuit in the battery or inhibiting safety. Therefore, the content of the sacrificial positive electrode material is preferably 15% by weight or less based on the total weight of the positive electrode material.

[0143] Specifically, the content of the sacrificial positive electrode material may be more than 0% by weight, or 0.5% by weight or more, or 1% by weight or more, or 2% by weight or more, or 3% by weight or more; and 15% by weight or less, or 12% by weight or less, or 10% by weight or less based on the total weight of the positive electrode material.

[0144] Preferably, the content of the sacrificial positive electrode material may be 0.5% by weight to 15% by weight, or 1% by weight to 15% by weight, or 1% by weight to 12% by weight, or 2% by weight to 12% by weight, or 2% by weight to 10% by weight, or 3% by weight to 10% by weight based on the total weight of the positive electrode material.

[0145] As the positive electrode active material, compounds known to be applicable to lithium secondary batteries in the technical field to which the present invention pertains can be used without particular limitation.

[0146] As non-limiting examples, the positive electrode active material may be NCM (Li[Ni, Co, Mn]O 2 ), NCMA (Li[Ni, Co, Mn, Al]O 2 ), LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 2 , LiNi 1-d Co d O 2 , LiCo 1-d Mn d O 2 , LiNi 1-d Mn d O 2(Above, 0 ≦ d < 1), Li(Ni a Co b Mn c )O 4 (0 < a < 2, 0 < b < 2, 0 < c < 2, a + b + c = 2), LiMn 2-e Ni e O 4 , LiMn 2-e Co e O 4 (Above, 0 < e < 2), LiCoPO 4 , and LiFePO 4 etc. may also be used. As the positive electrode active material, one or a mixture of two or more of the above-described examples can be used.

[0147] According to one embodiment, the positive electrode active material is contained in an amount of 80% to 98% by weight based on the total weight of the positive electrode material.

[0148] Specifically, the content of the positive electrode active material may be 80% by weight or more, or 82% by weight or more, or 85% by weight or more based on the total weight of the positive electrode material; and 98% by weight or less, or 95% by weight or less, or 93% by weight or less, or 90% by weight or less.

[0149] Preferably, the content of the positive electrode active material may be 82% to 98% by weight, or 82% to 95% by weight, or 82% to 93% by weight, or 85% to 93% by weight, or 85% to 90% by weight based on the total weight of the positive electrode material.

[0150] The positive electrode for the lithium secondary battery is formed by laminating a positive electrode material containing the positive electrode active material, the conductive material, the sacrificial positive electrode material, and the binder on the current collector.

[0151] The filler is selectively used as a component for suppressing the expansion of the positive electrode, and is not particularly limited as long as it is a fibrous material that does not induce a chemical change in the battery. For example, olefin polymers such as polyethylene and polypropylene; fibrous substances such as glass fiber and carbon fiber are used.

[0152] Regarding the conductive material, the binder, and the current collector included in the positive electrode material, all of the above-described content is included.

[0153] On the other hand, as the electrolyte, any electrolyte known to be applicable to a lithium secondary battery in the technical field to which the present invention pertains can be used without particular limitation. For example, the electrolyte may be an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel polymer electrolyte, a solid inorganic electrolyte, a molten inorganic electrolyte, an aqueous electrolyte, or the like.

[0154] The aqueous electrolyte is obtained by dissolving a salt in an aqueous solvent such as water or alcohol. In the case of a lithium secondary battery using such an aqueous electrolyte, it is advantageous in terms of high ionic conductivity and safety of the aqueous electrolyte, and the process and manufacturing cost are also low. In addition, there is an advantage that a battery using an aqueous electrolyte solution is more environmentally friendly than a non-aqueous organic electrolyte.

[0155] Specifically, the aqueous electrolyte can contain an aqueous solvent and a lithium salt.

[0156] The aqueous solvent is a solvent containing water and is not particularly limited, but can contain 1% by weight or more of water based on the total weight of the aqueous solvent forming the electrolyte. Water may be used alone as the aqueous solvent, or a solvent miscible with water may be used in combination.

[0157] The solvent miscible with water may be a polar solvent and can include, for example, one or more selected from the group consisting of C1-C5 alcohols and C1-C10 glycol ethers.

[0158] For example, the C1-C5 alcohol may be one or more selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, glycerol, and 1,2,4-butanetriol, but is not limited thereto.

[0159] Further, the C1-C10 glycol ether may be one or more selected from the group consisting of ethylene glycol monomethyl ether (MG), diethylene glycol monomethyl ether (MDG), triethylene glycol monomethyl ether (MTG), polyethylene glycol monomethyl ether (MPG), ethylene glycol monoethyl ether (EG), diethylene glycol monoethyl ether (EDG), ethylene glycol monobutyl ether (BG), diethylene glycol monobutyl ether (BDG), triethylene glycol monobutyl ether (BTG), propylene glycol monomethyl ether (MFG), and dipropylene glycol monomethyl ether (MFDG), but is not limited thereto.

[0160] The lithium salt contained in the electrolyte is dissolved in the aqueous solvent and acts as a source of lithium ions in the battery to enable the operation of a basic lithium secondary battery, and plays a role in promoting the movement of lithium ions between the positive electrode and the negative electrode.

[0161] Specifically, the lithium salt is LiPF 6 、LiClO 4 、LiAsF 6 、LiBF 4 、LiSbF 6 、LiAlO 4 、LiAlCl 4 、LiCF 3 SO 3 、LiC 4 F 9 SO 3 、LiN(C 2 F 5SO 3 ) 2 、 LiN(C 2 F 5 SO 2 ) 2 、 LiN(CF 3 SO 2 ) 2 、 LiN(SO 2 F) 2 (LiFSI, lithium bis(fluorosulfonyl)imide), LiCl, LiI, and LiB(C 2 O 4 ) 2 etc. may also be used. Preferably, the lithium salt is LiPF 6 , LiFSI, and mixtures thereof may also be used.

[0162] The lithium salt is contained in the electrolyte at a concentration of 0.1 M to 2.0 M. The lithium salt contained within this concentration range can exhibit excellent electrolyte performance by imparting appropriate conductivity and viscosity to the electrolyte.

[0163] Alternatively, the electrolyte may contain a non-aqueous organic solvent and a lithium salt.

[0164] As the non-aqueous organic solvent, any medium that can serve as a medium through which ions involved in the electrochemical reaction of the battery can move can be used without particular limitation.

[0165] Specifically, the non-aqueous organic solvent may be an ester solvent such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; an ether solvent such as dibutyl ether and tetrahydrofuran; a ketone solvent such as cyclohexanone; an aromatic hydrocarbon solvent such as benzene and fluorobenzene; a carbonate solvent such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); an alcohol solvent such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may contain a double bond, aromatic ring, or ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; and sulfolane, etc.

[0166] Among the above examples, carbonate solvents are preferably used as the non-aqueous organic solvent.

[0167] In particular, considering the charge-discharge performance of the battery and the compatibility with the sacrificial positive electrode material, as the non-aqueous organic solvent, a mixture of a cyclic carbonate having high ionic conductivity and high dielectric constant (e.g., ethylene carbonate, propylene carbonate) and a linear carbonate having low viscosity (e.g., ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate) can be preferably used. In this case, mixing the cyclic carbonate and the linear carbonate in a volume ratio of 1:1 to 1:9 may be advantageous for the manifestation of the above-described performance.

[0168] Further, as the non-aqueous organic solvent, a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 1:2 to 1:10; or a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) in a volume ratio of 1 to 3:1 to 9:1 can be preferably used.

[0169] The lithium salt contained in the electrolyte dissolves in the non-aqueous organic solvent and acts as a source of lithium ions in the battery to enable the operation of a basic lithium secondary battery, and plays a role in promoting the movement of lithium ions between the positive electrode and the negative electrode.

[0170] Specifically, the lithium salt is LiPF 6 、LiClO 4 、LiAsF 6 、LiBF 4 、LiSbF 6 、LiAlO 4 、LiAlCl 4 、LiCF 3 SO 3 、LiC 4 F 9 SO 3 、LiN(C 2 F 5 SO 3 ) 2 、LiN(C 2 F 5 SO 2 ) 2 、LiN(CF 3 SO2 ) 2 , LiN(SO 2 F) 2 (LiFSI, lithium bis(fluorosulfonyl)imide), LiCl, LiI, and LiB(C 2 O 4 ) 2 etc. may also be used. Preferably, the lithium salt is LiPF 6 , LiFSI, and mixtures thereof may also be used.

[0171] The lithium salt is contained in the electrolyte at a concentration of 0.1 M to 2.0 M. The lithium salt contained within this concentration range can exhibit excellent electrolyte performance by imparting appropriate conductivity and viscosity to the electrolyte.

[0172] Optionally, the electrolyte contains additives for the purpose of improving the battery life characteristics, suppressing the decrease in battery capacity, improving the discharge capacity of the battery, etc.

[0173] For example, the additives may be haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, n-glyme, hexamethylphosphoric triamide, nitrobenzene derivatives, sulfur, quinonimine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, aluminum trichloride, etc. The additives are contained at 0.1 wt% to 5 wt% based on the total weight of the electrolyte.

[0174] The lithium secondary battery of the one embodiment may be a lithium ion battery, a lithium ion polymer battery, or a lithium polymer battery depending on the type of electrolyte and / or the type of separator.

[0175] The liquid electrolyte may be a non-aqueous electrolyte containing a lithium salt. The non-aqueous electrolyte containing a lithium salt consists of a non-aqueous electrolyte and lithium. As the non-aqueous electrolyte, non-aqueous organic solvents, organic solid electrolytes, inorganic solid electrolytes, etc. are used, but it is not limited to these only.

[0176] As the organic solid electrolyte, for example, polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate esters polymers, polyaditization lysine, polyester sulfides, polyvinyl alcohol, polyvinylidene fluoride, polymers containing ionic dissociation groups, etc. can be used.

[0177] As the inorganic solid electrolyte, for example, Li 3 N, LiI, Li 5 NI 2 、Li 3 N-LiI-LiOH, LiSiO 4 、LiSiO 4 -LiI-LiOH, Li 2 SiS 3 、Li 4 SiO 4 、Li 4 SiO 4 -LiI-LiOH, Li 3 PO 4 -Li 2 S-SiS 2 such as lithium nitrides, halides, sulfates of Li, etc. can be used.

[0178] In addition, for the purpose of improving charge and discharge characteristics, flame retardancy, etc., the lithium salt-containing non-aqueous electrolyte may be added with, for example, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, triamide hexaline, nitrobenzene derivative, sulfur, quinoneimine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride, etc. In some cases, for imparting non-flammability, it may further contain halogen-containing solvents such as carbon tetrachloride and vinylidene fluoride, and for improving high-temperature storage characteristics, it may further contain carbon dioxide gas, or it may further contain FEC (Fluoro-Ethylene Carbonate), PRS (Propene sultone), etc.

[0179] In one specific example, lithium salts such as LiPF 6 , LiClO 4 , LiBF 4 , LiN(SO 2 CF 3 ) 2 are added to a mixed solvent of a cyclic carbonate of EC or PC as a high-dielectric constant solvent and a linear carbonate of DEC, DMC or EMC as a low-viscosity solvent to produce a lithium salt-containing non-aqueous electrolyte.

[0180] The lithium secondary battery can be used as an energy supply source having improved performance and safety in the fields of portable electronic devices such as mobile phones, notebook computers, tablet computers, mobile batteries, digital cameras, etc.; and in the fields of means of transportation such as electric vehicles, electric bicycles, and personal mobility devices.

[0181] The lithium secondary battery can have various forms such as square, cylindrical, and pouch-shaped.

[0182] The lithium secondary battery of the above-described other embodiments can be realized by a battery module including this as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source.

[0183] At this time, specific examples of the device may be, but are not limited to, an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a power storage system.

Advantages of the Invention

[0184] According to the present invention, it is possible to provide an electrode for a lithium secondary battery that can ensure the insulation of the electrode periphery and prevent defects due to short circuits during cell assembly, and a lithium secondary battery including the same.

Brief Description of the Drawings

[0185]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0186] Hereinafter, the operation and effects of the invention will be described more specifically through specific embodiments of the invention. However, this is presented as an example of the invention, and the scope of rights of the invention is not limited in any way thereby.

[0187] Example 1 (1) Manufacture of negative electrode Carbon powder as the negative electrode active material, carboxymethyl cellulose (CMC) as the binder, and carbon black as the conductive material were respectively added to ion-exchanged water at 96 wt%, 3 wt%, and 1 wt% to produce a negative electrode slurry. The negative electrode slurry was applied and dried on a copper (Cu) thin film, which is a negative electrode current collector with a thickness of 10 μm, using a comma coater, and roll press was performed to manufacture a negative electrode. The loading amount of the negative electrode was controlled so that the finally manufactured capacity (Half-cell standard) was 5.3 mAh / cm 2 was achieved.

[0188] (2) Manufacture of positive electrode 92 wt% of lithium cobalt composite oxide as the positive electrode active material, 4 wt% of carbon black as the conductive material, and 4 wt% of PVDF as the binder were added to N-methyl-2-pyrrolidone (NMP) as the solvent to produce a positive electrode slurry. After the positive electrode slurry was applied and dried on an aluminum (Al) thin film, which is a positive electrode current collector with a thickness of 10 μm, to manufacture a positive electrode, roll press was performed to manufacture a positive electrode. The loading amount of the positive electrode was controlled so that the finally manufactured capacity (Half-cell standard) was 4.8 mAh / cm 2 was achieved.

[0189] (3) Manufacture of insulating layer 10 g of poly(vinylidene fluoride - chlorotrifluoroethylene) (PVdF - CTFE) was added to 10 g of N - methyl - 2 - pyrrolidone (NMP), and dissolved at 50 °C for about 12 hours or more to produce a binder polymer solution. 10 g of alumina powder was added to the produced polymer solution, and the alumina powder was crushed and dispersed to 400 nm using the ball mill method for 12 hours or more to produce a composition for forming an insulating layer.

[0190] (4) Production of the composition for forming the coating layer 10 g of poly(vinylidene fluoride) (PVdF) was added to 10 g of N - methyl - 2 - pyrrolidone (NMP), and dissolved at 50 °C for about 12 hours or more to produce a binder polymer solution. 10 g of boehmite (AlO(OH)) powder was added to the produced polymer solution, and the boehmite powder was crushed and dispersed to 300 nm using the ball mill method for 12 hours or more to produce a composition for forming the coating layer.

[0191] (5) Production of the battery The composition for forming the insulating layer was coated on the produced negative electrode by the doctor - blade coating method under 30% humidity, and dried at 90 °C to form an insulating layer (pore size: 100 nm, porosity: 63%) with a thickness of 20 μm.

[0192] Thereafter, the laminate with the insulating layer formed on the negative electrode was punched into a size of 32 mm × 44 mm. Then, the composition for forming the coating layer was coated on the side surface of the laminate and a part of the upper surface of the insulating layer by the dip - coating method under 30% humidity, and dried at 90 °C to form a coating layer (pore size: 100 nm) on the periphery of the laminate including the side surface of the laminate and a part of the upper surface of the insulating layer. The thickness and length of each coating region of the specific coating layer are as described in Table 1 below.

[0193] Also, the manufactured positive electrode was punched into a size of 30×42 mm and assembled with the negative electrode having the coating layer formed thereon using a lamination method. After welding an electrode lead to the tab of the assembled cell, it was placed in an aluminum pouch, and the remaining peripheries except for one periphery were sealed. After injecting an electrolytic solution (ethylene carbonate (EC) / ethyl methyl carbonate (EMC) = 3 / 7 (volume ratio), lithium hexafluorophosphate (LiPF 6 ) 0.7 mol, LiFSI 0.5 M, vinylene carbonate 1.5%, 1,3-propane sultone 0.5%, ethylene sulfate 1%, LiBF 4 0.2%) and then performing vacuum sealing, it was aged at room temperature for 10 hours so that the electrolytic solution was impregnated into the cell. Thereafter, the aluminum pouch monocell was mounted on a jig, and a lithium secondary battery was manufactured by crimping at 29 kgf.

[0194] Example 2 A lithium secondary battery was manufactured in the same manner as in Example 1, except that the length of the second coating region measured from the tangent line of the first coating region and the second coating region was adjusted to 200 μm.

[0195] Example 3 A lithium secondary battery was manufactured in the same manner as in Example 1, except that 13 g of boehmite powder was added during the production of the composition for forming the coating layer.

[0196] Example 4 A lithium secondary battery was manufactured in the same manner as in Example 1, except that the length of the second coating region measured from the tangent line of the first coating region and the second coating region was adjusted to 1.5 mm.

[0197] Comparative Example 1 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a polyolefin separator (16 μm thick, having adhesion performance on both sides) with a size 2 mm longer than the length and width of the negative electrode was interposed between the positive electrode and the negative electrode manufactured in Example 1, and they were laminated at 90 °C to assemble a positive electrode / separator / negative electrode.

[0198] Comparative Example 2 A lithium secondary battery was manufactured in the same manner as in Example 1, except that the negative electrode with an insulating layer formed thereon and the positive electrode were assembled using a lamination method without forming a coating layer.

[0199] Comparative Example 3 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a polyimide tape was attached in place of the coating layer on a part of the side surface and the upper surface of the laminate.

[0200] Comparative Example 4 A lithium secondary battery was manufactured in the same manner as in Example 1, except that boehmite powder was not added during the production of the composition for forming the coating layer.

[0201] Comparative Example 5 A lithium secondary battery was manufactured in the same manner as in Example 1, except that 3 g of boehmite powder was added during the production of the composition for forming the coating layer.

[0202] Experimental Example 1: Coating Layer Analysis The thickness of the first coating region, the thickness of the second coating region, the length (L1) of the second coating region measured from the tangents of the first coating region and the second coating region, and the porosity of the coating layer of the lithium secondary batteries manufactured in the above Examples and Comparative Examples were analyzed and shown in Table 1 below.

[0203] The porosity of each coating layer was determined by the following formula after measuring the volume and mass of the applied layer to obtain the measured density and then calculating the theoretical density with respect to the solid content of the applied composition.

[0204] Void fraction (%) = (1 - measured density / theoretical density) × 100

[0205] Experimental Example 2: Charge-discharge formation characteristics of the battery For the lithium secondary batteries of the examples, comparative examples, and reference examples, formation was carried out at 0.1 C-rate at 2.5 - 4.2 V at room temperature. The discharge capacity and the Coulombic Efficiency, which is the ratio of the discharge capacity to the charge capacity, were measured and shown in Table 1 below.

[0206] Experimental Example 3: High-temperature safety After the lithium secondary batteries of the examples, comparative examples, and reference examples were formed, with the SOC (State of Charge) set to 5%, they were stored in a chamber at 130 °C for 30 minutes and then cooled back to room temperature. The OCV (open circuit voltage) was measured to check whether the battery short-circuited and shown in Table 1 below.

[0207]

Table 1

[0208] As shown in Table 1 above, the lithium secondary battery of the example has a discharge capacity of 47 mAh or more and 53 mAh or less, a Coulombic Efficiency value of 78% or more, not only has excellent battery characteristics, but also the OCV after storage at 130 °C is 3.29 V or more, and it was confirmed that it has excellent high-temperature stability.

[0209] In contrast, in the case of Comparative Example 1, the OCV after storage at 130°C was only 0.002V, indicating that the polyolefin separator membrane shrank at high temperature and short-circuiting of the electrodes occurred. It was also revealed that in Comparative Example 2, the OCV after storage at 130°C was only 2.42V. By not including a coating member on the periphery of the electrode portion, it was confirmed that the high-temperature stability was insufficient due to the detachment phenomenon occurring during punching of the electrode portion and the minute deviation occurring during cell assembly.

[0210] Also, in the case of Comparative Example 2, it was revealed that the discharge capacity was 12 mAh and the Coulombic Efficiency value was only 25%. By not including a coating member on the periphery of the electrode portion, it was confirmed that short-circuiting of the cell occurred due to the detachment phenomenon during punching of the electrode portion, resulting in insufficient battery characteristics.

[0211] Also, in the case of Comparative Example 3, it was revealed that the discharge capacity was 50.1 mAh and the Coulombic Efficiency value was only 78.3%. By using a polyimide tape as the insulating layer, it was confirmed that the battery characteristics were insufficient.

[0212] Also, in the case of Comparative Example 4, it was revealed that the discharge capacity was 38.5 mAh and the Coulombic Efficiency value was only 53.9%. When forming a coating layer with only a binder without inorganic particles, it was confirmed that the battery characteristics were insufficient. Moreover, it was confirmed that out of five single cells, only two were finally produced as good products, resulting in a high short-circuit defect rate of the single cells.

[0213] In the case of Comparative Example 5, it was confirmed that the discharge capacity and the Coulombic Efficiency value were inferior because the porosity of the first and second coating regions exceeded 50% and stable insulation could not be achieved.

Description of Reference Numerals

[0214] 100: Electrode part 101: Current collector 102: Electrode layer 103: Insulating layer 200: Second electrode part 201: Second electrode layer 202: Second current collector 10: First coating region 11: Thickness of the first coating region 20: Second coating region 21: Thickness of the second coating region 30: 1 / 2 * (Difference between the length in the extending direction of the electrode part and the length in the extending direction of the second electrode part) 40: Tangent line of the first coating region and the second coating region

Claims

1. A current collector, an electrode layer formed on the current collector, and an insulating layer formed on the electrode layer, the electrode part including the above, including a coating member including a first coating region in contact with a side surface of the electrode part and a second coating region continuous with the first coating region and in contact with a part of the insulating layer, each of the first coating region and the second coating region includes inorganic fine particles and a binder resin, each of the first coating region and the second coating region contains 50 parts by weight or more and 100 parts by weight or less of the inorganic fine particles with respect to 100 parts by weight of the binder resin, an electrode for a lithium secondary battery.

2. The electrode for a lithium secondary battery according to claim 1, wherein a thickness of the first coating region measured from a side surface of the electrode part is 1 μm or more and 100 μm or less.

3. The electrode for a lithium secondary battery according to claim 1, wherein a thickness of the second coating region measured from an interface with the insulating layer is 1 μm or more and 500 μm or less.

4. The electrode for a lithium secondary battery according to claim 1, wherein a length of the second coating region measured from a tangent line of the first coating region and the second coating region is 50 μm or more and 2 mm or less.

5. The electrode for a lithium secondary battery according to claim 1, wherein a ratio of a thickness of the second coating region measured from an interface with the insulating layer to a length of the second coating region measured from a tangent line of the first coating region and the second coating region is 0.001 or more and 1.0 or less.

6. The electrode for a lithium secondary battery according to claim 1, wherein the coating member has a porosity of 10% or more and 50% or less.

7. The electrode for a lithium secondary battery according to claim 1, wherein the insulating layer has a porosity of 30% or more and 70% or less.

8. The electrode for a lithium secondary battery according to claim 1, wherein the insulating layer has a thickness of 10 μm or more and 30 μm or less.

9. The electrode for a lithium secondary battery according to claim 1, wherein the inorganic fine particles include inorganic fine particles having a particle size of 10 nm or more and 1 μm or less.

10. The inorganic fine particles are one or more inorganic fine particles selected from the group consisting of alumina, boehmite, aluminum hydroxide, silica, titania, zirconia, zirconium titanate, La ２ O ３ , Y ２ O ３ , SrTiO ３ , BaTiO ３ , magnesia, magnesium hydroxide, aluminosilicate, zeolite, LLZO, LATP, PZT, and the electrode for a lithium secondary battery according to claim 1 containing one or more inorganic fine particles selected from the group consisting of

11. The electrode for a lithium secondary battery according to claim 1, comprising at least one binder resin selected from the group consisting of polyvinylidene fluoride, polyvinylidene fluoride - hexafluoropropylene, polyvinylidene fluoride - trichloroethylene, polyvinylidene fluoride - chlorotrifluoroethylene, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, ethylene vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, acrylonitrile - styrene - butadiene copolymer, polyurethane, polyacrylic acid, polyetherimide, polyimide, silicone, polyvinyl alcohol, and styrene butadiene rubber.

12. The electrode for a lithium secondary battery according to claim 1; and A lithium secondary battery including a second electrode portion formed on the electrode for a lithium secondary battery.

13. The second electrode portion includes a second electrode layer; and The lithium secondary battery according to claim 12, including a second current collector formed on the second electrode layer.

14. The lithium secondary battery according to claim 12, wherein the length of the electrode portion in the extension direction is 0.2 mm or more and 2 mm or less longer than the length of the second electrode portion in the extension direction.

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