Negative electrode comprising porous matrix and current collector, and lithium secondary battery comprising the same

Abstract

The present invention relates to a negative electrode for a lithium secondary battery comprising a porous support layer and a lithium secondary battery comprising the same. Specifically, the invention relates to a negative electrode for a lithium secondary battery comprising a porous support layer and a negative electrode current collector layer coated on at least one surface of the porous support, for reducing thickness variation of the lithium secondary battery caused by lithium deposition and reducing stress thereby improving the safety and performance of the battery, and a lithium secondary battery comprising the same.

Description

Technology Field

[0001] The present invention relates to a negative electrode comprising a porous support and a current collector layer, and a lithium secondary battery comprising the same. Specifically, the invention relates to a negative electrode for a lithium secondary battery comprising a porous support and a negative electrode current collector layer formed on at least one surface of the porous support, and a lithium secondary battery comprising the same, wherein the negative electrode suppresses the generation of stress due to thickness change during charging and discharging, thereby improving battery life. Background Technology

[0002] Lithium secondary batteries are used in various high-capacity batteries due to their high energy density, low self-discharge rate, and long lifespan. However, lithium secondary batteries face problems such as damage to the separator between the positive and negative electrodes or an increase in battery volume caused by lithium dendrites generated during charging and discharging.

[0003] Even all-solid-state batteries with enhanced safety have failed to solve the problem caused by lithium dendrites. Lithium dendrites grow due to the process of pressurizing the all-solid-state battery to reduce interfacial resistance between the positive electrode, the solid electrolyte layer, and the negative electrode. Lithium dendrites cause damage to the solid electrolyte layer or an increase in the battery volume.

[0004] Figure 1 is a schematic diagram of a lithium secondary battery according to the prior art.

[0005] As can be seen in FIG. 1, a lithium secondary battery according to the prior art has a positive electrode (10) having a positive current collector (11) and a positive active material layer (12) coated on both sides thereof, a separator / solid electrolyte layer (20), and a negative electrode (30) having a negative current collector (31) and a negative active material layer (32) coated on both sides thereof. Unlike FIG. 1, the negative electrode may be used as a lithium plating and stripping mechanism using a negative current collector alone or lithium metal without a separate negative active material layer (32) to improve the overall capacity of the lithium secondary battery.

[0006] In a lithium secondary battery according to the prior art, pressure (F) is applied from the top and bottom of the battery to reduce the interfacial resistance between the positive electrode (10), the separator / solid electrolyte layer (20), and the negative electrode (30). When initial charging and discharging are performed by applying pressure, lithium is inserted into the negative electrode active material, causing the active material to expand or lithium to be deposited on the negative electrode (30), thereby increasing the thickness (z-axis) of the lithium secondary battery, and consequently, the pressure applied inside the lithium secondary battery also increases. When the pressure applied inside the lithium secondary battery increases, problems arise in which the position and shape of the positive electrode (10), the separator / solid electrolyte layer (20), and the negative electrode (30) inside the lithium secondary battery are deformed. Furthermore, if the lithium deposited on the negative electrode (30) is not uniform, the lithium secondary battery cannot be pressurized by a uniform pressure (F), and there is a risk that the jig applying pressure from the outside may also be damaged.

[0007] The lithium metal used in lithium secondary batteries is soft, so the capacity and performance of the unit cell vary depending on the degree or duration of pressurization. As the pressure (F) increases, the reactivity between the separator / solid electrolyte and the lithium metal increases, and the lithium metal may flow into the interior through defects in the separator / solid electrolyte layer, increasing the likelihood of a short circuit occurring within the lithium secondary battery.

[0008] To address this, it is necessary to evenly distribute or reduce the reactivity with lithium metal or the stress inside the lithium secondary battery.

[0009] Patent Document 1 describes a laminate composed of a positive electrode, a solid electrolyte layer, and a negative electrode that is pressurized to improve conductivity, electronic conductivity, and lithium-ion conductivity, but it does not recognize the fact that it reduces the stress applied to the all-solid-state battery to prevent cell short circuits in the unit cell.

[0010] Patent Document 2 also pressurizes a laminate consisting of an anode, a solid electrolyte layer, and a cathode to reduce interfacial resistance, but does not recognize the intention to improve the safety of the unit cell by reducing the stress applied to the all-solid-state battery. Prior art literature

[0011] Japanese Published Patent Application No. 2018-181451 (Nov. 15, 2018) Japanese Published Patent Application No. 2019-200890 (Nov. 21, 2019) The problem to be solved

[0012] The present invention aims to solve the aforementioned problems by providing a configuration for applying constant pressure during pressurization for interface formation in a lithium secondary battery. It also aims to evenly distribute or reduce internal stress in the lithium secondary battery.

[0013] In addition, the purpose is to provide a lithium secondary battery that improves safety and extends lifespan by preventing cell short circuits. means of solving the problem

[0014] To achieve the above objectives, the negative electrode for a lithium secondary battery according to the present invention comprises a porous support and a negative electrode current collector layer formed on at least one surface of the porous support.

[0015] The above cathode may not include a separate cathode active material.

[0016] In addition, the above-mentioned negative current collector layer may include one or more metals and / or metal alloys selected from the group including lithium, copper, and nickel.

[0017] The above negative electrode current collector layer may be made of a conductive material having lithium affinity. The lithium affinity material may be one or more of metals including materials such as Au, Ag, Pt, Zn, Si, Sn, Ni, Bi, and Mg, and metal oxides including materials such as CuO, ZnO, MnO, and CoO.

[0018] In addition, the porous support may include an elastic material.

[0019] The above porous support may be an olefin-based porous substrate, or a sheet or nonwoven fabric made of one or more selected from the group including glass fiber and polyethylene.

[0020] The above porous support may further include at least one of ceramic, metal, or metal alloy in a polymer having a porous structure.

[0021] The above porous support may have a nonwoven fabric structure or be formed by uniaxial stretching or biaxial stretching.

[0022] The porous support may include pores of 0.01 μm to 10 μm.

[0023] In addition, the porosity of the porous support may be 10% to 90%.

[0024] The present invention provides a lithium secondary battery comprising the negative electrode for a lithium secondary battery described above.

[0025] The positive electrode of the above lithium secondary battery may include a porous support on at least one surface.

[0026] The present invention may be a battery module or battery pack comprising the lithium secondary battery mentioned above. It may also be a device equipped with the unit cell.

[0027] The present invention may select and combine one or more non-conflicting configurations among the above configurations. Effects of the invention

[0028] As explained above, the lithium secondary battery according to the present invention uses a porous support and a negative electrode current collector layer formed on at least one surface of the porous support as a negative electrode, thereby evenly distributing or reducing the stress applied when the lithium secondary battery is pressurized, and reducing cell short circuits.

[0029] In addition, cell short circuits are reduced, improving the safety and lifespan of lithium secondary batteries.

[0030] In addition, the porous support is deformed even when the external pressure of the lithium secondary battery increases or when there is a change in thickness due to the formation of lithium dendrites, which has the advantage of maintaining a constant thickness of the lithium secondary battery. Brief explanation of the drawing

[0031] Figure 1 is a schematic diagram of a lithium secondary battery according to the prior art. FIG. 2 is a schematic diagram of a lithium secondary battery according to one embodiment of the present invention. FIG. 3 is a schematic diagram of a lithium secondary battery after charging and pressurizing according to one embodiment of the present invention. Specific details for implementing the invention

[0032] Embodiments that enable a person skilled in the art to easily practice the present invention are described in detail below with reference to the attached drawings. However, in describing the operating principles of preferred embodiments of the present invention in detail, if it is determined that a specific description of related known functions or configurations may unnecessarily obscure the essence of the present invention, such detailed description is omitted.

[0033] In addition, the same reference numerals are used for parts having similar functions and operations throughout the drawings. Throughout the specification, when a part is described as being connected to another part, this includes not only cases where they are directly connected, but also cases where they are indirectly connected with other elements in between. Furthermore, unless specifically stated otherwise, the inclusion of a certain component does not exclude other components but implies that additional components may be included.

[0034] Furthermore, descriptions that specify components by limiting or adding them may be applied to all inventions unless there are special limitations, and are not limited to specific inventions.

[0035] In addition, throughout the description of the invention and claims of this application, items indicated in the singular include cases where they are plural unless otherwise noted.

[0036] In addition, throughout the description of the invention and the claims of the present invention, "or" includes "and" unless otherwise noted. Therefore, "comprising A or B" means all three of the above cases: including A, including B, or including both A and B.

[0037] In addition, all numerical ranges include the values ​​at both ends and all intermediate values ​​in between, unless explicitly stated to be excluded.

[0038] The negative electrode for a lithium secondary battery according to the present invention comprises a porous support and a negative electrode current collector layer coated on at least one surface of the porous support. The negative electrode for a lithium secondary battery according to the present invention is to be explained through a schematic diagram of the entire lithium secondary battery. FIG. 2 is a schematic diagram of a lithium secondary battery according to the present invention.

[0039] As can be seen in FIG. 2, the lithium secondary battery according to the present invention comprises a positive electrode (100) comprising a positive electrode current collector (110) and a positive electrode active material layer (120) coated on at least one surface thereof, a separator / solid electrolyte layer (200), a porous support (310), and a negative electrode (300) comprising a negative electrode current collector layer (320) coated on at least one surface of the porous support (310).

[0040] The above anode (100) can be manufactured, for example, by applying an anode mixture comprising a positive active material composed of positive active material particles or particles coated with positive active material, a conductive material, and a binder to a positive current collector (110) to form a positive active material layer (120), and if necessary, a filler may be further added to the positive mixture.

[0041] The above positive current collector (110) is generally manufactured with a thickness of 3㎛ to 500㎛ and is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. For example, one selected from stainless steel, aluminum, nickel, titanium, and aluminum or stainless steel surface treated with carbon, nickel, titanium, or silver can be used, and specifically, aluminum can be used. The current collector may have fine irregularities formed on its surface to increase the adhesion of the positive active material, and various forms such as film, sheet, foil, net, porous body, foam, and nonwoven fabric are possible.

[0042] The positive active material included in the positive active material layer (120) above is, for example, a layered compound such as lithium nickel oxide (LiNiO2) or a compound substituted with one or more transition metals in addition to the positive active material particles; chemical formula Li 1+x Mn 2-x Lithium manganese oxides such as O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2, etc.; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7, etc.; chemical formula LiNi 1-x M x Ni-site type lithium nickel oxide represented by O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = 0.01 ~ 0.3); chemical formula LiMn 2-x M xIt may be composed of lithium manganese complex oxides represented by O2 (where M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which some of the Li in the chemical formula is substituted with alkaline earth metal ions; disulfide compounds; Fe2(MoO4)3, etc., but is not limited to these.

[0043] However, the positive active material used in the present invention preferably uses a metal oxide containing lithium or includes the same in order to deposit lithium on the negative electrode (300).

[0044] The above conductive material is typically added in an amount of 0.1 to 30 weight percent based on the total weight of the mixture containing the positive electrode active material. Such conductive material is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; conductive fibers such as carbon fibers or metal fibers; metal powders such as carbon fluoride, aluminum, or nickel powder; conductive whiskey such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive materials such as polyphenylene derivatives may be used.

[0045] The binder included in the above anode (100) is a component that assists in the bonding of the active material and the conductive material, and the bonding to the current collector, and is typically added in an amount of 0.1 to 30% by weight based on the total weight of the mixture containing the anode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, and various copolymers.

[0046] The above-mentioned separator / solid electrolyte layer (200) may use organic solid electrolytes or inorganic solid electrolytes, but is not limited to these.

[0047] The above organic solid electrolyte may be, for example, a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, agitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, a polymer containing an ionic dissociator, etc.

[0048] Examples of the above-mentioned inorganic solid electrolytes include sulfide-based solid electrolytes and oxide-based solid electrolytes.

[0049] As oxide-based solid electrolytes, for example, Li 6.25 La3Zr2A l0 . 25 O 12 , Li3PO4, Li3+xPO4-xN x Li sulfides, nitrides, halides, etc., such as (LiPON), Li3N, LiI, Li5NI2, Li3N-LiI-LiOH, LiSiO4, LiSiO4-LiI-LiOH, Li2SiS3, Li4SiO4, Li4SiO4-LiI-LiOH, etc., may be used.

[0050] The above sulfide is not specifically limited in the present invention and any known sulfide-based material used in the field of lithium batteries may be used. The above sulfide-based material may be purchased commercially or manufactured by undergoing a crystallization process of an amorphous sulfide-based material. For example, the above sulfide-based solid electrolyte may be a crystalline sulfide-based solid electrolyte, an amorphous sulfide-based solid electrolyte, or any one of these or a mixture thereof. Examples of composite compounds that may be used include sulfur-halogen compounds, sulfur-germanium compounds, and sulfur-silicon sulfides; specifically, they may include sulfides such as SiS2, GeS2, and B2S3, and may contain added Li3PO4, halogens, or halogen compounds. Preferably, 10 -4 Sulfide-based electrolytes capable of achieving lithium ion conductivity of S / cm or higher can be used.

[0051] Representative examples include Li6PS5Cl (LPSCl) and Thio-LISICON(Li 3.25 Ge 0.25 P 0.75 S4), Li2S-P2S5-LiCl, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li2S-P2S5, Li3PS4, Li7P3S 11 , LiI-Li2S-B2S3, Li3PO4-Li2S-Si2S, Li3PO4-Li2S-SiS2, LiPO4-Li2S-SiS, Li 10 GeP2S 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , Li7P3S 11 Includes the back

[0052] The porous support (310) used in the negative electrode (300) for a lithium secondary battery according to the present invention can be any polymer material that does not interfere with the operation of the battery. However, in order to more effectively perform the role of reducing pressure by deforming when pressure is applied, the porous support (310) may be a material that has a similar thickness before and after applying pressure and undergoes significant deformation when pressure is applied, i.e., an elastic material.

[0053] The above elastic material may be, for example, one or more selected from the group consisting of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, polyethylene naphthalene, and mixtures thereof.

[0054] Since the porous support (310) is made of an elastic material, the porous support (310) can be deformed by the pressure (F) that pressurizes the lithium secondary battery, thereby dispersing or reducing the stress applied to the negative electrode (300).

[0055] Additionally, the porous support (310) may use a material similar to the material used in the separator / solid electrolyte layer (200). The porous support (310) may include an olefin-based porous substrate comprising chemically resistant and hydrophobic polypropylene, or a sheet or nonwoven fabric made of one or more selected from the group including glass fiber and polyethylene. The olefin-based porous substrate used in the porous support (310) is a polyolefin porous substrate used in a secondary battery separator that does not have an inorganic coating layer added to both sides, and may be, for example, polyethylene or polypropylene.

[0056] The porous support (310) may be a nonwoven fabric structure or a porous structure formed by uniaxial stretching or biaxial stretching. The porous support (310) may include pores with a diameter of 0.01 μm to 10 μm. Additionally, the porosity of the porous support may be 10% to 90%. In the case where there are many fine pores inside as described above, the stress generated inside the lithium secondary battery can be reduced by decreasing the size or number of the pores, even if the structure of the porous support (310) does not change significantly.

[0057] In addition, the porous support (310) according to the present invention may have a thickness of 5㎛ to 300㎛ to efficiently reduce stress generated inside the lithium secondary battery. If the thickness of the porous support (310) is excessively thin, it cannot reduce stress inside the lithium secondary battery, and if the thickness is excessively thick, it is undesirable as it reduces the performance relative to the size of the secondary battery.

[0058] When the porous support (310) has a plurality of pores and is made of an elastic material, the pores become smaller or the number of pores decreases compared to when only an elastic material is used, thereby reducing changes in the position or shape of the porous support (310), so that stress reduction within the lithium secondary battery can be performed more effectively. In addition, due to the elasticity, when the pressure is removed, the pores are easily restored to their original state.

[0059] Furthermore, if the porous support (310) is made of the same material as the separator / solid electrolyte layer (200), the lithium secondary battery using the negative electrode (200) for the lithium secondary battery according to the present invention has the advantage of being able to be stacked without a separate separator or insulating material between unit cells.

[0060] The porous structure polymer of the porous support (310) may further include at least one of a ceramic, a metal, or a metal alloy. This allows the porous support (310) to include a ceramic, a metal, or a metal alloy so that the porous support (310) can perform the role of a cathode (300) together with the cathode current collector layer (320). However, in this case, when stacking unit cells, a separate separator or insulating material is required.

[0061] The above negative current collector layer (320) is generally manufactured with a thickness of 3 μm to 500 μm. Such negative current collector layer (320) is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, metals and / or metal alloys such as copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper, or stainless steel surface treated with carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloys may be used. In addition, fine irregularities may be formed on the surface to strengthen the bonding strength of the negative active material, and it may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven body, etc.

[0062] The negative electrode current collector layer (320) according to the present invention may include a conductive material capable of performing electron movement by storing and transferring lithium ions.

[0063] The above negative current collector layer (320) may be made of a lithium-affinity material. For example, the metal may be gold (Au), silver (Ag), platinum (Pt), zinc (Zn), silicon (Si), and magnesium (Mg), and the metal oxide may be a non-metal such as copper oxide, zinc oxide, manganese oxide, cobalt oxide, etc.

[0064] Since the above negative electrode current collector layer (320) is made of a lithium-affinity material, the deposition of lithium ions on the above negative electrode current collector layer (320) can occur more easily.

[0065] The above-mentioned negative current collector layer (320) may be located on at least one surface of the separator / solid electrolyte layer (200). At this time, the negative current collector layer (320) may be positioned on the opposite surface of the separator / solid electrolyte layer (200) to facilitate smooth ion and electron exchange with the anode (100).

[0066] The above-mentioned cathode current collector layer (320) may be coated on the above-mentioned porous support (310). The coating method is not particularly limited and may be carried out, for example, by immersing, spin coating, dip coating, spray coating, doctor blade, solution casting, drop coating, PVD (Physical Vapor Deposition), or CVD (Chemical Vapor Deposition).

[0067] At this time, it is also possible for the conductive material of the cathode current collector layer (320) to be uniformly arranged within the porous support (310). Additionally, the cathode current collector layer (320) may form fine irregularities on its surface to strengthen the bonding force with the porous support (310), and may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0068] FIG. 3 is a schematic diagram of a lithium secondary battery according to the present invention after charging and pressurizing.

[0069] As can be seen in FIG. 3, the lithium secondary battery according to the present invention forms a lithium layer (330) by depositing lithium after charging. The lithium layer (330) is charged under constant current / constant voltage (CC / CV) conditions, and the pressure (F) applied to the entire lithium secondary battery at this time may vary depending on the amount of lithium formed in the battery, the charging / discharging speed, and the time.

[0070] The porous support (310), which receives a constant force due to the pressure (F), first reduces the size or amount of pores within the porous support (310), thereby relieving the stress caused by the pressure (F). When the pressure (F) is applied further, the porous support (310) increases in length due to the pressure (F) in the direction perpendicular to the pressure direction, that is, in the horizontal (f1, x) and vertical (f2, y) directions of the porous support (310), and decreases in the pressure direction, that is, in the thickness (f3, z) of the porous support (310), thereby reducing the pressure (F) applied to the lithium secondary battery and reducing the force applied to the lithium layer (330) and the entire lithium secondary battery.

[0071] At this time, the porous support (310) may be present on one side of the anode (100). The porous support (310) may have the same shape as the cathode (300) used in the present invention, so that the porous support (310) is present on the anode (100) instead of the cathode (300), or it may be a shape in which the porous support (310) is present on the anode (100) while using the cathode (300).

[0072] That is, the lithium secondary battery according to the present invention is operated by performing charging and discharging through a manufacturing method comprising: S1) forming a laminate comprising a positive electrode, a separator / solid electrolyte layer and a porous support and a negative electrode current collector layer coated on at least one surface of the porous support; S2) pressing the laminate; and S3) charging while pressing the pressed laminate.

[0073] After step S3) above, lithium is deposited on the negative current collector layer or between the negative current collector layer and the porous polymer to form a lithium layer, and the lithium layer does not react with the separator / solid electrolyte layer by means of the porous polymer.

[0074] In addition, in steps S2) and S3), the porous polymer is deformed to reduce the externally applied pressure (F) and to ensure that the pressure (F) operates uniformly, thereby reducing the pressure applied to the entire lithium secondary battery. Through this, the positions of the positive electrode, separator / solid electrolyte layer, and negative electrode inside the lithium secondary battery are not altered, and they can receive a constant pressure when pressurized; ultimately, this prevents cell short circuits from occurring internally, thereby improving the safety of the lithium secondary battery.

[0075] At this time, the porous polymer is deformed so that its length decreases in the direction of pressure and it increases in the direction perpendicular to the direction of pressure, thereby reducing the pressure applied to the entire lithium secondary battery.

[0076] In the following, the present invention will be explained through an experimental example comparing an experimental example according to the present invention with a comparative example according to the prior art.

[0077] (Experimental Example 1) Elasticity test of porous support

[0078] A PE separator with a porosity of 45%, a PE separator with a porosity of 49%, a PET nonwoven fabric with a porosity of 47%, and a nickel foam with a porosity of 89% were each cut into 26.8 cm x 26.8 cm pieces and then pressurized at 5 MPa, 10 MPa, 15 MPa, and 20 MPa, respectively. The thicknesses of the PE separator with a porosity of 45%, the PE separator with a porosity of 49%, the PET nonwoven fabric with a porosity of 47%, and the nickel foam with a porosity of 89% were measured before and after pressurization, and are shown in Table 1 below.

[0079]

[0080] As can be seen in Table 1 above, PE separators with a porosity of 45%, PE separators with a porosity of 49%, and PET nonwoven fabrics with a porosity of 47% do not show significant changes in thickness even when the pressure increases, whereas in the case of nickel foam with a porosity of 89%, which is made of metal, the amount of change in thickness according to pressure is very large. Through this, it can be seen that when the negative electrode according to the present invention is used, the thickness of the negative electrode for a secondary battery does not change due to the increase in thickness of the deposited lithium generated during charging, whereas when a negative electrode not according to the present invention is used, the thickness of the negative electrode for a secondary battery decreases when the thickness increases due to the deposited lithium generated during charging, and it is difficult to maintain a constant internal pressure of the battery because this thickness cannot be restored to its original state during discharge.

[0081] (Experimental Example 2)

[0082] In Experimental Example 2, a laminate formed with the following configuration was used to perform an initial charge and discharge cycle (charge condition: CC / CV, (4.25V, 0.05C, 0.01C current cut-off), discharge condition: CC condition 3V, 0.05C, 60℃), and the initial capacity, efficiency, and cell short-circuit occurrence rate were measured.

[0083] The above initial capacity was measured by performing charge and discharge under 60℃ conditions, and the above efficiency was calculated by dividing the discharge capacity by the charge capacity and is shown in Table 2 below.

[0084] (Example 1)

[0085] Cathode active material NCM811 (LiNi 0.8 Ci 0.1 Mn 0.102 A positive electrode slurry was prepared by dispersing and stirring a solid electrolyte agarodite (Li6PS5Cl), a conductive carbon, and a PTFE binder in an anisole in a weight ratio of 77.5:19.5:1.5:1. The positive electrode slurry was applied to an aluminum current collector with a thickness of 15 μm using a doctor blade, and a positive electrode was prepared by vacuum drying at 100°C for 12 hours.

[0086] A solid electrolyte layer slurry was formed by mixing and stirring agirodite (Li6PS5Cl) and a PTFE binder in a weight ratio of 95:5, coating the slurry onto a release film, and then vacuum drying it at 100°C for 12 hours to form a solid electrolyte layer.

[0087] A laminate was fabricated by sequentially stacking the above anode, a solid electrolyte layer, a nickel foil with a thickness of 11 μm, and a PE separator with a porosity of 45%.

[0088] After fastening the above laminate to a jig to apply a force of 5 MPa, the above charge and discharge were performed.

[0089] (Example 2)

[0090] The experiment was conducted in the same manner as in Example 1, except that a PE membrane with a porosity of 49% was applied instead of the PE membrane with a porosity of 45% in Example 1.

[0091] (Example 3)

[0092] The experiment was performed in the same manner as in Example 1, except that the laminate fabricated in Example 1 was fastened to a jig to apply a force of 10 MPa.

[0093] (Comparative Example 1)

[0094] The experiment was performed in the same manner as Example 1, except that the PE separator with a porosity of 45% was laminated without the above Example 1.

[0095] (Comparative Example 2)

[0096] The experiment was conducted in the same manner as in Example 1, except that a PET nonwoven fabric with a porosity of 47% was used instead of a PE separator with a porosity of 45% in Example 1.

[0097]

[0098] As can be seen in Table 2, when a porous support with good elasticity is used, as in Examples 1 to 3 of the present invention, it can be seen that the rate of short circuits in the battery is significantly lower compared to cases where it is not. In particular, the support of Comparative Example 2 is in the form of a nonwoven fabric with an excessively small change in thickness according to pressure, so the fibers within the nonwoven fabric do not particularly shrink, and pressure is concentrated at the junctions between the fibers. As a result, lithium is deposited unevenly on the surface of the current collector during charging and discharging, and it can be seen that the effect of reducing the short circuit rate of the secondary battery is lower than that of Examples 1 to 3.

[0099] In addition, as shown in Table 2, it can be seen that the safety of the secondary battery is improved when the negative electrode according to the present invention is used. Furthermore, it can be seen that the battery performance is also improved, as the efficiency of Examples 1 to 3 according to the present invention is better than that of Comparative Examples 1 and 2.

[0100] The present invention also provides a battery module including the lithium secondary battery, a battery pack, and a device including the battery pack. Since such battery packs and devices are known in the art, a detailed description thereof is omitted in this specification.

[0101] The above-mentioned device may be, for example, a laptop computer, netbook, tablet PC, mobile phone, MP3, wearable electronic device, power tool, electric vehicle (EV), hybrid electric vehicle (HEV), plug-in hybrid electric vehicle (PHEV), electric bicycle (E-bike), electric scooter (E-scooter), electric golf cart, or power storage system, but is not limited to these.

[0102] A person skilled in the art to which the present invention pertains would be able to perform various applications and modifications within the scope of the present invention based on the above content. Explanation of the symbols

[0103] 10, 100 : positive electrode 11, 110: Positive current collector 12, 120: Anode active material layer 20, 200 : Separator / Solid Electrolyte Layer 30, 300: Cathode 31: Cathode current collector 32: Cathode active material layer 310 : Porous support 320: Cathode current collector layer 330: Lithium layer F: Pressure f1 : horizontal f2 : vertical f3 : thickness

Claims

Claim 1 A negative electrode for a lithium secondary battery comprising: a porous support; and a negative electrode current collector layer formed on at least one surface of the porous support; wherein the porous support comprises an elastic material and the pores return to their original state when pressure is removed, the porous support comprises an olefin-based porous substrate or a sheet or nonwoven fabric manufactured from one or more selected from the group including glass fiber and polyethylene, and the porous support has a thickness retention rate of 70% or more under pressure of 20 MPa. Claim 2 In claim 1, the negative electrode is a negative electrode for a lithium secondary battery that does not include a separate negative electrode active material. Claim 3 In claim 1, the negative electrode current collector layer comprises one or more metals and / or metal alloys selected from the group including lithium, copper, and nickel, for a negative electrode for a lithium secondary battery. Claim 4 In claim 1, the negative electrode current collector layer is a negative electrode for a lithium secondary battery made of a conductive material having lithium affinity. Claim 5 In claim 4, the conductive material having lithium affinity is a negative electrode for a lithium secondary battery comprising one or more of metals including materials such as Au, Ag, Pt, Zn, Si, Sn, Ni, Bi, and Mg, and metal oxides including materials such as CuO, ZnO, MnO, and CoO. Claim 6 delete Claim 7 delete Claim 8 In claim 1, the porous support is a negative electrode for a lithium secondary battery comprising at least one of a ceramic, a metal, or a metal alloy in addition to a polymer having a porous structure. Claim 9 In claim 1, the porous support is a nonwoven fabric structure or a negative electrode for a lithium secondary battery formed by uniaxial stretching or biaxial stretching. Claim 10 In claim 1, the porous support comprises pores of 0.01 μm to 10 μm, for a negative electrode for a lithium secondary battery. Claim 11 A negative electrode for a lithium secondary battery according to claim 1, wherein the porosity of the porous support is 10% to 90%. Claim 12 A lithium secondary battery comprising a negative electrode for a lithium secondary battery according to any one of claims 1 to 5 and claims 8 to 11. Claim 13 In claim 12, the positive electrode of the lithium secondary battery comprises a porous support on at least one surface.

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