Negative electrode for lithium secondary battery and method for manufacturing same

Abstract

The present disclosure provides a negative electrode for a lithium secondary battery and a method for manufacturing same. The negative electrode for a lithium secondary battery according to the present disclosure comprises: a metal current collector substrate; an electrodeposition inducing layer formed on at least one side of the metal current collector substrate; and a protective layer formed on the electrodeposition inducing layer, wherein the electrodeposition inducing layer comprises a conductive polymer, and the protective layer may include an electroactive polymer.

Description

Negative electrode for lithium secondary battery and method for manufacturing the same

[0001] The present disclosure relates to a negative electrode for a lithium secondary battery and a method for manufacturing the same.

[0002]

[0003] Recently, accompanied by the rapid proliferation of battery-powered electronic devices such as mobile phones, laptop computers, and electric vehicles, the demand for high-energy-density, high-capacity rechargeable batteries is rapidly increasing. Accordingly, research and development to improve the performance of lithium-ion batteries is actively underway.

[0004] A lithium secondary battery is a battery comprising a positive electrode and a negative electrode containing an active material capable of lithium ion intercalation and deintercalation, and an electrolyte, and produces electrical energy through oxidation and reduction reactions when lithium ions are intercalated / deintercalated from the positive electrode and the negative electrode.

[0005] Currently commercially available lithium secondary batteries mainly use carbon-based negative electrode active materials such as graphite. Carbon-based negative electrode active materials do not change in volume during charging and discharging, so the stability of lithium secondary batteries is high. The theoretical electric capacity of graphite is small, about 372 mAh / g.

[0006] Lithium metal can be used as a negative electrode active material. Lithium metal has a very large theoretical electric capacity of about 3860 mAh / g. Therefore, this battery has the advantage of having a significantly higher energy density per unit weight compared to conventional lithium-ion batteries in which a thick carbon-based negative electrode active material is coated on a negative electrode current collector.

[0007] However, during charging and discharging, dendrites may form on the surface of the lithium metal due to side reactions with the electrolyte, and as the dendrites grow, they can cause a short circuit between the anode and the cathode. Consequently, the lifespan characteristics and thermal stability of the lithium metal battery containing lithium metal are degraded.

[0008] Therefore, a method is required to improve the lifespan characteristics and thermal stability of lithium metal secondary batteries containing lithium metal.

[0009] The information described above disclosed in the background technology of this invention is intended only to enhance understanding of the background of the present invention and may therefore include information that does not constitute prior art.

[0010]

[0011] One embodiment provides a negative electrode for a lithium secondary battery and a method for manufacturing the same to solve the above technical problem.

[0012] Another embodiment provides a lithium secondary battery comprising a negative electrode for a lithium secondary battery to solve the above technical problem.

[0013]

[0014] A negative electrode for a lithium secondary battery according to one embodiment of the present invention for solving the above technical problem comprises a metal current collector, an electrodeposition inducing layer formed on at least one surface of the metal current collector, and a protective layer formed on the electrodeposition inducing layer, wherein the electrodeposition inducing layer comprises a conductive polymer and the protective layer may comprise an electroactive polymer.

[0015] A method for manufacturing a negative electrode for a lithium secondary battery according to one embodiment of the present invention comprises the steps of providing a metal current collector, forming an electrodeposition inducing layer on at least one surface of the metal current collector, and forming a protective layer on the electrodeposition inducing layer, wherein the electrodeposition inducing layer comprises a conductive polymer and the protective layer may comprise an electroactive polymer.

[0016] A lithium secondary battery according to one embodiment of the present invention comprises a positive electrode, a negative electrode for a lithium secondary battery, and an electrolyte disposed between the positive electrode and the negative electrode. The negative electrode for a lithium secondary battery comprises a metal current collector, an electrodeposition inducing layer formed on at least one surface of the metal current collector, and a protective layer formed on the electrodeposition inducing layer. The electrodeposition inducing layer may comprise a conductive polymer, and the protective layer may comprise an electroactive polymer.

[0017]

[0018] A negative electrode for a lithium secondary battery according to some embodiments of the present disclosure can effectively reduce the surface roughness of a metal current collector by forming an electrodeposition-inducing layer containing a conductive polymer on the surface of a metal current collector, and the electrodeposition-inducing layer can induce uniform nucleation of lithium during the charging process by acting as a lithium electrodeposition substrate.

[0019] A negative electrode for a lithium secondary battery according to some embodiments of the present disclosure may have a protective layer comprising an electroactive polymer that induces high-density electrodeposition of lithium and simultaneously acts as a protective film that prevents direct contact between lithium and the electrolyte.

[0020] A negative electrode for a lithium secondary battery according to some embodiments of the present disclosure can provide a round, uniform, and high-density lithium electrodeposition effect when applied to a secondary battery through the synergistic effect of a double-layer structure composed of an electrodeposition inducing layer and a protective layer.

[0021] A method for manufacturing a negative electrode for a lithium secondary battery according to some embodiments of the present disclosure can minimize the reduction in energy density of the battery by forming a thin double-sided structure on the surface of a metal current collector substrate through a method combining spray coating and spin coating.

[0022] However, the effects obtainable through the present invention are not limited to those described above, and other unmentioned technical effects will be clearly understood by those skilled in the art from the description of the invention below.

[0023]

[0024] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings.

[0025] FIG. 1 is a schematic diagram showing the structure of a negative electrode for a lithium secondary battery according to one embodiment of the present disclosure.

[0026] FIG. 2 is a drawing showing an SEM image of a copper current collector coated with Ag-doped PEDOT-co-PEG according to one embodiment of the present disclosure.

[0027] FIG. 3 is a drawing showing an SEM image of the surface in contact with the electrolyte in a negative electrode for a lithium secondary battery provided according to an embodiment of the present disclosure.

[0028] FIG. 4 is a drawing showing an SEM image of the surface in contact with the electrolyte in a negative electrode for a lithium secondary battery provided according to a comparative example of the present disclosure.

[0029] FIG. 5 is a drawing showing SEM images of the surface and cross-section of a negative electrode after an initial charging process has been performed on a negative electrode for a lithium secondary battery provided according to an embodiment of the present disclosure.

[0030] FIG. 6 is a drawing showing SEM images of the surface and cross-section of a negative electrode after 30 charging cycles have been performed on a negative electrode for a lithium secondary battery provided according to an embodiment of the present disclosure.

[0031] FIG. 7 is a drawing showing SEM images of the surface and cross-section of a negative electrode after an initial charging process has been performed on a negative electrode for a lithium secondary battery provided according to a comparative example of the present disclosure.

[0032] FIG. 8 is a drawing showing SEM images of the surface and cross-section of a negative electrode after 30 charging cycles in a negative electrode for a lithium secondary battery provided according to a comparative example of the present disclosure.

[0033] FIG. 9 is a flowchart illustrating an example of a method for manufacturing a negative electrode for a lithium secondary battery according to the present disclosure.

[0034] FIG. 10 is a drawing showing the step of forming an electrodeposition-inducing layer on at least one surface of a metal current collector according to one embodiment of the present disclosure.

[0035] FIG. 11 is a drawing showing the step of forming a protective layer on an electrodeposition inducing layer according to one embodiment of the present disclosure.

[0036] FIG. 12 is a drawing showing a stacked structure of a lithium secondary battery according to one embodiment of the present disclosure.

[0037] FIG. 13 is a diagram showing the structure in which lithium metal layers are stacked after charging the lithium secondary battery of FIG. 12.

[0038] FIG. 14 is a perspective view illustrating a lithium secondary battery according to one embodiment.

[0039] FIG. 15 is a perspective view illustrating a lithium secondary battery according to one embodiment.

[0040] FIG. 16 is a perspective view illustrating a lithium secondary battery according to one embodiment.

[0041] FIG. 17 is a perspective view illustrating a lithium secondary battery according to one embodiment.

[0042] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below.

[0043] Unless otherwise specifically stated in this specification, when a part such as a layer, film, region, plate, etc. is described as being "on" another part, this includes not only cases where it is "immediately on" another part, but also cases where there is another part in between.

[0044] Unless otherwise specified in this specification, a singular form may also include a plural form. Additionally, unless otherwise specified, "A or B" may mean "including A, including B, or including A and B."

[0045] In this specification, "combination of these" may mean a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, and a reaction product, etc.

[0046] Methods and materials similar or equivalent to those described herein may be used in the practice or testing of the present invention, but suitable methods and materials are described herein. The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0047] In this specification, terms such as “comprising” or “having” are intended to indicate the existence of the features, numbers, steps, actions, components, parts, components, materials, or combinations thereof described in the specification, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, components, materials, or combinations thereof.

[0048] In this specification, the term “combination of these” means a mixture or combination with one or more of the described components, and may mean a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, and a reaction product, etc.

[0049] In this specification, the term “and / or” means any combination of one or more items described in relation and all combinations thereof. In this specification, the term “or” means “and / or”.

[0050] In this specification, when a part such as a layer, film, region, plate, etc. is described as being "on" another part, this includes not only cases where it is directly above the other part, but also cases where there is another part in between.

[0051] In this specification, terms such as "first," "second," etc., may be used to describe various components, but the components should not be limited by these terms. The terms are used solely for the purpose of distinguishing one component from another.

[0052] In this specification, “metal” includes both metals and metalloids such as silicon and germanium in an elemental or ionic state.

[0053] In this specification, "alloy" means a mixture of two or more metals.

[0054] In this specification, "anode active material" refers to an anode material capable of undergoing lithiation and delithiation.

[0055] In this specification, "anode active material" refers to an anode material capable of undergoing lithiation and delithiation.

[0056] In this specification, "lithiation" and "to lithiate" refer to the process of adding lithium to a positive electrode active material or a negative electrode active material.

[0057] In this specification, "delithiation" and "to delithiate" refer to the process of removing lithium from a positive electrode active material or a negative electrode active material.

[0058] In this specification, "charge" and "to charge" refer to the process of providing electrochemical energy to a battery.

[0059] In this specification, "discharge" and "discharge" refer to the process of removing electrochemical energy from a battery.

[0060] In this specification, "anode" and "cathode" refer to electrodes where electrochemical reduction and lithiation occur during the discharge process.

[0061] In this specification, "cathode" and "anode" refer to electrodes where electrochemical oxidation and delithiation occur during the discharge process.

[0062] Exemplary embodiments will be described in more detail below.

[0063]

[0064] cathode

[0065] FIG. 1 is a schematic diagram showing the structure of a negative electrode for a lithium secondary battery according to one embodiment of the present disclosure.

[0066] Referring to FIG. 1, a negative electrode (100) for a lithium secondary battery according to one embodiment of the present invention may include a metal current collector (110), an electrodeposition inducing layer (120) formed on at least one surface of the metal current collector (110), and a protective layer (130) formed on the electrodeposition inducing layer (120).

[0067] In one embodiment, the metal current collector (110) may comprise copper, nickel, stainless steel, aluminum, or a combination thereof. For example, the metal current collector (110) may be a copper foil, a nickel foil, or a nickel-plated copper foil.

[0068] In one embodiment, the electrodeposition inducing layer (120) may include a conductive polymer. To enable the electrodeposition inducing layer (120) to serve as a lithium electrodeposition substrate, the conductive polymer may include a lithium-affinity functional group. Due to the lithium-affinity functional group, the formation of SEI on the negative electrode (100) for a lithium secondary battery may be promoted.

[0069] In one embodiment, the conductive polymer may include a first polymer.

[0070] The first polymer may have a pi-conjugated structure. For example, the first polymer may include poly(3,4-ethylenedioxythiophene) (PEDOT), polyaniline, polypyrrole, polyacetylene, polydopamine, polythiophene, poly(p-phenylene vinylene) or a combination thereof.

[0071] In one embodiment, the conductive polymer may include a second polymer.

[0072] The second polymer may have a hydrophilic chain structure. For example, the second polymer may include polyethylene glycol (PEG), polypropylene glycol (PPG), PVP (Polyvinylpyrrolidone), PVA (Polyvinyl Alcohol), PHEMA (Poly(2-hydroxyethyl methacrylate)), PDMS (Polydimethylsiloxane), or a combination thereof.

[0073] In one embodiment, the conductive polymer may comprise a copolymer of a first polymer and a second polymer. For example, the conductive polymer may comprise a block copolymer of a first polymer having a pi-conjugated structure and a second polymer having a hydrophilic chain structure.

[0074] In one embodiment, the protective layer (130) may include an electroactive polymer. Here, the electroactive polymer may be a ferroelectric polymer that induces a high electrodeposition density of lithium.

[0075] For example, the electroactive polymer may include polyvinylidene fluoride (PVDF). Polyvinylidene fluoride may have various crystalline forms depending on the drying conditions after coating. For example, the crystalline form of polyvinylidene fluoride may be β (beta). When the crystalline form of polyvinylidene fluoride is β, the fluorine functional groups are aligned in a direction in contact with the electrolyte on the protective layer (130), which helps to uniformly electrodeposit lithium and suppress side reactions between lithium and the electrolyte during the charge-discharge cycle.

[0076] According to some embodiments of the present disclosure, a negative electrode for a lithium secondary battery may have a protective layer comprising an electroactive polymer that induces high-density electrodeposition of lithium and simultaneously acts as a protective film that prevents direct contact between lithium and the electrolyte.

[0077] In one embodiment, the thickness of the electrodeposition inducing layer (120) or the protective layer (130) may be 1 μm to 20 μm. Specifically, the thickness of the electrodeposition inducing layer may be 1 μm to 10 μm, 1 μm to 5 μm, 2 μm to 7 μm, or 4 μm to 6 μm. Additionally, the thickness of the protective layer may be 1 μm to 20 μm, 1 μm to 10 μm, 2 μm to 7 μm, or 4 μm to 6 μm.

[0078] According to some embodiments of the present disclosure, a negative electrode (100) for a lithium secondary battery can provide a round, uniform, and high-density lithium electrodeposition effect when applied to a secondary battery through the synergistic effect of a double-layer structure composed of an electrodeposition inducing layer (120) and a protective layer (130).

[0079] FIG. 2 is a drawing showing an SEM image of a copper current collector coated with Ag-doped PEDOT-co-PEG according to one embodiment of the present disclosure.

[0080] Referring to FIG. 2, in one embodiment, the conductive polymer forming the electrodeposition-inducing layer may include Ag. Specifically, the electrodeposition-inducing layer formed on at least one surface of a metal current collector substrate may include a conductive polymer. Here, the conductive polymer may include a material in which silver (Ag) is doped into a copolymer of a first polymer having a pi-conjugation structure and a second polymer having a hydrophilic chain structure. As shown in FIG. 2, by doping silver between the copolymer polymers, electrical conductivity can be improved and a more stable electrodeposition-inducing layer can be formed.

[0081] FIG. 3 is a drawing showing an SEM image of a surface in contact with an electrolyte in a negative electrode for a lithium secondary battery provided according to an embodiment of the present disclosure. FIG. 4 is also a drawing showing an SEM image of a surface in contact with an electrolyte in a negative electrode for a lithium secondary battery provided according to a comparative example of the present disclosure.

[0082] Referring to FIG. 3, the surface in contact with the electrolyte in the negative electrode for a lithium secondary battery according to Examples 1, 2, 3, and 4 of the present disclosure can be observed through SEM analysis from the left. Additionally, referring to FIG. 4, the surface in contact with the electrolyte in the negative electrode for a lithium secondary battery according to Comparative Example 1, 2, and 3 from the left can be observed. The negative electrode for a lithium secondary battery used in the SEM analysis has a negative electrode structure in which the negative electrode active material is absent.

[0083] As described below, for the negative electrode of a lithium secondary battery according to Example 1, a copper foil was provided as a metal current collector, and then a PEDOT-block-PEG conductive polymer was coated on the copper foil to form an electrodeposition-inducing layer. Subsequently, a protective layer containing β-phase PVdF was formed on the electrodeposition-inducing layer.

[0084] As described below, for the negative electrode of a lithium secondary battery according to Example 2, a copper foil was provided as a metal current collector, and then a PEDOT conductive polymer was coated on the copper foil to form an electrodeposition-inducing layer. Subsequently, a protective layer containing β-phase PVdF was formed on the electrodeposition-inducing layer.

[0085] As described below, for the negative electrode of a lithium secondary battery according to Example 3, a copper foil was provided as a metal current collector, and then a PEDOT-block-PEG conductive polymer was coated on the copper foil to form an electrodeposition-inducing layer. Subsequently, a protective layer was formed on the electrodeposition-inducing layer to include α-phase PVdF.

[0086] As described below, for the negative electrode of a lithium secondary battery according to Example 4, a copper foil was provided as a metal current collector, and then a PEDOT-block-PEG conductive polymer was coated on the copper foil to form an electrodeposition-inducing layer. Subsequently, a protective layer containing γ-phase PVdF was formed on the electrodeposition-inducing layer.

[0087] As described below, for the negative electrode of a lithium secondary battery according to Comparative Example 1, a copper foil was provided as a metal current collector, and then a PEDOT-block-PEG conductive polymer was coated on the copper foil to form an electrodeposition-inducing layer.

[0088] As described below, the negative electrode for a lithium secondary battery according to Comparative Example 2 is provided with a copper foil as a metal current collector, and then a protective layer is formed on the copper foil to include β-phase PVdF.

[0089] The negative electrode for a lithium secondary battery according to Comparative Example 3 was formed by providing a copper foil as a metal current collector without forming an electrodeposition inducing layer and a protective layer, as described below.

[0090] Referring to the SEM images in FIGS. 3 and 4, the surface in contact with the electrolyte in the negative electrode for a lithium secondary battery according to Example 1 and Example 2 is different from Comparative Example 1 and similar to Comparative Example 2. Through this, it can be confirmed that a protective layer containing β-phase PVdF is formed on the surface in contact with the electrolyte in the negative electrode for a lithium secondary battery according to Example 1 and Example 2.

[0091] FIG. 5 is a drawing showing SEM images of the surface and cross-section of a negative electrode after an initial charging process has been performed on a negative electrode for a lithium secondary battery provided according to an embodiment of the present disclosure. FIG. 6 is also a drawing showing SEM images of the surface and cross-section of a negative electrode after 30 charge-discharge cycles have been performed on a negative electrode for a lithium secondary battery provided according to an embodiment of the present disclosure.

[0092] FIG. 7 is a drawing showing SEM images of the surface and cross-section of a negative electrode after an initial charging process in a negative electrode for a lithium secondary battery provided according to a comparative example of the present disclosure. FIG. 8 is also a drawing showing SEM images of the surface and cross-section of a negative electrode after 30 charge-discharge cycles in a negative electrode for a lithium secondary battery provided according to a comparative example of the present disclosure.

[0093] Referring to FIGS. 5 and 7, the surface of the negative electrode for a lithium secondary battery provided according to the embodiments and comparative examples of the present disclosure can be observed through SEM analysis after the initial charging process. Here, it can be confirmed that lithium is most densely electrodeposited on the surface of the negative electrode for a lithium secondary battery provided according to Example 1.

[0094] Referring to FIGS. 6 and FIGS. 8, the surface of the negative electrode for a lithium secondary battery provided according to the embodiments and comparative examples of the present disclosure can be observed through SEM analysis after 30 charge-discharge cycles. Here, as in FIG. 5, it can be confirmed that lithium is most densely electrodeposited on the surface of the negative electrode for a lithium secondary battery provided according to Example 1.

[0095] Referring to FIGS. 5 and 6, through SEM analysis, a cross-section showing lithium electrodeposited before and after an initial charging process and 30 charge-discharge cycles can be observed on the negative electrode for a lithium secondary battery provided according to an embodiment of the present disclosure. Additionally, referring to FIGS. 7 and 8, through SEM analysis, a cross-section showing lithium electrodeposited before and after an initial charging process and 30 charge-discharge cycles can be observed on the negative electrode for a lithium secondary battery provided according to a comparative example of the present disclosure.

[0096] Specifically, the change in thickness of the electrodeposited lithium before and after the initial charging process and 30 charge-discharge cycles is observed as follows: Example 1 (29.9 μm → 32.1 μm), Example 2 (33.2 μm → 39.7 μm), Example 3 (34.3 μm → 41.8 μm), Example 4 (32.1 μm → 37.9 μm), Comparative Example 1 (31.2 μm → 37.2 μm), Comparative Example 2 (33.7 μm → 40.9 μm), and Comparative Example 3 (36.7 μm → 48.1 μm). Therefore, it can be confirmed that lithium is electrodeposited most densely in Example 1.

[0097] A negative electrode for a lithium secondary battery according to some embodiments of the present disclosure can effectively reduce the surface roughness of a metal current collector by forming an electrodeposition-inducing layer containing a conductive polymer on the surface of a metal current collector, and the electrodeposition-inducing layer acts as a lithium electrodeposition substrate to induce uniform nucleation of lithium during the charging process. The results of additional tests related to the above-described embodiments and comparative examples are as follows. However, the embodiments are for illustrative purposes only and are not limited thereto.

[0098]

[0099] Example 1: Preparation of a negative electrode for a lithium secondary battery

[0100] A copper foil was prepared as a metal current collector. A solution containing 1 wt% of a conductive polymer, Poly(3,4-ethylenedioxythiophene)-block-poly(ethylene glycol) (PEDOT-block-PEG), dispersed in nitromethane solvent was coated onto the copper foil using a method combining spin coating and spray coating to form an electrodeposition-inducing layer. Subsequently, a solution containing 10 wt% of a polyvinylidene fluoride (PVdF) polymer dissolved in dimethylformamide (N-Dimethylformamide) solvent was dropped onto the electrodeposition-inducing layer and spun at 8000 rpm. Afterward, a protective layer containing β-phase PVdF was formed by vacuum drying at room temperature for 2 hours followed by drying at 60°C for 12 hours, thereby manufacturing a cathode.

[0101]

[0102] Example 2: Preparation of a negative electrode for a lithium secondary battery

[0103] Based on the composition listed in Table 1, a cathode was prepared in the same manner as in Example 1.

[0104]

[0105] Example 3: Preparation of a negative electrode for a lithium secondary battery

[0106] Based on the composition listed in Table 1, a cathode was prepared in the same manner as in Example 1.

[0107] Example 4: Preparation of a negative electrode for a lithium secondary battery

[0108] Based on the composition listed in Table 1, a cathode was prepared in the same manner as in Example 1.

[0109] Comparative Example 1: Preparation of a negative electrode for a lithium secondary battery

[0110] A copper foil was prepared as a metal current collector. A solution in which a conductive polymer, Poly(3,4-ethylenedioxythiophene)-block-poly(ethylene glycol) and PEDOT-block-PEG, is dispersed at a content of 1 wt% in a nitromethane solvent was coated onto the copper foil using a method combining spin coating and spray coating to form an electrodeposition-inducing layer. Subsequently, a cathode was manufactured without forming a protective layer.

[0111]

[0112] Comparative Example 2: Preparation of a negative electrode for a lithium secondary battery

[0113] A copper foil was prepared as a metal current collector. Subsequently, without forming an electrodeposition inducing layer, a solution containing 10 wt% of polyvinylidene fluoride (PVdF) polymer dissolved in dimethylformamide (N-Dimethylformamide) solvent was dropped onto the copper foil and spun at 8000 rpm. Afterward, a cathode was prepared by forming a protective layer containing β-phase PVdF by vacuum drying at room temperature for 2 hours followed by drying at 60°C for 12 hours.

[0114]

[0115] Comparative Example 3: Preparation of a negative electrode for a lithium secondary battery

[0116] A copper foil was prepared as a metal current collector, and a cathode was manufactured without forming an electrodeposition induction layer or a protective layer.

[0117]

[0118] Classification Metal Current Collector Substrate Electrodeposition Inducing Layer (Conductive Polymer) Protective Layer (Electroactive Polymer) Crystalline Form of Electroactive Polymer Example 1 Copper Foil PEDOT-block-PEGPVdFβ-phase Example 2 Copper Foil PEDOTTPVdFβ-phase Example 3 Copper Foil PEDOT-block-PEGPVdFα-phase Example 4 Copper Foil PEDOT-block-PEGPVdFγ-phase Comparative Example 1 Copper Foil PEDOT-block-PEG-- Comparative Example 2 Copper Foil-PVdFβ-phase Comparative Example 3 Copper Foil---

[0119] Evaluation Example 1: Verification of average Coulomb efficiency (%) Negative electrode for a lithium secondary battery, LiNi prepared according to Examples 1 to 4 and Comparative Examples 1 to 3 1-x-y Co x Al y A negative electrode lithium secondary battery was fabricated using an O2 (NCA) cathode, a polyolefin-based separator, and a carbonate-based liquid electrolyte. Subsequently, each lithium secondary battery was charged at a constant current rate of 0.1C at 45°C until the voltage reached 4.30V (vs. Li), and then cut off at a current rate of 0.05C while maintaining 4.30V in constant voltage mode. Subsequently, during discharge, the battery was discharged at a constant current rate of 0.1C until the voltage reached 3.6V (vs. Li) (formation stage, 1st cycle).

[0120] The formation process was completed by performing this charge-discharge process once.

[0121] Each lithium secondary battery that has undergone the formation stage was charged at 45°C with a constant current of 0.2C in a voltage range of 3.6 to 4.3 V relative to lithium metal, and then cut off at a current rate of 0.05C while maintaining 4.30V in constant voltage mode. Subsequently, constant current discharge was performed at 0.5C until a cut-off voltage of 3.6V was reached. The aforementioned charge-discharge process was repeated a total of 200 times. In all charge-discharge cycles, a 5-minute pause was observed after each cycle. Here, the Coulomb efficiency in the Nth cycle is defined by Equation 1 below.

[0122]

[0123] [Equation 1]

[0124] Capacity Retention Rate (%) = (Discharge Capacity at Nth Cycle / Discharge Capacity at 1st Cycle) × 100

[0125]

[0126] According to Evaluation Example 1 above, the capacity retention rate (%) at the 200th cycle for each of the example and comparative example is listed in Table 2 below.

[0127]

[0128] Classification 1st Cycle 200th Cycle Capacity Retention Rate (% @ 200 cy) Charge Capacity Discharge Capacity Charge Capacity Discharge Capacity Example 1 177.6 165.0 119.2 118.6 71.9 Example 2 172.1 157.8 104.6 102.8 65.4 Example 3 180.7 168.8 104.9 106.0 62.8 Example 4 172.5 159.4 105.8 105.8 66.4 Comparative Example 1 171.4 160.4 96.9 97.8 61.0 Comparative Example 2 176.6 165.8 100.7 100.9 60.9 Comparative Example 3 179.1 165.5 87.2 85.7 51.8

[0129] Figure 9 is a flowchart illustrating an example of a method for manufacturing a negative electrode for a lithium secondary battery according to the present disclosure. A method for manufacturing a negative electrode for a lithium secondary battery (500) according to one embodiment of the present invention may be disclosed by providing a metal current collector (S510). The metal current collector may include copper, nickel, stainless steel, aluminum, or a combination thereof.

[0130] In one embodiment, the step of providing a metal current collecting substrate (S510) may include the step of rotating the metal current collecting substrate.

[0131] Subsequently, an electrodeposition-inducing layer can be formed on at least one surface of a metal current collector (S520). Here, the electrodeposition-inducing layer may include a conductive polymer. The conductive polymer may include a first polymer having a pi-conjugation structure and a second polymer having a hydrophilic chain structure. Specifically, the conductive polymer may include a block copolymer of the first polymer having a pi-conjugation structure and the second polymer having a hydrophilic chain structure. In one embodiment, the conductive polymer may include Ag.

[0132] In one embodiment, the step of forming an electrodeposition-inducing layer (S520) may include the step of coating a solution containing a conductive polymer onto a metal current collector substrate in a manner combining spin coating and spray coating. For example, to ensure uniformity of the electrodeposition-inducing layer, a solution containing a conductive polymer may be sprayed with a spray coater while rotating the metal current collector substrate. The solution containing the conductive polymer may correspond to a solution in which a PEDOT-block-PEG polymer is dissolved in a solvent containing nitromethane, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), or a combination thereof at a ratio of 1 wt% to 30 wt%. In one embodiment, the solution containing the conductive polymer may include a dispersion of 1 wt% to 5 wt%.

[0133] After that, a protective layer can be formed on the electrodeposition-inducing layer (S530). The protective layer may include an electroactive polymer. The electroactive polymer may include polyvinylidene fluoride. Here, the crystalline form of polyvinylidene fluoride may be β.

[0134] In one embodiment, the step of forming a protective layer (S530) may include the step of coating a solution containing an electroactive polymer on an electrodeposition-inducing layer. For example, the solution containing the electroactive polymer may correspond to a solution in which a polyvinylidene fluoride (PVdF) polymer is dissolved in a solvent containing dimethylformamide (N-N-Dimethylformamide), N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), cyclohexanone (CYC), acetone (ACE), methyl ethyl ketone (MEK), γ-butyrolactone (GBL), propylene carbonate (PC), or a combination thereof, at a ratio of 1% to 20% by weight.

[0135] FIG. 10 is a drawing showing the step of forming an electrodeposition-inducing layer on at least one surface of a metal current collector according to one embodiment of the present disclosure.

[0136] Referring to FIG. 10, the step of forming an electrodeposition-inducing layer may include the step of spray-coating a solution containing a conductive polymer onto a rotating metal current collector.

[0137] Specifically, in the first step (610), the metal current collector (612) can be rotated at a constant speed. Then, in the second step (620), a solution (622) containing a conductive polymer can be sprayed onto the rotating metal current collector (612) using a spray coater. After that, in the third step (630), the metal current collector (612) can be further rotated to more uniformly coat the solution (622) containing the conductive polymer, while simultaneously drying the solution (622) containing the conductive polymer. For example, to dry the solution (622) containing the conductive polymer, the metal current collector (612) can be further rotated at 2000 rpm for 30 seconds.

[0138] The thickness of the electrodeposition inducing layer may be 1 μm to 10 μm, 2 μm to 7 μm, or 4 μm to 6 μm.

[0139] FIG. 11 is a drawing showing the step of forming a protective layer on an electrodeposition inducing layer according to one embodiment of the present disclosure.

[0140] Referring to FIG. 11, the step of forming a protective layer may include the step of coating a solution containing an electroactive polymer on the electrodeposition-inducing layer formed in FIG. 10.

[0141] Specifically, in the first step (710), a solution (714) containing an electroactive polymer can be dropped onto an electrodeposition induction layer. Then, in the second step (720), the solution (714) containing the electroactive polymer can be uniformly coated by rotating the metal current collector (712) at a constant speed (8000 rpm) for 10 to 30 seconds. After that, in the third step (730), the solution (714) containing the electroactive polymer can be dried while rotating the metal current collector (712) for an additional 5 to 10 seconds compared to the second step (720) in order to coat the solution (714) containing the electroactive polymer more uniformly.

[0142] The thickness of the protective layer may be 1 μm to 10 μm, 2 μm to 7 μm, or 4 μm to 6 μm.

[0143] A method for manufacturing a negative electrode for a lithium secondary battery according to some embodiments of the present disclosure can minimize the reduction in energy density of the battery by forming a thin double-sided structure on the surface of a metal current collector substrate through a method combining spray coating and spin coating.

[0144]

[0145] lithium secondary battery

[0146] FIG. 12 is a drawing showing a stacked structure of a lithium secondary battery according to one embodiment of the present disclosure, and FIG. 13 is a drawing showing a structure in which a lithium metal layer is stacked after the lithium secondary battery of FIG. 12 is charged.

[0147] The present disclosure describes lithium metal secondary batteries primarily but is not limited thereto. For example, it may be a lithium primary battery, and may also be applied to lithium-sulfur batteries, lithium-air batteries, etc.

[0148] Referring to FIG. 12, a lithium secondary battery according to one embodiment of the present disclosure may be a negative electrode-free lithium secondary battery (800) in which a negative electrode active material layer is absent (free) on the negative electrode before charging is performed. Referring to FIG. 13, as the negative electrode-free lithium secondary battery (800) is charged, lithium may be precipitated in a metallic state on the negative electrode (840) to form a lithium metal layer (850). Alternatively, a lithium secondary battery according to one embodiment may be a lithium metal secondary battery in which lithium metal is used as the negative electrode active material layer. The thickness of each layer shown in FIG. 12 and FIG. 13 is shown as an arbitrary size and is not necessarily limited thereto.

[0149] Specifically, a lithium secondary battery (800) according to one embodiment of the present invention may include a negative electrode (840) for a lithium secondary battery, an electrolyte (860) disposed on top of the negative electrode (840), and a positive electrode (830) disposed on top of the electrolyte (860). The positive electrode (830) may include a positive electrode current collector (810) and a positive electrode active material layer (820) disposed on the positive electrode current collector (810).

[0150] A negative electrode (840) for a lithium secondary battery according to one embodiment of the present invention may include a metal current collector, an electrodeposition inducing layer formed on at least one surface of the metal current collector, and a protective layer formed on the electrodeposition inducing layer. Here, the electrodeposition inducing layer may include a conductive polymer, and the protective layer may include an electroactive polymer.

[0151] The metal current collector, the electrodeposition inducing layer, and the protective layer are as described above with reference to FIGS. 1 to 11. For example, the metal current collector may comprise copper, nickel, stainless steel, aluminum, or a combination thereof, the conductive polymer may comprise a block copolymer of poly(3,4-ethylenedioxythiophene) (PEDOT) and polyethylene glycol (PEG), and the electroactive polymer may comprise polyvinylidene fluoride (PVDF) in the Beta phase.

[0152] As the non-anode lithium secondary battery (800) is charged, the lithium secondary battery (800) may include a lithium metal layer (850) disposed between the negative electrode (840) and the electrolyte (860). For example, the lithium secondary battery (800) may include a negative electrode (840), a lithium metal layer (850) disposed above the negative electrode (840), an electrolyte (860) disposed above the lithium metal layer (850), and a positive electrode (830) disposed above the electrolyte (860).

[0153] Here, the electrolyte (860) may have a solid, liquid, or gel form.

[0154] The lithium metal layer (850) may include lithium metal or a lithium alloy. For example, the lithium metal layer (850) may dissociate into lithium ions and metal cations during the discharge process, thereby reducing the thickness of the lithium metal layer (850). Conversely, the lithium metal layer (850) may increase in thickness by electrodepositing lithium ions during the charging process.

[0155] According to one embodiment, one or more of the stacked structures of the lithium secondary battery (800) as described above may be stacked or wound and accommodated in a case, and the case may be classified into cylindrical, prismatic, thin film, coin, pin type, etc.

[0156] FIGS. 14 to 17 are schematic diagrams illustrating a lithium secondary battery according to one embodiment, where FIG. 14 is cylindrical, FIG. 15 is prismatic, and FIGS. 16 and 17 are pouch-type batteries. Referring to FIGS. 14 to 17, the lithium secondary battery (1) includes a battery structure (7, electrode assembly) having a separator (4, separator) interposed between a positive electrode (3) and a negative electrode (2), and a case (5) in which the battery structure (7) is housed. The positive electrode (3), the negative electrode (2), and the separator (4) may be impregnated with an electrolyte (not shown). The lithium secondary battery (1) may include an assembly (6, sealing member) that seals the case (5) as in FIG. 14. Additionally, in FIG. 15, the lithium secondary battery (1) may include a positive lead tab (3') and a positive terminal (3"), a negative lead tab (2') and a negative terminal (2"). As shown in FIGS. 16 and 17, the lithium secondary battery (1) may include electrode tabs (70), namely a positive electrode tab (71) and a negative electrode tab (72), which serve as electrical passages for inducing current formed in the battery structure (7) to the outside.

[0157] Referring to FIG. 14, a lithium secondary battery (1) according to one embodiment includes the anode (3), the cathode (2), and the separator (4) described above. The anode (3), the cathode (2), and the separator (4) are wound or folded to form a battery structure (7). The formed battery structure (7) is housed in a case (5). An electrolyte is injected into the case (5) and sealed with a cap assembly (6) to complete the lithium secondary battery (1). The case (5) is cylindrical but is not necessarily limited to this shape and may be, for example, prismatic, thin film, etc.

[0158] Referring to FIG. 15, a lithium secondary battery (1) according to one embodiment includes a positive electrode (3), the aforementioned negative electrode (2), and a separator (4). The positive electrode (3), the negative electrode (2), and the separator (4) are wound, folded, or stacked to form a battery structure (7). The formed battery structure (7) is housed in a case (5). An electrolyte is injected into the case (5), cross-linked, and sealed to complete the lithium secondary battery (1). The case (5) is prismatic, but is not necessarily limited to this shape and may be, for example, cylindrical, thin film, etc. A positive lead tab (3') and a positive terminal (3") are electrically connected to the positive electrode (3). A negative lead tab (2') and a negative terminal (2") are electrically connected to the negative electrode (2).

[0159] Referring to FIG. 16, a lithium secondary battery (1) according to one embodiment includes a positive electrode (3), the aforementioned negative electrode (2), and a separator (4). A separator (4) is disposed between the positive electrode (3) and the negative electrode (2), and the positive electrode (3), the negative electrode (2), and the separator (4) are wound or folded to form a battery structure (7). The formed battery structure (7) is housed in a case (5). It may include an electrode tab (70) that serves as an electrical path for inducing the current formed in the battery structure (7) to the outside. An electrolyte is injected into the case (5) and sealed to complete the lithium secondary battery (1). The case (5) is prismatic but is not necessarily limited to this shape and may be, for example, cylindrical, thin film, etc.

[0160] Referring to FIG. 17, a lithium secondary battery (1) according to one embodiment includes a positive electrode (3), a negative electrode (2) and a separator (4) as described above. An electrolyte as described above, including a separator (4), is disposed between the positive electrode (3) and the negative electrode (2) to form a battery structure. For example, the battery structure (7) is stacked in a bicell structure and then housed in a case (5). It may include a positive electrode tab (71) and a negative electrode tab (72) that serve as electrical pathways for inducing current formed in the battery structure (7) to the outside. The electrolyte is injected into the case (5) and sealed to complete the lithium secondary battery (1). The case (5) is prismatic but is not necessarily limited to this shape and may be, for example, cylindrical, thin film, etc.

[0161] However, the present invention is not limited to this, and the case (5) may be configured in various shapes such as circular or pouch type. For example, the pouch-type lithium secondary battery corresponds to the lithium secondary battery (1) of FIGS. 14 to 17 in which a pouch is used as the case (5). The pouch-type lithium secondary battery includes one or more battery structures (7). A separator (4) is disposed between the positive electrode (3) and the negative electrode (2) to form the battery structure (7). The battery structure (7) is stacked in a bicell structure, then impregnated with an electrolyte, and then housed and sealed in a pouch to complete the pouch-type lithium secondary battery.

[0162] Specifically, the battery structure (7) including the aforementioned positive electrode (3), negative electrode (2), and separator (4) is simply stacked and contained in a pouch, or wound into a jelly roll shape or folded and contained in a pouch. Subsequently, an electrolyte is injected into the pouch and sealed to complete the lithium secondary battery (1).

[0163] The case (5) may be made of metal such as aluminum, aluminum alloy, nickel-plated steel, or a laminate film or plastic that constitutes the pouch.

[0164] Lithium secondary battery (1) has excellent lifespan characteristics and high rate characteristics, so it is used in, for example, electric vehicles (EV). For example, it is used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEV). In addition, it is used in fields where a large amount of power storage is required. For example, it is used in electric bicycles, power tools, etc.

[0165] A plurality of lithium secondary batteries (1) are stacked to form a battery module, and a plurality of battery modules form a battery pack. Such a battery pack can be used in any device requiring high capacity and high output. For example, it can be used in laptops, smartphones, electric vehicles, etc. A battery module includes, for example, a plurality of batteries and a frame that holds them.

[0166] A battery pack includes, for example, a plurality of battery modules and a bus bar connecting them. The battery modules and / or battery pack may further include a cooling device. A plurality of battery packs are controlled by a battery management system. The battery management system includes a battery pack and a battery control device connected to the battery pack.

[0167]

[0168] Cathode: Cathode current collector

[0169] The negative current collector may not include a negative active material layer. In a negative current collector that does not include a negative active material layer, lithium metal may be plated onto the negative current collector by charging. The plated metal layer may comprise plated lithium, lithium metal foil, lithium metal powder, lithium alloy foil, lithium alloy powder, an organic compound containing lithium, or a combination thereof. The metal layer may comprise non-fibrous lithium, non-needle lithium, plate lithium, or any combination thereof. The lithium alloy contains lithium and a first metal, and the first metal may include indium (In), silicon (Si), gallium (Ga), tin (Sn), aluminum (Al), titanium (Ti), zirconium (Zr), niobium (Nb), germanium (Ge), antimony (Sb), bismuth (Bi), gold (Au), platinum (Pt), palladium (Pd), magnesium (Mg), silver (Ag), zinc (Zn), nickel, iron, cobalt, chromium, cesium, sodium, potassium, calcium, yttrium, bismuth, tantalum, hafnium, barium, vanadium, strontium, lanthanum, or a combination thereof.

[0170] The material constituting the negative electrode current collector can be any material that does not react with lithium, that is, a material that does not form an alloy or compound with lithium and possesses conductivity. The metal substrate is, for example, a metal or an alloy. The metal substrate may be composed of, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or alloys thereof. The electrode current collector may have a form selected from, for example, a sheet, foil, film, plate, porous body, mesoporous body, through-hole containing body, polygonal ring body, mesh body, foam, and nonwoven body, but is not necessarily limited to these forms and any form used in the relevant technical field is possible.

[0171] The negative current collector comprises, for example, a first metal substrate. The first metal substrate comprises the first metal as a main component or is composed of the first metal. The first metal substrate comprises the first metal as a main component or is composed of the first metal. The content of the first metal included in the first metal substrate is, for example, 90 weight% or more, 95 weight% or more, 99 weight% or more, or 99.9 weight% or more with respect to the total weight of the first metal substrate. The first metal substrate may be composed of, for example, a material that does not react with lithium, that is, does not form an alloy and / or compound with lithium.

[0172] The first metal may be, for example, copper (Cu), nickel (Ni), stainless steel (SUS), iron (Fe), and cobalt (Co), but is not necessarily limited to these; any metal used as a current collector in the relevant technical field may be used. The first metal substrate may be composed of, for example, one of the metals described above, or may be composed of an alloy of two or more metals. The first metal substrate is, for example, in the form of a sheet or foil.

[0173] The negative current collector may further include a coating layer (not shown) containing a second metal on a first metal substrate.

[0174] The cathode current collector may include, for example, a first metal substrate and a coating layer disposed on the first metal substrate and comprising a second metal. The second metal has a higher Mohs hardness than the first metal. That is, since the coating layer comprising the second metal is harder than the substrate comprising the first metal, deterioration of the first metal substrate can be prevented. The Mohs hardness of the material constituting the first metal substrate is, for example, 5.5 or less. The Mohs hardness of the first metal is, for example, 5.5 or less, 5.0 or less, 4.5 or less, 4.0 or less, 3.5 or less, or 3.0 or less. The Mohs hardness of the first metal may be, for example, 2.0 to 6.0. The coating layer comprises the second metal. The coating layer may, for example, comprise the second metal as a main component or be composed of the second metal. The content of the second metal included in the coating layer is, for example, 90% by weight or more, 95% by weight or more, 99% by weight or more, or 99.9% by weight or more with respect to the total weight of the coating layer. The coating layer may be composed of, for example, a material that does not react with lithium, that is, does not form an alloy and / or compound with lithium. The Mohs hardness of the material constituting the coating layer is, for example, 6.0 or more. For example, the Mohs hardness of the second metal is 6.0 or more, 6.5 or more, 7.0 or more, 7.5 or more, 8.0 or more, 8.5 or more, or 9.0 or more. The Mohs hardness of the second metal may be, for example, 6.0 to 12. If the Mohs hardness of the second metal is excessively low, it may be difficult to suppress the deterioration of the negative electrode current collector. If the Mohs hardness of the second metal is excessively high, processing may not be easy. The second metal is one or more selected from, for example, titanium (Ti), manganese (Mn), niobium (Nb), tantalum (Ta), iridium (Ir), vanadium (V), rhenium (Re), osmium (Os), tungsten (W), chromium (Cr), boron (B), ruthenium (Ru), and rhodium (Rh).The coating layer may be composed of, for example, one of the metals described above, or an alloy of two or more metals. The difference in Mohs hardness between the first metal included in the first metal substrate and the second metal included in the coating layer may be, for example, 2 or more, 2.5 or more, 3 or more, 3.5 or more, or 4 or more. By having such a difference in Mohs hardness between the first metal and the second metal, the deterioration of the negative current collector can be suppressed more effectively. The coating layer may have a single-layer structure or a multilayer structure of two or more layers. The coating layer may have a two-layer structure including, for example, a first coating layer and a second coating layer. The coating layer may have a three-layer structure including, for example, a first coating layer, a second coating layer, and a third coating layer. The thickness of the coating layer may be, for example, 10 nm to 1 μm, 50 nm to 500 nm, 50 nm to 200 nm, or 50 nm to 150 nm. The coating layer may be deposited on the first metal substrate by, for example, vacuum deposition, sputtering, plating, etc., but is not necessarily limited to these methods; any method capable of forming a coating layer in the relevant technical field is possible.

[0175] For example, the cathode current collector may have a reduced thickness compared to a conventional cathode current collector. Accordingly, the cathode according to the present disclosure is distinguished from a conventional electrode comprising a thick film current collector by including, for example, a thin film current collector.

[0176] As a result, the energy density of a lithium metal secondary battery employing such an electrode is increased. The thickness of the negative electrode current collector may be, for example, less than 15 µm, 14.5 µm or less, or 14 µm or less. The thickness of the negative electrode current collector may be, for example, 0.1 µm to less than 15 µm, 1 µm to 14.5 µm, 2 µm to 14 µm, 3 µm to 14 µm, 5 µm to 14 µm, or 10 µm to 14 µm.

[0177] The cathode current collector may have a form selected from, for example, a sheet, foil, film, plate, porous body, mesoporous body, through-hole containing body, polygonal ring body, mesh body, foam, and nonwoven body, but is not necessarily limited to these forms, and any form used in the relevant technical field is possible.

[0178] According to one embodiment, a negative electrode active material layer may be free on the negative electrode current collector before charging and discharging. For example, a lithium metal layer may be free on the negative electrode current collector before charging and discharging.

[0179] According to one embodiment, a lithium metal layer including a plate-shaped lithium metal thin film may be disposed on a negative electrode current collector before performing charging and discharging.

[0180]

[0181] Cathode: Lithium metal layer

[0182] A lithium metal layer can be formed as lithium ions contained in the electrolyte are electrodeposited onto the negative current collector while the lithium secondary battery is being charged. For example, the lithium metal layer may include a lithium alloy and lithium metal. For instance, the lithium alloy included in the lithium metal layer weakens the reactivity of the lithium metal, thereby effectively preventing adverse reactions between the lithium metal layer and the electrolyte. Additionally, the lithium metal layer has excellent electrical conductivity, which can reduce the internal resistance of the lithium secondary battery containing it. Accordingly, a lithium secondary battery containing a lithium metal layer can improve not only its lifespan characteristics but also its charge / discharge efficiency.

[0183] According to one embodiment, the lithium metal layer may comprise, for example, lithium foil, lithium powder, plated lithium, a carbon-based material, or a combination thereof. For example, the lithium metal layer may comprise lithium foil. In this case, the lithium metal layer may be a negative electrode active material layer. For example, the lithium metal layer may be introduced by coating a slurry containing lithium powder and a binder, etc., onto a negative electrode current collector. For example, the binder may be a fluorine-based binder such as polyvinylidene fluoride (PVDF).

[0184] According to one embodiment, it may comprise only lithium metal or lithium alloy electrodeposited with a lithium metal layer. In this case, the lithium metal layer may be a lithium electrodeposited layer.

[0185] According to one embodiment, the lithium metal layer may not include a carbon-based negative electrode active material. Accordingly, the lithium metal layer may be composed of a metal-based negative electrode active material.

[0186] For example, the thickness of the lithium metal layer may be, for example, 0.1 μm to 100 μm, 0.1 μm to 80 μm, 1 μm to 80 μm, or 10 μm to 80 μm, but is not necessarily limited to these ranges and can be adjusted according to the required shape, capacity, etc. of the lithium secondary battery. If the thickness of the lithium metal layer increases excessively, the structural stability of the lithium secondary battery may decrease and side reactions may increase. If the thickness of the lithium metal layer is excessively small, the energy density of the lithium metal secondary battery may decrease.

[0187] According to one embodiment, the thickness of the lithium foil included in the lithium metal layer may be, for example, 1 μm to 50 μm, 1 μm to 30 μm, or 10 μm to 30 μm, or 10 μm to 80 μm. By having the lithium foil within this range of thickness, the lifespan characteristics of the lithium metal secondary battery can be further improved.

[0188] According to one embodiment, the particle size of the lithium powder included in the lithium metal layer may be, for example, 0.1 μm to 3 μm, 0.1 μm to 2 μm, or 0.1 μm to 1 μm. By having the lithium powder have a thickness within this range, the lifespan characteristics of the lithium secondary battery can be further improved.

[0189]

[0190] electrolytes

[0191] The electrolyte may be, for example, a liquid electrolyte, a solid electrolyte, a gel electrolyte, or a combination thereof.

[0192] The electrolyte is, for example, an organic electrolyte. The organic electrolyte is prepared, for example, by dissolving a lithium salt in an organic solvent. Any organic solvent used as an organic solvent in the relevant technical field may be used. Organic solvents are, for example, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether, or mixtures thereof.

[0193] Any lithium salt used as a lithium salt in the relevant technical field is also acceptable. Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(CxF2x+1SO2)(CyF2y+1SO2)(1≤x≤20, 1≤y≤20), LiCl, LiI, or mixtures thereof. The concentration of the lithium salt is, for example, 0.1 M to 5.0 M.

[0194] Solid electrolytes are, for example, oxide-based solid electrolytes, sulfide-based solid electrolytes, polymeric solid electrolytes, or combinations thereof.

[0195] Solid electrolytes are, for example, oxide-based solid electrolytes. Oxide-based solid electrolytes are Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(O≤x<1, O≤y<1), PB(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Li3PO4, Li x Ti y (PO4)3(0 <x<2, 0<y<3), Li x Al y Ti z (PO4)3(0 <x<2, 0<y<1, 0<z<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1 0≤y≤1), Li x La y TiO3(0 <x<2, 0<y<3), Li2O, LiOH, Li2CO3, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2, Li 3+x La3M2O 12 It is one or more selected from (M = Te, Nb, or Zr, where x is an integer from 1 to 10). Solid electrolytes are produced by sintering methods, etc. For example, oxide-based solid electrolytes include Li7La3Zr2O 12(LLZO) and Li 3+x La3Zr 2-a MaO 12 It is a garnet-type solid electrolyte selected from (M doped LLZO, M=Ga, W, Nb, Ta, or Al, x is an integer from 1 to 10).

[0196] Sulfide-based solid electrolytes may comprise, for example, lithium sulfide, silicon sulfide, phosphorus sulfide, boron sulfide, or combinations thereof. Sulfide-based solid electrolyte particles may comprise Li2S, P2S5, SiS2, GeS2, B2S3, or combinations thereof. Sulfide-based solid electrolyte particles may be Li2S or P2S5. Sulfide-based solid electrolyte particles have high lithium ion conductivity compared to other inorganic compounds. For example, sulfide-based solid electrolytes comprise Li2S and P2S5. When the sulfide solid electrolyte material constituting the sulfide-based solid electrolyte comprises Li2S-P2S5, the mixed molar ratio of Li2S to P2S5 may be, for example, in the range of about 50:50 to about 90:10. Additionally, Li3PO4, halogen, halogen compound, Li 2+2x Zn 1-x GeO4("LISICON", 0≤x<1), Li 3+y PO 4-x N x ("LIPON", 0 <x<4, 0<y<3), Li 3.25 Ge 0.25 P 0.75An inorganic solid electrolyte prepared by adding S4 ("ThioLISICON"), Li2O-Al2O3-TiO2-P2O5 ("LATP"), etc., to an inorganic solid electrolyte of Li2S-P2S5, SiS2, GeS2, B2S3, or a combination thereof can be used as a sulfide solid electrolyte. Non-limiting examples of sulfide solid electrolyte materials include Li2S-P2S5, Li2S-P2S5-LiX (X = halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-ZmSn (0 <m<10, 0<n<10, Z=Ge, Zn 또는 Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, 및 Li2S-SiS2-Li p MO q (0 <p<10, 0<q<10, M=P, Si, Ge, B, Al, Ga 또는 In)을 포함한다. 이와 관련하여, 황화물계 고체전해질 재료는 황화물계 고체전해질 물질의 원료 시작 물질(예를 들면, Li2S, P2S5, 등)을 용융 담금질법(melt quenching method), 기계적 밀링법 등에 의해 처리함으로써 제조될 수 있다.

[0197] In addition, a calcination process may be performed after the above treatment. The sulfide-based solid electrolyte may be amorphous, crystalline, or a mixture thereof.

[0198] Polymer solid electrolytes are electrolytes that, for example, contain a mixture of a lithium salt and a polymer, or contain a polymer having ion-conducting functional groups. Polymer solid electrolytes are, for example, polymer electrolytes that do not contain a liquid electrolyte. The polymers included in the polymeric solid electrolyte are, for example, polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyethylene oxide (PEO), poly(styrene-b-ethylene oxide) block copolymer (PS-PEO), poly(styrene-butadiene), poly(styrene-isoprene-styrene), poly(styrene-b-divinylbenzene) block copolymer, poly(styrene-ethylene oxide-styrene) block copolymer, polystyrene sulfonate (PSS), polyvinyl fluoride (PVF), poly(methylmethacrylate) (PMMA), polyethylene glycol (PEG), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), polyethylenedioxythiophene (PEDOT), polypyrrole (PPY), polyacrylonitrile (PAN), Polyaniline, Polyacetylene, Nafion, Aquivion, Flemion, Gore, Aciplex, Morgane ADP, Sulfonated poly, (ether ether ketone)(sulfonated poly(ether ether ketone), SPEEK), Sulfonated poly(arylene ether ketone ketone sulfone)(sulfonated poly(aryl ether ketone, SPAEK), Poly[bis(benzimidazobenzisoquinolinones)](poly[bis(benzimidazobenzisoquinolinones)], SPBIBI), Poly(styrene sulfonate)(Poly(styrene sulfonate), PSS), Lithium 9,It may be 10-diphenylanthracene-2-sulfonate (lithium 9,10-diphenylanthracene-2-sulfonate, DPASLi+) or a combination thereof, but is not limited thereto; any that is used as a polymer electrolyte in the relevant technical field is acceptable. Any lithium salt that can be used as a lithium salt in the relevant technical field is acceptable. Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C, x F 2x+1 SO2)(C y F 2y+1 SO2)(x and y are each 1 to 20), LiCl, LiI, or mixtures thereof, etc.

[0199] A gel electrolyte is, for example, a gel polymer electrolyte. A gel polymer electrolyte is an electrolyte that includes, for example, a liquid electrolyte and a polymer, or includes an organic solvent and a polymer having ion-conducting functional groups. The liquid electrolyte may be, for example, an ionic liquid, a mixture of a lithium salt and an organic solvent, a mixture of an ionic liquid and an organic solvent, or a mixture of a lithium salt, an ionic liquid, and an organic solvent. The polymer may be selected from among the polymers used in solid polymer electrolytes. The organic solvent may be selected from among the organic solvents used in liquid electrolytes. The lithium salt may be selected from among the lithium salts used in solid polymer electrolytes. An ionic liquid refers to a salt in a liquid state at room temperature or a room temperature molten salt that has a melting point below room temperature and consists solely of ions. The ionic liquid comprises, for example, a) one or more cations selected from ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, triazolium, and mixtures thereof, and b) BF4 - , PF6 - , AsF6 -, SbF6 - , AlCl4 - , HSO4 - , ClO4 - , CH3SO3 - , CF3CO2 - , Cl - , Br - , I - , BF4 - , SO4 - , CF3SO3 - , (FSO2)2N - , (C2F5SO2)2N - , (C2F5SO2)(CF3SO2)N - , and (CF3SO2)2N - It may include one or more compounds selected from those containing one or more anions selected from among. A gel polymer electrolyte may be formed by impregnating the polymer solid electrolyte into the electrolyte in a lithium secondary battery. The gel electrolyte may further include inorganic particles.

[0200]

[0201] anode

[0202] A positive active material layer is disposed on a positive current collector to form a positive electrode. A positive active material layer is disposed on an electrolyte, and a positive current collector may be disposed on the positive active material layer.

[0203]

[0204] Positive: Positive current collector

[0205] The positive electrode includes a positive electrode current collector. For example, a positive electrode can be prepared by forming a layer of positive electrode active material on the positive electrode current collector.

[0206] For example, the positive current collector may include indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof.

[0207] According to one embodiment, the anode current collector may include aluminum (Al).

[0208] For example, the positive current collector may include a base film and a metal substrate layer disposed on one or both sides of the base film, in the same way as the negative current collector described above.

[0209]

[0210]

[0211] Anode: Anode active material layer

[0212] The positive active material layer may include a positive active material, a conductive material, and a binder.

[0213] As a positive electrode active material, a compound capable of reversible intercalation and deintercalation of lithium (a lithated intercalation compound) may be used. Specifically, one or more composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof may be used. The composite oxide may be a lithium transition metal composite oxide, and specific examples include a lithium nickel-based oxide, a lithium cobalt-based oxide, a lithium manganese-based oxide, a lithium iron phosphate-based compound, a cobalt-free nickel-manganese-based oxide, or a combination thereof.

[0214] As an example, a compound represented by any one of the following chemical formulas may be used. Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05), Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05), Li a Ni 1-b-c Co b X c O 2-α D α(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2), Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2), Li a Ni b Co c L 1 d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1), Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1), Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1), Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1), Li a Mn2GbO4(0.90≤a≤1.8, 0.001≤b≤0.1), Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5), Li (3-f) Fe2(PO4)3(0≤f≤2), Li a FePO4(0.90≤a≤1.8).

[0215] In the chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; and L 1 is Mn, Al, or a combination thereof.

[0216] For example, the cathode active material may be a high-nickel cathode active material in which the nickel content relative to 100 mol% of the metal excluding lithium in a lithium transition metal composite oxide is 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more and 99 mol% or less. The high-nickel cathode active material can achieve high capacity and can be applied to high-capacity, high-density lithium secondary batteries.

[0217] For example, the lithium transition metal oxide may be a compound represented by the following chemical formula 1:

[0218]

[0219] <Chemical Formula 1>

[0220] Li a Ni x Co y M z O 2-b A b

[0221]

[0222] In Chemical Formula 1, 1.0≤a≤1.2, 0≤b≤0.2, 0.6≤x<1, 0≤y≤0.3, 0 <z≤0.3, x+y+z=1, M은 망간(Mn), 바나듐(V), 마그네슘(Mg), 갈륨(Ga), 실리콘(Si), 텅스텐(W), 몰리브덴(Mo), 철(Fe), 크롬(Cr), 구리(Cu), 아연(Zn), 티타늄(Ti), 알루미늄(Al) 및 보론(B)으로 이루어진 군으로부터 선택된 하나 이상이고, A는 F, S, Cl, Br 또는 이들의 조합이다.

[0223] In Chemical Formula 1, for example, 0.7≤x<1, 0 <y≤0.3, 0<z≤0.3, 0.8≤x<1, 0<y≤0.3, 0<z≤0.3, 0.8≤x<1, 0<y≤0.2, 0<z≤0.2, 0.83≤x<0.97, 0<y≤0.15, 0<z≤0.15, 또는 0.85≤x<0.95, 0<y≤0.1, 0<z≤0.1일 수 있다.

[0224] For example, the lithium transition metal oxide may be at least one of the compounds represented by the following chemical formulas 1-1 and 3-2:

[0225]

[0226] <Chemical Formula 1-1>

[0227] LiNi x Co y Mn z O2

[0228]

[0229] In Chemical Formula 1-1, 0.6≤x≤0.95, 0 <y≤0.2, 0<z≤0.1이다. 예를 들어, 0.7≤x≤0.95, 0<y≤0.3, 0<z≤0.3이다.

[0230]

[0231] <Chemical Formula 1-2>

[0232] LiNi x Co y Al z O2

[0233]

[0234] In Chemical Formula 1-2, 0.6≤x≤0.95, 0 <y≤0.2, 0<z≤0.1이다. 예를 들어, 0.7≤x≤0.95, 0<y≤0.3, 0<z≤0.3이다. 예를 들어, 0.8≤x≤0.95, 0<y≤0.3, 0<z≤0.3이다. 예를 들어, 0.82≤x≤0.95, 0<y≤0.15, 0<z≤0.15이다. 예를 들어, 0.85≤x≤0.95, 0<y≤0.1, 0<z≤0.1이다.

[0235] For example, lithium transition metal oxides are LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.88 Co 0.08 Mn 0.04O2 , LiNi 0.8 Co 0.15 Mn 0.05O2 , LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.88 Co 0.1 Mn0.02O2 , LiNi 0.8 Co 0.15 Al 0.05O2 , LiNi 0.8 Co 0.1 Mn 0.2O2 or LiNi 0.88 Co 0.1 Al 0.02O2 It could be.

[0236] For example, the positive electrode active material may be one having a coating layer on the surface of a lithium transition metal oxide, or a mixture of a lithium transition metal oxide and a lithium transition metal oxide having a coating layer may be used.

[0237] For example, the coating layer may include a coating element compound of an oxide, hydroxide, oxyhydroxide, oxycarbonate, or hydroxycarbonate of a coating element.

[0238] For example, the compound forming the coating layer may be amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. For the coating layer formation process, any coating method may be used as long as the coating can be applied to the lithium transition metal oxide using the coating elements in a manner that does not adversely affect the physical properties of the cathode active material (e.g., spray coating, immersion method, etc.).

[0239] For example, the anode may additionally include an additive that can serve as a sacrificial anode.

[0240] The content of the positive active material is 90% to 99.5% by weight with respect to 100% by weight of the positive active material layer, and the content of the binder and the conductive material may each be 0.5% to 5% by weight with respect to 100% by weight of the positive active material layer.

[0241] The binder serves to adhere the positive active material particles well to each other and also to adhere the positive active material well to the current collector. Representative examples of binders include, but are not limited to, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride (PVDF), polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, nylon, etc.

[0242] A conductive material is used to impart conductivity to an electrode, and any electronically conductive material that does not cause chemical changes can be used in the battery being constructed. Examples of conductive materials include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and carbon nanotube; metal-based materials in the form of metal powder or metal fibers containing copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0243]

[0244] separator

[0245] A lithium battery according to one embodiment may further include a separator (not shown).

[0246] As a separator, polyethylene, polypropylene, polyvinylidene fluoride, or multilayer films of two or more layers thereof may be used, and of course, mixed multilayer films such as polyethylene / polypropylene two-layer separator, polyethylene / polypropylene / polyethylene three-layer separator, polypropylene / polyethylene / polypropylene three-layer separator may be used.

[0247] The separator may include a porous substrate and a coating layer comprising an organic material, an inorganic material, or a combination thereof located on one or both sides of the porous substrate.

[0248] The porous substrate may be a polymer membrane formed from any one of the following: polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyacetal; polyamide; polyimide; polycarbonate; polyetherketone; polyaryletherketone; polyetherimide; polyamideimide; polybenzimidazole; polyethersulfone; polyphenylene oxide; cyclic olefin copolymer; polyphenylene sulfide; polyethylene naphthalate; glass fiber; Teflon; and polytetrafluoroethylene, or a copolymer or mixture of two or more of these.

[0249] The organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.

[0250] The inorganic material may include, but is not limited to, inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0251] Organic and inorganic materials may exist mixed in a single coating layer, or may exist in a stacked form with a coating layer containing organic materials and a coating layer containing inorganic materials.

[0252] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto and can be implemented with various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and it is obvious that such modifications also fall within the scope of the present invention.

Claims

1. Metal current collector; An electrodeposition-inducing layer formed on at least one surface of the above-mentioned metal current collector; and It includes a protective layer formed on the electrodeposition inducing layer, and The above electrodeposition-inducing layer comprises a conductive polymer, and The above protective layer comprises an electroactive polymer, a negative electrode for a lithium secondary battery.

2. In Paragraph 1, The above metal current collector comprises copper, nickel, stainless steel, aluminum, or a combination thereof, for a negative electrode of a lithium secondary battery.

3. In Paragraph 1, The above conductive polymer comprises a first polymer having a pi conjugation structure, a negative electrode for a lithium secondary battery.

4. In Paragraph 3, The above-mentioned first polymer comprises poly(3,4-ethylenedioxythiophene, PEDOT), polyaniline, polypyrrole, polyacetylene, polydopamine, polythiophene, poly(p-phenylene vinylene)), or a combination thereof, for a negative electrode for a lithium secondary battery.

5. In Paragraph 1, The above conductive polymer comprises a second polymer having a hydrophilic chain structure, a negative electrode for a lithium secondary battery.

6. In Paragraph 5, The above-mentioned second polymer comprises polyethylene glycol (PEG), polypropylene glycol (PPG), PVP (Polyvinylpyrrolidone), PVA (Polyvinyl Alcohol), PHEMA (Poly(2-hydroxyethyl methacrylate)), PDMS (Polydimethylsiloxane), or a combination thereof, for a negative electrode for a lithium secondary battery.

7. In Paragraph 1, The above conductive polymer comprises a block copolymer of a first polymer having a pi-conjugation structure and a second polymer having a hydrophilic chain structure, for use as a negative electrode for a lithium secondary battery.

8. In Paragraph 7, The above conductive polymer is a negative electrode for a lithium secondary battery containing Ag.

9. In Paragraph 1, The above electroactive polymer comprises polyvinylidene fluoride (PVDF), a negative electrode for a lithium secondary battery.

10. In Paragraph 9, A negative electrode for a lithium secondary battery, wherein the crystalline form of the above polyvinylidene fluoride is β(beta).

11. In Paragraph 1, A negative electrode for a lithium secondary battery, wherein the thickness of the electrodeposition inducing layer or the protective layer is 1 μm to 20 μm.

12. Step of providing a metal current collector; A step of forming an electrodeposition-inducing layer on at least one surface of the metal current collector; and A step of forming a protective layer on the electrodeposition inducing layer; Includes, The above electrodeposition-inducing layer comprises a conductive polymer, and A method for manufacturing a negative electrode for a lithium secondary battery, wherein the above protective layer comprises an electroactive polymer.

13. In Paragraph 12, A method for manufacturing a negative electrode for a lithium secondary battery, wherein the conductive polymer comprises a block copolymer of a first polymer having a pi-conjugation structure and a second polymer having a hydrophilic chain structure.

14. In Paragraph 12, The step of forming the electrodeposition-inducing layer above is, A method for manufacturing a negative electrode for a lithium secondary battery, comprising the step of coating a solution containing the conductive polymer onto the metal current collector substrate in a manner combining spin coating and spray coating.

15. In Paragraph 14, A method for manufacturing a negative electrode for a lithium secondary battery, wherein the solution containing the conductive polymer is a solution in which a PEDOT-block-PEG polymer is dissolved in a solvent comprising nitromethane, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), or a combination thereof at a ratio of 1% to 30% by weight.

16. In Paragraph 12, The step of forming the above protective layer is, A method for manufacturing a negative electrode for a lithium secondary battery, comprising the step of coating a solution containing the electroactive polymer on the electrodeposition-inducing layer.

17. In Paragraph 16, A method for manufacturing a negative electrode for a lithium secondary battery, wherein the solution containing the above-mentioned electroactive polymer corresponds to a solution in which a polyvinylidene fluoride (PVdF) polymer is dissolved in a solvent comprising dimethylformamide (N-N-Dimethylformamide), N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), cyclohexanone (CYC), acetone (ACE), methyl ethyl ketone (MEK), γ-butyrolactone (GBL), propylene carbonate (PC), or a combination thereof, at a ratio of 1% to 20% by weight.

18. Bipolar; Negative electrode for a lithium secondary battery; and Electrolyte disposed between the anode and the cathode Includes, The negative electrode for the above lithium secondary battery is Metal current collector; An electrodeposition-inducing layer formed on at least one surface of the above-mentioned metal current collector; and It includes a protective layer formed on the electrodeposition inducing layer, and The above electrodeposition-inducing layer comprises a conductive polymer, and A lithium secondary battery in which the above protective layer comprises an electroactive polymer.

19. In Paragraph 18, Before charging, the above negative electrode is a lithium secondary battery in which the negative electrode active material layer is absent (free).

20. In Paragraph 18, The above metal current collector comprises copper, nickel, stainless steel, aluminum, or a combination thereof, and The above conductive polymer comprises a block copolymer of poly(3,4-ethylenedioxythiophene) (PEDOT) and polyethylene glycol (PEG), and A lithium secondary battery comprising the above electroactive polymer, polyvinylidene fluoride (PVDF) in the Beta phase.

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