Thick-film electrode for lithium ion batteries, method of manufacturing the thick-film electrode, and lithium ion batteries having the thick-film electrode

Abstract

A method for manufacturing a thick film electrode for a lithium secondary battery is disclosed. The method for manufacturing a thick film electrode for a lithium secondary battery comprises: a first step of dry-mixing a positive electrode active material, a conductive material, and PVDF [Poly(vinylidene fluoride)] to form a mixed electrode material; a second step of coating the mixed electrode material onto a support and then placing a current collector thereon; a third step of hot-pressing the mixed electrode material and the current collector against the support to form a laminate of the electrode active material layer and the current collector; and a fourth step of rapidly cooling the laminate of the electrode active material layer and the current collector.

Description

Technology Field

[0001] The present invention relates to a thick film electrode for a lithium-ion battery capable of improving the energy density of a lithium-ion battery (LIB), a method for manufacturing the same, and a lithium-ion battery equipped with the same. Background Technology

[0002] Lithium-ion batteries (LIBs), based on host materials and intercalation chemistry, have firmly established themselves through rigorous research and development driven by the rapidly growing demands of the portable electronic device and electric vehicle markets. Continuous advancements in host materials have increased the energy density of LIBs from 150 Wh / kg of initial cell models. -1 250 Wh kg in the modern version -1 However, the traditional research paradigm for increasing the proportion of high-capacity transition metal components has reached a theoretical peak. Furthermore, efforts to develop new high-energy cathode materials suitable for commercialization are facing significant challenges. These issues highlight the need for pioneering research strategies to meet market demands.

[0003] The emergence of thick electrode technology has emerged as a significant innovation in efforts to drastically increase the energy density of LIBs without requiring changes to existing chemistry or infrastructure. Current LIB cell configurations allocate approximately 40% to active material. The application of thick electrode technology can increase this ratio to about 80% and boost energy density by 30%. Such a significant improvement requires a complex redesign of the electrode, which necessitates increasing the active material load from about 15–20 mg cm⁻² to 40 mg cm⁻². Importantly, this must maintain ion and electron transfer resistance at levels similar to those observed in traditional electrodes.

[0004] Poly(vinylidene fluoride) (PVDF) is a semicrystalline thermoplastic fluoropolymer that is currently the most widely used binder for LIB anodes. PVDF maintains a strong position as a binder despite environmental concerns, along with advantages in slurry processes. However, the pursuit of thick anodes utilizing high-energy density electrodes has highlighted the limitations of slurry-based manufacturing methods, particularly issues such as cracking and peeling at the electrodes. Consequently, solvent-free dry processes are gaining attention as an alternative strategy. Furthermore, because the properties of PVDF fall short of the enhanced functional requirements of thick anodes, research into potential substitutes continues. Recent reports have identified new high-performance binder materials for thick anode applications, each demonstrating excellent electrochemical performance and high potential. Additionally, performance enhancements achieved through reduced crystallinity of PVDF were accomplished via wet processes involving mixtures of PVDF and polyaniline, as well as the grafting of male anhydride onto PVDF. These modifications suggest that binder performance can be significantly improved through simple physical structural control without requiring major changes to existing electrode systems. The problem to be solved

[0005] One objective of the present invention is to provide a method for manufacturing a thick film electrode for a lithium secondary battery that can improve performance by controlling the crystallinity of the binder.

[0006] Another objective of the present invention is to provide a thick film electrode for a lithium secondary battery manufactured by the above-described manufacturing method.

[0007] Another objective of the present invention is to provide a lithium secondary battery having the thick film electrode. means of solving the problem

[0008] A method for manufacturing a thick film electrode for a lithium secondary battery according to one embodiment of the present invention may include: a first step of dry-mixing a positive electrode active material, a conductive material, and PVDF [Poly(vinylidene fluoride)] to form a mixed electrode material; a second step of coating the mixed electrode material on a support and then placing a current collector thereon; a third step of hot-pressing the mixed electrode material and the current collector against the support to form a laminate of the electrode active material layer and the current collector; and a fourth step of rapidly cooling the laminate of the electrode active material layer and the current collector.

[0009] In one embodiment, the thick film electrode for a lithium secondary battery may further include a step of roll-pressing the laminate after the fourth step.

[0010] In one embodiment, the thickness of the electrode active material layer after the roll pressing process may be 150 to 350 μm.

[0011] In one embodiment, in the mixed electrode material of the first step, the content of the positive active material is 65 to 85 weight%, and the content of the conductive material and the PVDF, respectively, may be 5 to 20 weight% independently of each other.

[0012] In one embodiment, the positive active material is NCM (LiNi 1-x-y Co x Mn y O2, 0 <x, y≤0.1) 또는 NCA(LiNi 1-a-b Co a Al b O2, 0 <a, b≤0.1)을 포함할 수 있다.

[0013] In one embodiment, the conductive material may include one or more selected from the group consisting of Super P, Ketjen Black, Acetylene Black, Carbon Nanotubes (CNT), and Graphene.

[0014] In one embodiment, the current collector may include a conductive metal sheet.

[0015] In one embodiment, the hot pressing of the third step may be performed at a temperature above the melting point of the PVDF.

[0016] In one embodiment, the hot pressing can be performed at 180 to 200°C.

[0017] In one embodiment, the quenching of the fourth step may be performed by cooling the laminate at a rate of 50°C / min to 500°C / min. For example, the quenching may be performed by immersing the laminate in liquid nitrogen.

[0018] A thick film electrode for a lithium secondary battery according to one embodiment of the present invention can be manufactured according to the above manufacturing method.

[0019] In one embodiment, the degree of crystallization (Xc) of the PVDF calculated according to the following Equation 1 based on the differential scanning calorimetry (DSC) curve of the PVDF may be 40 to 50%.

[0020] [Formula 1]

[0021]

[0022] In the above Equation 1, △H measured and △H 100% crystalline represents the measured enthalpy of PVDF and the enthalpy of 100% crystalline PVDF, respectively.

[0023] In one embodiment, the PVDF may include an α-phase crystal structure.

[0024] In one embodiment, in the electrode active material layer, the loading amount of the positive active material is 45 to 55 mg·cm² -2 and the reversible capacity of the thick film electrode is 200 to 220 mA·h·g -1 It could be.

[0025] A method for manufacturing a thick film electrode for a lithium secondary battery according to another embodiment of the present invention may include: a first step of dissolving PVDF in molten succinonitrile (SN) and then solidifying it to form a composite binder; a second step of dry-mixing a positive electrode active material, a conductive material, and the composite binder to form a mixed electrode material; a third step of applying the mixed electrode material onto a support and then placing a current collector thereon thereon; a fourth step of hot-pressing the mixed electrode material and the current collector against the support to form a laminate of the electrode active material layer and the current collector; and a fifth step of cooling the laminate.

[0026] In one embodiment, the method for manufacturing a thick film electrode for a lithium secondary battery may further include a step of roll-pressing the laminate after the fifth step.

[0027] In one embodiment, in the first step, the composite binder may include the PVDF and the SN in a weight ratio of 1:05 to 1:1.5.

[0028] In one embodiment, in the mixed electrode material of the first step, the content of the positive active material is 65 to 85 weight%, and the content of the conductive material and the PVDF, respectively, may be 5 to 20 weight% independently of each other.

[0029] A thick film electrode for a lithium secondary battery according to another embodiment of the present invention can be manufactured according to the above manufacturing method.

[0030] In one embodiment, the thickness of the electrode active material layer may be 150 to 350 μm.

[0031] In one embodiment, the degree of crystallization (Xc) of the PVDF calculated according to the following Equation 1 based on the differential scanning calorimetry (DSC) curve of the PVDF may be 25 to 35%.

[0032] [Formula 1]

[0033]

[0034] In the above Equation 1, △H measured and △H 100% crystalline represents the measured enthalpy of PVDF and the enthalpy of 100% crystalline PVDF, respectively.

[0035] In one embodiment, the PVDF may include an α-phase crystal structure.

[0036] In one embodiment, in the electrode active material layer, the loading amount of the positive active material is 45 to 55 mg·cm² -2 and the reversible capacity of the thick film electrode is 200 to 220 mA·h·g -1 It could be.

[0037] A lithium secondary battery according to one embodiment of the present invention comprises a positive electrode and a negative electrode arranged facing each other; an electrolyte filling the space between the positive electrode and the negative electrode; and a separator arranged between the positive electrode and the negative electrode within the electrolyte, wherein the positive electrode may include a thick film electrode manufactured according to one embodiment of the present invention.

[0038] A lithium secondary battery according to another embodiment of the present invention comprises a positive electrode and a negative electrode positioned opposite each other; an electrolyte filling the space between the positive electrode and the negative electrode; and a separator positioned between the positive electrode and the negative electrode within the electrolyte, wherein the positive electrode comprises a thick film electrode manufactured according to another embodiment of the present invention, and the SN of the composite binder may be leached into the electrolyte. Effects of the invention

[0039] According to the method for manufacturing a thick film electrode for a lithium secondary battery according to an embodiment of the present invention, the thick film electrode for a lithium secondary battery manufactured according to the same, and the lithium secondary battery equipped with the same, the performance of the thick film electrode can be significantly improved by increasing the amorphousness of the PVDF applied as a binder through methods such as rapid cooling treatment or the application of an SN plasticizing agent. Brief explanation of the drawing

[0040] FIG. 1 is a flowchart illustrating a method for manufacturing a thick film electrode for a lithium secondary battery according to one embodiment of the present invention. FIG. 2 is a flowchart illustrating a method for manufacturing a thick film electrode for a lithium secondary battery according to another embodiment of the present invention. Figure 3 is a graph showing the design principles for explaining the manufacturing method of the thick film electrodes of the examples and comparative examples, and the results of the performance comparison of the manufactured thick film electrodes. Figure 4 shows the results of measuring the material properties of PVDF films manufactured through a different cooling process after a mechanical-thermal process. Figure 5 is a diagram showing the results of analyzing the characteristics of a PVDF / SN mixed binder and a thick film electrode manufactured using it. Figure 6 is a diagram showing the results of analyzing the electrochemical performance of Li / 3D-CNS / / s-DHC, Li / 3D-CNS / / a-DHC, and Li / 3D-CNS / / n-DHC full cells. Figure 7 is a diagram showing FE-SEM cross-sectional images of n-DHC and c-DHC, respectively, and EDS mapping images for Ni, C, and F, respectively. FIG. 8 is a figure showing the analysis results of rate capability and reversibility measured under different C-rate (current rate) conditions from 0.1C to 0.5C for a-DHC, n-DHC, and c-DHC (a) and the analysis results of cycle performance over 100 cycles measured at 0.1 C-rate (b). Figure 9 is a diagram showing the analysis results of rate capability and reversibility measured for W-DLC and WLC under different C-rate (current rate) conditions from 0.1C to 0.5C. Figure 10 shows optical images of the contact angles measured for the electrolyte on each PVDF film. Figure 11 shows optical images of a PVDF-SN solution and a PVDF-SN film. Figure 12 is an optical image of the contact angle for the electrolyte on the PVDF-SN film. Figure 13 shows optical images of the electrode (a, b), a cross-sectional SEM image (b), and EDS mapping images of Ni, C, and F. Figure 14 shows the EIS profiles (a) of a-DHC, n-DHC, c-DHC, and s-DHC, and the EIS bar graph (b) measured near Rs and Rct. FIG. 15 is a galvanostatic charge / discharge profile (a, b, c) of capacity reduction after 100 cycles for a DHC, n-DHC and c-DHC and a bar graph (d) of reduced capacity. Figure 16 shows the EIS profiles (a) after 100 cycles for a-DHC, n-DHC, c-DHC, and s-DHC, and a bar graph (b) of increased resistance after 100 cycles. Figure 17 shows FE-SEM images of the upper surface of s-DHC after several cycles. Figure 18 shows FE-SEM images of the upper surface of c-DHC after several cycles. Specific details for implementing the invention

[0041] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. Since the present invention is susceptible to various modifications and may take various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed forms, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the present invention. Similar reference numerals have been used for similar components in the description of each drawing. In the attached drawings, the dimensions of the structures are shown enlarged compared to the actual dimensions for the clarity of the present invention.

[0042] Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component.

[0043] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "having" are intended to indicate the presence of the features, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, steps, actions, components, parts, or combinations thereof.

[0044] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0046] FIG. 1 is a flowchart illustrating a method for manufacturing a thick film electrode for a lithium secondary battery according to one embodiment of the present invention.

[0047] Referring to FIG. 1, a method for manufacturing a thick film electrode for a lithium secondary battery according to one embodiment of the present invention may include: a first step (S110) of dry mixing a positive electrode active material, a conductive material, and PVDF [Poly(vinylidene fluoride)] to form a mixed electrode material; a second step (S120) of coating the mixed electrode material on a support and then placing a current collector thereon; a third step (S130) of hot pressing the mixed electrode material and the current collector against the support to form a laminate of the electrode active material layer and the current collector; and a fourth step (S140) of rapidly cooling the laminate of the electrode active material layer and the current collector.

[0048] In one embodiment, the method for manufacturing a thick film electrode for a lithium secondary battery may further include a step of roll-pressing the laminate after the fourth step. In this case, the electrode active material layer may be formed with a relatively thick thickness after the roll-pressing process. For example, the electrode active material layer may be formed with a thickness of about 150 to 350 μm.

[0049] In the first step (S110) above, to form the mixed electrode material, about 65 to 85 weight% of the positive active material, about 5 to 20 weight% of the conductive material, and about 5 to 20 weight% of the PVDF may be mixed.

[0050] In one embodiment, the method of dry mixing the cathode active material, the conductive material, and the PVDF is not particularly limited. For example, the cathode active material, the conductive material, and the PVDF may be mixed through a high-energy ball mill process.

[0051] In one embodiment, known cathode active materials for lithium secondary batteries may be applied as the cathode active material without limitation. In one embodiment, the cathode active material may include a high-nickel cathode active material. For example, the cathode active material is NCM (LiNi 1-x-y Co x Mn y O2, 0 <x, y≤0.1) 또는 NCA(LiNi 1-a-b Co a Al b O2, 0 <a, b≤0.1)을 포함할 수 있다.

[0052] In one embodiment, known conductive materials for lithium secondary batteries may be applied as the conductive material without limitation. In one embodiment, the conductive material may include one or more selected from Super P, Ketjen Black, Acetylene Black, Carbon Nanotubes (CNT), Graphene, etc.

[0053] In one embodiment, the PVDF may be used having a weight-average molecular weight of about 400,000 to 700,000 g / mol. For example, the PVDF may be used having a weight-average molecular weight of about 500,000 to 600,000 g / mol.

[0054] In the second step (S120) above, the method of applying the mixed electrode material onto the support is not particularly limited. At this time, the support may be a support for press processing.

[0055] In one embodiment, the current collector may include a conductive metal sheet or plate. For example, the current collector may include an aluminum or copper sheet or plate.

[0056] In the above third step (S130), the mixed electrode material can be formed into a film-shaped electrode active material layer by a hot pressing process using the support and the pressure plate, and can be attached to the current collector to form the laminate.

[0057] In one embodiment, the hot pressing may be performed at a temperature near or above the melting point of the PVDF. For example, the hot pressing may be performed at 175 to 200°C.

[0058] In the above fourth step (S140), the electrode active material layer formed by thermal pressure molding at a temperature near or above the melting point of the PVDF can be rapidly cooled, thereby reducing the crystallization of the PVDF.

[0059] In one embodiment, the laminate including the electrode active material layer may be cooled at a rate of about 50°C / min to 500°C / min. For example, the electrode active material layer may be rapidly cooled by immersing the laminate in liquid nitrogen.

[0060] In the thick film electrode for a lithium secondary battery manufactured by the above manufacturing method, the degree of crystallization (Xc) of the PVDF calculated according to the following Equation 1 based on the differential scanning calorimetry (DSC) curve of the PVDF may be approximately 40 to 50%.

[0061] [Formula 1]

[0062]

[0063] In the above Equation 1, △H measured and △H 100% crystalline represents the measured enthalpy of PVDF and the enthalpy of 100% crystalline PVDF, respectively.

[0064] When the degree of crystallization of the above PVDF is low, the reversible capacity can be improved. Specifically, crystalline PVDF domains adjacent to the cathode active material can not only reduce the lithium ion concentration due to their sorbophobic properties but also physically block lithium ion pathways, thereby hindering lithium ion transport. In particular, alpha-phase PVDF crystals, which are mainly formed during the dry process, exhibit non-polar characteristics due to their symmetrical structure, which can enhance their sorbophobic behavior. Consequently, the crystalline PVDF can significantly reduce the active surface area and cause non-uniform intercalation reactions, leading to a substantial decrease in reversible capacity.

[0065] In one embodiment, in the thick film electrode for a lithium secondary battery manufactured through the dry process, the partially crystallized PVDF may have an α-phase crystal structure.

[0066] In one embodiment, in the thick film electrode, the thickness of the electrode active material layer may be about 150 to 350 μm.

[0067] In one embodiment, in the electrode active material layer, the loading amount of the positive active material is about 45 to 55 mg·cm² -2 It may be, and the reversible capacity of the thick film electrode is about 200 to 220 mA·h·g -1 It could be.

[0069] FIG. 2 is a flowchart illustrating a method for manufacturing a thick film electrode for a lithium secondary battery according to another embodiment of the present invention.

[0070] Referring to FIG. 2, a method for manufacturing a thick film electrode for a lithium secondary battery according to another embodiment of the present invention may include: a first step (S210) of dissolving PVDF in molten succinonitrile (SN) and then solidifying it to form a composite binder; a second step (S220) of dry mixing a positive electrode active material, a conductive material, and the composite binder to form a mixed electrode material; a third step (S230) of applying the mixed electrode material onto a support and then placing a current collector thereon thereon; a fourth step (S240) of hot-pressing the mixed electrode material and the current collector against the support to form a laminate of the electrode active material layer and the current collector; and a fifth step (S250) of cooling the laminate.

[0071] In one embodiment, the method for manufacturing a thick film electrode for a lithium secondary battery may further include a step of roll-pressing the laminated body performed after the fifth step.

[0072] In the first step (S210) above, the PVDF can be dissolved in the molten liquid SN, mixed with the SN and the PVDF, and then cooled to a temperature below the melting temperature of the SN, for example, room temperature, to produce the composite binder.

[0073] In one embodiment, to manufacture the composite binder, the PVDF and the SN may be mixed in a weight ratio of about 1:05 to 1:1.5.

[0074] In the second step (S220) above, to form the mixed electrode material, about 65 to 85 weight% of the positive active material, about 5 to 20 weight% of the conductive material, and about 5 to 20 weight% of the PVDF may be mixed.

[0075] In one embodiment, the method of dry mixing the cathode active material, the conductive material, and the PVDF is not particularly limited. For example, the cathode active material, the conductive material, and the PVDF may be mixed through a high-energy ball mill process.

[0076] In one embodiment, known cathode active materials for lithium secondary batteries may be applied as the cathode active material without limitation. In one embodiment, the cathode active material may include a high-nickel cathode active material. For example, the cathode active material is NCM (LiNi 1-x-y Co x Mn y O2, 0 <x, y≤0.1) 또는 NCA(LiNi 1-a-b Co a Al b O2, 0 <a, b≤0.1)을 포함할 수 있다.

[0077] In one embodiment, known conductive materials for lithium secondary batteries may be applied as the conductive material without limitation. In one embodiment, the conductive material may include one or more selected from Super P, Ketjen Black, Acetylene Black, Carbon Nanotubes (CNT), Graphene, etc.

[0078] In one embodiment, the PVDF may be used having a weight-average molecular weight of about 400,000 to 700,000 g / mol. For example, the PVDF may be used having a weight-average molecular weight of about 500,000 to 600,000 g / mol.

[0079] In the above third step (S230), the method of applying the mixed electrode material onto the support is not particularly limited. At this time, the support may be a support for press processing.

[0080] In one embodiment, the current collector may include a conductive metal sheet or plate. For example, the current collector may include an aluminum or copper sheet or plate.

[0081] In the above fourth step (S140), the mixed electrode material can be formed into a film-shaped electrode active material layer by a hot pressing process using the support and the pressure plate, and can be attached to the current collector to form the laminate.

[0082] In one embodiment, the hot pressing may be performed at a temperature near or above the melting point of the PVDF. For example, the hot pressing may be performed at 175 to 200°C.

[0083] In the above fifth step (S250), the electrode active material layer, which is thermally pressurized at a temperature near or above the melting point of the PVDF, may be cooled to room temperature. At this time, the electrode active material layer may be naturally cooled or rapidly cooled.

[0084] During the cooling of the electrode active material layer, the SN acts as a plasticizing agent, which can significantly lower the crystallinity of the PVDF, and as a result, as described above, can improve the reversible capacity of the thick film electrode.

[0085] In the thick film electrode for a lithium secondary battery manufactured by the above manufacturing method, the degree of crystallization (Xc) of the PVDF calculated according to the following Equation 1 based on the differential scanning calorimetry (DSC) curve of the PVDF may be approximately 25 to 35%.

[0086] [Formula 1]

[0087]

[0088] In the above Equation 1, △H measured and △H 100% crystalline represents the measured enthalpy of PVDF and the enthalpy of 100% crystalline PVDF, respectively.

[0091] In one embodiment, in the thick film electrode for a lithium secondary battery manufactured through the dry process, the partially crystallized PVDF may have an α-phase crystal structure.

[0092] In one embodiment, in the thick film electrode, the thickness of the electrode active material layer may be about 150 to 350 μm.

[0093] In one embodiment, in the electrode active material layer, the loading amount of the positive active material is about 45 to 55 mg·cm² -2 It may be, and the reversible capacity of the thick film electrode is about 200 to 220 mA·h·g -1 It could be.

[0094] A lithium secondary battery according to one embodiment of the present invention may include a positive electrode and a negative electrode arranged facing each other; an electrolyte filling the space between the positive electrode and the negative electrode; and a separator arranged between the positive electrode and the negative electrode within the electrolyte, wherein the positive electrode may include a thick film electrode manufactured according to the manufacturing method described with reference to FIG. 1.

[0095] A lithium secondary battery according to another embodiment of the present invention may include a positive electrode and a negative electrode arranged opposite each other; an electrolyte filling the space between the positive electrode and the negative electrode; and a separator arranged between the positive electrode and the negative electrode within the electrolyte, wherein the positive electrode may include a thick film electrode manufactured according to the manufacturing method described with reference to FIG. 2.

[0096] In one embodiment, SN included in the composite binder of the anode may be leached into the electrolyte, and the leached SN may function as an additive that improves ion conductivity within the electrolyte. Furthermore, when SN is leached from the electrode active material layer, the surface area of ​​the electrode active material layer exposed to the electrolyte may be increased, and as a result, ion conductivity may be improved more significantly.

[0098] Specific embodiments of the present invention are described in detail below. However, the following embodiments are merely partial embodiments of the present invention, and the scope of the present invention is not limited to the following embodiments.

[0100] [Examples 1-1 to 1-3]

[0101] NCM (Posco Future M, South Korea), Super P (Alfa Aesar, Belgium), and PVDF (molecular weight = 534,000 g / mol, Sigma-Aldrich, USA) were pre-mixed using a high-energy ball mill. At this time, NCM, Super P, and PVDF were mixed in weight ratios of 8:1:1 (Example 1-1), 7:2:1 (Example 1-2), and 7:1:2 (Example 1-3), and NCM and Super P were dried in a convection oven at 80°C before use.

[0102] Next, the pre-mixed powder was compressed using a hot press machine at 30 MPa and 180°C for 5 minutes, and then the compressed electrode was immersed in liquid nitrogen to rapidly cool it.

[0103] Next, the electrode was roll-pressed at room temperature.

[0105] [Comparative Examples 1-1~1-3]

[0106] In the same manner as in Examples 1-1 to 1-3, the pre-mixed powder was compressed using a hot press machine at 30 MPa and 180°C for 5 minutes, then the compressed electrode was naturally cooled at room temperature, and then the electrode was roll-pressed at room temperature.

[0108] [Comparative Examples 1-4~1-6]

[0109] In the same manner as in Examples 1 to 3, the pre-mixed powder was compressed using a hot press machine at 30 MPa and 180°C for 5 minutes, the compressed electrode was maintained at 120°C for 20 minutes and then naturally cooled to room temperature, and then the electrode was roll-pressed at room temperature.

[0111] [Example 2]

[0112] 10 g of PVDF was dissolved in 10 g of molten SN solution (Mw = 80.09 g / mol, Sigma-Aldrich, USA) at 130°C while stirring to form a liquid-phase mixture, which was then cooled to room temperature to solidify. Subsequently, 10 wt.% of a PVDF and SN composite binder, 80 wt.% of NCM, and 10 wt.% of Super P were pre-mixed at room temperature using a high-energy ball mill. The pre-mixed powder was then compressed using a hot press machine at 30 MPa and 180°C for 5 minutes, followed by cooling to room temperature. The electrode was then roll-pressed at room temperature. The thickness and active material loading of the roll-pressed electrode were approximately 200 μm and 50 mg·cm², respectively. -2 It was.

[0114] [Example 3]

[0115] A CR2032 type coin cell was prepared using a positive electrode prepared according to Examples 1 and 2, a lithium metal foil negative electrode, a polyethylene separator (thickness 16 μm), and a liquid electrolyte solution containing 1 M LiPF6 in a 1:1 (v / v) mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC).

[0117] [Experimental Example]

[0118] Figure 3 is a graph showing the design principles for explaining the manufacturing method of the thick film electrodes of the examples and comparative examples, and the results of the performance comparison of the manufactured thick film electrodes.

[0119] Referring to FIGS. 3a through g, the dry process included a procedure of mixing NCM, a conductive additive, and a binder in an 8:1:1 ratio using a high-energy ball mill (Fig. 3a), followed by heat treatment using a hot press at 180°C at 30 MPa (Fig. 3b). Afterward, three distinct cooling processes were applied, and the procedure was completed with a roll press process (Figs. 3c and d).

[0120] Optical images of a-DHC fabricated via a dry process (electrode fabricated by quenching treatment in c) show a uniformly well-fabricated thick film electrode without signs of cracking or peeling ((Fig. 3e). The substrate adheres well even when bent around the aluminum current collector, exhibiting robust structural integrity ((Fig. 3f). Further analysis using FE-SEM images and EDS data confirms that the NCM, conductive additive, and binder are uniformly mixed at approximately 50 mg·cm⁻³ -2 It was confirmed that a thick film electrode with an NCM loading and a uniform film thickness of 200 μm was fabricated ((g in Fig. 3). Similar results were observed for n-DHC (electrode fabricated by room temperature cooling treatment in c) and c-DHC (electrode fabricated by 120°C annealing treatment in c), which confirms the effect of the dry process and the integrity of the fabricated thick anode even when performed without a cooling process (see Fig. 7).

[0121] The electrochemical performance of the thick anode is 2.7 to 4.3 V at 0.1 C-rate vs. Li + It was evaluated using the galvanostatic method through a voltage window of / Li. The galvanostatic charge / discharge profiles showed significant differences in capacity, which are illustrated in h and m of Fig. 3. The reversible capacity of a-DHC is approximately 208 mA·h·g -1 As such, these were approximately 12% and 30% higher than the doses of n-DHC and c-DHC, respectively, and were approximately 185 and 159 mA·h·g, respectively. -1 The capacity was shown. The rate capability and cycling performance results of the DHC series showed that the initial capacity gap at 0.1 C-rate gradually increased at higher C-rates and cycle counts (see Fig. 8).

[0122] The NCM loading density is approximately 17 mg·cm² -2When the thickness is reduced to about 80 μm, the capacity difference was found to narrow to about 4% and 17% for n-DLC and c-DLC, respectively (i and m in Fig. 3). These results suggest that the crystal structure of the PVDF binder plays an important role in the electrochemical performance, especially for thick anodes.

[0123] To further investigate the source of the capacity difference, the content ratio of the conductive additive and binder was increased to 20%, and the change in reversible capacity was observed.

[0124] When the conductive additive content was increased to 20%, the reversible capacities of a-DHC, n-DHC, and c-DHC were 207, 185, and 160 mA·h·g, respectively. -1 As such, it was very similar to when the conductive additive content was 10% (j and m in Fig. 3). This supports the conclusion that the capacity reduction observed in the n-DHC and c-DHC samples was not due to electrical conductivity issues.

[0125] When the binder content is increased to 20%, the reversible capacity of a-DHC remains similar, whereas the reversible capacity of n-DHC is approximately 170 mA·h·g -1 It decreased by about 8% compared to the original (k and m in Fig. 3). In the case of c-DHC, the charge / discharge cycle did not operate normally. This result suggests that the difference in capacity is likely due to the crystal structure of the binder.

[0126] In addition, as a result of fabricating NCM cathodes via a slurry process and testing their electrochemical performance under conditions similar to DLC, the reversible capacity of the wet process-based low-load cathode (WLC, l and m in Fig. 3) was approximately 190 mA·h·g -1 It was found to be. This capacity is located between n-DLC and c-DHC and is approximately 20 mA·h·g higher than a-DLC. -1 It was low.

[0127] As a result of applying a dry process including a heat press following natural cooling to the WLC, the reversible capacity was 198 mA·h·g -1 It has been improved to be similar to n-DLC. The gap in reversible capacity is 35 mA·h·g at 0.5 C-rate. -1 It increased to (see Fig. 9).

[0128] These findings suggest that post-treatment using dry process techniques can significantly improve electrochemical performance beyond traditional wet treatment methods.

[0130] <Influence of Cooling Process on Degree of Crystallinity>

[0131] To explain the differences in the crystalline microstructure of the PVDF binder, PVDF films were prepared using various cooling processes similar to those used in anode fabrication.

[0132] Figure 4 shows the results of measuring the material properties of PVDF films manufactured through a different cooling process after a mechanical-thermal process.

[0133] Referring to Fig. 4, differential scanning calorimetry (DSC) curves for PVDF films of 10 mg each were recorded at a heating rate of 10 °C per minute at temperatures ranging from 0 to 250 °C (Fig. 4a). A distinct endothermic peak found at approximately 161 °C indicates the melting of the crystal structure. The crystallinity (Xc) of the PVDF film was calculated according to the following Equation 1, which obtains the heat of fusion (ΔH measured) by integrating the area under the peak and compares it with the enthalpy of 100% crystalline PVDF (ΔH 100% crystalline) reported in the literature.

[0134] [Formula 1]

[0135]

[0136] Quick cooling, natural cooling, T caPVDF, nPVDF, and cPVDF prepared using natural cooling after annealing in [location] exhibited crystallinities of 45.7%, 53.3%, and 65.7%, respectively (Fig. 4c). This result demonstrates that crystallinity can be systematically controlled by diversifying the manufacturing process. The wet-process-based PVDF film (wPVDF) prepared by solution casting after dissolution in NMP was measured to have a crystallinity of 59.6%, which falls between the values ​​of the nPVDF and cPVDF films. Furthermore, the melting peak of the wPVDF film was observed at a lower temperature (158 °C) than that of the dry-process-based film, and this shift suggests that the crystalline phase of wPVDF differs from that of the dry-process-based film. The wPVDF film T c When heat-treated and then naturally cooled (wdPVDF), the melting peak of the resulting wdPVDF shifted to 162 °C, and the crystallinity decreased slightly to 55.7%. These changes indicate microstructural changes associated with dry process post-treatment.

[0137] X-ray diffraction (XRD) analysis was performed to further investigate the crystal structure and crystallinity of the PVDF films (Fig. 4b). The samples prepared by the dry process showed distinct peaks at 17.7, 18.4, and 20.0°, which correspond to the (100), (020), and (110) crystallographic planes of the alpha phase, respectively. Similarly, wdPVDF showed the same alpha phase pattern, while wPVDF showed broader peaks at 18.5 and 20.3°, which were identified as the (020) and (110) peaks of the gamma phase, suggesting a different crystal structure from the dry process samples.

[0138] Crystallinity was calculated by comparing peak regions with the amorphous region, and the aPVDF, nPVDF, cPVDF, wdPVDF, and wPVDF films yielded values ​​of 38.5%, 47.9%, 60.1%, 49.6%, and 55.2%, respectively (Fig. 4c). While consistent with the crystallinity trends derived from DSC results, the values ​​in the XRD data are generally lower. This difference is because XRD applies stricter criteria for recognizing crystalline phases, whereas DSC reflects enthalpy changes in less defined crystal melting in addition to clear crystal transitions.

[0139] The difference in crystal structure between wPVDF and dry-process-based PVDF samples is explained in more detail through infrared (IR) spectroscopic analysis (Fig. 4d). The IR spectrum of wPVDF shows characteristic peaks in the gamma phase at 812, 837, and 1233 cm⁻¹. -1 This is clearly demonstrated in [figure]. On the other hand, PVDF samples prepared via the dry process, including wdPVDF, consistently exhibit characteristic alpha peaks at 763, 795, and 975 cm⁻¹. -1 This is shown in [figure]. Therefore, based on the results of DSC, XRD, and IR spectroscopic analysis, the crystalline phase of PVDF produced through the dry process is mainly the alpha phase, which contrasts with the gamma phase generally observed in PVDF synthesized through the wet process.

[0140] The effect of changes in the crystalline microstructure of the PVDF binder on electrochemical properties was systematically evaluated through electrolyte absorption, wettability, and electrochemical impedance spectroscopy (EIS) tests (e to g in Fig. 4).

[0141] In the electrolyte absorption experiment, weight changes were measured after immersing PVDF films treated with various methods in the electrolyte for 48 hours under an argon atmosphere (Fig. 4e). The largest weight increase was observed in aPVDF (25.8%), followed by nPVDF (13.9%) and cPVDF (8.0%), while wdPVDF showed an intermediate increase (12.1%) between nPVDF and cPVDF. The gamma phase wPVDF showed a lower weight increase (9.4%) than wdPVDF. A similar trend was observed when performing electrolyte absorption tests on electrodes containing PVDF binders with different crystal structures. Electrodes with high electrolyte absorption demonstrate enhanced electrolyte absorption capacity due to increased surface area and porosity. Furthermore, this increase in electrolyte absorption indicates improved electrolyte affinity.

[0142] This trend is supported by the fact that the contact angle experiment in the wettability measurement of the electrolyte solution decreased the contact angle value (Fig. 4f). Throughout the series, the contact angle values ​​ranged from 34.7° to 55.3°, reflecting the effect of changes in crystallinity (see Fig. 10).

[0143] Figure 4g shows the EIS profile of the PVDF film, where the semicircular characteristic corresponds to the film resistance (Rf). Films with low crystallinity, such as aPVDF, nPVDF, and cPVDF, have progressively lower Rf values ​​of 68.5, 111.7, and 160 Ω, respectively. f Represents the value, indicating that lithium-ion transport becomes more efficient as crystallinity decreases. Intermediate R f The values ​​of wdPVDF (131.0 Ω) and wPVDF (153.4 Ω) highlight their position between nPVDF and cPVDF, reinforcing the correlation between crystal structure and ion transport properties. A similar trend is observed in WLC and WDLC, including the DLC series, with overall higher R fDespite showing values, it further emphasizes the effect of binder crystallinity on ion transport (h in Fig. 4). This result highlights the important role of crystallinity in controlling electrolyte affinity and lithium ion mobility in various crystal structures of PVDF.

[0144] These findings confirm that changes in the crystallinity of the PVDF binder significantly affect the electrochemical properties of electrodes designed with this binder, influencing electrolyte absorption, wettability, and ion transport characteristics. These factors are particularly important in thick cathodes. Consequently, electrodes fabricated through various processes exhibit distinct differences in reversible capacity. A schematic image illustrating the effect of PVDF binder crystallinity on electrode performance is shown in Fig. 4i. Crystalline PVDF domains adjacent to the active material can hinder lithium ion transport by not only reducing lithium ion concentration due to their sorbophobic properties but also physically blocking lithium ion pathways. In particular, alpha-phase PVDF crystals, primarily formed during dry processes, exhibit non-polar characteristics due to their symmetrical configuration, which enhances their sorbophobic behavior. The combination of these physical and chemical effects can lead to a significant reduction in the active surface area and result in non-uniform intercalation reactions, causing a substantial decrease in reversible capacity.

[0146] <PVDF / SN 혼합 바인더 기반 후막 전극의 전기화학 성능>

[0147] It is emphasized that there is a close relationship between electrochemical performance and binder crystallinity in thick anodes, which serves as an important guideline when designing binder materials. However, although aDHC exhibited the best electrochemical performance among the tested samples, the aPVDF film prepared by the same method maintained a high crystallinity of 45.7%. This reveals the inherent limitations of reducing the crystallinity of PVDF polymers using a quenching method in the dry process. Therefore, to more effectively reduce the crystallinity of PVDF, SN, a plasticizing agent that mixes well with PVDF, was introduced. PVDF plasticized with SN was prepared by mixing PVDF to SN at a weight ratio of 50 wt.%, and the PVDF / SN mixed films before and after SN removal were named PVDF-SN and sPVDF, respectively.

[0148] As shown in Fig. 11a, PVDF dissolved in the SN solution at 80°C to form a transparent mixed solution, indicating that PVDF and SN were mixed in a uniform liquid phase. After solution casting, the PVDF-SN film maintained a uniform phase and showed no phase separation, supporting good miscibility between PVDF and SN (Fig. 11b). In the DSC curve of PVDF-SN, two endothermic peaks observed at 62°C and 135°C are associated with the melting of SN and PVDF (Fig. 5a). In particular, the melting peak of PVDF was significantly reduced by about 25°C compared to the PVDF series film without SN, and the peak position was maintained even after removing SN by immersion in the electrolyte solution (Figs. 5a and b). This result indicates that SN effectively alters the crystal structure of PVDF and is completely dissolved in the electrolyte solution. The crystallinity of sPVDF calculated in the peak region was 29.6%, which was significantly lower than the crystallinity of the original PVDF series film. Furthermore, the crystallinity of sPVDF obtained from the decomposed XRD data was 24.1%, supporting much greater amorphousness due to SN addition (Fig. 5c). Due to the very low crystallinity, the electrolyte absorption rate of sPVDF increased by 30.4%, and its wettability decreased by 21.3° (see Fig. 12). Additionally, the electrolyte absorption rate of s-DHC further increased to 44.2%, which is 7.0% higher than that of a-DHC, indicating more solvent-friendly characteristics of the sPVDF binder-based electrode system. The crystallographic structure of sPVDF was further investigated by infrared spectroscopy (IR) (Fig. 5e). Plasticized PVDF also exhibited characteristic alpha phase peaks at 763, 795, and 975 cm⁻¹. -1 As shown in [figure], it indicates that SN did not affect the crystal phase of sPVDF.

[0149] One of the characteristic features of the s-DHC system is that SN, used as a plasticizer, dissolves into the electrolyte and functions as an additive that enhances ion conductivity. Even with the dissolution of SN, the physical integrity of the sPVDF-based thick anode fabricated via a solvent-free process was maintained. As shown in Fig. 13a, optical images after electrode fabrication confirmed a uniform s-DHC coating on the current collector with no evidence of cracking or delamination. Furthermore, this uniform adhesion persisted even after mechanical bending, highlighting the robust bonding characteristics of the coating (Fig. 13b). Cross-sectional FE-SEM and EDS mapping further demonstrate a uniform and dense distribution of the sPVDF binder, conductive carbon, and active material across the entire electrode (Fig. 13c). The introduction of SN dissolved in the electrolyte increases the surface area of ​​the active material exposed to the electrolyte within the s-DHC matrix, thereby promoting more efficient ion transport. This mechanism relaxes the sorbophobic crystal structure, enhances solvent-philic properties, and promotes ion exchange with the electrolyte, thereby having a positive effect on electrochemical performance.

[0150] Solution resistance (Rs) and charge transfer resistance (R) of the s-DHC system ct The change was evaluated using EIS (Fig. 5f). To clarify the role of SN in spontaneously dissolving into the electrolyte upon contact in the s-DHC system, a control sample (ds-DHC) was prepared by removing SN from the s-DHC prior to electrode fabrication. A second comparison sample (sn-ds-DHC) was tested by introducing SN as an additive into the electrolyte along with the ds-DHC electrode. R of the s-DHC system s and R ct The values ​​were measured as 3.1 and 54.0 Ω, respectively, which is significantly lower than the ds-DHC system (8.7 and 62.1 Ω) and R sA distinct difference is observed (Fig. 5g). On the other hand, the values ​​of the sn-ds-DHC system (2.9 and 50.1 Ω) are very similar to those of s-DHC, which highlights the beneficial effect of SN in enhancing ionic conductivity and charge transfer. Furthermore, R of s-DHC ct The value is significantly lower than that of the a-DHC, n-DHC, and c-DHC systems (87.2–310.1 Ω), enhancing the excellent performance of the sPVDF binder (see Fig. 14).

[0151] The galvanostatic charge / discharge profile further demonstrates the effect of the sPVDF binder (Fig. 5h). The initial reversible capacity of the s-DHC system is approximately 216 mA·h·g -1 Ro, 200 mA·h·g after 100 cycles -1 It decreased slightly, representing a significant improvement compared to the low initial reversible capacity and capacity retention rates of the a-DHC, n-DHC, and c-DHC systems (see Fig. 15). The ratio capability at a C-rate from 0.05 to 0.5 was characterized by reversible capacity recovery at 0.05 C after 30 cycles of ratio testing (Fig. 5i). At 0.05 C, the areal capacities of the s-DHC, a-DHC, n-DHC, and c-DHC systems were 11.0, 10.8, 10.0, and 9.0 mA·h·cm², respectively. -2 As the C-rate increased, it gradually decreased. At 0.5 C, these systems were 8.2, 7.9, 5.6, and 3.3 mA·h·cm, respectively. -2 Maintaining the area capacity, the initial reversible capacity was fully recovered after rate cycling, except for the c-DHC system.

[0152] Cycling performance data over 100 consecutive cycles at a C-rate of 0.1 confirmed the reversibility and stability of the sorbophobic binder crystallinity-controlled electrode system (Fig. 5j). For s-DHC, approximately 9.8 mA·h·cm -2Approximately 90.7% was maintained after 100 cycles, which is 9.3, 7.2, and 3.9 mA·h·cm for a-DHC, n-DHC, and c-DHC, respectively. -2 It was significantly higher compared to the corresponding capacity retention rates of 88.8%, 78.2%, and 49.3%. The significant difference in cycling performance cannot be explained solely by the difference in Rct values, and the Rct values ​​of all samples decreased after 100 cycles compared to the initial measurement (see k in Fig. 5 and Fig. 16).

[0153] On the other hand, in the s-DHC system exhibiting excellent cycling performance, the shape of the active material particles was well preserved even after 100 cycles (see Fig. 5, l and Fig. 17). Conversely, in the electrode with poor cycling performance, it was observed that the active material particles located on the top surface broke or were damaged after 100 cycles (see Fig. 5, m and Fig. 18). This phenomenon is understood to stem from an imbalance in the current distribution across the entire electrode. In samples with high charge transfer resistance, the active material located on the top of the thicker anode, which is more favorable for ion contact, experiences a higher current density load. This excessive load can lead to particle breakage or damage, which can ultimately contribute to capacity reduction. As cycling progresses, the particles on the top may degrade, and the deeper active material inside the electrode gradually becomes more active. This transition can result in a more uniform current distribution across the entire electrode, which may explain the decrease in resistance observed over time with continuous cycling.

[0155] <s-DHC 기반 고에너지 리튬 금속 배터리>

[0156] 50 mg·cm -2The practicality of high-performance s-DHCs with an active material load was evaluated in LMB whole cells paired with a lithium metal anode (LMA). This LMA was hosted on a 3D nanofiber scaffold (3D-CNS) coated with a LiNO3 additive. The fabricated 3D-CNSs underwent 20 cycles of pre-cycling in a 1 M LiPF6 in EC / DMC (1:1 v / v) electrolyte prior to whole-cell testing, and at the end of the pre-cycling process, an excess lithium equivalent to approximately 100% of the anode capacity (11 mA·h·cm²) was present. -2 ) is added. The initial electrolyte-to-cell capacity (E / C) ratio is 2.5 g·A·h -1 Under conditions where the cathode state of charge (SoC) was 50%, the Li / 3D-CNS / / s-DHC cell was cycled for 50 cycles in a voltage range of 2.7–4.3 V at various C-rates (Fig. 6a). For comparison, the same active substance loading (50 mg·cm²) was used. -2 Li / 3D-CNS / / a-DHC and Li / 3D-CNS / / n-DHC cells containing ) were also tested under the same conditions. At a C-rate of 0.1, the Li / 3D-CNS / / s-DHC cell yielded 212 mA·h·g -1 Specific capacity of and 10.6 mA·h·cm -2 It exhibited an area capacity that was 2% and 15% higher than that of Li / 3D-CNS / / a-DHC and Li / 3D-CNS / / n-DHC cells, respectively (Fig. 6b).

[0157] The area capacity gradually decreases as the C-rate increases from 0.05 to 0.1, 0.2, 0.3, 0.4, and 0.5 C, reaching 11.0, 10.6, 10.2, 9.4, 8.7, and 8.2 mA·h·cm. -2The value was maintained. After 30 cycles of the rate cycling test, the initial capacity was fully recovered at 0.05 C (Fig. 6c). In addition, at a 0.1 C-rate, the Li / 3D-CNS / / s-DHC cell demonstrated very stable cycling performance, showing nearly 100% capacity retention for 50 cycles (Fig. 6d). This contrasts with the 92.7% and 81.7% capacity retentions observed in the Li / 3D-CNS / / a-DHC and Li / 3D-CNS / / n-DHC cells, respectively.

[0158] The s-DHC system is 11.0 mA·h·cm -2 It provides a high areal capacity, the average voltage is 3.8 V, and the specific energy density of the Li / 3D-CNS / / s-DHC cell is 418 W·h·kg excluding packaging material. -1 It was found to reach [value] (Fig. 6e). This was significantly higher than previously reported cells produced through a dry process. Even when considering 20% ​​of the total weight of the packaging material, the energy density remained about 35% higher than that of commercial LIBs.

[0159] More detailed characteristic data can be found in Table 1 below.

[0160] [Table 1]

[0161] (Specific weights and specific energy of respective components in the Li / 3D-CNS / / DHC full cells)

[0162]

[0163] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as set forth in the following claims.

Claims

Claim 1 A method for manufacturing a thick film electrode for a lithium secondary battery, comprising: a first step of dry-mixing a positive electrode active material, a conductive material, and PVDF [Poly(vinylidene fluoride)] to form a mixed electrode material; a second step of coating the mixed electrode material onto a support and then placing a current collector thereon; a third step of hot-pressing the mixed electrode material and the current collector against the support to form a laminate of the electrode active material layer and the current collector; and a fourth step of rapidly cooling the laminate of the electrode active material layer and the current collector. Claim 2 A method for manufacturing a thick film electrode for a lithium secondary battery, characterized in that, in claim 1, it further includes a step of roll-pressing the laminate after the fourth step. Claim 3 A method for manufacturing a thick film electrode for a lithium secondary battery, characterized in that, in paragraph 2, the thickness of the electrode active material layer after the roll pressing process is 150 to 350 μm. Claim 4 A method for manufacturing a thick film electrode for a lithium secondary battery, wherein, in the mixed electrode material of the first step, the content of the positive active material is 65 to 85 weight%, and the content of the conductive material and the PVDF are each independently 5 to 20 weight%. Claim 5 In paragraph 4, the positive active material is NCM (LiNi 1-x-y Co x Mn y O2, 0 <x, y≤0.1) 또는 NCA(LiNi 1-a-b Co a Al b O2, 0 <a, b≤0.1)을 포함하는 것을 특징으로 하는, 리튬 이차전지용 후막 전극의 제조방법. Claim 6 A method for manufacturing a thick film electrode for a lithium secondary battery, wherein, in claim 4, the conductive material comprises one or more selected from the group consisting of Super P, Ketjen Black, Acetylene Black, Carbon Nanotubes (CNT), and Graphene. Claim 7 A method for manufacturing a thick film electrode for a lithium secondary battery, wherein, in claim 1, the current collector comprises a conductive metal sheet. Claim 8 A method for manufacturing a thick film electrode for a lithium secondary battery, wherein, in claim 1, the hot pressing of the third step is performed at a temperature above the melting point of the PVDF. Claim 9 A method for manufacturing a thick film electrode for a lithium secondary battery, wherein, in claim 8, the hot pressing is performed at 175 to 200°C. Claim 10 A method for manufacturing a thick film electrode for a lithium secondary battery, wherein, in claim 1, the rapid cooling of the fourth step is characterized by cooling the laminate at a rate of 50℃ / min to 500℃ / min. Claim 11 A method for manufacturing a thick film electrode for a lithium secondary battery, wherein, in claim 10, the rapid cooling is performed by immersing the laminate in liquid nitrogen. Claim 12 A thick film electrode for a lithium secondary battery manufactured according to the manufacturing method of any one of claims 1 to 11. Claim 13 A thick film electrode for a lithium secondary battery according to claim 12, characterized in that the degree of crystallization (Xc) of the PVDF calculated according to the following Equation 1 based on the differential scanning calorimetry (DSC) curve of the PVDF is 40 to 50%: [Equation 1] In the above Equation 1, △H measured and △H 100% crystalline represents the measured enthalpy of PVDF and the enthalpy of 100% crystalline PVDF, respectively. Claim 14 A thick film electrode for a lithium secondary battery according to claim 13, characterized in that the PVDF comprises an α-phase crystal structure. Claim 15 In claim 13, in the electrode active material layer, the loading amount of the positive active material is 45 to 55 mg / cm² -2 And, the reversible capacity of the thick film electrode is 200 to 220 mAhg -1 A thick film electrode for a lithium secondary battery, characterized by being. Claim 16 A method for manufacturing a thick film electrode for a lithium secondary battery, comprising: a first step of dissolving PVDF in molten succinonitrile (SN) and then solidifying it to form a composite binder; a second step of dry mixing a positive active material, a conductive material, and the composite binder to form a mixed electrode material; a third step of applying the mixed electrode material onto a support and then placing a current collector thereon; a fourth step of hot-pressing the mixed electrode material and the current collector against the support to form a laminate of the electrode active material layer and the current collector; and a fifth step of cooling the laminate. Claim 17 A method for manufacturing a thick film electrode for a lithium secondary battery, characterized in that, in claim 16, it further includes a step of roll-pressing the laminate after the above 5th step. Claim 18 A method for manufacturing a thick film electrode for a lithium secondary battery, wherein, in the first step of claim 16, the composite binder comprises the PVDF and the SN in a weight ratio of 1:05 to 1.

5. Claim 19 A method for manufacturing a thick film electrode for a lithium secondary battery according to claim 16, wherein in the mixed electrode material of the first step, the content of the positive active material is 65 to 85 weight%, and the content of the conductive material and the PVDF are each independently 5 to 20 weight%. Claim 20 A thick film electrode for a lithium secondary battery manufactured according to the manufacturing method of any one of claims 16 to 19. Claim 21 A thick film electrode for a lithium secondary battery according to claim 20, characterized in that the thickness of the electrode active material layer is 150 to 350 μm. Claim 22 A thick film electrode for a lithium secondary battery according to claim 20, characterized in that the degree of crystallization (Xc) of the PVDF calculated according to the following Equation 1 based on the differential scanning calorimetry (DSC) curve of the PVDF is 25 to 35%: [Equation 1] In the above Equation 1, △H measured and △H 100% crystalline represents the measured enthalpy of PVDF and the enthalpy of 100% crystalline PVDF, respectively. Claim 23 A thick film electrode for a lithium secondary battery according to claim 22, characterized in that the PVDF comprises an α-phase crystal structure. Claim 24 In claim 22, in the electrode active material layer, the loading amount of the positive active material is 45 to 55 mg / cm² -2 And, the reversible capacity of the thick film electrode is 200 to 220 mAhg -1 A thick film electrode for a lithium secondary battery, characterized by being. Claim 25 A lithium-ion secondary battery comprising: a positive electrode and a negative electrode positioned opposite each other; an electrolyte filling the space between the positive electrode and the negative electrode; and a separator positioned between the positive electrode and the negative electrode within the electrolyte; wherein the positive electrode comprises the thick film electrode of claim 12. Claim 26 A lithium-ion secondary battery comprising: a positive electrode and a negative electrode arranged facing each other; an electrolyte filling the space between the positive electrode and the negative electrode; and a separator arranged between the positive electrode and the negative electrode within the electrolyte; wherein the positive electrode comprises the thick film electrode of claim 20, and the SN of the composite binder is leached into the electrolyte.

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