Composite electrode and preparation method thereof

Abstract

A composite electrode and a method for manufacturing the same are disclosed. The composite electrode comprises a composite cathode material layer coated on a carrier surface of an electrode plate. The composite cathode material layer comprises a plurality of cathode material particles, a first conductive carbon, and a Li-Nafion polymer material. The cathode material particles are composed of ternary materials. The first conductive carbon is pre-coated on the surface of the cathode material particles by dry mechanical mixing. The weight percentage of the first conductive carbon relative to the cathode material particles is 1 weight% to 5.5 weight%. The Li-Nafion polymer material covers the surface of the cathode material particles and is bonded between the surfaces of the cathode material particles. The weight percentage of the Li-Nafion polymer material relative to the cathode material particles is in the range of 10 weight% to 20 weight%.

Description

Technology Field

[0001] The present invention relates to an electrode for a secondary battery, and more specifically, to a composite electrode and a method for manufacturing the same, wherein a composite anode sheet is manufactured through a dry process surface pretreatment of conductive carbon in combination with a Li-Nafion polymer material to improve high-rate charge / discharge performance and optimize capacity retention rate. Background Technology

[0002] Recently, performance requirements for electric vehicles and energy storage devices have been increasing, and secondary batteries used in these applications are also required to have good performance. Among various types of batteries, lithium-ion batteries using ternary cathode materials such as nickel-cobalt-manganese (NCM) have high capacity characteristics and are currently the mainstream choice.

[0003] Since the nickel content in the aforementioned cathode material is directly proportional to its power density and the price of cobalt metal fluctuates significantly, the current mainstream development trend is to increase the nickel content to raise power density and reduce manufacturing costs. However, high-nickel cathode materials are prone to adverse reactions with the electrolyte due to their high nickel content, leading to a reduction in cycle life.

[0004] Conventionally, inorganic metal oxides are used to modify the surface of high-nickel materials. However, it is difficult to obtain a uniform and complete coating using general engineering methods. Furthermore, metal oxides are typically coated using conventional liquid-phase methods, requiring evaluation of solvent selection and recyclability. Since additional heat treatment procedures must be performed, the process and cost of material production increase significantly.

[0005] Meanwhile, the binder is also a core and indispensable component in the process of manufacturing the cathode material of a lithium-ion secondary battery into an electrode. Selecting an inappropriate binder can affect the performance of the cathode material within the electrode after surface modification.

[0006] Therefore, it is necessary to provide a composite anode sheet and a method for manufacturing the same that can improve high-rate charge / discharge performance and optimize capacity retention rate, while simultaneously overcoming the disadvantages faced by conventional technology, by manufacturing a composite anode sheet through dry process surface pretreatment of conductive carbon in combination with a Li-Nafion polymer material. means of solving the problem

[0007] The objective of the present invention is to provide a composite electrode for a secondary battery and a method for manufacturing the same. The conductive carbon is pre-coated on the surface of a high-nickel NCM cathode material via a dry mechanofusion method to improve the surface hydrophobicity of the high-nickel NCM cathode material and to enhance the coating performance of the lithiated Nafion (Li-Nafion) polymer material in a subsequent process, thereby effectively maintaining the original spherical secondary particle shape of the high-nickel NCM cathode material. The dry mechanofusion process is fast and does not require additional solvent and gas protection. Through the dry mechanofusion process, an appropriate amount of conductive carbon can be coated on the surface of the high-nickel NCM cathode material, which helps improve the hydrophobicity of the cathode material surface and can enhance the coating performance of the (Li-Nafion) polymer material on the surface of the high-nickel NCM material without affecting the shape of the NCM cathode material. Furthermore, the Li-Nafion polymer material is used to replace conventional binders (PVDF, PAA, CMC-SBR, etc.) used in the secondary battery process. Since Li-Nafion polymer materials have excellent ion conductivity, composite cathode materials can have a superior capacity retention rate when charged and discharged under high rate (6CC / 6CD) conditions.

[0008] In other words, pre-treating the surface with conductive carbon enables the Li-Nafion polymer material, which is a functional coating, to be coated more uniformly on the surface of the high-nickel cathode material. Furthermore, rapid charge / discharge performance and cycle life are improved. In this regard, a fast and effective means is provided to obtain a functional coating that can be uniformly coated using a binder.

[0009] According to one aspect of the present disclosure, a composite electrode is provided, comprising an electrode plate and a composite positive active material layer. The electrode plate comprises a support. The composite positive active material layer is coated on the support of the electrode plate. The composite positive active material layer comprises a plurality of positive active material particles, a first conductive carbon, and a Li-Nafion polymer material. The plurality of positive active material particles are Li[NixCoyMnz]O2, and x+y+z=1, 0.8 <x<1, 0<y<0.2, 0<z<0.2]의 조성을 갖는 삼원계 물질로 구성된다. 상기 복수의 양극 활물질 입자의 표면에 건식 기계적 혼합법을 통해 제1전도성 탄소를 미리 코팅하고, 상기 복수의 양극 활물질 입자에 대한 상기 제1전도성 탄소의 중량%는 1 중량% 내지 5.5 중량%의 범위를 갖는다. 상기 Li-Nafion 고분자 물질은 상기 복수의 양극 활물질 입자의 표면을 덮고, 상기 복수의 양극 활물질 입자의 표면 중에 결합되며, 상기 복수의 양극 활물질 입자에 대한 상기 Li-Nafion 고분자 물질의 중량%는 10 중량% 내지 20 중량%의 범위를 갖는다.

[0010] In one embodiment, the dry mechanical mixing method comprises the step of mixing at a first rotational speed of 600 rpm for 10 minutes and mixing at a second rotational speed of 4200 rpm for 30 minutes, and the operating temperature is a mechanical fusion method of 30℃ to 40℃.

[0011] In one embodiment, the Li-Nafion polymer material is mixed with a solvent to form a Li-Nafion polymer solution, and then mixed with the plurality of anode material particles and the first conductive carbon, the weight% concentration of the Li-Nafion polymer solution is 10 weight%, the solvent is composed of ethanol and n-butanol, and the weight ratio of the ethanol to the n-butanol is 1:2.

[0012] In one embodiment, the composite anode material layer further comprises a second conductive carbon, wherein the second conductive carbon is mixed with the first conductive carbon and the plurality of anode material particles pre-coated with the Li-Nafion polymer material, and the weight percentage of the second conductive carbon relative to the plurality of anode material particles is 5.5 weight% to 15 weight%.

[0013] In one embodiment, the composite anode material layer has a compressive density in the range of 3.1 g / cm³ to 3.3 g / cm³.

[0014] In one embodiment, the electrode plate is an aluminum plate.

[0015] In one embodiment, the plurality of cathode material particles are characterized by having a first average particle size of 10㎛ to 20㎛, and the first conductive carbon is characterized by having a second average particle size of 50nm to 200nm.

[0016] According to another aspect of the present invention, a method for manufacturing a composite electrode is provided, comprising the step of (a) providing a plurality of anode material particles and a first conductive carbon, wherein the plurality of anode material particles are Li[NixCoyMnz]O2, and x+y+z=1, 0.8 <x<1, 0<y<0.2, 0<z<0.2]; (b) 상기 복수의 양극재 입자에 대한 상기 제1전도성 카본의 중량%가 1.5 중량% 내지 5.5 중량%인 건식 기계적 혼합 방법을 통해 상기 복수의 양극재 입자의 표면에 상기 제1전도성 카본을 코팅하는 단계; (c) 상기 복수의 양극재 입자에 대한 상기 Li-Nafion 고분자 물질의 중량%가 10 중량% 내지 20 중량%인 Li-Nafion 고분자 물질을 제공하는 단계; (d) 상기 Li-Nafion 고분자 물질 및 상기 제1전도성 카본으로 미리 코팅된 상기 복수의 양극재 입자를 혼합하여 복합 양극재 슬러리를 형성하는 단계; (e) 상기 복합 양극재 슬러리를 극판의 담지면에 코팅하는 단계; 및 (f) 건조하여 상기 복합전극을 형성하는 단계; 및 상기 Li-Nafion 고분자 물질이 상기 복수의 양극재 입자의 표면을 덮고 상기 복수의 양극재 입자의 표면 사이에 결합되는 것을 포함한다.

[0017] In one embodiment, the dry mechanical mixing method in step (b) comprises mixing for 10 minutes at a first rotational speed of 600 rpm and mixing for 30 minutes at a second rotational speed of 4200 rpm, and the operating temperature is a mechanical fusion method of 30℃ to 40℃.

[0018] In one embodiment, the Li-Nafion polymer material provided in step (c) is mixed with a solvent to form a Li-Nafion polymer solution, and then mixed with the plurality of anode material particles and the first conductive carbon so that the weight% concentration of the Li-Nafion polymer solution is 10 weight%, the solvent is composed of ethanol and n-butanol, and the weight ratio of ethanol and n-butanol is 1:2.

[0019] In one embodiment, a second conductive carbon is further added in step (d) so that a plurality of positive active material particles, which are pre-coated with the first conductive carbon and the Li-Nafion polymer material, are mixed with the second conductive carbon, and the weight percentage of the second conductive carbon relative to the plurality of positive active material particles is 5.5 weight% to 15 weight%.

[0020] In one embodiment, in step (e), the composite cathode material slurry is coated onto the supporting surface of the electrode plate using a doctor blade method, and the surface density of the composite cathode material slurry has a range of 9 mg / ㎠ to 12 mg / ㎠.

[0021] In one embodiment, the composite anode material layer has a compressive density in the range of 3.1 g / cm³ to 3.3 g / cm³.

[0022] In one embodiment, the electrode plate is an aluminum plate.

[0023] In one embodiment, the plurality of cathode material particles have a first average particle size of 10㎛ to 20㎛, and the first conductive carbon has a second average particle size of 50nm to 200nm. Brief explanation of the drawing

[0024] The above content of the present invention will be more readily understood by a person skilled in the art after reviewing the following detailed description and the attached drawings: FIG. 1 is a schematic structural diagram showing a composite electrode according to one embodiment of the present disclosure; FIG. 2 is a schematic structural diagram showing a plurality of positive active material particles according to one embodiment of the present disclosure; FIG. 3 is a schematic structural diagram showing a plurality of positive active material particles pre-coated with a first conductive carbon according to one embodiment of the present disclosure; FIG. 4 shows an SEM image of a plurality of cathode material particles of the present invention; FIG. 5 shows an SEM image of a plurality of cathode material particles pre-coated with the first conductive carbon of the present invention; Figure 6a shows the results of the water droplet contact angle analysis of multiple compressed cathode material particles; FIG. 6b shows the results of the water droplet contact angle analysis of a plurality of cathode material particles pre-coated with a first orbital conductive carbon; Figure 7 shows the chemical structure of the Li-Nafion polymer material; FIG. 8 is a flowchart of a method for manufacturing a composite electrode according to an embodiment of the present invention; Figure 9 shows the SEM / EDS analysis results of the comparative example; FIG. 10 shows the SEM / EDS analysis results of an exemplary example of the present disclosure; FIG. 11a shows the cyclic charge / discharge test of the comparative example at 0.1C / 1C / 3C / 5C / 6C; FIG. 11b shows a cyclic charge / discharge test of an exemplary embodiment of the present invention at 0.1C / 1C / 3C / 5C / 6C; FIG. 11c is a comparative diagram showing the specific capacity of the comparative example and the specific capacity of the embodiment of the present invention charged and discharged at 3C; FIG. 11d is a comparative diagram showing the specific capacity of a comparative example and the specific capacity of an exemplary embodiment of the present invention charged and discharged at 6C; FIG. 12 shows a cyclic charge / discharge test of a comparative example and an exemplary example of the present invention under 1 CC / 1 CD cycle test conditions; FIG. 13 shows the cyclic charge / discharge test of the comparative example and the demonstration example of the present invention under 6CC / 6CD cycle test conditions; Figure 14 shows the cycle charge / discharge test of the first PVDF comparative example and the second PVDF comparative example under 1 CC / 1 CD cycle test conditions. Figure 15 shows the cycle charge / discharge test of the first PVDF comparative example and the second PVDF comparative example under 6CC / 6CD cycle test conditions. Specific details for implementing the invention

[0025] The present disclosure is now described more specifically with reference to the following embodiments. It should be noted that the following descriptions of preferred embodiments of the present disclosure are presented in this specification merely for illustrative and descriptive purposes. This is not intended to be complete or limited to the exact form disclosed. For example, forming a first feature on or over a second feature in the specification described below may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which an additional feature may be formed between the first and second features so that the first and second features do not come into direct contact. Additionally, "first," "second," "third," etc. in the claims may be used to describe various elements, but these elements should not be limited by these terms, and these elements are used to represent different reference numerals in each embodiment, and these terms are used only to distinguish one element from another. For example, a first element may be named a second element without departing from the scope of the embodiment, and similarly, a second element may be named a first element. In addition, terms such as "and / or" may be used herein to include any or all combinations of one or more of the related enumerated items. Alternatively, the word "about" means within the acceptable standard error of ordinary art from the average recognized by the art. In addition to operation / operation examples, or in all cases, unless specifically stated otherwise, all numerical ranges, quantities, values, and percentages, such as numbers, time durations, temperatures, operating conditions, and ratios of quantities for materials disclosed herein, should be understood as the word "about." Accordingly, unless otherwise indicated, the numerical parameters of the invention and the scope of the proposed appended patent follow variations of the desired approximation. At least, the significant digits for each numerical parameter should be reported and described by at least conventional rounding techniques.Here, it may be expressed as a range between one endpoint and another endpoint or between both endpoints. Unless otherwise specified, all ranges disclosed herein are included.

[0027] FIG. 1 is a schematic structural diagram illustrating a composite electrode according to an embodiment of the present invention. In this embodiment, a composite electrode (1) is provided, which is a positive electrode suitable for a conventional lithium battery or a lithium metal battery. In this embodiment, the composite electrode (1) includes an electrode plate (2) and a composite positive active material layer (3). Preferably, the electrode plate (2) is a current collector made of an aluminum plate including a return surface (21). The composite positive active material layer (3) is coated on the return surface (21) of the electrode plate (2) by the method for manufacturing a composite electrode according to the present invention. The composite positive active material layer (3) obtained by the method for manufacturing the present invention includes a plurality of positive active material particles (10), a first conductive carbon (20), and a Li-Nafion polymer material (30). The plurality of positive active material particles (10) are Li[NixCoyMnz]O2, and x+y+z=1, 0.8 <x<1, 0<y<0.2, 0<z<0.2)의 조성을 갖는 삼원계 물질로 구성된다. 바람직하게는 그러나 독점적이지는 않지만, 상기 삼원계 물질의 조성은 높은 니켈 함유량(니켈 함유량 > It has 80%). In particular, in this embodiment, the first conductive carbon (20) is pre-coated on the surface of a plurality of positive active material particles (10) through a dry mechanical mixing method such as a mechanical fusion method. Preferably, although not exclusively, the weight percentage of the first conductive carbon (20) relative to the plurality of positive active material particles (10) is 1 weight% to 5.5 weight%. FIG. 2 is a schematic structural diagram illustrating a plurality of positive active material particles according to one embodiment of the present invention. FIG. 3 is a schematic structural diagram illustrating a plurality of positive material particles pre-coated with the first conductive carbon according to one embodiment of the present disclosure. In this embodiment, the first conductive carbon (20) is pre-coated on the surface of a plurality of positive material particles (10) through a mechanical fusion method, and the first conductive carbon (20) is made to be uniformly distributed on the surface of the plurality of positive material particles (10) in a dot shape.When making electrodes, not only is the effect on electrical performance reduced due to uneven distribution or excessive addition of conductive carbon, but the surface characteristics of multiple anode particles (10) are further improved.

[0029] FIG. 4 shows an SEM image of a plurality of anode material particles of the present invention. FIG. 5 shows an SEM image of a plurality of anode material particles pre-coated with a first conductive carbon of the present invention. In this embodiment, the plurality of anode material particles (10) have a first average particle size of 10 μm to 20 μm, and the first conductive carbon (20) has a second average particle size of 50 nm to 200 nm. The plurality of anode material particles (10) are processed by a mechanical fusion mixing method so that the first conductive carbon (20) is uniformly distributed on the surface of the plurality of anode material particles (10) in a dot shape, and the shape and particle size of the plurality of anode material particles (10) are not changed.

[0030] FIG. 6a shows the results of the water droplet contact angle analysis of a plurality of compressed positive active material particles. FIG. 6b shows the results of the water droplet contact angle analysis of a plurality of positive active material particles pre-coated with a first ball-conductive carbon. As shown in FIG. 6a, a powder of a plurality of positive active material particles (10) (structure as in FIG. 2) was compressed and tested to obtain a water droplet contact angle of approximately 10˚.

[0031] After compressing the powder of a plurality of positive active material particles (10) that were pre-coated with a first conductive carbon (20) (structure as shown in FIG. 3), the powder was tested with a water droplet contact angle of about 27˚ as shown in FIG. 6b.

[0032] Comparing the two results above, it can be seen that when a plurality of positive active material particles (10) are pre-coated with a first conductive carbon (20) by a mechanical fusion mixing method, the hydrophobicity of the surface of the plurality of positive active material particles (10) can be increased. FIG. 7 shows the chemical structure of a Li-Nafion polymer material. As shown in FIG. 7, the structure of the Li-Nafion polymer material (30) includes long-chain hydrophobic segments (31). Therefore, after coating the surface of the plurality of positive active material particles (10) with the first conductive carbon (20) by a mechanical fusion mixing method, the surface of the plurality of positive active material particles (10) can be modified to have higher hydrophobicity. In this way, it is more advantageous to combine the plurality of positive active material particles (10) with the Li-Nafion polymer material (30).

[0033] Of course, the type, composition ratio, and material characteristics of the plurality of anode material particles (10) pre-coated with the first conductive carbon (20) and Li-Nafion polymer material (30) selected for mixing into the composite anode active material layer (3) can be adjusted according to practical requirements and are not limited thereto. Below, a method for manufacturing the composite electrode (1) of the present invention will be described.

[0034] FIG. 8 is a flowchart of a method for manufacturing a composite electrode according to an embodiment of the present invention. In this embodiment, first, as shown in step S1 above, a plurality of anode material particles (10) and a first conductive carbon (20) are provided. Preferably but not exclusively, the plurality of anode material particles (10) are Li[NixCoyMnz]O2, x+y+z=1, 0.8 <x<1, 0<y<0.2, 0<z<0.2]의 조성을 갖는 삼원계 물질로 구성된다. 본 실시예에서 복수의 양극재 입자(10)는 제1 평균 입자의 크기가 10 ㎛ 내지 20 ㎛ 이다. 바람직하지만 독점적인 것은 아니며, 제1 전도성 카본(20)는 Super-P이고, 제2 평균 입자의 크기가 50 ㎚ 내지 200 ㎚ 이다.

[0035] Next, as in step S2, a plurality of anode material particles (10) and a first conductive carbon (20) are coated onto the surface of the plurality of anode material particles (10) in a specific ratio, for example, by a dry mechanical fusion mixing method, and the obtained structure is as shown in FIG. 3. In this embodiment, the weight percentage of the first conductive carbon relative to the plurality of anode material particles (10) is in the range of 1 weight% to 5.5 weight%. In this way, an appropriate amount of the first conductive carbon (20) is uniformly distributed in a dot-like form on the surface of the plurality of anode material particles (10). As a result, surface modification of the plurality of anode material particles (10) is achieved, and there is no change in the shape and particle size of the plurality of anode material particles (10). In particular, the weight percentage of the first conductive carbon for the plurality of cathode material particles (10) is less than 5.5 weight%, thereby preventing the first conductive carbon (20) from being over-coated on the surface of the plurality of cathode material particles (10) and affecting the subsequent mixing and coating of the Li-Nafion polymer material (30). Meanwhile, when surface modification is performed by mechanical fusion, the mixing process includes the step of mixing for 10 minutes at a first rotational speed of 600 rpm and mixing for 30 minutes at a second rotational speed of 4200 rpm, and the working temperature is 30°C to 40°C. By controlling the mixing method, the working temperature for surface modification and pre-coating, the rotational speed and mixing time, and the working temperature, rotational speed and time, structural defects caused by high temperature and excessive friction between particles can be avoided. Furthermore, simultaneously, the plurality of cathode material particles (10) are made to exhibit the effect of surface modification through the pre-coating of the first conductive carbon (20).

[0036] Furthermore, in this embodiment, a Li-Nafion polymer material (30) is provided as in step S3 above. To obtain a good coating effect, the weight percentage of the Li-Nafion polymer material (30) relative to a plurality of cathode material particles (10) ranges from 10 weight% to 20 weight%. In this embodiment, the Li-Nafion polymer material (30) and a solvent are further mixed to form a Li-Nafion polymer solution, which is then mixed with a plurality of cathode material particles (10) and a first conductive carbon (20). Preferably, but not exclusively, the weight percentage concentration of the Li-Nafion polymer solution is 10 weight%, and the solvent consists of ethanol and n-butanol, with a weight ratio of ethanol to n-butanol of 1:2. Of course, the present invention is not limited thereto.

[0037] Subsequently, in step S4, a composite cathode material slurry is formed by mixing a plurality of cathode material particles (10) pre-coated with the first conductive carbon (20) in step S2 and the Li-Nafion polymer material (30) provided in step S3. In particular, in some embodiments, the composite cathode material layer (3) of the composite electrode (1) requires the addition of a higher content of conductive carbon exceeding the content of the first conductive carbon (20) in step S2. Subsequently, an additional content of conductive carbon can be added by adding the second conductive carbon (40) in step S4, so that the additional conductive carbon is well mixed with the plurality of cathode material particles (10) pre-coated with the first conductive carbon (20) and the Li-Nafion polymer material (30). Of course, the weight percentage of the second conductive carbon (40) relative to the plurality of cathode material particles (10) can be adjusted according to practical requirements. Although desirable, it is not exclusive to that, but the weight percentage of the second conductive carbon (40) relative to the plurality of anode particles (10) is in the range of 5.5 weight% to 15 weight%.

[0038] In step S5, the composite cathode material slurry is coated onto the supporting surface (21) of the electrode plate (2). Preferably, but not alone, the composite cathode material slurry is coated onto the supporting surface (21) of the electrode plate (2) using a doctor blade method. Preferably, but not alone, the surface density of the composite cathode material slurry coated onto the supporting surface (21) of the electrode plate (2) is 9 mg / cm² to 12 mg / cm². Of course, the present invention is not limited thereto.

[0039] Finally, in step S6, the composite anode material slurry coated on the return surface (21) of the electrode plate (2) is dried to form a composite electrode (1). The structure of the result is shown in FIG. 1. In this embodiment, the Li-Nafion polymer material (30) covers the surface of a plurality of anode material particles (10) and is bonded between the surfaces of the plurality of anode material particles (10).

[0040] In an exemplary embodiment, 495g of NCM material is provided to serve as a plurality of anode material particles (10). The NCM material has the chemical formula Li[Ni0.83Co0.12Mn0.05]O2 (Ni:Co:Mn=83:12:5) and has a surface area BET = 0.32 m² / g. Additionally, 27.5g of Super-P is provided to serve as a first conductive carbon (20) which is a precursor for surface modification of the plurality of anode material particles (10). The 495g of NCM and 27.5g of Super-P are mixed using a mechanical fusion method. First, the mixing process is set to a low output of 7.5% and mixed for 10 minutes at a first rotational speed of 600 rpm. Then, the mixing process is set to an output of 80% and mixed for 30 minutes at a second rotational speed of 4200 rpm. In order to prevent the high temperature generated by high-speed mixing from adversely affecting the sample, the operating temperature of the equipment is controlled and has a range of 30°C to 40°C during the mixing process. The surface-modified sample obtained in this way is shown in Fig. 5 and is referred to as NCM@C.

[0041] In addition, the above Li-Nafion polymer material (30) is provided in the form of a solution. To prepare the Li-Nafion polymer solution, 20.981 g of LiOH·H2O powder is placed in a 500 mL quantitative bottle and 300 mL of deionized water is added. After the LiOH·H2O is completely dissolved, additional deionized water is added to make 500 mL, thereby completing the preparation of the 1N LiOH solution. Another 250 mL round-bottom flask is provided, and 60 g of 5% H-Nafion solution is added to this round-bottom flask. The H-Nafion solution is lithiated through the above 1N LiOH solution and titrated to pH=6.

[0042] Next, the previously titrated Li-Nafion solution is concentrated under reduced pressure at a temperature of 60°C to 80°C to completely remove the solvent. Finally, after the solvent is completely removed, a solvent having a weight ratio of 1:2 consisting of ethanol and n-butanol is added to prepare a Li-Nafion polymer solution with a total weight concentration of 10 wt.%. After complete dissolution, the pretreated Li-Nafion polymer solution is obtained.

[0043] In the subsequent manufacture of composite electrode 1, NCM@C: Super-P (provided as the second conductive carbon): 10 wt.% Li-Nafion solution = 8.42g: 0.58g: 10g is provided and then added to a mixing bottle for mixing through a planetary rotary mixer.

[0044] These materials are mixed at a rotational speed of 1200 rpm for 10 minutes to obtain a composite cathode material slurry. The obtained composite cathode material slurry is uniformly coated onto an aluminum plate using a doctor blade method, and the surface density of the composite cathode material slurry is 9 mg / cm² to 12 mg / cm². The coated semi-finished electrode is dried at 100°C for 1 hour. The dried semi-finished electrode is rolled using an electrode sheet rolling mill. During the rolling process, the compacted density of the composite electrode is controlled to a range of 3.1 g / cm³ to 3.3 g / cm³. That is, the manufacture of the composite electrode (1) of the present invention is completed. The completed composite electrode (1) is cut into a circular electrode with a diameter of 1 cm using an electrode sheet cutter. As a result, the obtained CR2032 button cell can be used for electrochemical analysis.

[0045] In the comparative example, an NCM material that uses the same cathode material but omits surface modification is referred to as NCM. To manufacture the electrode of the comparative example, a mixture of NCM: Super-P (provided as the second conductive carbon): 10 wt.% Li-Nafion solution = 8g:1g:10g is provided and then placed in a mixing bottle to be mixed using a planetary rotary mixer. These materials are mixed at a rotational speed of 1200 rpm for 10 minutes to obtain a cathode material slurry. The obtained cathode material slurry is coated onto an aluminum plate using the doctor blade method, and the surface density of the cathode material slurry is 9 mg / cm² to 12 mg / cm². The coated semi-finished electrode is dried at 100°C for 1 hour. The dried semi-finished electrode is rolled using an electrode sheet rolling mill. During the rolling process, the compacted density of the composite electrode is controlled and has a range of 3.1 g / cm³ to 3.3 g / cm³. In other words, the manufacture of the electrode of the comparative example is complete. The electrode of the comparative example is cut into a circular electrode with a diameter of 1 cm using an electrode sheet cutter. The resulting CR2032 button cell can be used for electrochemical analysis.

[0046] In the examples, the distribution of Ni and F elements in the comparative example and the example was analyzed using SEM / EDS. Figure 9 shows the SEM / EDS analysis results of the comparative example. As shown in Figure 9, in the cross-section of the electrode plate of the comparative example, the F element is mainly provided by the Li-Nafion polymer material, and the Ni element is provided by the NCM material. However, it can be seen from Figure 9 that the F signal and the Ni signal do not overlap. This means that the Li-Nafion polymer material is not uniformly coated on the surface of the NCM material. Furthermore, Figure 10 shows the SEM / EDS analysis results of the example of the present invention. As shown in Figure 10, it can be confirmed that the F signal and the Ni signal overlap. This means that the Li-Nafion polymer material is uniformly coated on the surface of the NCM material. From this, it can be confirmed that after surface modification of the NCM material is performed by the mechanical fusion mixing method of the present invention, the obtained NCM@C material is easily combined with the Li-Nafion polymer material in a subsequent mixing process, and the Li-Nafion polymer material is uniformly coated on the surface of the NCM@C material.

[0047] For the CR2032 button batteries obtained in the above comparative example and embodiment, charge and discharge performance can be analyzed at different charge and discharge rates such as 0.1C, 1C, 3C, 5C, and 6C. FIG. 11a shows the cyclic charge and discharge test of the comparative example at 0.1C / 1C / 3C / 5C / 6C. FIG. 11b shows the cyclic charge and discharge test of the embodiment of the present invention at 0.1C / 1C / 3C / 5C / 6C. FIG. 11c is a comparative diagram showing the specific capacity of the comparative example and the specific capacity of the embodiment of the present invention charged and discharged at 3C. FIG. 11d is a comparative diagram showing the specific capacity of the comparative example and the specific capacity of the embodiment of the present invention charged and discharged at 6C. Table 1 shows the analysis results of the comparative example and the embodiment under charge and discharge rates of 3C / 5C / 6C. The results of FIGS. 11a to 11d and Table 1 show that the charge / discharge performance of the example of the NCM@C material uniformly coated with Li-Nafion polymer material is superior at a high charge / discharge rate (the above 3C).

[0048] Comparison Table of Charge and Discharge Capabilities at Different Charge and Discharge Rates Sample CD rate Charge capacity (mAh / g) Discharge capacity (mAh / g) Comparative example 3C 179.76 179.42 5C 159.40 158.74 6C 135.33 135.33 Examples 3C 178.68 178.55 5C 166.23 165.78 6C 153.19 153.18

[0050] FIG. 12 shows the cycle charge-discharge test of the comparative example and the embodiment of the present invention under 1CC / 1CD cycle test conditions. Under 1CC / 1CD cycle test conditions, the capacity retention rate of the comparative example is 88% after 100 cycles, and the capacity retention rate of the embodiment is 91% after 100 cycles. Unlike the comparative example, in which the Li-Nafion polymer material is directly coated onto the NCM material, the present invention obtains an NCM@C material by pre-mixing the conductive carbon and the NCM material using a mechanical fusion mixing method, which helps to increase the uniformity of the Li-Nafion polymer material coating on the surface of the anode material particles. This not only improves the performance of high-rate charge-discharge but also extends the lifespan of the charge-discharge cycle.

[0051] FIG. 13 shows the cycle charge-discharge test of the comparative example and the embodiment of the present invention under 6CC / 6CD cycle test conditions. Under 6CC / 6CD cycle test conditions, the capacity retention rate of the comparative example is 74% after 100 cycles, and the capacity retention rate of the embodiment is 84% ​​after 100 cycles. Compared to the comparative example, it can be seen that the cycle life of the rapid charge-discharge of the embodiment is significantly improved. That is, by pre-mixing conductive carbon using the mechanical fusion mixing method of the present invention, it helps improve the uniformity of the Li-Nafion polymer material covering the cathode material. Not only does it improve ion conductivity, but it also significantly slows down the capacity degradation of the cathode material.

[0052] In addition, it should be noted that a dry mechanical fusion method involving the mixing of conductive carbon is used to perform the pretreatment for surface modification of the cathode material particles, and that the pretreatment further collaborates with a Li-Nafion polymer material having long-chain hydrophobic segments. Under the same preparation conditions, the first PVDF comparative example is obtained by replacing the Li-Nafion polymer material used in the aforementioned comparative example with PVDF. Furthermore, the second PVDF comparative example is obtained by replacing the Li-Nafion polymer material with PVDF, pre-mixing the conductive carbon and NCM material through a mechanical fusion mixing method, and then obtaining a PVDF-coated NCM@C material. Fig. 14 shows the cyclic charge-discharge test of the first PVDF comparative example and the second PVDF comparative example under 1 CC / 1 CD cycle test conditions. Fig. 15 shows the cyclic charge-discharge test of the first PVDF comparative example and the second PVDF comparative example under 6 CC / 6 CD cycle test conditions. Referring to FIGS. 13 to 15, it can be seen that when PVDF is used instead of a Li-Nafion polymer material as a binder, the resulting composite electrode does not show an improvement in cycle life at high charge-discharge rates even when pretreatment for surface modification of cathode material particles is performed by mixing conductive carbon in the dry mechanical fusion method. In other words, it can be seen that pretreatment for surface modification of cathode material particles by mixing conductive carbon in the dry mechanical fusion method is more suitable for the application of Li-Nafion polymer materials as binders. Of course, Li-Nafion polymer materials may also be replaced with other polymer material binders having long-chain hydrophobic segments. The present invention is not limited thereto and is not described redundantly below.

[0053] In summary, the present invention provides a composite electrode for a secondary battery and a method for manufacturing the same. Conductive carbon is pre-coated onto the surface of a high-nickel NCM cathode material via a dry mechanofusion method to improve the surface hydrophobicity of the high-nickel NCM cathode material and enhance the coating performance of the lithiated Nafion (Li-Nafion) polymer material in a subsequent process, thereby effectively maintaining the original spherical secondary particle shape of the high-nickel NCM cathode material. The dry mechanofusion process is fast and does not require additional solvent and gas protection. By coating an appropriate amount of conductive carbon onto the surface of the high-nickel NCM cathode material through the dry mechanofusion process, it helps improve the hydrophobicity of the cathode material surface and helps improve the coating performance of the Li-Nafion polymer material on the surface of the high-nickel NCM material without affecting the shape of the NCM cathode material. Furthermore, the Li-Nafion polymer material is used to replace conventional binders (PVDF, PAA, CMC-SBR, etc.) used in the secondary battery process. Since Li-Nafion polymer materials possess excellent ionic conductivity, composite cathodes can achieve a superior capacity retention rate during charge-discharge cycles at high rates (6CC / 6CD). Specifically, by pre-treating the surface with conductive carbon, the functional coating of the Li-Nafion polymer material can be coated more uniformly on the surface of the high-nickel cathode material. Furthermore, rapid charge-discharge performance and cycle life are improved. In this regard, a fast and effective means is provided to obtain a functional coating that can be uniformly applied by using it as a binder.

[0054] Although the disclosure has been described in terms of what is currently considered to be the most practical and desirable embodiment, it will be understood that the disclosure is not limited to the disclosed embodiment. Rather, it is intended to include various modifications and similar arrangements that fall within the spirit and scope of the appended claims, in accordance with the broadest interpretation to encompass all such modifications and similar structures.

Claims

Claim 1 A composite electrode comprising the following: an electrode plate including a transport surface; and a composite anode material layer coated on the transport surface of the electrode plate, wherein the composite anode material layer is a plurality of anode material particles composed of a ternary material having the composition of Li[NixCoyMnz]O2, x+y+z=1, 0.8 <x<1, 0<y<0.2, 0<z<0.2; 상기 복수의 양극재 입자에 대한 제1전도성 카본의 중량%는 1 중량% 내지 5.5 중량%인 것을 특징으로 하는 건식 기계적 혼합 방법을 통해 상기 복수의 양극재 입자의 표면에 미리 코팅된 제1전도성 카본- 상기 건식 기계적 혼합 방법은 기계적 융합법임; 및 상기 복수의 양극재 입자의 표면을 덮고 상기 복수의 양극재 입자의 표면 중에서 결합된 Li-Nafion 고분자 물질로서, 상기 복수의 양극재 입자에 대한 상기 Li-Nafion 고분자 물질의 중량%는 10 중량% 내지 20 중량%인 것; 을 포함하는 것을 특징으로 복합 전극. Claim 2 A composite electrode, which is a mechanical fusion method according to claim 1, characterized in that the mechanical fusion method includes the step of mixing at a first rotational speed of 600 rpm for 10 minutes and mixing at a second rotational speed of 4200 rpm for 30 minutes, and the operating temperature is 30℃ to 40℃. Claim 3 A composite electrode according to claim 1, wherein the Li-Nafion polymer material is mixed with a solvent to form a Li-Nafion polymer solution, and then mixed with the plurality of anode material particles and the first conductive carbon, wherein the weight% concentration of the Li-Nafion polymer solution is 10 wt.%, the solvent is composed of ethanol and n-butanol, and the weight ratio of the ethanol to the n-butanol is 1:

2. Claim 4 A composite electrode according to claim 1, wherein the composite anode material layer further comprises a second conductive carbon, the second conductive carbon is mixed with the first conductive carbon and the plurality of anode material particles pre-coated with the Li-Nafion polymer material, and the weight percentage of the second conductive carbon relative to the plurality of anode material particles is 5.5 weight% to 15 weight%. Claim 5 In claim 1, the composite anode material layer is a composite electrode having a compressive density of 3.1 g / cm³ to 3.3 g / cm³. Claim 6 In claim 1, the electrode plate is a composite electrode that is an aluminum plate. Claim 7 A composite electrode according to claim 1, wherein the plurality of anode material particles have a first average particle size of 10㎛ to 20㎛ and the first conductive carbon has a second average particle size of 50nm to 200nm. Claim 8 A method for manufacturing a composite electrode comprising the following steps: (a) providing a plurality of anode material particles and a first conductive carbon, wherein the plurality of anode material particles are composed of a ternary material having the composition of Li[NixCoyMnz]O2, and x+y+z=1, 0.8 <x<1, 0<y<0.2, 0<z<0.2;(b) 상기 복수의 양극재 입자의 표면에 상기 복수의 양극재 입자에 대한 상기 제1전도성 카본의 중량%가 1 중량% 내지 5.5 중량%인 건식 기계적 혼합법을 통해 상기 제1전도성 카본을 코팅하는 단계- 상기 건식 기계적 혼합법은 기계적 융합법임;(c) 복수의 양극 물질 입자에 대한 Li-Nafion 고분자 물질의 중량 퍼센트가 10 중량% 내지 20 중량%인 Li-Nafion 고분자 물질을 제공하는 단계;(d) 상기 Li-Nafion 고분자 물질과 상기 제1전도성 카본으로 미리 코팅된 복수의 양극재 입자를 혼합하여 복합 양극재 슬러리를 형성하는 단계;(e) 복합 양극재 슬러리를 전극판의 운반 표면에 코팅하는 단계; 및(f) 건조하여 복합전극을 형성하는 단계에 있어서, 상기 Li-Nafion 고분자 물질이 상기 복수의 양극재 입자의 표면을 덮어 복합 양극재층을 형성하고, 상기 복수의 양극재 입자의 표면 사이에 결합되는 것을 특징으로 하는 제조방법. Claim 9 A method for manufacturing a composite electrode according to claim 8, wherein in step (b) above, the mechanical fusion method comprises mixing at a first rotational speed of 600 rpm for 10 minutes and mixing at a second rotational speed of 4200 rpm for 30 minutes, and the operating temperature is 30℃ to 40℃. Claim 10 A method for manufacturing a composite electrode according to claim 8, wherein the Li-Nafion polymer material provided in step (c) above is mixed with a solvent to form a Li-Nafion polymer solution, and then mixed with the plurality of anode material particles and the first conductive carbon, wherein the weight% concentration of the Li-Nafion polymer solution is 10 weight%, the solvent is composed of ethanol and n-butanol, and the weight ratio of the ethanol to the n-butanol is 1:

2. Claim 11 A method for manufacturing a composite electrode according to claim 8, wherein in step (d) above, a second conductive carbon is further added, and the second conductive carbon is mixed with a plurality of positive active material particles that are pre-coated with the first conductive carbon and the Li-Nafion polymer material, and the weight percentage of the second conductive carbon relative to the plurality of positive active material particles is 5.5 weight% to 15 weight%. Claim 12 A method for manufacturing a composite electrode according to claim 8, wherein in step (e), the composite anode material slurry is coated on the supporting surface of the electrode plate through a doctor blade method, and the surface density of the composite anode material slurry is 9 mg / ㎠ to 12 mg / ㎠. Claim 13 A method for manufacturing a composite electrode according to claim 8, characterized in that the composite anode material layer has a compressive density of 3.1 g / cm³ to 3.3 g / cm³. Claim 14 A method for manufacturing a composite electrode in which, in claim 8, the electrode plate is an aluminum plate. Claim 15 A method for manufacturing a composite electrode according to claim 8, wherein the plurality of anode material particles have a first average particle size of 10㎛ to 20㎛ and the first conductive carbon has a second average particle size of 50nm to 200nm.

Images