Title of Invention:THREE-DIMENSIONALLY STRUCTURED ELECTRODE AND ELECTROCHEMICAL DEVICE COMPRISING SAME

Technical field
[1]
It relates to a three-dimensional structure electrode, and an electrochemical device including the same.
[2]
This application claims priority based on Korean Application No. 10-2017-0148354 filed on November 8, 2017, and all contents disclosed in the specification of the application are incorporated in this application.
Background
[3]
Recently, the market demand for IT electronic devices such as smart phones, tablet PCs, and high-performance notebook PCs is increasing. In addition, as the demand for large-capacity power storage devices such as electric vehicles and smart grids increases significantly as part of countermeasures against global warming and resource depletion, demand for electrochemical devices including secondary batteries is rapidly increasing. Is increasing.
[4]
In particular, a lithium secondary battery corresponds to the most attention-grabbing electrochemical device due to its excellent cycle life and high energy density. However, in order to meet the demand for high power and high capacity, it is necessary to prepare an improvement plan for an electrochemical device that satisfies this.
[5]
In this connection, the electrode contributing to the capacity of the electrochemical device is composed of a mixture of a metal current collector and an active material, a conductive material, and a binder applied thereon, but substantially the capacity of the electrochemical device and It is only the active material that contributes to the energy density. Accordingly, studies on various structures and components of the active material have been conducted.
[6]
However, even an active material having a high theoretical capacity has an intrinsic electron and ionic conductivity and shows insufficient reversible capacity. In addition, in order to compensate for these shortcomings, an excessive amount of conductive material is included in the electrode design, which is a big problem in increasing the energy density of the battery.
[7]
Therefore, when minimizing additive materials such as a conductive material and a binder, the capacity per weight or volume of the electrode increases, and ultimately, the energy density of the electrochemical device can be increased.
[8]
In addition, it is better to use a light current collector instead of a metal current collector. In the case of a metal current collector, since the weight and volume occupied in the electrode are large, it is one of the reasons for reducing the capacity per weight and volume of the electrode.
[9]
In addition, if a conductive material serving as a conductive material is used, the electrode may have a uniform electron conductive network. This is because the electron conductivity is improved by forming a uniform electron conductive network between active materials in the electrode, and as a result, it can help to improve the output characteristics of the electrochemical device.
[10]
As described above, when an additive material such as a conductive material and a binder is minimized, a current collector made of a light material is used instead of a metal current collector, and an electrode having an excellent electron conduction network is applied to an electrochemical device, high capacity, high output, and high Although excellent properties such as energy density can be achieved, research on electrodes considering all three aspects is still insufficient.
Detailed description of the invention
Technical challenge
[11]
In order to solve the problems pointed out above, the object of the present invention is to provide an electrode of a three-dimensional structure that satisfies all three aspects of minimization of additives in the electrode layer, a light collector, and an excellent electron conduction network. To do.
[12]
Another object to be solved by the present invention is to provide an electrochemical device including the three-dimensional structure electrode.
Means of solving the task
[13]
According to one aspect of the invention,
[14]
Porous nonwoven fabric including a plurality of polymer fibers;
[15]
An active material composite positioned between the plurality of polymer fibers and including active material particles and a first conductive material; And
[16]
Including; a second conductive material positioned on the outer surface of the active material composite,
[17]
An interconnected porous network is formed by the plurality of polymer fibers,
[18]
There is provided a three-dimensional electrode having a three-dimensional filling structure by uniformly filling the active material composite and the second conductive material in the interconnected pore structure.
[19]
The porous nonwoven fabric may be an assembly in which the plurality of polymer fibers are three-dimensionally irregularly and continuously connected.
[20]
Meanwhile, the porosity of the three-dimensional electrode may be 5 to 95% by volume.
[21]
The three-dimensional structure electrode may include 5 to 50 parts by weight of a porous nonwoven fabric, 1 to 50 parts by weight of a first conductive material, and 0.1 to 20 parts by weight of a second conductive material based on 100 parts by weight of the active material particles.
[22]
The average diameter of the plurality of polymer fibers may be 0.001 to 1000 μm.
[23]
The average diameter of the active material particles may be 0.001 to 30 μm.
[24]
The thickness of the three-dimensional electrode may be 1 to 1000 ㎛.
[25]
The weight per area of ​​the three-dimensional electrode may be 0.001 mg /cm 2 to 1 g/cm 2 .
[26]
The three-dimensional structure electrode may have a multilayer structure in which a plurality of electrodes are stacked.
[27]
The weight per area of ​​the three-dimensional structure electrode, which is such a multi-layer structure, may be 0.002 g/cm 2 to 10 g/cm 2 .
[28]
Polymers constituting the plurality of polymer fibers are polyethylene terephthalate, polyimide, polyamide, polysulfone, polyvinylidene fluoride, polyacrylonitrile, polyethylene, polypropylene, polyetherimide, polyvinyl alcohol, polyethylene oxide, At least one selected from the group consisting of polyacrylic acid, polyvinylpyrrolidone, agarose, alginate, polyvinylidene hexafluoropropylene, polyurethane, polypyrrole, poly 3,4-ethylenedioxythiophene, polyaniline, and derivatives thereof It can be.
[29]
According to an embodiment of the present invention, at least one selected from the group including carbon nanotubes, graphene, graphene oxide, reduced graphene oxide, and carbon nanotubes in the porous nonwoven fabric It may contain more.
[30]
The active material particles are at least one selected from the group containing carbon-based materials, lithium metal-based oxides, silicon (Si), tin (Sn), germanium (Ge), sulfur (S), derivatives thereof, and mixtures thereof. , The oxide is an iron-based oxide, cobalt-based oxide, tin-based oxide, titanium-based oxide, nickel-based oxide, zinc-based oxide, manganese-based oxide, silicon-based oxide, vanadium-based oxide, copper-based oxide, and a combination thereof It may be at least one selected from.
[31]
The first conductive material and the second conductive material are each independently carbon nanotube, silver nanowire, nickel nanowire, gold nanowire, graphene, graphene oxide, reduced graphene oxide, polypyrrole, poly It may be at least one selected from the group including 3,4-ethylenedioxythiophene, polyaniline, derivatives thereof, and mixtures thereof.
[32]
The three-dimensional structure electrode may be polar.
[33]
The three-dimensional structure electrode may be any one selected from an anode or a cathode.
[34]
According to another aspect of the invention,
[35]
anode; cathode; A separator positioned between the anode and the cathode; And an electrolyte impregnated in the positive electrode, the negative electrode, and the separator; and
[36]
At least one of the anode or the cathode is an electrochemical device that is the three-dimensional structure electrode described above.
[37]
The electrochemical device is in the group comprising a lithium secondary battery, a super capacitor, a lithium-sulfur battery, a sodium ion battery, a lithium-air battery, a zinc-air battery, an aluminum-air battery, and a magnesium ion battery. It may be any one selected.
[38]
According to another aspect of the invention,
[39]
Preparing an active material composite by complexing the active material and the first conductive material;
[40]
Dissolving the polymer in a solvent to prepare a polymer solution;
[41]
Dispersing the active material composite and the second conductive material in a dispersion medium to prepare a colloidal solution;
[42]
Simultaneously spinning the polymer solution and the colloid solution to produce a three-dimensional structure fiber; And
[43]
There is provided a method of manufacturing a three-dimensional structure electrode comprising the step of compressing the three-dimensional structure fiber.
[44]
The step of simultaneously spinning the polymer solution and the colloidal solution to prepare a three-dimensional structure fiber; forming a porous nonwoven fabric including a plurality of polymer fibers, and between a plurality of polymer fibers included in the porous nonwoven fabric, the active material Particles and the conductive material may be uniformly filled, and a process of forming pores may be included.
[45]
The composite of the active material particles and the first conductive material may be performed by mixing the active material particles and the first conductive material using a grinding device.
[46]
When complexing the active material particles and the first conductive material, a dispersant for generating a uniform composite may be added.
[47]
The dispersant is polyvinylpyrrolidone, poly 3,4-ethylenedioxythiophene: polystyrene sulfonate (poly(3,4-ethylenedioxythiophene): polystyrene sulfonate) from the group containing derivatives thereof, and mixtures thereof. It may be at least one selected.
[48]
Specifically, in the step of simultaneously spinning the polymer solution and the colloidal solution to produce a three-dimensional structural fiber, double electrospinning, double electrospray, double spray, and combinations thereof are selected from the group consisting of It can be either way.
[49]
The spinning rate of the polymer solution may be 2 to 15 μl/min, and the spinning rate of the colloid solution may be 30 to 150 μl/min.
[50]
The content of the polymer in the polymer solution may be 5 to 30% by weight based on the total weight of the polymer solution.
[51]
The solvent may be at least one selected from the group containing dimethylformamide (N,N-dimethylformamide), dimethylacetamide (N,N-dimethylacetamide), methyl pyrrolidone (N-Methylpyrrolidone), and combinations thereof. have.
[52]
The content of the active material particles in the colloidal solution may be 1 to 50% by weight, based on the total weight of the colloidal solution.
[53]
The colloidal solution may further include a dispersant, and the content of the dispersant in the colloidal solution may be 0.001 to 10% by weight based on the total weight of the colloidal solution.
[54]
Specifically, the dispersant may be at least one selected from the group including polyvinylpyrrolidone, poly3,4-ethylenedioxythiophene, and mixtures thereof.
[55]
The dispersion medium is deionized water, isopropyl alcohol, buthalol, ethanol, hexanol, acetone, dimethylformamide (N,N-dimethylformamide) ), dimethylacetamide (N,N-dimethylacetamide), methyl pyrrolidone (N,N-Methylpyrrolidone), and may be any one selected from the group including a combination thereof.
Effects of the Invention
[56]
According to one embodiment of the present invention, by minimizing the additive material and using a light collector by using the current collector made of a light material by the above-described three-dimensional dense filling structure of the active material/conductive material composite, uniformity while improving the weight and capacity per volume of the electrode. By forming an electron conducting network, it is possible to provide a three-dimensional structure electrode, which contributes to the high output characteristics of the electrochemical device.
[57]
According to another embodiment of the present invention, it is possible to provide an electrochemical device having excellent weight and capacity per volume of an electrode, and having high energy density and high output characteristics.
Brief description of the drawing
[58]
1 is a scanning electron microscope (SEM) photograph of an active material composite of an active material/first conductive material prepared in Example 1 observed.
[59]
2 schematically illustrates a method of manufacturing a three-dimensional electrode according to another embodiment of the present invention, together with a three-dimensional structure electrode according to an embodiment of the present invention.
[60]
3 is a schematic diagram of a lithium secondary battery module including a three-dimensional fiber structure electrode according to an embodiment of the present invention.
[61]
4 is a result of observing the high and low magnifications of the cross section of the electrode prepared according to Example 1 of the present invention with a scanning electron microscope (SEM), respectively.
[62]
5 is. It is a photograph of the appearance of the electrode manufactured according to Example 1 of the present invention.
[63]
6 is a result of measuring and comparing the respective electric conductivity of the three-dimensional structure electrode prepared by Example 1 of the present invention, and the electrodes prepared by Comparative Example 1, Comparative Example 2, and Comparative Example 3.
[64]
7 is a result of measuring and comparing each resistance change by repeatedly bending the three-dimensional structure electrode manufactured by Example 1 and the electrode manufactured by Comparative Example 1 of the present invention.
[65]
8 shows the results of observing the discharge capacity per weight of the active material particles for the lithium secondary batteries prepared according to Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present invention while changing the discharge rate. It is a graph to show.
Mode for carrying out the invention
[66]
Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, and the present invention is not limited thereby, and the present invention is only defined by the scope of the claims to be described later.
[67]
Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used with meanings that can be commonly understood by those of ordinary skill in the art to which the present invention belongs. When a certain part in the specification "includes" a certain element, it means that other elements may be further included rather than excluding other elements unless specifically stated to the contrary. Also, the singular form includes the plural form unless specifically stated in the text.
[68]
2 schematically illustrates a method of manufacturing a three-dimensional electrode according to another embodiment of the present invention, together with a three-dimensional structure electrode according to an embodiment of the present invention. In the following description, it will be described with reference to FIG. 2. In this regard, the same reference numerals throughout the specification refer to the same components.
[69]
According to an aspect of the present invention, a porous nonwoven fabric including a plurality of polymer fibers;
[70]
An active material composite positioned between the plurality of polymer fibers and including active material particles and a first conductive material; And a second conductive material positioned on the outer surface of the active material composite, wherein an interconnected porous network is formed by the plurality of polymer fibers, and the active material composite and the agent in the interconnected pore structure 2 A three-dimensional structure electrode is provided in which a conductive material is uniformly filled to form a three-dimensional filling structure.
[71]
Referring to Figure 2, the three-dimensional structure electrode is a three-dimensional filling structure (super lattice), a plurality of polymer fibers 110 included in the porous non-woven fabric serves as a support, and between the plurality of polymer fibers 110 The active material particle 120 / the active material composite of the first conductive material 130 and the second conductive material 140 are uniformly filled and interconnected by the plurality of polymer fibers 110 (interconnected porous network) ) May be formed.
[72]
This is a type of electrode in which all three aspects of minimization of additive materials, a light collector, and an excellent electron conduction network are considered.
[73]
Specifically, by not including a separate binder, the additive material is minimized, and by using the porous nonwoven fabric, which is a light material in place of the metal current collector, the weight and capacity per volume of the electrode can be improved.
[74]
In addition, the active material particle/active material complex of the first conductive material in the three-dimensional filling structure forms a shape surrounded by the second conductive material, thereby uniformizing the electron conduction network and contributing to high power characteristics of the electrochemical device, which The discharge characteristics by rate may be improved compared to a general electrode. In particular, even when active material particles having poor electronic conductivity are applied, output characteristics can be maximized.
[75]
Hereinafter, a three-dimensional structure electrode provided in an embodiment of the present invention will be described in more detail.
[76]
As described above, the three-dimensional structure electrode forms a plurality of non-uniform spaces as the plurality of polymer fibers 110 included in the porous nonwoven fabric form a three-dimensionally irregular and continuously connected aggregate.
[77]
Between the spaces formed as described above, the active material composite including the active material particles 120 / first conductive material 130 and the second conductive material 140 are uniformly filled, and the plurality of polymer fibers 110 An interconnected porous network is formed.
[78]
At this time, as the complex of the first conductive material and the active material particles is formed, quasi-secondary particles are formed, not the simple active material nanoparticles, so obtained by simply mixing the active material particles and the conductive material through colloidal The structure and performance are different from the mixture.
[79]
The active material composite is a secondary particle composed of a first conductive material and an active material particle, and a first conductive material may be located inside and on the surface of the secondary particle. Accordingly, the first conductive material inside the secondary particle serves as a binder for connecting and fixing the active material particles, and at the same time, the first conductive material located on the surface of the secondary particle is on the surface of the adjacent active material composite. It may serve to connect to the other located first conductive material and the second conductive material.
[80]
As a result, in the three-dimensional structure electrode according to an embodiment of the present invention, an electron conducting network between active material particles constituting the active material composite is formed by the first conductive material in the active material composite, and further, a second conductive material formed on the outer surface of the active material composite. Accordingly, a uniform electron conducting network can be formed even between active material composites.
[81]
Specifically, the porosity of the three-dimensional structure electrode may be 5 to 95% by volume. When the porosity is within this range, the electrolyte can be easily absorbed and the mobility of ions can be appropriately adjusted, thereby contributing to the improvement of the performance of the electrochemical device.
[82]
In addition, when the porosity satisfies the above range, the problem that the loading value of the electrode is too small compared to the volume does not occur, and the distance between the active material particles and the conductive material is properly controlled to form an electron conducting network well. , The ion conductivity of the three-dimensional structure electrode can be smoothly maintained.
[83]
More specifically, the porosity of the three-dimensional structure electrode may be 30 to 90% by volume, and in this case, the ionic conductivity of the three-dimensional structure electrode may be further increased, and the mechanical strength may be improved.
[84]
In addition, the porosity of the three-dimensional structure electrode can be controlled by the diameter or content of the active material particles, which will be described later.
[85]
Meanwhile, the content of each material included in the three-dimensional structure electrode will be described as follows.
[86]
The content of the porous nonwoven fabric in the three-dimensional structure electrode may be 5 to 50 parts by weight, specifically 10 to 40 parts by weight, and more specifically 15 to 30 parts by weight based on 100 parts by weight of the active material particles in the three-dimensional structure electrode. By including the porous nonwoven fabric in the above range instead of the metal current collector, the capacity per weight and capacity per volume of the electrode can be increased.
[87]
When the content of the porous non-woven fabric satisfies the above range, the porous non-woven fabric sufficiently performs the role of a support, thereby maintaining the structure of the three-dimensional structure electrode, and the active material particles and the content of the conductive material are appropriately included. The problem of deteriorating the electronic conductivity of can be prevented.
[88]
In addition, when the content of the porous nonwoven fabric satisfies the above range compared to the content of the active material particles, the capacity and energy density of the electrochemical device may be improved, and it may contribute to forming the porosity of the three-dimensional structure electrode within the above range. . This is a factor in which the active material particles substantially contribute to the capacity and energy density expression of the electrochemical device among materials constituting the three-dimensional structure electrode, and the content of the active material particles in the three-dimensional structure electrode increases the porosity of the three-dimensional structure electrode. This is because it becomes one of the determining factors.
[89]
The first conductive material constituting the active material composite together with the active material particles may be 1 to 50 parts by weight, specifically 5 to 40 parts by weight, and more specifically 10 to 30 parts by weight based on 100 parts by weight of the active material particles.
[90]
When the content of the first conductive material satisfies this range, an electron conductive network between the active material particles and the first conductive material is easily formed, thereby improving the life characteristics and output characteristics of the electrode, and the volume of the active material. Even if expansion occurs, the electron conducting network can be maintained.
[91]
The second conductive material may be 0.1 to 20 parts by weight, specifically 1 to 15 parts by weight, and more specifically 5 to 10 parts by weight, based on 100 parts by weight of the active material particles. When the content of the second conductive material satisfies this range, the dispersion state of the spinning solution can be stably maintained during electrode manufacturing, and the electron conducting network can be maintained even when physical deformation of the electrode occurs. From this point of view, it is easier to improve the physical properties of the electrode as the second conductive material has a larger aspect ratio than the first conductive material.
[92]
When a porous nonwoven fabric and an electrode are composed of only the active material composite including the active material particles and the first conductive material without the second conductive material, conductivity between the active material composites cannot be imparted with only the first conductive material trapped in the active material composite. . The second conductive material is located between the active material composites and is connected to each other while in contact with each other on the outer surfaces of the active material composites, thereby forming a uniform electron conductive network capable of imparting conductivity between the active material composites.
[93]
The content of the second conductive material may be 0.2 to 2,000, specifically 2.5 to 300, more specifically 10 to 100, based on 100 parts by weight of the first conductive particles. When the weight ratio is satisfied, electron movement can be maximized by connecting a uniform electron conduction network.
[94]
The average diameter of the plurality of polymer fibers may be 0.001 to 1000 µm, specifically 0.005 to 50, and more specifically 0.01 to 5. As a plurality of polymer fibers having an average diameter in the above range form a three-dimensional aggregate, it is possible to secure an easy space for filling the active material particles and the conductive material, and have a uniform pore structure. Absorption of electrolyte and movement of ions in the electrode may be smooth.
[95]
In addition, when the average diameter range is satisfied, the thickness of the support formed by the plurality of polymer fibers is appropriately controlled to secure pores to be filled with the active material composite and the second conductive material, and serve as the support. It can have sufficient physical properties. Specifically, the average diameter of the plurality of polymer fibers may be about 0.01 to 1 μm, and in this case, the above effect may be maximized.
[96]
The average diameter of the active material particles may be 0.001 to 30 µm, specifically 0.001 to 10 µm. Active material particles having an average diameter in such a range contribute to controlling the porosity of the three-dimensional structure electrode within the aforementioned range. In addition, in the method of manufacturing a three-dimensional electrode to be described later, by improving the dispersibility in the colloidal solution containing the active material particles and minimizing the occurrence of problems in the double electrospinning method, the pores of the finally obtained three-dimensional electrode are uniformly formed. can do.
[97]
In addition, when the average diameter of the active material particles satisfies this range, the dispersion state of the spinning solution for electrode manufacturing is maintained, and the handling of the particles during the process may be facilitated.
[98]
The weight per surface area of the three-dimensional structure of the electrode, 0.001mg / cm 2 to about 1g / cm 2 , particularly mg 0.01 / cm 2 to g 0.1 / cm 2 , and more specifically mg 0.5 / cm 2 to 20 mg / cm Can be 2 . By minimizing the additive material in the three-dimensional electrode and using the porous nonwoven fabric, the weight per area of ​​the electrode was improved as described above by removing the metal current collector. As a result, the energy density of the electrode and the electrochemical device Dosage can be increased.
[99]
On the other hand, when the three-dimensional structure electrode is formed as one layer, the weight per area cannot exceed 1 g/cm 2 .
[100]
In this regard, the three-dimensional structure electrode may include a plurality of electrodes forming a multilayer structure. Accordingly, the loading value of the electrode material including the active material composite and the second conductive material in the three-dimensional structure electrode can be maximized, and as a result, the capacity and energy density of the electrochemical device can be improved.
[101]
Specifically, the weight (loading) of the electrode material per area in the multilayered three-dimensional electrode is 0.002 g/cm 2 to 10 g/cm 2 , or 0.005 g/cm 2 to 10 g/cm 2 , or 0.007 g/ cm 2 to 10 g/cm 2 .
[102]
Independently of this, the thickness of the three-dimensional structure electrode may be 1 to 1000 μm. Within the above range, the higher the thickness, the better the energy density of the electrode.
[103]
In general, as the thickness of the electrode increases, there is a problem that the electronic conductivity in the thickness direction decreases, so that the output characteristics of the battery decrease. However, in the case of the three-dimensional structure electrode, there is an advantage that a smooth electron conduction network is maintained even in the thickness direction within the thickness range.
[104]
On the other hand, detailed description of each material included in the three-dimensional structure electrode is as follows.
[105]
The plurality of polymer fibers are not particularly limited as long as they are non-uniformly aggregated to form the porous nonwoven fabric, but when the polymer constituting the plurality of polymer fibers is a heat-resistant polymer, it is advantageous to secure thermal stability of the electrode.
[106]
Specifically, the polymer constituting the plurality of polymer fibers is polyethylene terephthalate, polyimide, polyamide, polysulfone, polyvinylidene fluoride, polyacrylonitrile, polyethylene, polypropylene, polyetherimide, polyvinyl alcohol, From the group consisting of polyethylene oxide, polyacrylic acid, polyvinylpyrrolidone, agarose, alginate, polyvinylidene hexafluoropropylene, polyurethane, polypyrrole, poly 3,4-ethylenedioxythiophene, polyaniline, and derivatives thereof It may be at least one selected.
[107]
According to an embodiment of the present invention, at least one selected from the group including carbon nanotubes, graphene, graphene oxide, reduced graphene oxide, and carbon nanotubes in the porous nonwoven fabric It may contain more. In this case, it is possible to improve the strength and electronic conductivity of the porous nonwoven fabric.
[108]
The active material particles are at least one selected from the group containing the aforementioned lithium metal oxide, silicon (Si), tin (Sn), germanium (Ge), sulfur (S), derivatives thereof, and mixtures thereof. Can be. Specifically, lithium metal-based oxides and derivatives thereof are known as positive electrode active materials, and may be used as positive electrodes. On the other hand, oxides, silicon (Si), tin (Sn), germanium (Ge), sulfur (S), and derivatives thereof are known as negative electrode active materials, and before applying them can be a negative electrode.
[109]
In addition, the active material particles may have a surface coated with a carbon-based compound. Since this is generally widely known, a detailed description is omitted.
[110]
The lithium metal oxide among the active material particles is a lithium nickel oxide, a lithium cobalt oxide, a lithium manganese oxide, a lithium titanium oxide, a lithium nickel manganese oxide, a lithium nickel cobalt manganese oxide, a lithium nickel cobalt aluminum oxide, It may be at least one selected from the group including lithium iron phosphate-based oxide, lithium vanadium phosphate-based oxide, lithium manganese phosphate, lithium manganese silicate-based oxide, lithium iron silicate-based oxide, and combinations thereof.
[111]
That is, one or more of cobalt, manganese, nickel, or a composite oxide of lithium and a metal of a combination thereof may be used. As a specific example, a compound represented by any one of the following chemical formulas can be used.
[112]
Li a A 1 - b R b D 2 (in the above formula, 0.90 ≤ a ≤ 1.8 and 0 ≤ b ≤ 0.5); Li a E 1 - bR b O 2-c D c (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, and 0 ≤ c ≤ 0.05); LiE 2-b R b O 4-c D c (where 0≦b≦0.5, 0≦c≦0.05); Li a Ni 1 -b- c Co b R c D α(In the above formula, 0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05 and 0<α≦2); Li a Ni 1 -b- c Co b R c O 2 - α Z α (wherein the expression, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 , and 0 <α <2); LiaNi1-b-cCobRcO2-αZ2 (in the above formula, 0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05 and 0<α<2); Li a Ni 1 -b- c Mn b R c D α (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 <α ≤ 2); Li a Ni 1-bc Mn b R c O 2-α Z α (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 <α <2); Li a Ni 1 -b- c Mn b R c O 2 - α Z 2 (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 , and 0 <α <2); Li a Ni b E c G d O 2 (in the above formula, 0.90≦a≦1.8, 0≦b≦0.9, 0≦c≦0.5 and 0.001≦d≦0.1); Li a Ni b Co c Mn d GeO 2 (wherein, 0.90≦a≦1.8, 0≦b≦0.9, 0≦c≦0.5, 0≦d≦0.5, and 0.001≦e≦0.1.); Li a NiG b O 2 (in the above formula, 0.90≦a≦1.8 and 0.001≦b≦0.1); Li a CoG b O 2 (wherein, 0.90≦a≦1.8 and 0.001≦b≦0.1.); Li a MnGbO 2 (wherein, 0.90≦a≦1.8 and 0.001≦b≦0.1); Li a Mn 2 G b O 4 (in the above formula, 0.90≦a≦1.8 and 0.001≦b≦0.1); QO 2 ; QS 2; LiQS 2 ; V 2 O 5 ; LiV 2 O 5 ; LiTO 2 ; LiNiVO 4 ; Li (3-f) J 2 (PO 4 ) 3 (0 ≤ f ≤ 2); Li (3-f) Fe 2 (PO 4 ) 3 (0 ≤ f ≤ 2); 및 LiFePO 4 , LiMnPO 4 , LiCoPO 4 , Li 3 V 2 (PO 4 ) 3, Li 4 Ti 5 O 12 , LiMnSiO 4 , LiFeSiO 4 .
[113]
In the above formula, A is Ni, Co, Mn, or a combination thereof; R is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, or combinations thereof; D is O, F, S, P or a combination thereof; E is Co, Mn or a combination thereof; Z is F, S, P or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; T is Cr, V, Fe, Sc, Y or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.
[114]
In addition, the oxide of the active material particles, iron oxide, cobalt oxide, tin oxide, titanium oxide, nickel oxide, zinc oxide, manganese oxide, silicon oxide, vanadium oxide, copper oxide, and these It may be at least one selected from the group including a combination.
[115]
That is, Fe x O y , Co x O y , S n O y , TiO y , NiO, Mn x O y , Si x O y , V x O y , Cu x O y selected from the group containing a combination thereof It may be at least one (in the above equation, 0.90≦x≦2.2 and 0.9≦y≦6).
[116]
Specifically, in an example to be described later, over-lithiated oxide (0.33Li 2 MnO 3 ·0.67LiNi 0.18 Co 0.17 Mn 0.65 O 2, OLO) was selected as the active material particle .
[117]
Meanwhile, the first conductive material and the second conductive material are not particularly limited as long as they are materials capable of forming an electron conductive network, and one-dimensional (1D) or two-dimensional (2D) carbon, metal, or conductive polymer compound may be used. have.
[118]
For example, the first conductive material and the second conductive material are each independently carbon nanotube, silver nanowire, nickel nanowire, gold nanowire, graphene, graphene oxide, reduced graphene oxide , Polypyrrole, poly 3,4-ethylenedioxythiophene, polyaniline, derivatives thereof, and mixtures thereof may be at least one selected from the group.
[119]
According to an embodiment of the present invention, the first conductive material and the second conductive material are each independently a carbon nanotube, graphene, graphene oxide, reduced graphene oxide, or a mixture of two or more thereof. Can be In addition, according to an embodiment of the present invention, the first conductive material and the second conductive material are carbon nanotubes, graphene, graphene oxide, reduced graphene oxide, or a mixture of two or more thereof. , Silver nanowire, nickel nanowire, gold nanowire, polypyrrole, poly 3,4-ethylenedioxythiophene, polyaniline, derivatives thereof, or mixtures thereof may further be included.
[120]
As the carbon nanotube, a multi-wall carbon nanotube (MWCNT) may be used.
[121]
A description of the three-dimensional structure electrode is as follows.
[122]
The three-dimensional structure electrode may be polar. In this case, excellent wettability to the electrolyte can be achieved.
[123]
The three-dimensional structure electrode may be any one selected from an anode or a cathode.
[124]
The three-dimensional structure electrode may include preparing an active material composite by combining an active material and a first conductive material; Dissolving the polymer in a solvent to prepare a polymer solution; Dispersing the active material composite and the second conductive material in a dispersion medium to prepare a colloidal solution; Simultaneously spinning the polymer solution and the colloid solution to produce a three-dimensional structure fiber; And compressing the three-dimensional structure fibers.
[125]
At this time, the step of simultaneously spinning the polymer solution and the colloidal solution to prepare a three-dimensional structure fiber; forming a porous nonwoven fabric including a plurality of polymer fibers, and between a plurality of polymer fibers included in the porous nonwoven fabric, The active material particles and the conductive material may be uniformly filled and manufactured through a series of processes for forming pores.
[126]
This is a method of manufacturing a three-dimensional electrode having excellent characteristics as described above by simultaneously spraying two solutions of the polymer solution and the colloid solution.
[127]
In the series of processes, the active material particles include lithium metal oxides, silicon (Si), tin (Sn), germanium (Ge), sulfur (S), derivatives thereof, and mixtures thereof. At least one selected may be used.
[128]
Specifically, by simultaneously spinning a colloidal solution including the active material composite and the second conductive material with the polymer solution, an interconnected porous network is formed by a plurality of polymer fibers serving as a support, and the This is a method of manufacturing a three-dimensional electrode by forming an active material composite of active material particles and a first conductive material, and a three-dimensional dense filling structure by the second conductive material.
[129]
Hereinafter, a method of manufacturing a three-dimensional structure electrode provided in an embodiment of the present invention will be described in detail, and a description overlapping with that described above will be omitted.
[130]
First, a polymer solution and a colloidal solution are simultaneously spun to produce a three-dimensional structure fiber.
[131]
The polymer solution is prepared by dissolving a polymer in a solvent, and the content of the polymer in the polymer solution may be adjusted to obtain an appropriate viscosity according to the type of the polymer. According to an embodiment of the present invention, it may be 5 to 30%, 5 to 25%, and more specifically 10 to 20%, in terms of weight% based on the total weight of the polymer solution. If this range is satisfied, a plurality of polymer fibers may be formed by spraying the polymer solution, and the porous nonwoven fabric may be formed through this.
[132]
In addition, when the content of the polymer in the polymer solution satisfies this range, the problem of hardening at the tip of the nozzle from which the polymer solution is spun is suppressed, so that the polymer solution is smoothly spun, and the polymer solution is evenly spun to bead ( Bead) may not be formed.
[133]
The solvent is not particularly limited as long as it can dissolve the polymer. For example, at least one selected from the group containing dimethylformamide (N,N-dimethylformamide), dimethyl acetamide (N,N-dimethylacetamide), methylpyrrolidone (N,N-Methylpyrrolidone), and combinations thereof It can be.
[134]
A method capable of spinning the polymer solution and the colloidal solution at the same time is not particularly limited, but any one selected from the group including double electrospinning, double electrospray, double spray, and combinations thereof It could be a way.
[135]
Specifically, a method of double electrospinning may be used, and it is advantageous for forming the three-dimensional dense filling structure and uniform pores.
[136]
Also. It may be performed for 50 minutes to 24 hours. The three-dimensional structure electrode may be formed within the range of the execution time, and in particular, as the execution time increases, the loading value of the active material particles in the three-dimensional structure electrode may be improved.
[137]
The spinning rate of the polymer solution may be 2 to 15 μl/min, and the spinning rate of the colloid solution may be 30 to 150 μl/min. When all of the spinning speed ranges of each of these solutions are satisfied, the three-dimensional electrode may be formed. In particular, when the spinning speed of the colloidal solution is increased within the above range, the loading value of the active material particles in the three-dimensional electrode may be improved.
[138]
However, when the range of the spinning speed of the polymer solution is not satisfied, the polymer solution may not be evenly radiated, and thus a problem may occur in that beads are formed. In addition, when the range of the colloidal solution spinning speed is not satisfied, the colloidal solution may not be uniformly radiated and may fall into a large droplet state. For this reason, the spinning speed of each solution is respectively limited as described above.
[139]
In addition, when the active material particles and the first conductive material are combined to produce an active material composite, it may be performed by mixing the active material particles and the first conductive material using a grinding device. A ball mill or the like may be used as the grinding equipment.
[140]
When complexing the active material particles and the first conductive material, a pulverizing solvent and a dispersant for generating a uniform composite may be added.
[141]
The dispersant is polyvinylpyrrolidone, poly 3,4-ethylenedioxythiophene: polystyrene sulfonate (poly(3,4-ethylenedioxythiophene): polystyrene sulfonate) from the group containing derivatives thereof, and mixtures thereof. It may be at least one selected.
[142]
Water (deionized water, etc.), alcohols, and the like may be used as the type of the grinding solvent.
[143]
In this case, the content of the dispersant may be 0.01 to 20 parts by weight, specifically 0.1 to 10 parts by weight, more specifically 0.25 to 5 parts by weight, based on 100 parts by weight of the active material particles.
[144]
In addition, the step of preparing a colloidal solution by dispersing the active material composite and the second conductive material in a dispersion medium; will be described as follows.
[145]
An active material composite is formed in the process of pulverizing the active material particles and the first conductive material to pulverize the active material particles and the first conductive material together. That is, forming an active material composite by coagulating the active material particles and the first conductive material with each other during the grinding process; And dispersing the formed active material composite and the second conductive material in the dispersion medium to prepare the colloidal solution.
[146]
This is for uniform dispersion of the active material composite in the colloidal solution, and is related to limiting the average diameter of the active material composite particles. Specifically, before pulverizing the active material composite particles having an average diameter in μm before the colloid is produced, it is advantageous to uniformly disperse in the colloidal solution when pulverized to have an average diameter in nm.
[147]
The weight ratio of the active material composite and the second conductive material in the colloidal solution may be 100:50, specifically 100:30, and more specifically 100:15.
[148]
[149]
By containing the second conductive material in the above range, it is possible to contribute to improving the output of the electrochemical device by providing an electron conduction network in the electrode, and the reasons for limiting the upper and lower limits are as described above.
[150]
The colloidal solution may further include a dispersant, and the content of the dispersant in the colloidal solution may be 0.001 to 10% by weight based on the total weight of the colloidal solution.
[151]
When the dispersant is included in the above range, it may help to disperse the active material particles and the conductive material in the colloidal solution, and the amount of dispersant is too large to increase the viscosity of the colloidal solution or the amount of dispersant is too small to serve as a dispersant. The problem of not being able to do this can be prevented.
[152]
Specifically, the dispersant may be at least one selected from the group including polyvinylpyrrolidone, poly3,4-ethylenedioxythiophene, and mixtures thereof.
[153]
In addition, the dispersion medium is not particularly limited as long as it is capable of dispersing the active material particles and the conductive material. For example, deionized water, iso-propylalcohol, buthalol, ethanol, hexanol, acetone, dimethylformamide (N,N-dimethylformamide) ), dimethylacetamide (N,N-dimethylacetamide), methyl pyrrolidone (N,N-Methylpyrrolidone), and may be any one selected from the group including a combination thereof.
[154]
In another embodiment of the present invention, the anode; cathode; A separator positioned between the anode and the cathode; And an electrolyte impregnated in the positive electrode, the negative electrode, and the separator, wherein at least one of the positive electrode or the negative electrode is the three-dimensional structure electrode described above.
[155]
This, by including the three-dimensional structure electrode having the above-described characteristics, the weight and volume of the electrode is excellent, and corresponds to an electrochemical device having high energy density and high power characteristics.
[156]
The electrochemical device is a lithium secondary battery, a super capacitor (Super Capacitor), a lithium-sulfur battery, a sodium ion battery, a lithium-air battery, a zinc-air battery, an aluminum-air battery, and a magnesium ion battery. It may be any one selected.
[157]
Specifically, it may be a lithium secondary battery, and examples thereof will be described later. 3 is a schematic diagram of a lithium secondary battery module including a three-dimensional fiber structure electrode according to an embodiment of the present invention.
[158]
3, a lithium secondary battery 200 according to an embodiment of the present invention includes a positive electrode 212, a negative electrode 213, and a separator 210 disposed between the positive electrode 212 and the negative electrode 213, and the A positive electrode 212, a negative electrode 213, and an electrolyte (not shown) impregnated in the separator 200, and a battery container 220 and a sealing member 240 for sealing the battery container 220 The secondary battery module may be configured as a main part.
[159]
In general, the lithium secondary battery 200 has a separator 210 interposed between a positive electrode 212 including a positive electrode active material and a negative electrode 213 including a negative electrode active material, and the positive electrode 212 and the negative electrode 213 And the separator 210 stored in the battery container 220, and after injecting the lithium secondary battery electrolyte, the battery container 220 is sealed to impregnate the pores of the separator 210 with lithium secondary battery electrolyte. have. The battery container 220 may have various shapes such as a cylindrical shape, a square shape, a coin type, and a pouch type. In the case of a cylindrical lithium secondary battery, a positive electrode 212, a negative electrode 213, and a separator 210 are sequentially stacked and then stored in the battery container 220 in a spiral wound state to constitute a lithium secondary battery. have.
[160]
Since the structure and manufacturing method of the lithium secondary battery are widely known in the art, detailed descriptions thereof will be omitted in order to avoid obscuring interpretation of the present invention.
[161]
In addition, as the electrolyte, a non-aqueous electrolyte in which a lithium salt is dissolved in an organic solvent, a polymer electrolyte, an inorganic solid electrolyte, a polymer electrolyte, and a composite material with an inorganic solid electrolyte may be used.
[162]
The non-aqueous organic solvent of the non-aqueous electrolyte serves as a medium through which ions involved in the electrochemical reaction of the battery can move. As the non-aqueous organic solvent, a carbonate-based, ester-based, ether-based, ketone-based, alcohol-based or aprotic solvent may be used. The non-aqueous organic solvent may be used alone or in combination of one or more, and the mixing ratio in the case of using one or more mixtures may be appropriately adjusted according to the desired battery performance, which will be widely understood by those in the field. I can.
[163]
The lithium salt is a material that is dissolved in a non-aqueous organic solvent, acts as a source of lithium ions in the battery, enables basic lithium secondary battery operation, and promotes the movement of lithium ions between the positive electrode and the negative electrode. .
[164]
Representative examples of the lithium salt include LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiC 4 F 9 SO 3 , LiClO 4 , LiAlO 2 , LiAlCl 4 , LiN(C x F 2x + 1 SO 2 )(C y F 2y + 1 SO 2 ) (where x and y are natural numbers), LiCl, LiI, LiB(C 2 O 4 ) 2(Lithium bis(oxalato) borate; LiBOB) or a combination thereof may be mentioned, and these are included as a supporting electrolytic salt. The concentration of the lithium salt is used in the range of 0.1 to 2.0M. Okay, if the concentration of the lithium salt is included in the range, since the electrolyte has an appropriate conductivity and viscosity, it can exhibit excellent electrolyte performance, and lithium ions can move effectively.
[165]
Hereinafter, preferred embodiments of the present invention and experimental examples thereof will be described. However, the following examples are only preferred examples of the present invention, and the present invention is not limited to the following examples.
[166]
[167]
Manufacture of an electrode for a lithium secondary battery and fabrication of a lithium secondary battery including the same
[168]
Example 1
[169]
Preparation of polymer solution
[170]
First, as a polymer for preparing a porous polymer, polyacrylonitrile (PAN) was used as a polymer, and dimethylformamide (N, N-dimethylformamide) was used as a solvent to dissolve it.
[171]
After the polyacrylonitrile (PAN) was added to dimethylformamide (N, N-dimethylformamide), the content of polyacrylonitrile (PAN) in the solution was 10% by weight (wt%). A polymer solution was prepared as much as possible.
[172]
[173]
Preparation of active material composite of active material particles/first conductive material
[174]
The active material particles include 0.33Li 2 MnO 3 ·0.67LiNi 0 , which is an over-lithiated oxide (OLO) having an average diameter of 5 um . 18 Co 0 . 17 Mn 0 . 65 O 2 was used, a multi-wall carbon nanotube (MWCNT) was used as the first conductive material, and deionized water was used as the grinding solvent. In this case, 20 parts by weight of the first conductive material was used based on 100 parts by weight of the active material particles.
[175]
At this time, 1 part by weight of polyvinylpyrrolidone was added as a dispersant to 100 parts by weight of the grinding solvent, and then pulverized for 1 hour at 500 rpm with a ball mill to 0.33Li 2 MnO 3 ·0.67LiNi 0 . 18 Co 0 . 17 Mn 0 . 65 O 2 particles and MWCNT were uniformly combined to prepare an active material composite.
[176]
[177]
Preparation of colloidal solution
[178]
In addition, in order to prepare a colloidal solution including the active material particle/the active material composite of the first conductive material and the second conductive material, a multi-wall carbon nanotube (MWCNT) is used as the second conductive material, As the dispersion medium, deionized water and iso-propylalcohol were used as co-solvants.
[179]
Specifically, 0.33Li 2 MnO 3 ·0.67 LiNi 0.18 Co 0.17 Mn 0.65 O 2 /MWCNT prepared prior to the dispersion medium (deionized water): weight ratio of iso-propylalcohol = 3:7) After the active material complex was added and dispersed, the active material complex solution was prepared so that the content of the active material complex of 0.33Li 2 MnO 3 ·0.67LiNi 0.18 Co 0.17 Mn 0.65 O 2 /MWCNT in the solution was 5% by weight.
[180]
The second conductive material was added to the active material composite solution in an amount of 10% by weight based on the weight of the active material particles (0.33Li 2 MnO 3 ·0.67LiNi 0.18 Co 0.17 Mn 0.65 O 2 ), and the active material composite and the carbon nanotube were added together. A dispersed colloidal solution was prepared. At this time, polyvinylpyrrolidone as a dispersant was added to contain 1% by weight of the colloidal solution.
[181]
[182]
Preparation of electrodes through double electrospinning
[183]
After introducing the polymer solution and the colloidal solution into an electrospinning device (purchased from: NanoNC), the injection rate of the polymer solution is 5 μl/min, and the injection rate of the colloidal solution is 100 μl/min, Simultaneously spinning (double electrospinning) for about 240 minutes to prepare a porous nonwoven fabric as a three-dimensional structure fiber.
[184]
The prepared porous nonwoven fabric was compressed using a roll press (Purchased from: Kibae &T Co., Ltd.), and polyvinylpyrrolidone as a dispersant was removed through a washing process using an aqueous solution. Through this , a three-dimensional structure electrode having a weight per area (loading) of about 7 mg/cm 2 and a thickness of about 30 μm of the electrode material including the active material composite and the second conductive material could be obtained.
[185]
[186]
Fabrication of lithium secondary battery
[187]
A lithium secondary battery was produced by applying the obtained three-dimensional structure electrode as an anode.
[188]
Specifically, lithium metal was used as the negative electrode, and polyethylene (Tonen 20 μm) was used as the separator.
[189]
An organic solvent (ethylene carbonate (EC): diethyl carbonate (DEC) = 1:1 (v:v)) was dissolved in a concentration of 1 M LiPF 6 to prepare a non-aqueous electrolyte.
[190]
After forming a coin-type cell by putting the prepared positive electrode, negative electrode, and separator, the non-aqueous electrolyte was injected to prepare a coin-type lithium secondary battery.
[191]
[192]
Comparative Example 1
[193]
Manufacture of electrodes
[194]
Active material composite prepared in Example 1 (0.33Li 2 MnO 3 ·0.67LiNi 0.18 Co 0.17 Mn 0.65 O 2 /MWCNT) 80 parts by weight, 10 parts by weight of carbon black as a conductive material, polyvinylidene as a binder polymer 10 parts by weight of fluoride (polyvinylidene fluoride, PVDF) was added to 120 parts by weight of N-methyl-2 pyrrolidone (NMP) as a solvent, to prepare a slurry of a positive electrode mixture.
[195]
The positive electrode mixture slurry is coated on an aluminum (Al) thin film of a positive electrode current collector having a thickness of 20 μm and then dried to prepare a positive electrode, followed by roll press to perform an electrode material including an active material composite and a conductive material. An electrode with a loading of about 7 mg/cm 2 was prepared.
[196]
[197]
Fabrication of lithium secondary battery
[198]
A lithium secondary battery was manufactured in the same manner as in Example 1, except that such an electrode was used as a positive electrode.
[199]
[200]
Comparative Example 2
[201]
When preparing the colloidal solution, an electrode and a lithium secondary battery were manufactured in the same manner as in Example 1, except that only active material particles were used instead of'active material particles/active material composite of the first conductive material'.
[202]
[203]
Comparative Example 3
[204]
In place of the active material composite prepared in Example 1 (0.33Li 2 MnO 3 ·0.67LiNi 0.18 Co 0.17 Mn 0.65 O 2 /MWCNT) 0.33Li 2 MnO 3 ·0.67LiNi 0 . 18 Co 0 . 17 Mn 0 . An electrode and a lithium secondary battery were manufactured in the same manner as in Comparative Example 1, except that only 65 O 2 was used.
[205]
[206]
Electrode for lithium secondary battery and evaluation of lithium secondary battery comprising the same
[207]
Test Example 1: Observation of the active material composite of the active material/first conductive material prepared in Example 1
[208]
Pure 0.33 Li 2 MnO 3 0.67 LiNi 0.18 Co 0.17 Mn 0.65 O 2 particles (Fig. 1 a), 0.33 Li 2 MnO 3 0.67 LiNi 0.18 Co 0.17 Mn 0.65 O 2 with a scanning electron microscope (SEM) /MWCNT complex (Fig. 1 b and c) was observed. 0.33Li 2 MnO 3 .0.67LiNi 0 prepared by Example 1 . 18 Co 0 . 17 Mn 0 . 65The O 2 /MWCNT composite is obtained after pulverization by mixing 10% by weight MWCNT of pure 0.33Li 2 MnO 3 ·0.67LiNi 0.18 Co 0.17 Mn 0.65 O 2 particles. At this time, polyvinyl pyrrolidone is added as a grinding solvent. Ionized water was used. Polyvinyl pyrrolidone acts as a dispersant and is 0.33Li 2 MnO 3 ·0.67LiNi 0 . 18 Co 0 . 17 Mn 0 . 65 O 2 particles and MWCNTs formed a uniform complex (FIG. 1 b ). When the dispersant was not used, the complex was not formed as shown in c of FIG. 1.
[209]
Specifically, the pulverization was performed at 500 rpm for 30 minutes using a planetary mill of Taemyung Science Co., Ltd.
[210]
[211]
Test Example 2: Observation of the electrode prepared in Example 1
[212]
A cross section of the electrode prepared according to Example 1 was observed with a scanning electron microscope (SEM), and the results are shown in FIG. 4.
[213]
Referring to Figure 4, Example 1, a large number of spaces are present between the active material particles contained in the porous polymer fiber nonwoven fabric for (0.33Li 2 MnO 3 · 0.67LiNi 0 . 18 Co 0 . 17 Mn 0 . 65 O 2 ) And the carbon nanotubes are completely filled, the carbon nanotubes are surrounded by the active material particles, and it can be seen that a uniform electron conduction network is formed.
[214]
In addition, according to FIG. 4, it can be seen that the active material particles and the carbon nanotubes are uniformly mixed even in the cross section of the electrode manufactured according to Example 1 to form an electron conducting network in the thickness direction of the electrode.
[215]
In addition, Figure 5 is a photograph of the appearance of the electrode manufactured according to Example 1.
[216]
According to FIG. 5, it can be seen that even though a separate binder is not used, the electrode structure is well maintained without desorbing active material particles even when the electrode is bent.
[217]
[218]
Test Example 3: Comparison of surface resistance of electrodes
[219]
In order to compare the resistance of the surfaces of each electrode prepared in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3, electron conductivity measurements were performed.
[220]
Specifically, the electronic conductivity measurement was performed by measuring the surface resistance using a 4 probe tip of Dasol ENG Co., Ltd., and the results are shown in FIG. 6.
[221]
According to FIG. 6, compared to Comparative Example 1 in which an electronic conductivity of 0.17 S/cm was recorded, Example 1 showed a value increased by about 44 times to 7.55 S/cm. In particular, the electrode of Comparative Example 2 having a similar electrode structure also exhibited an electronic conductivity of 3.25 S/cm, which is a lower value than that of Example 1. On the other hand, compared to Comparative Example 3, it can be seen that the electron conductivity was improved in the electrode of Comparative Example 1, which is primarily the basis for supporting the improvement of electronic conductivity even with a conventional electrode structure when an electron conductive network is formed inside the active material composite. . Through this, it can be seen that the electrode of Example 1 has high electronic conductivity by forming an electron conductive network in the interior of the active material composite by the first conductive material that is combined with the active material to form the active material composite, and without a separate current collector. It can be used as an electrode, and it can be inferred that the output characteristics of the battery including the same can also be improved compared to Comparative Examples 1 and 2.
[222]
[223]
Test Example 4: Comparison of resistance change according to repeated bending of electrodes
[224]
In order to compare the resistance change according to the repeated bending of each electrode manufactured through Example 1 and Comparative Example 1, electron conductivity was measured.
[225]
Specifically, the resistance change measurement was performed by repeatedly bending an electrode having a width of 1 cm and a width of 5 cm with a UTM device at a speed of 20 mm s - 1 to draw a circle with a radius of 5 mm for 300 times, and the results are shown in FIG. Done. At this time, R in FIG. 7 is a resistance value when bent, and R 0 is a resistance value when fully extended.
[226]
Referring to FIG. 7, it can be seen that the electrode of Example 1 has little resistance change, whereas the electrode of Comparative Example 1 gradually increases the resistance change. Through this, it can be seen that the uniform electron conduction network of Example 1 remains unchanged even when the electrode is bent, and the electrode performance in a flexible state will also be excellent.
[227]
[228]
Test Example 5: battery performance comparison
[229]
In order to measure the performance of each battery manufactured through Example 1 and Comparative Example 1, Comparative Example 2, and Comparative Example 3, the discharge capacity was observed while increasing the coin cell discharge current rate from 0.2 C to 5 C.
[230]
8 shows the results of observing the discharge capacity per weight of the electrode for the lithium secondary batteries prepared according to Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3.
[231]
According to FIG. 8, as the discharge current rate increased, the lithium secondary battery of Example 1 exhibited higher discharge capacity than the lithium secondary batteries of Comparative Examples 1 and 2. This is because in Comparative Example 1, the electron conduction network by carbon black was not sufficiently uniformly formed, and polyvinylidene fluoride used as a binder polymer interfered with the electron conduction network.
[232]
On the other hand, as it is seen that the lithium secondary battery of Comparative Example 1 exhibits a higher discharge capacity than the lithium secondary battery of Comparative Example 3, the electron conductive network formed in the composite of the active material and the first conductive material improves the discharge characteristics by rate even in a conventional electrode structure. It was confirmed that it can be done.
[233]
On the other hand, the electrode of Example 1 does not have a binder polymer unlike Comparative Example 1, and forms a uniform electron conducting network by carbon nanotubes, so that when driving a lithium secondary battery, it has better performance than Comparative Example 1. It is evaluated to be seen. In addition, unlike Comparative Example 1 using a metal current collector, since Example 1 used only nonwoven fibers as a support and only carbon nanotubes to form an electron conducting network, the discharge capacity per electrode weight was decreased according to the decrease of the additive material. It can be seen that it is significantly increased compared to Comparative Example 1. Additionally, it can be seen that when the electrode structure is compared with Comparative Example 2 having a similar electrode structure, a uniform electron conduction network is formed inside the active material composite through the combination of the active material and the first conductive material, thereby further improving the electrode performance. Through this, it can be said that the lithium secondary battery of Example 1 is lighter than that of Comparative Example 1 and exhibits characteristics of high power, high capacity, and high energy density.
[234]
[235]
The present invention is not limited to the above embodiments, but may be manufactured in a variety of different forms, and those of ordinary skill in the art to which the present invention pertains, other specific forms without changing the technical spirit or essential features of the present invention. It will be appreciated that it can be implemented with. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.
[236]
[237]
[Explanation of code]
[238]
100: three-dimensional structure electrode 110: polymer fiber 120: active material particles
[239]
130: first conductive material 140: second conductive material
[240]
200: lithium secondary battery 212: positive electrode 213: negative electrode
[241]
210: separator 220: battery container 240: sealing member

Claims
[Claim 1]
Porous nonwoven fabric including a plurality of polymer fibers; An active material composite positioned between the plurality of polymer fibers and including active material particles and a first conductive material; And a second conductive material located on an outer surface of the active material complex, wherein a porous structure interconnected by the plurality of polymer fibers is formed, and the active material complex and the agent in the interconnected pore structure. 2 A three-dimensional structure electrode in which a conductive material is uniformly filled to form a three-dimensional filling structure.
[Claim 2]
The three-dimensional structure electrode according to claim 1, wherein the porous non-woven fabric is a three-dimensionally irregular and continuously connected assembly of the plurality of polymer fibers.
[Claim 3]
The three-dimensional structure electrode of claim 1, wherein the porosity of the three-dimensional structure electrode is 5 to 95% by volume.
[Claim 4]
The method of claim 1, wherein the three-dimensional structure electrode comprises 5 to 50 parts by weight of a porous nonwoven fabric, 1 to 50 parts by weight of a first conductive material, and 0.1 to 20 parts by weight of a second conductive material based on 100 parts by weight of active material particles. Phosphorus three-dimensional structure electrode.
[Claim 5]
The three-dimensional structure electrode of claim 1, wherein the average diameter of the plurality of polymer fibers is 0.001 to 1000 µm.
[Claim 6]
The three-dimensional structure electrode of claim 1, wherein the active material particles have an average diameter of 0.001 to 30 µm.
[Claim 7]
The three-dimensional structure electrode of claim 1, wherein the three-dimensional structure electrode has a thickness of 1 to 1000 μm.
[Claim 8]
The three-dimensional structure electrode of claim 1, wherein the weight per area of ​​the electrode material including the active material composite and the second conductive material in the three-dimensional structure electrode is 0.001 mg/cm 2 to 1 g/cm 2 .
[Claim 9]
The three-dimensional structure electrode of claim 1, wherein the three-dimensional structure electrode is a multi-layer structure in which a plurality of electrodes are stacked.
[Claim 10]
The three-dimensional structure electrode of claim 9, wherein the weight per area of ​​the electrode material including the active material composite and the second conductive material in the three-dimensional structure electrode is 0.002 g/cm 2 to 10 g/cm 2 .
[Claim 11]
The method of claim 1, wherein the polymer constituting the plurality of polymer fibers is polyethylene terephthalate, polyimide, polyamide, polysulfone, polyvinylidene fluoride, polyacrylonitrile, polyethylene, polypropylene, polyetherimide, polyvinyl Composed of alcohol, polyethylene oxide, polyacrylic acid, polyvinylpyrrolidone, agarose, alginate, polyvinylidene hexafluoropropylene, polyurethane, polypyrrole, poly 3,4-ethylenedioxythiophene, polyaniline, and derivatives thereof A three-dimensional structure electrode that is at least one selected from the group.
[Claim 12]
The method of claim 1, wherein the active material particle comprises a carbon-based material, a lithium metal-based oxide, silicon (Si), tin (Sn), germanium (Ge), sulfur (S), derivatives thereof, and mixtures thereof. At least one selected from the group, and the lithium metal oxide is an iron oxide, a cobalt oxide, a tin oxide, a titanium oxide, a nickel oxide, a zinc oxide, a manganese oxide, a silicon oxide, a vanadium oxide, a copper oxide , And a three-dimensional structure electrode that is at least one selected from the group containing a combination thereof.
[Claim 13]
The method of claim 1, wherein the first conductive material and the second conductive material are each independently a carbon nanotube, a silver nanowire, a nickel nanowire, a gold nanowire, graphene, graphene oxide, and reduced graphene. Pin oxide, polypyrrole, poly 3,4-ethylenedioxythiophene, polyaniline, derivatives thereof, and a three-dimensional structure electrode that is at least one selected from the group consisting of mixtures thereof.
[Claim 14]
The three-dimensional structure electrode of claim 1, wherein the three-dimensional structure electrode is an anode or a cathode.
[Claim 15]
anode; cathode; A separator positioned between the anode and the cathode; And an electrolyte impregnated in the anode, cathode, and separator, wherein at least one of the anode or the cathode is a three-dimensional electrode according to any one of claims 1 to 14.
[Claim 16]
The method of claim 15, wherein the electrochemical device is a lithium secondary battery, a super capacitor, a lithium-sulfur battery, a sodium ion battery, a lithium-air battery, a zinc-air battery, an aluminum-air battery, and a magnesium ion battery. An electrochemical device that is any one selected from the group containing.