KR102105147B1 - Electrode, secondary battery, and method thereof - Google Patents

Abstract

A flexible secondary battery electrode is provided. It is made of a slurry comprising an electrode active material, polyurethane as a binder, and a conductive agent comprising carbon. The conductive agent may include carbon nanotubes. A method of manufacturing a secondary battery electrode includes preparing a slurry containing an electrode active material, a polyurethane as a binder, and a conductive agent containing carbon, casting a slurry on a substrate, and removing the cast slurry from the substrate It includes.

Description

Secondary battery electrode, battery containing same, and manufacturing method therefor {ELECTRODE, SECONDARY BATTERY, AND METHOD THEREOF}

The present invention relates to the field of secondary battery electrodes, and more particularly, to a secondary battery electrode having excellent discharge capacity and cycle stability while being flexible, and a battery including the same and a method for manufacturing the same.

Recently, lithium-ion batteries (LIBs) are expanding the market in various fields including small mobile IT devices such as cellular phones and notebook computers, power sources for electric vehicles, and energy storage systems. As part of this trend, there is an increasing demand for flexible lithium-ion batteries that can meet the various design and power requirements for portable electronics, including roll-up displays and wearable devices. Furthermore, active radio frequency identification tags and integrated circuit smart cards also require batteries that are flexible or at least bendable in practical use.

Generally, a lithium-ion battery is composed of a cathode, an anode, an electrolyte between these electrodes, and a separator. Existing electrodes include active materials, conductive agents, binders and metal foils as current collectors. Conventional electrodes based on such metal foils are not suitable for use as a flexible lithium ion battery because the active material may be separated or cracked in the active material layer during repeated bending or folding, and in that case, they do not act as electrodes. .

For lithium-ion batteries, there are several reports of free-standing materials made of carbon nanotubes (CNT). Very flexible and conductive CNT paper electrodes have been produced using a filtration method in a pressurized nitrogen atmosphere. This CNT paper electrode shows that it is suitable for a flexible lithium-ion electrode by showing improved capacity and cycle stability compared to a conventional CNT electrode. Bendable cellulose paper electrodes containing CNTs for supercapacitors or batteries have also been proposed, which showed that the flexibility of the device can be greatly improved using CNT composites. However, the connection between the active materials may be broken while repeatedly bending or folding. Accordingly, a softer and more flexible material is required to realize a more robust and reliable flexible battery that is substantially bendable or bent.

Korean Patent Publication 10-2017-0024751

The present invention provides a flexible secondary battery electrode as a freestanding electrode from which a metal current collector is excluded.

The present invention provides a method for manufacturing the improved flexible secondary battery electrode described above.

The present invention also provides a secondary battery comprising the improved flexible electrode described above.

The present invention provides a flexible secondary battery electrode, which includes: an electrode active material; Polyurethane as a binder; And a conductive agent containing carbon.

Preferably, the polyurethane may include 5 to 25 wt%, and more preferably, the polyurethane may be included in 11.5 wt%.

The conductive agent may contain 10 to 12.4wt%, and in this case, preferably, carbon black and carbon nanotubes may be included at 50%.

The electrode active material may include lithium, cobalt, and oxygen.

The present invention provides a method for manufacturing a flexible electrode, which comprises: (i) preparing a slurry comprising an electrode active material, a polyurethane as a binder, and a conductive agent containing carbon; (Ii) casting the slurry on a substrate; And (iii) detaching the cast slurry from the substrate.

And drying the cast slurry prior to desorption in step (iii).

The present invention also provides a flexible secondary battery including a freestanding electrode without a metal current collector.

According to the present invention, a flexible secondary battery electrode is provided. It is possible to implement a freestanding electrode with a relatively small amount by employing polyurethane as a binder. By appropriately adding carbon nanotubes in the slurry employing polyurethane as a binder, mechanical strength can be improved while obtaining suitable electronic conductivity. In addition, the electrode can be provided as a freestanding electrode for a lithium ion battery in a simple way to peel after casting on a glass substrate.

1 is a schematic diagram of a flexible secondary battery electrode according to a preferred embodiment of the present invention.
2 is a graph showing peel strength of a metal-based electrode employing polyurethane and PVDF as a binder.
3A is a graph showing the initial charge / discharge curve of a metal-based electrode employing a polyurethane and PVDF binder.
3B shows the rate capability of a metal-based electrode employing a polyurethane and PVDF binder.
3C and 3D are graphs showing the stability of metal-based electrodes employing polyurethane and PVDF binders.
4A is a view showing a manufacturing process of a freestanding electrode according to Comparative Example 2.
4B is a view showing a manufacturing process of a freestanding electrode according to an embodiment of the present invention.
5A to 5C are SEM images of freestanding electrodes according to Example 1 of the present invention.
5D to 5F are SEM images of the freestanding electrode according to Comparative Example 1.
6A shows a stress-strain curve of a freestanding electrode according to Example 1 and Comparative Example 1 of the present invention.
Figure 6b shows the electronic conductivity of the freestanding electrode according to Example 1 and Comparative Example 1 of the present invention.
7A and 7B are graphs showing the electrochemical properties of the freestanding electrodes of Example 1 and Comparative Example 1 of the present invention.
7C is a graph showing cycling stability of a freestanding electrode according to Example 1 and Comparative Example 1 of the present invention.
8A shows the initial discharge capacity of the freestanding electrodes of Examples 1 to 4 of the present invention.
8B is a graph showing discharge capacities at various current densities of freestanding electrodes according to Examples 1 to 4 of the present invention.
8C is a graph showing cycle stability of the freestanding electrodes according to Examples 1 to 4 of the present invention.
9A is a view showing an illumination sample manufactured by including another freestanding electrode in Example 1 of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the embodiments of the present invention, when it is determined that detailed descriptions of related known functions or configurations may unnecessarily obscure the subject matter of the present invention, detailed descriptions thereof will be omitted.

Briefly described first, the present invention provides a freestanding electrode excluding a metal current collector, and for this purpose, is prepared by using a slurry containing an electrode active material, polyurethane as a binder, and CNT as a conductive agent. When polyurethane and CNT are included in an appropriate ratio, they have desirable electrochemical properties as well as improved mechanical properties having flexibility and mechanical strength. In addition, the production of such an electrode can be implemented through a simple process of casting the slurry onto a glass substrate and then removing it.

Polyurethane (PU) has been reported to have properties suitable for use as a gel polymer electrolyte (GPE), binder, and separator, which are attributed to the unique chemical and polymeric structure of the polyurethane. do. Polyurethane has a two-phase microstructure of hard segments and soft segments. The hard domain imparts mechanical strength to the polyurethane by hydrogen bonding at the end of the urethane group. In contrast, the linear soft segment allows the polyurethane to be flexible and stretchable in the soft domain.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

1 is a schematic diagram of a flexible secondary battery electrode according to a preferred embodiment of the present invention.

The flexible secondary battery electrode of the present invention includes an electrode active material, a polyurethane as a binder, and a conductive agent containing carbon. A preferred embodiment is a freestanding electrode that does not include a metal-based current collector.

The electrode active material may include lithium, cobalt, and oxygen, for example. That is, the flexible secondary battery electrode according to the preferred embodiment of the present invention may be an electrode for a lithium ion battery.

The polyurethane is included as a binder, and preferably 5 to 25 wt% may be included. When the content of polyurethane is less than 5wt%, a freestanding electrode is not realized, and when it exceeds 25wt%, tensile strength increases, but electrical conductivity is significantly reduced. More preferably, 11.5 wt% of polyurethane may be included.

The conductive agent may include 2 to 30 wt%, and preferably 10 to 12.4 wt%. In this case, preferably, carbon black and carbon nanotubes may be included by 50%.

In addition, the method of manufacturing a flexible secondary battery electrode of the present invention comprises the steps of: (i) preparing a slurry containing an electrode active material, a polyurethane as a binder, and a conductive agent containing carbon; and (ii) the prepared slurry as a substrate. Casting onto a phase, and (iii) detaching the cast slurry from the substrate. And drying the cast slurry prior to desorption in step (iii).

The above-mentioned slurry is prepared by ball milling a mixture having an electrode active material (LCO), a conductive agent, and a polyurethane having a composition of 77: 11.5: 11.5 (wt%) in THF (tetrahydrofuran) for 24 hours. The conductive agent may be, for example, a mixture of carbon black and carbon nanotubes.

After the prepared slurry is cast on, for example, a glass substrate and dried for about 30 minutes, the cast film can be detached from the glass substrate to obtain a freestanding electrode.

As shown in Figure 1, the prepared freestanding electrode of the present invention is a polyurethane and carbon nanotubes (MWNT; multi-walled carbon nanotube) is uniformly distributed and the empty space is an electrode active material (LCO) and carbon black (SUPER) P).

Ⅰ. Possibility of polyurethane as electrode binder

(1) Preparation of metal-based electrodes using polyurethane and PVDF binders

In order to determine whether polyurethane is suitable as a binder, metal-based electrodes each employing polyurethane and PVDF as a binder were prepared. The composition of each slurry was electrode active material (LCO): carbon black (super P): binder (polyurethane or PVDF) = 90: 5: 5 wt%. The slurry was cast on an aluminum foil using a doctor blade, and the amount of the electrode active material on the foil was 9.0 mg / cm ² .

(2) Mechanical analysis of metal-based electrodes employing polyurethane and PVDF binders

A peel strength test was performed on the metal-based electrodes using a test equipment (instron5960) to measure adhesion / cohesion. The electrode was cut to 20 cm (L) x 2.5 cm (W) to prepare a test piece and 3M tape was attached to the electrode. The average load was measured by pulling the tape at a constant speed of 10 mm / min.

2 is a graph showing peel strength of a metal-based electrode employing polyurethane and PVDF as a binder. As can be seen in the figure, the polyurethane (PU) binder exhibited an adhesive strength of about 0.5N higher than PVDF. Thus, PU has higher adhesive properties than PVDF, which means that it can be used as a polymer binder for lithium ion batteries.

(3) Electrochemical properties of metal-based electrodes employing polyurethane and PVDF binders

3A is a graph showing the initial charge / discharge curve of a metal-based electrode employing a polyurethane and PVDF binder. The electrode made of PVDF binder (Al-PVDF) and the electrode made of polyurethane binder (Al-PU) showed almost the same charge / discharge profile. The initial charge and discharge capacities of the Al-PVDF electrodes were 159.6mAh / g and 153.6mAh / g, and the initial charge and discharge capacities of the Al-PUV electrodes were 157.7mAh / g and 153.6mAh / g.

3B shows the rate capability of a metal-based electrode employing a polyurethane and PVDF binder. Speed characteristics were measured at various current densities from 0.1 to 5 ° C. Even at high C-rate (discharge rate), the two metal-based electrodes did not show a noticeable difference in capacity, and showed a difference in discharge capacity of about 1.1% at 5 ° C.

3C and 3D are graphs showing the stability of metal-based electrodes employing polyurethane and PVDF binders.

Cycling stability of the metal-based electrode was tested with constant current density (0.5C charge / 1.0C discharge) at ambient temperature and high temperature (45 ° C). 3C and 3D, even after 100 cycles, the electrodes did not show a noticeable difference in cycle stability. At atmospheric temperature, the discharge capacity retention ratio (compared to the first discharge capacity) of the Al-PVDF and Al-PU electrodes was 98.1 and 98.3%, respectively. Similarly, the Al-PVDF electrode and the Al-PU electrode showed 94.5% and 95.4%, respectively, even at an elevated temperature to 45 ° C., so there was no significant difference. The above results confirm that polyurethane (PU) is not only a problem in using as a binder for lithium ion batteries, but also because of its unique softness and flexibility, it can be one of the most promising candidates as a binder for flexible lithium ion batteries. Did.

Ⅱ. Freestanding electrode

(1) Preparation of freestanding electrode according to the present invention

In order to prepare the freestanding electrode according to the present invention, a mixture having an electrode active material (LCO), a conductive agent, and a polyurethane as a binder in the compositions of Examples 1 to 4 as shown in Table 1 is tetrahydrofuran (THF) Slurry was prepared by ball milling for 24 hours. A mixture of carbon black (Super P) and carbon nanotube (MWNT; Multi-Walled Carbon Nanotube) nanosolutions having the same weight as each other was used as a conductive agent. The slurry was cast on a glass substrate using a doctor blade and dried at ambient temperature for 30 minutes. Next, the cast film was peeled from the glass substrate to obtain a freestanding electrode.

1 is a view schematically showing a freestanding electrode of the present invention. As shown in the figure, carbon nanotubes (MWNT) and polyurethane are uniformly distributed, and empty spaces are filled with electrode active material (LCO) and carbon black.

(2) Preparation of the freestanding electrode of Comparative Example 1

In order to investigate the effect of adding carbon nanotubes (MWNT), as a comparative example, electrode active material (LCO) excluding MWNT, carbon black (Super P) and polyurethane (PU) as conductive agents were 77: 11.5: 11.5 (wt%) ) To prepare the freestanding electrode of Comparative Example 1.

(3) Preparation of the freestanding electrode of Comparative Example 2

In order to investigate the effect according to the type of the binder, the electrode active material (LCO), carbon black (Super P) and carbon nanotubes (MWNT) as a conductive agent, and PVDF as a binder, 77: 11.5: 11.5 (wt%) The freestanding electrode according to Comparative Example 2 was prepared by drying in a convection oven at 110 ° C. for 30 minutes.

The composition of the metal-based electrode, the freestanding electrode according to the embodiment of the present invention, and the freestanding electrode according to the comparative example are shown in Table 1 below.

electrode
type Electrode name Binder type Composition (wt%) Electrode active material (LCO) bookbinder Carbon black (Super P) Carbon nanotube (MWNT) metal
Based electrode Al-PU PU 90 5 5 0 Al-PVDF PVDF 90 5 5 0 free
Standing electrode FS-PU11.5-CNT00 PU 77.0 11.5 11.5 0 Comparative Example 1 FS-PU11.5-CNT50 PU 77.0 11.5 5.75 5.75 Example 1 FS-PU17.9-CNT50 PU 71.4 17.9 5.35 5.35 Example 2 FS-PU20.7-CNT50 PU 69.0 20.7 5.15 5.15 Example 3 FS-PU24.6-CNT50 PU 65.6 24.6 4.90 4.90 Example 4 FS-PVDF11.5-CNT50 PVDF 77.0 11.5 5.75 5.75 Comparative Example 2

(3) Mechanical analysis and micro-structure for freestanding electrodes

The stretchability of the electrode was evaluated by measuring the tensile strength using a test equipment (instron5960) for the freestanding electrode according to the examples and comparative examples of the present invention. Specimens were prepared in the form of 20 mm (L) x 10 mm (W) x 50 μm (T) and pulled at a constant strain rate of 1 mm / min until cracking occurred in the specimen.

4A and 4B are views showing a process of manufacturing the freestanding electrode of Comparative Example 2 and an embodiment of the present invention.

Figure 4a relates to the production of a freestanding electrode according to Comparative Example 2, a slurry (FS-PVDF11.5-CNT50) containing 11.5wt% PVDF as a binder was cast on a glass substrate (left) and dried Status (right). As shown in the right image of FIG. 4A, it can be observed that cracks are generated in the cast film during the drying process of the solvent (NMP). Comparative Example 2 was unable to perform further analysis of this electrode due to poor mechanical properties.

Figure 4b relates to the production of a free-standing electrode according to Example 1 of the present invention, a slurry (FS-PU11.5-CNT50) containing 11.5wt% polyurethane as a binder is cast on a glass substrate (left) After drying (center), it was peeled (right) from the glass substrate. As shown in the figure, Example 1 of the present invention formed a smooth state without cracks, and was very easily separated from the glass substrate. The freestanding electrode of the present invention showed very good stability in folding or folding, as shown in the images arranged below in FIG. 4B.

Although not described here as a comparative example, in previous studies, when using PVDF as a binder, it was found that a freestanding electrode is obtained only when the amount of PVDF binder is 20 wt% or more. This indicates that the polyurethane can form a flexible freestanding electrode even in a smaller amount than PVDF, which in turn means that the flexible electrode can be manufactured with a high energy density.

5A to 5F are SEM images of the freestanding electrode according to Example 1 (FS-PU11.5-CNT50) and Comparative Example 1 (FS-PU11.5-CNT00) of the present invention. 5A to 5C are related to the freestanding electrode according to Embodiment 1 of the present invention, FIGS. 5A and 5B are views showing the surface of the freestanding electrode according to Embodiment 1, and FIG. 5C is a freestanding electrode according to Embodiment 1 It is a diagram showing a cross section of. 5D to 5F are related to the freestanding electrode according to Comparative Example 1, and FIGS. 5D and 5E are views showing the surface of the freestanding electrode according to Comparative Example 1, and FIG. 5F is a view of the freestanding electrode according to Comparative Example 1 It is a diagram showing a cross section.

5A and 5B, the electrode active material (LCO) and carbon black (super P) particles are uniformly distributed throughout the electrode along the network provided by the carbon nanotube (MWNT) and polyurethane (PU) binders. This uniform distribution can also be seen in FIG. 5C.

On the contrary, as shown in FIGS. 5D to 5F, the free standing electrode (FS-PU11.5-CNT00) of Comparative Example 1, which does not contain carbon nanotubes (MWNT), is uniformly dispersed with electrode active material (LCO). Many voids are observed between the carbon black (super P) particles. These voids are expected to interfere with electron transfer from the electrode or adversely affect the mechanical properties of the electrode.

In addition, by comparing the tensile strength and electron conductivity of the freestanding electrode according to Example 1 and Comparative Example 1, the effect of adding carbon nanotubes (MWNT) was examined. 6A shows the stress-strain curve of the freestanding electrode. In this figure, it can be seen that mechanical properties were improved by adding carbon nanotubes (MWNT). Comparative Example 1 (FS-PU11.5-CNT00) showed an elongation of only 13.1% at a tensile stress of 3.73 MPa. In contrast, Example 1 according to the present invention (FS-PU11.5-CNT50) showed elongation of 24.9% at the same load and was broken at 4.63 MPa. That is, it can be seen that when the carbon nanotube (MWNT) is added to the freestanding electrode as in Example 1, the tensile strain of the electrode is doubled at the maximum load.

As described above, the freestanding electrode of Comparative Example 1 (FS-PU11.5-CNT00) contains many voids in the electrode that prevent close contact between the binder and the active material and reduce the bonding region (FIG. 5E), This weakens the mechanical properties of the electrode. On the other hand, in the freestanding electrode according to Example 1 of the present invention containing carbon nanotubes (MWNTs), the pores are much smaller, so that polyurethane and carbon nanotubes (MWNTs) are contacted in a dense structure over a wide area (FIG. 5B). ), Improve the mechanical strength.

At the same time, the presence of carbon nanotubes (MWNT) increases the electronic conductivity of the freestanding electrode as shown in FIG. 6B. The free-standing electrode of Example 1 (FS-PU11.5-CNT50) of the present invention has an electron conductivity of 2.73 S / cm, which is about 4.5 times that of the free-standing electrode of Comparative Example 1 (FS-PU11.5-CNT00). Indicates.

The excellent elongation properties of the freestanding electrode of Example 1 of the present invention show excellent impact performance against impact, which means that the freestanding electrode of Example 1 shows excellent toughness.

As described above, the freestanding electrode comprising the polyurethane binder and the carbon nanotubes of the present invention has excellent mechanical properties, thereby reducing the risk of damage due to external force, and also having a high electrical conductivity, which is very suitable for use in flexible electrodes. can do.

(3) Electrochemical analysis of freestanding electrodes

First, the compatibility of the polyurethane used as a binder in the present invention for an organic solvent was tested, and the results are shown in Table 2.

PC EC / DEC EC / EMC AN DOL / DME Whether polyurethane is dissolved Insoluble Dissolution Dissolution Dissolution Dissolution

A solution of 1.0M LiBF ₄ was used as the electrolyte, and glass fiber was used as the separator. It was manufactured as a coin-type half cell in a glove box filled with argon using lithium metal as a counter electrode. The electrochemical properties were tested while charging and discharging the cells in the CC / CV and CC modes, respectively, in the potential range of 3.0V to 4.3V (vs. Li ⁺ / Li). The speed characteristics of the electrodes were measured at various current densities of 0.1C to 5C, and the cycling stability was measured at the electrostatic density of 0.5C charge / 1C discharge.

7A and 7B are graphs showing the electrochemical properties of the freestanding electrodes of Example 1 and Comparative Example 1 of the present invention. 7A and 7B show the velocity characteristics of the electrodes measured while adjusting the current density to 0.1 to 5 ° C. At low current densities, the initial capacity was almost similar regardless of the presence of carbon nanotubes (MWNT). However, the freestanding electrode of Example 1 (FS-PU11.5-CNT50) exhibited a large overvoltage at the beginning of charging. At the same time, the freestanding electrode of Example 1 (FS-PU11.5-CNT50) provides higher capacity over a large area of discharge current density.

The freestanding electrode of Example 1 (FS-PU11.5-CNT50) of the present invention maintained a high discharge capacity of 101.08mAh / g, while the freestanding electrode of Comparative Example 1 (FS-PU11.5-CNT00) At 2 C, only 36.5 mAh / g was shown. From these results, it can be seen that carbon nanotubes (MWNT) impart better speed capability of the freestanding electrode.

7C is a graph showing cycling stability of a freestanding electrode according to Example 1 and Comparative Example 1 of the present invention. In order to investigate cycling stability, the freestanding electrodes were subjected to a cycle life test at a constant current density of 0.5C charge / 1C discharge at room temperature, and the results are shown in FIG. 7C.

It can be seen from FIG. 7C that the cycle stability of the freestanding electrode is greatly improved by adding the carbon nanotube (MWNT) to the electrode. The freestanding electrode according to Example 1 (FS-PU11.5-CNT50) of the present invention maintained 94.29% of the initial capacity even after 100 cycles, while the freestanding according to Comparative Example 1 (FS-PU11.5-CNT00) The electrode had a retention rate of only 85.40%.

Hereinafter, the effect of the amount of the polyurethane binder on the electrochemical performance of the freestanding electrode will be described.

The composition of the embodiments of the present invention is shown in Table 1, where the amount of the conductive agent is maintained at a substantially constant level in order to exclude the effect of the conductive agent as much as possible.

Figure 8a shows the initial discharge capacity of the freestanding electrode of Examples 1 to 4 of the present invention containing various amounts of polyurethane binder of 11.5wt% to 24.6wt%. As the amount of polyurethane decreased from 24.6wt% to 17.9%, the discharge capacity of the freestanding electrode increased from 142.26mAh / g to 151.30mAh / g. From 17.9 wt%, the reduction in polyurethane amount did not affect the discharge capacity. Example 1 (FS-PU11.5-CNT50) and Example 2 (FS-PU17.9-CNT50) showed almost similar capacity of about 151 mAh / g.

8B is a graph showing discharge capacities at various current densities of freestanding electrodes according to Examples 1 to 4 of the present invention. As with the capacity at low current density, the electrodes with low polyurethane content exhibited a distinctly high discharge capacity at all current densities.

The freestanding electrode according to Example 3 (FS-PU20.7-CNT50) was Example 1 (FS-PU11.5-CNT50) and Example 2 (FS-PU17.9-CNT50) at a low current density of 0.1C. Although it shows a slightly lower discharge capacity than the freestanding electrode of, it showed similar performance to Example 4 (FS-PU24.6-CNT50) as the current density increased. The relatively low discharge capacity of the freestanding electrode having a relatively large amount of polyurethane may be due to the inherent high resistance of the polyurethane.

8C is a graph showing cycle stability of the freestanding electrodes according to Examples 1 to 4 of the present invention. As with the speed characteristic, the capacity of the freestanding electrode of the present invention increased from 84.54% to 97.49% after 100 cycles while the amount of polyurethane decreased from 24.6wt% to 17.9wt%.

Finally, a full cell was prepared using the freestanding electrode according to Example 1 (FS-PU11.5-CNT50) of the present invention, and the LED was illuminated using all cells (FIGS. 9A and 9B). The anode was made identical to the cathode using graphite as the anode material. That is, polyurethane was used as a binder, and carbon nanotubes (MWNT) were added. As shown in Figs. 9A and 9B, the LED is lit with full cells even in a bent state without any problems.

From the above results, the freestanding electrode can be manufactured using a much smaller amount of polyurethane binder than PVDF, and since the polyurethane imparts excellent mechanical properties to the electrode, it can be preferably applied to a flexible freestanding electrode. Furthermore, the freestanding electrode according to the present invention can overcome the poor electronic conductivity problem of polyurethane with the help of added carbon nanotubes (MWNT).

As described above, specific embodiments have been described in the detailed description of the present invention, but it is apparent to those skilled in the art that various modifications are possible without departing from the scope of the present invention.

Claims (13)

As a flexible free-standing secondary battery electrode, the metal current collector is excluded;
Electrode Active Material,
Polyurethane as a binder, and
Conductive agent comprising a carbon nanotube (multi-walled carbon nanotube, MWNT); includes,
With respect to the total weight of the electrode active material, the polyurethane, and the conductive agent, the polyurethane is 11.5wt% to 24.6wt%, the conductive agent is 9.8wt% to 11.5wt%, and the electrode active material is 65.6wt% Flexible secondary battery electrode to be included in 77.0wt%.
delete delete delete The method according to claim 1,
The conductive agent further comprises a carbon black, flexible secondary battery electrode.
The method according to claim 5,
The conductive agent is a flexible secondary battery electrode containing carbon black and carbon nanotubes by 50wt%.
The method according to claim 1,
The electrode active material includes lithium, cobalt, and oxygen, a flexible secondary battery electrode.
As a method for manufacturing a flexible secondary battery electrode of any one of claims 1, 5, 6, and 7 above:
(Iii) with respect to the total weight of the conductive agent comprising the electrode active material, polyurethane, and carbon nanotubes, the polyurethane is 11.5 wt% to 24.6 wt%, the conductive agent is 9.8 wt% to 11.5 wt%, and the The electrode active material comprises the steps of preparing a slurry for the electrode material containing 65.6wt% to 77.0wt%;
(Ii) casting the slurry on a substrate; And
(Iii) detaching the cast slurry from the substrate; a method for manufacturing a flexible secondary battery electrode comprising a.
The method according to claim 8,
Method of manufacturing a flexible secondary battery electrode, comprising the step of drying the slurry cast before the desorption of step (iii).
delete delete The method according to claim 8,
The conductive agent further comprises carbon black, a method of manufacturing a flexible secondary battery electrode. delete

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