KR101878336B1 - Method for manufacturing negative electrode active material for rechareable batteries - Google Patents

Abstract

A method of manufacturing an anode material for a secondary battery, the method comprising: preparing a mixture by mixing an electrically conductive material, a biochemical anionic polymer, and a solvent; Ultrasonically treating the mixture; And drying the ultrasound-treated mixture. The present invention also provides a method of manufacturing an anode material for a secondary battery.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a negative electrode material for a secondary battery,

The present invention relates to a method of manufacturing an anode material for a secondary battery.

At present, carbonaceous materials are mainly used as an anode material of a secondary battery, but its reversible capacity is as low as 350 mAh / g. Recently, as a rapid development of a large energy storage application system, researches on a high capacity material to replace a carbonaceous anode material have been actively carried out.

Si (theoretical capacity: 4200 mAh / g) is attracting attention as a substitute for carbonaceous anode materials of secondary batteries, but life characteristics are poor due to volume expansion up to 400% at charging and disruption of active material during repeated charging and discharging not. In addition, the irreversible capacity in the first cycle reaches 50% of the theoretical capacity as compared with the theoretical capacity, and studies for solving these problems are continuously being carried out.

In fact, the negative electrode that implements a reversible capacity of 1000 mAh / g or more is limited to lithium metal, but it has problems such as deterioration due to dendrite growth during charging and a risk of explosion due to a short circuit.

In view of the problems such as the deterioration of the anode due to the growth of dendrite of metals such as lithium and sodium, the deterioration of lifetime characteristics, and the risk of explosion due to a short circuit, and new technologies capable of overcoming the limitations of theoretical capacity as an anode material There is a growing demand for such products.

An embodiment of the present invention is to provide a novel negative electrode material for a secondary battery capable of uniformly adsorbing and dissolving metal cations on the surface of an anode material and preventing dendrite growth of metal. As a result, the risk of deterioration due to deterioration of the negative electrode and short-circuiting can be reduced, and the lifetime characteristics of the secondary battery can be improved.

In addition, the negative electrode material for a secondary battery according to an embodiment of the present invention has a dramatically improved theoretical capacity as compared with the conventionally proposed negative electrode material for a secondary battery, and is expected to overcome the limit of the theoretical capacity.

One embodiment of the present invention is directed to a semiconductor device comprising: a core comprising an electrically conductive material; And a coating layer disposed on the core, the coating layer including a biochemical anionic polymer.

The biochemical anionic polymer may be DNA, siRNA, amino acid, or a combination thereof.

The biochemical anionic polymer may be DNA.

The negative electrode material for a secondary battery is characterized in that a base and / or a phosphate group (PO ₄ ^3- ) in the DNA binds to the surface of the electroconductive material through pi-pi stacking and / or electrostatic interaction, As shown in FIG.

The electrically conductive material may be a carbon-based material.

The electrically conductive material may be a carbon nanotube (CNT), a graphene, a carbon black, a carbon fiber, a graphite, or a combination thereof.

The diameter of the core may be 0.5 nm or more, and 300 nm or less.

The length of the core may be 100 nm or more.

The thickness of the coating layer may be 0.5 nm or more, and 100 nm or less.

The negative electrode material may include 1% by weight or more and 75% by weight or less of the core and 100% by weight or less of the total amount of the negative electrode material, and the remaining amount of the coating layer.

The negative electrode material may have a weight ratio (core: coating layer) of the core and the coating layer of 1: 0.1 or more and 1:20 or less.

The negative electrode material for a secondary battery may have a theoretical capacity of 4500 mAh / g or more.

Another embodiment of the present invention relates to a method for preparing a mixture comprising mixing an electroconductive substance, a biochemical anionic polymer, and a solvent to prepare a mixture; Ultrasonically treating the mixture; And drying the ultrasonic treated mixture. The present invention also provides a method for manufacturing an anode material for a secondary battery.

Preparing a mixture by mixing the electrically conductive material, the biochemical anionic polymer, and the solvent, wherein the mixture comprises not less than 1 wt% and not more than 75 wt% of the electrically conductive material, based on 100 wt% ; At least 10% by weight, and at most 95% by weight of the biochemical anionic polymer; And the solvent as the remainder.

In the mixture, the weight ratio of the electroconductive substance and the biochemical anionic polymer may be 1: 0.1 or more and 1:20 or less.

The biochemical anionic polymer may be DNA, siRNA, amino acid, or a combination thereof, wherein the biochemical anionic polymer is prepared by mixing the electroconductive substance, the biochemical anionic polymer, and the solvent.

The biochemical anionic polymer may be DNA.

The step of ultrasonic treatment to the mixture; in my bases and / or phosphate group (PO ₄ ^3-), the surface and the pi-pi interaction (π-π stacking) and / or electrostatic cross of the electrically conductive material to the DNA To the surface of the electrically conductive material.

In the step of preparing the mixture by mixing the electroconductive substance, the biochemical anionic polymer, and the solvent, the electroconductive substance may be a carbonaceous substance.

The electrically conductive material may be a carbon nanotube (CNT), a graphene, a carbon black, a carbon fiber, a graphite, or a combination thereof.

The ultrasonic treatment of the mixture may be performed two or more times.

The ultrasonic treatment of the mixture may include: a first ultrasonic treatment step of ultrasonic-treating the mixture in a bath type ultrasonic machine; And a second ultrasonic wave processing step of ultrasonically processing the first ultrasonic processed material with a tip type ultrasonic wave.

The first ultrasonic treatment step in which the ultrasonic treatment is performed in the bath type ultrasonic wave may be performed at a temperature of 5 占 폚 or higher and 40 占 폚 or lower for 30 minutes or more and 120 minutes or less.

A second ultrasonic wave processing step performed after the first ultrasonic wave processing step and ultrasonic wave processing in a tip type ultrasonic wave is performed at a temperature of not less than 1 ° C and not more than 10 ° C for not less than 5 minutes and not more than 120 minutes ≪ / RTI >

Drying the ultrasonic treated mixture may be performed at a temperature of 25 ° C or higher, and 60 ° C or lower.

Drying the ultrasonic treated mixture may be performed for 24 hours or more and 72 hours or less.

According to another embodiment of the present invention, there is provided a positive electrode comprising: the positive electrode including the negative electrode material for the secondary battery; A separator; And an electrolyte.

One embodiment of the present invention provides a negative electrode material for a secondary battery for a secondary battery capable of uniformly adsorbing and dissolving metal cations on the surface of an anode material and preventing dendrite growth of metal. As a result, the risk of deterioration due to deterioration of the negative electrode and short-circuiting can be reduced, and the lifetime characteristics of the secondary battery can be improved.

In addition, the negative electrode material for a secondary battery according to an embodiment of the present invention has an improved theoretical capacity as compared with the conventionally proposed negative electrode material for a secondary battery, thereby overcoming the limit of the theoretical capacity and drastically improving the capacity characteristics of the secondary battery.

1 is a conceptual diagram schematically showing a uniform lithium plating mechanism due to anionic functional groups of DNA.
FIG. 2 is a conceptual view briefly showing a manufacturing process of a CNT-DNA cathode.
3 is a photograph of the CNT-DNA cathode manufactured.
4 is a scanning electron microscope (SEM) image of CNT cathodes a and c and CNT-DNA cathodes b and d.
5 is a scanning electron microscope (SEM) image of CNT (a), CNT-PSS (b), and CNT-DNA (c) cathodes after discharging at 1000 mAh / g based on CNT.
FIG. 6 shows charge and discharge results of the CNT anode, the CNT-PSS cathode, and the CNT-DNA cathode of FIG.
FIG. 7 shows the results of charge / discharge of a CNT-DNA cathode according to the content of DNA.
8 is a scanning electron microscope (SEM) image of CNT (a) and CNT-DNA (b) cathodes after 5000 mAh / g of CNT-based discharge.
FIG. 9 shows charge and discharge results of the CNT anode and the CNT-DNA cathode of FIG.

Hereinafter, embodiments of the present invention will be described in detail. However, it should be understood that the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

As described above, Si (theoretical capacity: 4200 mAh / g) is seen as a substitute material as a substitute for a carbonaceous anode material having a low capacity characteristic. However, deterioration of a cathode due to growth of dendrite such as lithium upon charging, There are problems such as deterioration of characteristics, and further, risk of explosion due to short circuit. Thus, there is a growing demand for new technologies that can overcome the limitations of theoretical capacity as an anode material.

The present invention has been devised to solve such a problem, and one embodiment of the present invention is capable of uniformly adsorbing (plating) and eluting metal cations on the surface of an anode material, thereby preventing dendrite growth of metal A negative electrode material for a secondary battery is provided. This makes it possible to reduce the risk of deterioration due to deterioration of the negative electrode and short-circuit, and to improve the life characteristic of the negative electrode material.

In addition, the negative electrode material for a secondary battery according to an embodiment of the present invention has remarkably improved theoretical capacity as compared with the conventionally proposed negative electrode material for a secondary battery, and can overcome the limit of the theoretical capacity.

Specifically, one embodiment of the present invention is directed to a core comprising an electrically conductive material; And a coating layer disposed on the core, the coating layer including a biochemical anionic polymer.

The biochemical anionic polymer refers to a biochemical polymer having a negative charge on its surface. The biochemical anionic polymer may be exemplified by DNA, siRNA, amino acid, or a combination thereof, and more specifically, it may be DNA.

DNA is complementary to each base (adenine, thymine, guanine, cytosine) between the main chains of deoxyribose (C ₅ H ₁₀ O ₄ ) and phosphate group (PO ₄ ^3- ) and forms a double helix structure. In this overall structure, the phosphate group (PO ₄ ^3- ) has an anion, and in this sense DNA becomes a biochemical anionic polymer. Particularly, the base and the phosphate group (PO ₄ ^3- ) constituting the DNA contribute to forming a uniform coating layer through various interactions such as pi-pi interactions (π-π stacking) and electrostatic interactions.

The phosphate group (PO ₄ ^3- ) of the DNA can act on the electrostatic attraction with cations such as Li ⁺ , K ⁺ , Na ⁺ , Mg ^{2 +} , Cu ^{2 +} and Zn ^{2 +} (Plated) uniformly.

As such, a material containing a biochemical anionic polymer is coated on a core containing an electrically conductive material, whereby, for example, a phosphoric acid group (PO ₄ ^3- ) of DNA is uniformly positioned on an anode material and Li ⁺ , K ⁺ , Na ⁺ , Mg ^{2 +} , Cu ^{2 +} , and Zn ^{2 +} can be uniformly adsorbed (plated) on the negative electrode material by electrostatic attraction. Dendrite growth of the metal can be prevented, so that the reversible capacity and the like of the secondary battery can be improved, and the risk of deterioration due to the deterioration of the negative electrode and the short circuit can be significantly reduced. In addition, it is possible to fabricate a negative electrode having an improved theoretical capacity as compared with a Si negative electrode material and having no capacity limitation.

In addition, the present invention can be applied to all metal secondary batteries such as lithium secondary batteries, sodium secondary batteries, and magnesium secondary batteries, and its application range can be wide.

When the biochemical anionic polymer is coated on an electroconductive material, as shown in the following Examples, non-biochemical anions such as polystyrene sulfonate (PSS) and polyacrylic acid (PAA) The adsorption (plating) of the metal can be performed more uniformly as compared with the case where the polymer is coated. Thus, the reversible capacity of the battery can be further improved, and the risk of short circuit of the battery can be greatly reduced.

The electrically conductive material is not particularly limited, and various electrically conductive materials may be used. Specifically, it may be a carbon-based material. More specifically, it may be a carbon nanotube (CNT), a graphene, a carbon black, a carbon fiber, a graphite, or a combination thereof.

Depending on the type of the carbon-based material, the shape of the core including the electrically conductive material may be variously adjusted, such as spherical or cylindrical. Illustratively, when the core is a carbon nanotube, the core may have a length of 100 nm or more, and 1000um or less, a diameter of 0.5 nm or more, and 300 nm or less. In this range, the carbon-based material can be uniformly dispersed in the solvent, and the biochemical anionic polymer such as DNA can be uniformly coated on the core.

The thickness of the coating layer may be 0.5 nm or more, and 100 nm or less. More specifically 0.5 nm or more, and 10 nm or less; Not less than 0.5 nm, and not more than 8 nm; 0.5 nm or more, and 5 nm or less; 0.5 nm or more, and 3 nm or less; 0.5 nm or more, and 2 nm or less; Or 0.5 nm or more, and 1 nm or less; It is thinly and uniformly coated in the above range on the biochemical anionic polymer layer electroconductive material and the effect of loss of electrical conduction caused by the coating layer is very small and battery characteristics can be improved as compared with other negative electrode materials.

In the negative electrode material, at least 1 wt% and not more than 75 wt% of the core, based on 100 wt% of the total amount of the negative electrode material; And the coating layer as the remainder. Specifically, the coating layer may contain at least 10% by weight; And 95% by weight or less; Specifically, the weight ratio of the core and the coating layer (core: coating layer) may be 1: 0.1 or more, and 1:20 or less. More specifically 1: 1 or more, and 1:20 or less; Or 1: 1 or more, and 1:10 or less. When the content of the coating layer containing the biochemical anionic polymer is too large, the surplus polymer in the coating layer acts as a nonconductor, so that the coulombic efficiency can be reduced. On the other hand, if the content of the coating layer containing the biochemical anionic polymer is too small, there may arise a problem that the advantage of the biochemical anionic polymer coating is not sufficiently realized.

The negative electrode material for a secondary battery according to an embodiment of the present invention has a remarkably improved theoretical capacity as compared with the negative electrode material for a secondary battery, which has been proposed in the past, and can overcome the limit of the theoretical capacity. More specifically, the negative electrode material for a secondary battery has a theoretical capacity of 4500 mAh / g or more; , 4500 mAh / g or more, and 10000 mAh / g or less;

Another embodiment of the present invention relates to a method for preparing a mixture comprising mixing an electroconductive substance, a biochemical anionic polymer, and a solvent to prepare a mixture; Ultrasonically treating the mixture; And drying the ultrasonic treated mixture. The present invention also provides a method for manufacturing an anode material for a secondary battery.

Thus, an anode material for a secondary battery according to an embodiment of the present invention can be manufactured. Specifically, by thoroughly dispersing the electroconductive material and the biochemical anionic polymer in the mixture by mixing the electroconductive material, the biochemical anionic polymer, and the solvent, the biochemical anionic A uniform coating of the polymer can be made possible.

More specifically, ultrasonic treatment of the mixture may include: a first ultrasonic treatment step of ultrasonic-treating the mixture in a bath type ultrasonic wave; And a second ultrasonic wave processing step of ultrasonically processing the first ultrasonic processed material with a tip type ultrasonic wave.

By sequential ultrasonic treatment in a bath-type ultrasonic machine and a tip-type ultrasonic machine, it is possible to minimize the defects, cutting and structural deformation of the cores caused by a tip type ultrasonic machine and effectively achieve a uniform dispersion of the mixture .

The first ultrasonic wave treatment step may be performed at a temperature of 5 ° C or higher, and 40 ° C or lower, for 30 minutes or longer, and for 120 minutes or shorter. More specifically, at a temperature of 5 DEG C or more, and 30 DEG C or less for 90 minutes. In this condition, the first ultrasonic treatment can contribute to the uniform dispersion of the mixture, and the subsequent second ultrasonic treatment time can be minimized to minimize defects, cutting and structural deformation that may occur in the core.

The second ultrasonic wave treatment step may be performed at a temperature of 1 ° C or higher, and 10 ° C or lower, for 5 minutes or more, and for 120 minutes or less. More specifically, at a temperature of 1 ° C or more, and 10 ° C or less for 20 minutes. Under such conditions, the second ultrasonic wave treatment can provide an effect of making the dispersed state more uniform.

The final negative electrode material can be obtained by drying the mixture containing the negative electrode material coated with the electroconductive material by the biochemical anionic polymer through ultrasonic treatment. At this time, the step of drying the ultrasonic treated mixture can be performed at a temperature of 25 ° C or more, and a temperature of 60 ° C or less for 24 hours or more, and for 72 hours or less. However, the present invention is not limited thereto, and the drying temperature and time can be variously controlled within a range where the structure of the biochemical polymer is not deteriorated and a sufficient drying is performed.

Wherein the mixture comprises at least 0.0001% by weight and less than 0.002% by weight, based on 100% by weight of the mixture, of the electrically conductive material, biochemical anionic polymer and solvent, ; Not less than 0.0001% by weight, and not more than 0.002% by weight of the biochemical anionic polymer; And the solvent as the remainder.

In addition, the weight ratio of the electroconductive substance and the biochemical anionic polymer in the mixture may be 1: 0.1 or more and 1:20 or less. More specifically 1: 1 or more, and 1:20 or less; Or 1: 1 or more, and 1:10 or less. When the biochemical anionic polymer is mixed too much, the excess polymer in the coating layer of the prepared negative electrode material acts as a nonconductor, so that the coulomb efficiency of the secondary battery can be reduced. On the other hand, when the biochemical anionic polymer is mixed too little, there may arise a problem that the advantage of the produced anode material due to the biochemical anionic polymer coating is not fully realized.

The biochemical anionic polymer is a biochemical polymer having a negative charge that can act on the surface with positive charges such as Li ⁺ , K ⁺ , Na ⁺ , Mg ^{2 +} , Cu ^{2 +} , and Zn ^{2 +} do. The biochemical anionic polymer may be illustratively DNA, siRNA, amino acid, or a combination thereof, more preferably DNA.

DNA is complementary to each base (adenine, thymine, guanine, cytosine) between the main chains of deoxyribose (C ₅ H ₁₀ O ₄ ) and phosphate group (PO ₄ ^3- ) and forms a double helix structure. In this overall structure, the phosphate group (PO ₄ ^3- ) has an anion, and in this sense DNA becomes a biochemical anionic polymer. In particular, the base and the phosphate group (PO ₄ ^3- ) constituting the DNA contribute to the formation of a uniform coating layer through various interactions such as pi-pi interactions (π-π stacking) and electrostatic interactions.

The phosphate group (PO ₄ ^3- ) of the DNA can act on the electrostatic attraction with cations such as Li ⁺ , K ⁺ , Na ⁺ , Mg ^{2 +} , Cu ^{2 +} and Zn ^{2 +} (Plated) uniformly.

By coating a material containing such a biochemical anionic polymer on a core containing an electrically conductive material, for example, a phosphoric acid group (PO ₄ ^3- ) of DNA is uniformly positioned on the cathode material, and Li ⁺ , K ⁺ , Na ⁺ , Mg ^{2 +} , Cu ^{2 +} , and Zn ^{2 +} can be uniformly adsorbed (plated) on the negative electrode material by electrostatic attraction. Dendrite growth of the metal can be prevented, so that the reversible capacity and the like of the secondary battery can be improved, and the risk of deterioration due to the deterioration of the negative electrode and the short circuit can be significantly reduced. In addition, it is possible to fabricate a negative electrode having an improved theoretical capacity as compared with a Si negative electrode material and having no capacity limitation.

The electrically conductive material is not particularly limited, and various electrically conductive materials may be used. Specifically, it may be a carbon-based material. More specifically, it may be a carbon nanotube (CNT), a graphene, a carbon black, a carbon fiber, a graphite, or a combination thereof.

According to another embodiment of the present invention, there is provided a cathode comprising an anode material according to an embodiment of the present invention; anode; A separator; And an electrolyte.

The secondary battery may be a secondary battery such as a lithium secondary battery, a sodium secondary battery, and a manganese secondary battery. As described above, such a secondary battery has very few concerns such as an explosion due to short circuit and the like, and the reversible capacity remarkably increases, and it can have a very high capacity characteristic compared to the existing secondary battery.

Hereinafter, preferred embodiments and comparative examples of the present invention will be described. However, the following examples are only a preferred embodiment of the present invention, and the present invention is not limited to the following examples.

Examples and Comparative Examples

material

Carbon nanotubes (CNTs): TUBALL (TM), metal oxide <15 wt%, average diameter: 1.8 + 0.4 nm, length:> 5 μm, OCSiAl single walled carbon nanotubes (SWNT) al., Adv. Mater. 1999, 11 (16), 1354-1358).

DNA (Deoxyribonucleic acid sodium salt from salmon testes) was purchased from Sigma-Aldrich and used as supplied.

Poly (sodium 4-styrenesulfonate, PSS, Mw: ~ 70,000) was purchased from Sigma-Aldrich and used as supplied.

Example 1: Preparation of CNT-DNA cathode

A CNT-DNA cathode was prepared as follows.

After adding 2 mg of CNT (0.2 mg / ml) and 2 mg of DNA (0.2 mg / ml) to 10 ml of distilled water, ultrasonic treatment was performed at 30 ° C for 1 hour and 30 minutes in a bath type ultrasonic machine (CPX5800H, Branson) (1 s / 1 s, Amp: 20%, 10 min) at 10 ° C in a tip type ultrasonic machine (CV334, SONICS & MATERIALS, INC.).

Thereafter, 3 ml of the dispersion thus treated was drop-cast on a copper foil having a thickness of 20 μm, followed by vacuum drying at 50 ° C. for 24 hours.

Example 2: Preparation of CNT-DNA cathode

A CNT-DNA cathode was prepared in the same manner as in Example 1 except that 5 mg (0.5 mg / ml) of DNA was used.

Example 3: Preparation of CNT-DNA cathode

A CNT-DNA cathode was prepared in the same manner as in Example 1 except that 10 mg (1.0 mg / ml) of DNA was used.

Example 4: Preparation of CNT-DNA cathode

A CNT-DNA cathode was prepared in the same manner as in Example 1 except that 20 mg (2.0 mg / ml) of DNA was used.

Comparative Example 1: Preparation of CNT cathode

A CNT anode was prepared in the same manner as in Example 1, except that no DNA was used.

Comparative Example 2: Preparation of CNT-PSS cathode

A negative electrode of CNT-PSS was prepared in the same manner as in Example 1, except that sodium polystyrene sulfonate (PSS) was used instead of DNA.

Experimental Example

How to measure

- Scanning electron microscopy was performed using SU-8020 (Hitachi, Tokyo, Japan) at 5 kV and 10 kV.

- Charging and discharging tests were carried out using 2032 type coin cells and WBCS3000L (WonATech, Korea). The coin cell used was a general polyethylene (PE) separator of 18 psi (diameter: 18 mm) and a lithium foil of 16 psi (diameter: 16 mm) as a negative electrode and a 1 M LiPF 6 in EC / DEC . From these coin cells, lithium plating patterns and discharging capacities of the negative electrodes prepared in the above Examples and Comparative Examples were tested. The negative electrodes prepared in Examples and Comparative Examples were punched to have a size of 12 pi (diameter: 12 mm).

Experimental Example 1: Visual observation of CNT-DNA cathode

The CNT-DNA cathodes prepared in Examples 1 to 4 were visually observed.

As shown in FIG. 3, the CNT-DNT cathode surface after drying became uniform as the amount of DNA increased. This is because as the amount of DNA increases, the CNTs are dispersed and the CNTs are prevented from aggregating during the evaporation of the solvent.

Experimental Example 2: SEM photograph of CNT-DNA cathode

4 (a) and 4 (c) are SEM photographs of CNT cathodes of Comparative Example 1, and FIGS. 4 (b) and 4 (d) are SEM photographs of CNT-DNA cathodes of Example 1.

As a result of the observation that the CNT and DNA aggregates were not observed on the SEM photograph of Example 1, it was confirmed that the base and the phosphate group (PO ₄ ^3- ) constituting the DNA had a pi-pi interaction with the CNT surface (pi-pi stacking) It is found that a uniform coating layer is formed through various interactions such as interaction.

Here, as shown in Figs. 4 (b) and 4 (d), it can be seen that the CNT thicknesses of the CNTs not processed and the CNT-DNA cathodes are not significantly different. This means that the surface of the CNT is thin and uniformly coated with DNA, and it is also predictable that the effect of loss of electron conduction caused by the coating is negligible. In addition, the anionic functional groups of DNA are uniformly distributed on the CNT surface, and the utilization thereof can be maximized.

Experimental Example 3: Observation of electroplating pattern of CNT-DNA cathode

The effect of anionic functional groups in the DNA on the surface of CNTs in the electroplating process through discharging was examined in the coin cell for testing the negative electrodes of Comparative Examples 1, 2 and 1. The current density in the discharge process was 0.2 mA / cm ² .

 As a result, as shown in Fig. 5 (a), when CNT was used alone, after the discharge of 1000 mAh / g, no CNTs were observed and a dendrite which can be observed in a general lithium plating process was formed .

On the other hand, as shown in FIG. 5 (c), the CNT-DNA cathode showed uniform lithium growth in the radial direction. This means that as shown in FIG. 1, an electrostatic attractive force acts between the phosphate group of the DNA and the lithium ion in the electrolyte, thereby enabling uniform lithium plating.

These differences in plating types also differ in the process of reusing lithium. As shown in FIG. 6, the single CNT cathode exhibited a coulombic efficiency of about 14% during the re-dissolution process. This is due to the fact that during the re-dissolution process, lithium in the dendritic kink sites is first eluted and dead lithium is formed and contributes to the capacity reduction (Sin-ichi Tobishima et al., J. Power Sources. 1998, 74, 219-227). On the other hand, the CNT-DNA cathode exhibited a coulombic efficiency of about 86%. It can be seen that lithium uniformly grown in the diameter direction of the CNT does not produce dead lithium in the re-dissolution process and maintains electrically effective networking. The CNT-PSS cathode also exhibited a coulombic efficiency of 68% due to the action of an anionic polymer, PSS. However, the efficiency is lower than that of DNA-CNT cathodes.

Experimental Example 4: Effect of composition ratio on electroplating performance of CNT-DNA cathode

In the coin cell for testing the cathodes of Examples 1 to 4, the influence of the ratio of CNT and anionic functional groups on the lithium plating was examined. The C-rate in the charging and discharging process was 0.1 C (1000 mAh / g).

As a result, as shown in FIG. 7, the higher the ratio of DNA in the re-dissolution process, the lower the coulombic efficiency. This is because the surplus DNA that wraps the CNT acts as a nonconductor and interferes with the movement of electrons toward lithium.

Experimental Example 5: Comparison of Electroplating Effects between CNT-DNA Cathode and CNT-PSS Cathode

Experimental results of a coin cell for testing negative electrodes of Example 1 and Comparative Example 2 were compared and it was examined whether the same effect could be obtained when another polymer (PSS) having an anionic functional group was coated on CNTs. The C-rate in the charging and discharging process was 0.1 C (1000 mAh / g standard).

As shown in FIG. 6, the Coulomb efficiency of the CNT cathode is about 14%, the charge capacity is about 140 mAh / g, the Coulomb efficiency of the CNT-PSS cathode is about 68%, and the charge capacity is About 680 mAh / g, for a CNT-DNA cathode, the coulomb efficiency was about 86% and the charge capacity was about 860 mAh / g.

In the re-dissolution process, the coulombic efficiency of CNT-PSS is higher than that of the single CNT cathode but lower than that of the CNT-DNA cathode. This suggests that the interaction between the sulfonic acid group of PSS and lithium ion may contribute to uniform plating and re-dissolution of lithium.

However, the electrostatic interaction of DNA with lithium has proven to be more effective than PSS in the uniform plating and re - dissolution of lithium. This effect is also confirmed by scanning electron microscope results. As shown in FIG. 5 (a), the single CNT anode was actively growing with a lithium resin phase, and as shown in FIG. 5 (b), the CNT-PSS cathode showed lithium growth in the CNT diameter direction, . On the other hand, as shown in FIG. 5 (c), CNT-DNA cathodes show CNTs even after plating and re-dissolution experiments, suggesting highly uniform plating and re-dissolution of lithium.

Experimental Example 6: Confirmation of possibility of using CNT-DNA cathode according to discharge capacity

The effect of uniformly plating the surface of the CNT without observing the formation of the resin phase due to the influence of the anionic functional group of DNA while observing the discharge capacity of the coin cell for testing the negative electrode of Example 1 was observed. The C-rate during charging and discharging was 0.1 C (5000 mAh / g), and the current density during discharging was 0.2 mA / cm ² .

As shown in FIG. 8, when a CNT reference of 5000 mAh / g was discharged, a uniform dendrite formation was observed in a single CNT cathode as shown in FIG. 8 (a), whereas CNT- In the case of the cathode, uniform lithium growth was confirmed, and no dendrite formation was observed.

As shown in FIG. 9, under the above conditions, the charging capacity at the time of charging reaches about 4,500 mAh / g and the coulomb efficiency reaches about 90%, which exceeds the theoretical capacity of the silicon cathode. Thus, it was confirmed that the negative electrode material of the present embodiment has no limit of the theoretical capacity and can be used for a high capacity secondary battery and a large capacity battery.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. As will be understood by those skilled in the art. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (27)

delete delete delete delete delete delete delete delete delete delete delete delete Preparing a mixture by mixing an electrically conductive material, a biochemical anionic polymer, and a solvent;
Ultrasonically treating the mixture; And
Drying the ultrasonic treated mixture; and
A method for manufacturing an anode material for a secondary battery. The method of claim 13,
Mixing the electrically conductive material, the biochemical anionic polymer, and the solvent to prepare a mixture,
The mixture may contain,
For 100 wt% of the mixture,
At least 1 wt%, and at most 75 wt% of the electrically conductive material;
At least 10% by weight, and at most 95% by weight of the biochemical anionic polymer; And
And the solvent is contained as the remainder.
A method for manufacturing an anode material for a secondary battery. The method of claim 14,
In the mixture, the weight ratio of the electroconductive substance and the biochemical anionic polymer may be,
1: 0.1 or more, and 1: 20 or less.
A method for manufacturing an anode material for a secondary battery. The method of claim 13,
Mixing the electrically conductive material, the biochemical anionic polymer, and the solvent to prepare a mixture,
The biochemical anionic polymer may include,
DNA, siRNA, amino acids, or combinations thereof.
A method for manufacturing an anode material for a secondary battery. 17. The method of claim 16,
The biochemical anionic polymer may include,
DNA,
A method for manufacturing an anode material for a secondary battery. The method of claim 17,
In the ultrasonic treatment of the mixture,
The base and / or phosphate group (PO ₄ ^3- ) in the DNA binds to the surface of the electrically conductive material through pi-pi stacking and / or electrostatic interaction with the surface of the electrically conductive material. However,
A method for manufacturing an anode material for a secondary battery. The method of claim 13,
Mixing the electrically conductive material, the biochemical anionic polymer, and the solvent to prepare a mixture,
The electroconductive material may be,
Carbon-based material.
A method for manufacturing an anode material for a secondary battery. 20. The method of claim 19,
The electroconductive material may be,
Wherein the carbon nanotubes are carbon nanotubes (CNT), graphene, carbon black, carbon fiber, graphite, or a combination thereof.
A method for manufacturing an anode material for a secondary battery. The method of claim 13,
Ultrasonically treating the mixture; Quot;
Which is performed two or more times.
A method for manufacturing an anode material for a secondary battery. 22. The method of claim 21,
Ultrasonically treating the mixture,
A first ultrasonic treatment step of ultrasonic-treating the mixture in a bath type ultrasonic wave;
And a second ultrasonic treatment step of ultrasonically treating the first ultrasonic treated material with a tip type ultrasonic wave.
A method for manufacturing an anode material for a secondary battery. The method of claim 22,
A first ultrasonic wave processing step of performing ultrasonic wave processing in the bath type ultrasonic wave generator,
5 &lt; 0 &gt; C, and 40 &lt; 0 &gt; C or lower for 30 minutes or more, and 120 minutes or less.
A method for manufacturing an anode material for a secondary battery. The method of claim 22,
A second ultrasonic wave processing step performed after the first ultrasonic wave processing step and performing ultrasonic wave processing in a tip type ultrasonic wave,
At least 1 &lt; 0 &gt; C, and 10 &lt; 0 &gt; C or less for 5 minutes or more, and 120 minutes or less,
A method for manufacturing an anode material for a secondary battery. The method of claim 13,
Drying the ultrasonic treated mixture;
Lt; RTI ID = 0.0 &gt; 25 C, &lt; / RTI &
A method for manufacturing an anode material for a secondary battery. The method of claim 13,
Drying the ultrasonic treated mixture;
24 hours, and 72 hours or less.
A method for manufacturing an anode material for a secondary battery. delete

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