WO2014126413A1 - Anode active material for sodium secondary battery, method for manufacturing electrode using same, and sodium secondary battery comprising same - Google Patents

Abstract

The present invention relates to an anode active material for a sodium secondary battery, an electrode using the same, and a sodium secondary battery comprising the same. The anode active material for a sodium secondary battery of the present invention is characterized by comprising a phosphorus-carbon composite, wherein the phosphorus-carbon composite is at least one of red phosphorus, black phosphorus, white phosphorus, and yellow phosphorus.

Description

Anode active material for sodium secondary battery, manufacturing method of electrode using same and sodium secondary battery comprising same

The present invention relates to a cathode active material for a sodium secondary battery, a method for manufacturing an electrode using the same, and a sodium secondary battery including the same. More particularly, by forming a cathode active material using a phosphorus-carbon composite, a reversible capacity for sodium ions is achieved. It relates to a large, excellent initial efficiency of the anode active material for sodium secondary battery, a method for producing an electrode using the same and a sodium secondary battery comprising the same.

A secondary battery is a battery that can be used repeatedly through a charging process that is reverse to the discharge where chemical energy is converted into electrical energy. Among these, lithium secondary batteries can be used in various portable electronic devices such as laptops and mobile phones, and the market is expected to expand greatly in the future for electric vehicles and energy storage. However, despite the expansion of the market for lithium secondary batteries, lithium reserves are limited and thus secondary batteries are required.

As an alternative to lithium, it is abundantly buried in the world with even distribution of alkali metals belonging to group 1 of the periodic table, and is of interest as a next-generation sodium secondary battery with a high energy density with redox potential equal to that of lithium. This is concentrated.

However, since sodium ions are larger in size than lithium ions, they move slowly and do not have good reaction activity. So, when the electrode material used in the conventional lithium secondary battery is applied, the capacity is higher than that of the lithium ion secondary battery. In most cases, this is not expressed or results in rapid capacity deterioration and deterioration.

Japanese Patent Application Laid-Open No. 2007-35588 applies carbon as a negative electrode active material of a sodium ion secondary battery, but has the ability to reversibly store and discharge sodium ions, that is, a reversible capacity of less than 300 mAh / g. There is. Therefore, in order to implement a sodium secondary battery, it is urgent to develop a negative electrode and a positive electrode material having a high reversible capacity of sodium ions and a low charge / discharge voltage.

Accordingly, an object of the present invention is to solve such a conventional problem, and can reversibly store and discharge sodium ions, thereby improving electrical conductivity by compounding carbon in red phosphorus having excellent storage and releasing ability of sodium, and improving sodium conductivity. The purpose of the present invention is to provide a negative electrode active material, an electrode using the same, and a sodium secondary battery including the same, including a phosphorus-carbon composite having high capacity and high efficiency by increasing reactivity.

By adjusting the size of the primary and secondary particle size of the phosphorus-carbon composite, to provide a cathode active material comprising a phosphorus-carbon composite that can facilitate the diffusion of sodium ions, an electrode using the same and a sodium secondary battery comprising the same There is a purpose.

To provide a cathode active material comprising a phosphorus-carbon composite having a reversible capacity of 650 mAh / g or more and having a low charge / discharge voltage, an electrode using the same, and a sodium secondary battery including the same, compared to a cathode active material using only carbon or red phosphorus. There is this.

In order to achieve the above object, the negative electrode active material for a sodium secondary battery according to an embodiment of the present invention, including a phosphorus-carbon composite, phosphorus in the phosphorus-carbon composite is at least one of red phosphorus, black phosphorus, white phosphorus or sulfur Can be.

The weight ratio of the phosphorus and carbon of the phosphorus-carbon composite may be 1: 0.1 to 1: 2.5.

The average particle diameter of the phosphorus-carbon composite may be 0.01 to 10 μm, and the primary particle size may be 5 to 500 nm.

The phosphorus-carbon composite may further include graphene. Carbon of the phosphorus-carbon composite may have a specific surface area of 10 to 3000 m 2 / g.

Carbon of the phosphorus-carbon composite may include graphite.

Phosphorus of the phosphorus-carbon complex may be red phosphorus, and the red phosphorus may be in an amorphous phase.

The amorphous phase has a signal-to-noise ratio of less than 50 compared to the noise appearing at the baseline when X-ray diffraction analysis is performed at a scan rate of 1 ^o / min to 16 ^o / min per minute and 20 ^o to 70 ^o at 0.01 ^o intervals. Can be.

The negative electrode active material may have a peak at a wavenumber of 1582 cm ⁻¹ in Raman spectroscopy.

The cathode material may have a peak appearing at a wavenumber of 1582 cm ⁻¹ as measured by Raman spectroscopy than a peak appearing at a wave number of 1332 cm ⁻¹ .

The negative electrode active material may operate in a voltage range of 0.2 to 1.0V in preparation for the reduction potential of sodium.

The negative electrode active material may have a reversible capacity of 650 mAh / g or more.

Method for manufacturing a sodium secondary battery electrode according to an embodiment of the present invention, a paste preparation step of preparing a paste by mixing a negative active material powder, a binder and a dispersion consisting of a phosphorus-carbon composite; An application step of applying the paste to an electrode current collector; And a drying step of drying the paste at a temperature of 50 to 200 ° C.

In the paste preparation step, the dispersion may be 10 to 200 parts by weight, and the binder may be 3 to 50 parts by weight based on 100 parts by weight of the negative electrode active material.

In the paste preparation step, the dispersion may include at least one of N-methylpyrrolidone, isopropyl alcohol, acetone or water.

In the paste preparation step, the binder is polytetrafluoroethylene, polyvinylidene fluoride, cellulose styrene-butadiene rubber, polyimide, polyacrylic acid, polyacrylic acid alkali salt, polymethyl methacrylate or polyacrylonitrile It may include at least one of the reels.

In the paste preparation step, the paste may further include a powdery conductive material, and the conductive material may include at least one of carbon black, vapor-grown carbon fiber, or graphite.

The conductive material may be 1 to 30 parts by weight based on 100 parts by weight of the negative electrode active material.

A sodium secondary battery according to an embodiment of the present invention is a positive electrode including at least one of a negative electrode, a sodium metal oxide, sodium metal phosphate, sodium metal fluoride oxide or sodium metal fluoride oxide containing the negative electrode active material, the It may comprise a separator and an electrolyte present between the negative electrode and the positive electrode.

The sodium metal oxide is Na _x CoO ₂ , Na _x Co _2/3 Mn _1/3 O ₂ , Na _x Fe _1/2 Mn _1/2 O ₂ , NaCrO ₂ , NaLi _0.2 Ni _0.25 Mn _0.75 O _2.35 , Na _0.44 MnO ₂ , NaMnO ₂ , Na _0.7 VO ₂ , Na _0.33 V ₂ O ₅ , wherein 0 <x ≦ 1.

The sodium metal phosphate may include at least one of Na ₃ V ₂ (PO ₄ ) ₃ , NaFePO ₄ , NaMn _0.5 Fe _0.5 PO ₄ , Na ₃ V ₂ (PO ₄ ) ₃ .

The sodium metal fluorophosphate may include at least one of Na ₂ FePO ₄ F, Na ₃ V ₂ (PO ₄ ) ₃ .

The sodium metal fluoride oxide may be NaFeSO ₄ F.

The electrolyte may be dissolved in a sodium salt comprising at least one of NaClO ₄ , NaAsF ₆ , NaBF ₄ , NaPF ₆ , NaSbF ₆ , NaCF ₃ SO ₃ or NaN (SO ₂ CF ₃ ) ₂ in an organic solvent.

The organic solvent is ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, isopropyl methyl carbonate, vinylene carbonate, ethylene fluoride carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, at least one of γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxene, 4-methyl-1,3-dioxene, diethyl ether, tetraethylene glycol dimethyl ether or sulfolane It may include one.

The sodium salt may be 0.1 to 2 molar concentrations.

The electrolyte may include 0.1 to 10% by weight of ethylene fluoride as an additive.

According to the cathode active material for a sodium secondary battery of the present invention, an electrode using the same, and a sodium secondary battery including the same, one or more of the following effects are provided.

First, by forming a phosphorus-carbon composite combined with phosphorus and carbon, by using it as a negative electrode active material, by increasing the reactivity with sodium can realize a reversible capacity of 650mAh / g significantly higher than the reversible capacity of the conventional sodium secondary battery It has an excellent effect of low charge and discharge voltage.

Second, when the sodium secondary battery is implemented using the phosphorus-carbon composite as the negative electrode active material, the initial efficiency is high, and the output characteristics are excellent.

Third, in the case of implementing a sodium secondary battery using a negative electrode active material of the phosphorus-carbon composite, there is almost no capacity decrease even with continuous charging and discharging, thereby enabling stable and continuous use.

Fourth, the formation of the phosphorus-carbon composite can be formed by a simple method of mechanically synthesizing phosphorus and carbon using ball milling at room temperature, so that the anode active material can be easily produced economically.

The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

1 is a flowchart sequentially illustrating a method of manufacturing an electrode for sodium secondary battery according to the present invention.

2A is a graph showing the results of X-ray diffraction analysis of Example 1 negative active material in Experiment 1. FIG.

Figure 2b is a photograph taken in Example 1, the negative electrode active material of Example 1 with a transmission electron microscope.

3A is a graph showing the results of X-ray diffraction analysis of Example 2 negative active material in Experiment 1. FIG.

Figure 3b is a photograph taken in Example 1, the negative electrode active material of Example 2 with a transmission electron microscope.

4A is a graph showing the results of X-ray diffraction analysis of Comparative Example 1 negative electrode active material in Experiment 1. FIG.

Figure 4b is a photograph taken with a scanning electron microscope in Comparative Example 1, the negative electrode active material of Comparative Example 1.

FIG. 5 is a graph showing charge and discharge curves showing electrochemical characteristics associated with sodium ion storage of Example 3 in Experiment 2. FIG.

FIG. 6 is a graph showing charge and discharge curves showing electrochemical characteristics associated with sodium ion storage of Example 4 in Experiment 2. FIG.

FIG. 7 is a graph showing charge and discharge curves showing electrochemical characteristics associated with sodium ion storage of Example 7 in Experiment 2.

FIG. 8 is a graph showing charge and recharge curves showing electrochemical properties associated with sodium ion storage of Example 8 in Experiment 2.

FIG. 9 is a graph showing charge and discharge curves showing electrochemical characteristics related to sodium ion storage of Comparative Example 2 in Experiment 2.

10 is a graph showing the cycle characteristics when applying the sodium secondary battery of Example 3 in Experiment 3.

11 is a graph showing the results of ex-situ X-ray diffraction analysis according to the charge and discharge of Example 3 in Experiment 4.

FIG. 12 is a graph showing charge and discharge curves according to current magnitudes of Example 3 in Experiment 5. FIG.

FIG. 13 is a graph showing discharge capacity according to current magnitudes of Examples 3 to 6 in Experiment 5. FIG.

14 is a photograph taken by a scanning electron microscope of Example 9 the negative electrode active material in Experiment 1.

FIG. 15 is a result of photographing the cross-section of the cathode active material of Example 9 with a scanning electron microscope and analyzing the components with an energy dispersive X-ray spectrometer (EDS).

16 is a graph showing the results of X-ray diffraction analysis of Example 9, Comparative Example 1 and Comparative Example 5 negative electrode active material in Experiment 1.

17 is a graph showing Raman spectroscopy results of Example 9 and Comparative Example 1 negative electrode active material in Experiment 1. FIG.

FIG. 18 is a graph showing charge and discharge curves showing electrochemical characteristics associated with sodium ion storage of Example 10 in Experiment 2.

19 is a graph showing the cycle characteristics when the sodium secondary battery of Example 10 is applied in Experiment 3.

20 is a graph showing the charge and discharge curves showing the electrochemical characteristics associated with the storage of sodium ions of Example 11 in Experiment 2.

21 is a graph showing the cycle characteristics when the sodium secondary battery of Example 11 is applied in Experiment 3.

FIG. 22 is a graph showing charge and discharge curves showing electrochemical characteristics associated with storage of sodium ions of Example 12 in Experiment 2.

FIG. 23 is a graph showing the cycle characteristics when the sodium secondary battery of Example 12 is applied in Experiment 3. FIG.

24 is a graph showing charge and discharge curves showing the electrochemical properties associated with sodium ion storage of Example 13 in Experiment 2.

FIG. 25 is a graph showing the cycle characteristics when the sodium secondary battery of Example 13 is applied in Experiment 3. FIG.

FIG. 26 is a graph showing discharge capacity according to current magnitudes related to sodium ion storage of Example 10 in Experiment 6. FIG.

FIG. 27 is a graph showing discharge capacity according to current magnitudes related to sodium ion storage of Example 11 in Experiment 6.

28 is a graph showing the discharge capacity according to the magnitude of current associated with the storage of sodium ions of Example 12 in Experiment 6.

29 is a graph showing the discharge capacity according to the current magnitude associated with the sodium ion storage of Example 13 in Experiment 6.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and the general knowledge in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In this specification, the singular also includes the plural unless specifically stated otherwise in the phrase. As used herein, “comprises” and / or “comprising” refers to a component, step, and / or operation that excludes the presence or addition of one or more other components, steps, and / or operations. I never do that.

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used in a sense that can be commonly understood by those skilled in the art. In addition, the terms defined in the commonly used dictionaries are not ideally or excessively interpreted unless they are specifically defined clearly.

Hereinafter, a cathode active material for a sodium secondary battery according to the present invention, a method of manufacturing an electrode using the same, and a sodium secondary battery including the same will be described in detail with reference to the accompanying drawings.

The negative electrode active material for sodium secondary battery of the present invention comprises a phosphorus-carbon composite. Phosphorus has the ability to reversibly store / discharge sodium ions, but it is very low in electrical conductivity and cannot be used as an electrode material. However, the present invention solves the low electrical conductivity problem of phosphorus by complexing with carbon having high electrical conductivity.

Phosphorus has various allotropes, and red phosphorus, black phosphorus, white phosphorus, or sulfur phosphorus may be used as a composite material with carbon in the present invention, but red phosphorus is most effective.

Since sodium ions are much less reactive than lithium ions, and the diffusion rate of ions is also slow, the size of primary particles of the active material should be small, and the diffusion rate within the active material should be large. Therefore, it is important to sufficiently reduce the primary particle size of phosphorus in forming a composite of phosphorus and carbon, and to make a uniform composite with carbon having excellent electrical conductivity. For red phosphorus having a binding chain-like structure PP As one wakes up from P ₄ molecule of the WP, with an amorphous structure with no crystallinity, density represents a degree of 2.2 to 2.34g / ㎝ ^3, heukrin density of 2.69 g / ㎝ ³ Has a smaller value. That is, red phosphorus has a great advantage in the diffusion rate of ions because it has an amorphous phase without crystallinity, compared with black phosphorus, white phosphorus, and yellow phosphorus, and is more advantageous for ion diffusion because it forms a dense structure with low density. .

The weight ratio of phosphorus to carbon of the phosphorus-carbon composite is preferably 1: 0.1 to 1: 2.5, more preferably 1: 0.4 to 1: 1. If the weight ratio of phosphorus and carbon is less than 1: 0.1, there is a problem of low electrical conductivity, and if it exceeds 1: 2.5, the reversible capacity is small and is not suitable as an active material.

In addition, the phosphor-carbon composite preferably has an average particle diameter of 0.01 to 10 μm, more preferably 0.1 to 3 μm. If the average particle diameter is less than 0.01 μm, the reactivity with sodium decreases, making the electrode difficult. If the average particle diameter exceeds 10 μm, the diffusion of sodium ions becomes difficult and the possibility of defects caused by the large particles in the electrode manufacturing increases. .

The primary particle diameter of the phosphorus-carbon composite is preferably 5 to 500 nm, more preferably 10 to 100 nm. When the primary particle size is less than 10 nm or more than 100 nm, not only the reactivity with sodium is rather reduced, but also there is a problem that electrode formation is difficult.

Here, the primary particle diameter refers to the diameter of the primary particles, the primary particles are particles constituting the powder and aggregate, particles of the smallest unit that does not break the bond between molecules, each particle is a different particle It means the particles in a state of being present alone without aggregation with. In addition, the secondary particle means a particle formed by aggregation of a plurality of primary particles, that is, aggregated particles.

As a result, when observing the shape of the particles, the unit representing the unbroken mass is called primary particles, and the case where these primary particles aggregate to form powder is called secondary particles.

The phosphorus-carbon composite of the preferred embodiment of the present invention may further include graphene. Graphene has excellent electrical conductivity, a large surface area of more than 2600 m 2 / g, and is chemically stable. In addition, since the space between the graphene can buffer the volume expansion and contraction of the electrode generated during the charging / discharging process, it can improve the cycle efficiency of the battery when implementing the negative electrode active material further comprising graphene . The content of graphene is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the phosphorus-carbon composite. The carbon of the phosphorus-carbon composite preferably has a specific surface area of 10 to 3000 m 2 / g, more preferably 10 to 100 m 2 / g.

As described above, the phosphorus of the phosphorus-carbon complex is most preferably red phosphorus, which is characterized in that the amorphous phase.

Here, the amorphous phase means that the characteristic peak does not appear when the X-ray diffraction analysis is measured at 0.01 ^o intervals from 20 ^o to 70 ^o at a scanning speed of 1 ^o / min to 16 ^o / min per minute. The red phosphorus-carbon composite of the present invention is advantageous as the crystallinity is lower, the degree of crystallization can be determined by the experimental results of X-ray diffraction analysis (XRD). Therefore, the results of several experiments confirmed that the effect of the present invention can be exerted when the characteristic peak does not appear by performing X-ray diffraction analysis under the above conditions.

In addition, the presence of the characteristic peak can be determined by whether a signal having a characteristic peak sufficiently larger than the noise appearing in the base line is generated. When a sufficiently large signal was generated for the noise and the signal-to-noise ratio (S / N ratio) was 50 or more, it was determined that a characteristic peak existed. The magnitude of the noise refers to the amplitude of the base line in the region where no characteristic peak occurs, and it is also possible to set the standard deviation as a reference.

The signal-to-noise ratio is a value representing the magnitude ratio of the generated signal relative to the amount of noise based on the amplitude of the signal appearing on the baseline. More preferably, the signal having the signal-to-noise ratio of 10 or more does not occur. Is most effective. As a result of several experiments, the above conditions are most preferable to satisfy the effects of the present invention.

Although the type of carbon in the phosphorus-carbon composite anode active material is not limited, it is preferable that the electrical conductivity is high when constructing the composite. As such a material, a material including carbon black or graphite may be used, and in particular, it is preferable to have a structure having regularity manufactured using graphite.

Here, the regularity is the presence of a peak showing the regularity in Raman spectroscopy, it is advantageous that the G-band around 1582cm ^-1 due to carbon developed in the phosphor-carbon composite anode active material, in particular 1332cm ^-1 A structure in which the G band is more developed than the peak of the adjacent D band is preferable.

Phosphorus-carbon composite anode active material maximizes the increase in reactivity, and realizes high capacity, excellent output characteristics, and charging characteristics. The phosphorus-carbon composite anode active material according to the present invention operates in a voltage range of 0.2 to 1.0 V in comparison with the reduction potential of sodium, so that the charge and discharge voltage is very low. In addition, the reversible capacity per weight exerts an effect of 650mAh / g or more, it can be realized a reversible capacity of 1300mAh / g or more as shown in the following experiment.

The phosphorus-carbon composite anode active material of the present invention is most preferably implemented as a cathode active material of sodium secondary battery, but this does not limit the application to other batteries.

Next, the method of manufacturing an electrode using the phosphorus-carbon composite anode active material according to the present invention, as shown in Figure 1, comprises a paste preparation step (S10), coating step (S20) and drying step (S30). .

Paste preparation step (S10) is a step of preparing a paste by mixing a binder and a dispersion in a negative electrode active material powder consisting of a phosphorus-carbon composite. Here, the negative electrode active material composed of the phosphorus-carbon composite is as described above. In addition, the negative electrode active material, the binder is used in the form of a powder to make easily into a paste. Mixing is preferably performed through a stirring process, but any method may be used as long as it can be mixed evenly.

Phosphorus-carbon composites synthesize phosphorus and carbon using mechanical milling. Mechanical milling method is loaded with phosphorus and carbon together with a ball and mounted in a high-energy ball mill to perform mechanical synthesis at a rotation speed of 200 to 500 or more times per minute, which is performed in an argon gas atmosphere to minimize the effects of oxygen or moisture. It is preferable. This milling can be performed at room temperature, so that the phosphor-carbon composite can be easily synthesized in a simple process without a separate process. As described above, graphene may be further included to form a complex.

The binder comprises at least one of polytetrafluoroethylene, polyvinylidene fluoride, cellulose styrenebutadiene rubber, polyimide, polyacrylic acid, alkali alkali salt, polymethyl methacrylate or polyacrylonitrile can do.

The amount of the binder is effective to include 3 to 50 parts by weight based on 100 parts by weight of the negative electrode active material. If the binder is less than 3 parts by weight, the binder may not fully serve, and if it exceeds 50 parts by weight, there is a problem of inhibiting the reactivity of the negative electrode active material.

The dispersion may include at least one of N-methylpyrrolidone, isopropyl alcohol, acetone or water. This serves to easily disperse the negative electrode active material and the binder.

The content of the dispersion is preferably 10 to 200 parts by weight, more preferably 50 to 100 parts by weight based on 100 parts by weight of the negative electrode active material. If the dispersion is less than 10 parts by weight, there is a problem that the mixing action is difficult because the dispersion action does not occur sufficiently, if it exceeds 200 parts by weight, there is a problem that the economic efficiency, such as too thin to take a long drying process.

In the paste preparation step S10, a conductive material may be further added. The conductive material is mixed with the negative electrode active material, the binder, and the dispersion, and further reduces the resistance of the electrode, thereby increasing the output of the battery.

The conductive material is at least one of carbon black, vapor grown carbon fiber, or graphite, and may be powdery. It is preferable to add 1-30 weight part with respect to 100 weight part of negative electrode active materials, More preferably, it is effective to add 10-20 weight part. If the conductive material is less than 1 part by weight, the effect of reducing the resistance of the electrode is insignificant, and if it exceeds 30 parts by weight, not only economic efficiency is reduced, but rather there is a problem that can reduce the effect of the negative electrode active material.

Next, the applying step (S20) is a step of applying the paste to the electrode current collector. The current collector for the electrode is a highly conductive metal, and should be easily adhered to the paste. If the metal having such a performance is not limited in use, but at least one of copper, aluminum, stainless steel, nickel can be implemented to excellent performance.

The method of uniformly applying the paste prepared by the paste preparation step (S10) to the electrode current collector is possible in various ways, but after dispensing the paste on the electrode current collector, a doctor blade or the like is used. It is most preferable to uniformly disperse the liquid, and in some cases, a method of distributing and dispersing in one process may be used. In addition, methods such as die casting, comma coating, and screen printing may be used, and may be formed on a separate substrate and then bonded to the current collector by pressing or lamination. Can also be.

Finally, the drying step (S30) is a step of drying the paste. The drying temperature is preferably 50 to 200 ° C, more preferably 100 to 150 ° C. If the temperature is less than 50 ° C., there is a problem in that the drying time is increased and the economy is inferior. If the temperature is more than 200 ° C., the paste is carbonized or rapidly dried to increase the resistance of the electrode. Drying step (S30) is a process of evaporating the dispersion medium or the solvent passing through the hot air blowing region may be made at atmospheric pressure.

The electrode manufactured by the method of manufacturing an electrode using the phosphorus-carbon composite anode active material of the present invention may be used for a sodium secondary battery, but is not limited thereto.

Next, the sodium secondary battery including the phosphorus-carbon composite anode active material according to the present invention comprises a negative electrode, a positive electrode, a separator and an electrolyte.

The negative electrode includes the phosphorous-carbon composite negative active material described above.

The anode may include at least one of sodium metal oxide, sodium metal phosphate, sodium metal phosphate or sodium metal sulphate. The sodium metal oxide is Na _x CoO ₂ , Na _x Co _2/3 Mn _1/3 O ₂ , Na _x Fe _1/2 Mn _1/2 O ₂ , NaCrO ₂ , NaLi _0.2 Ni _0.25 Mn _0.75 O _2.35 , Na _0.44 At least one of MnO ₂ , NaMnO ₂ , Na _0.7 VO ₂ , Na _0.33 V ₂ O ₅ , wherein 0 <x ≦ ₁ , and the sodium metal phosphate is Na ₃ V ₂ (PO ₄ ) ₃ , NaFePO ₄ , NaMn _0.5 Fe _0.5 PO ₄ , Na ₃ V ₂ (PO ₄ ) ₃ It may include at least one, the sodium metal fluoride is Na ₂ FePO ₄ F, Na ₃ V ₂ (PO ₄ It may include at least one of ₃ ), the sodium metal fluoride oxide may be NaFeSO ₄ F. The optimum combination with the negative electrode active material can increase the reactivity, which speeds up the storage and release of sodium ions.

In addition, the separator is present between the cathode and the anode. This serves to block internal short circuits of the two electrodes and to impregnate the electrolyte. The material of the separator is preferably made of at least one of polypropylene and polyethylene to maximize the performance of the battery using the negative electrode and the positive electrode.

The electrolyte is a sodium salt dissolved in an organic solvent, including at least one of NaClO ₄ , NaAsF ₆ , NaBF ₄ , NaPF ₆ , NaSbF ₆ , NaCF ₃ SO ₃ or NaN (SO ₂ CF ₃ ) ₂ in an organic solvent Can be done.

The organic solvent is ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, isopropyl methyl carbonate, vinylene carbonate, ethylene fluoride carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxene, 4-methyl-1,3-dioxene, diethyl ether, tetraethylene glycol dimethyl ether or sulfolane And tetraethylene glycol dimethyl is effective. In some cases, two or more may be used in combination. It is effective to use the electrolyte to maximize the performance of the sodium secondary battery using the negative electrode and the positive electrode.

It is preferable to further add 0.1 to 5% by weight of fluorinated ethylene carbonate to the electrolyte.

Hereinafter, the phosphorus-carbon composite anode active material according to the present invention, a method of manufacturing an electrode using the same, and an embodiment of a sodium secondary battery including the same, will demonstrate the effect of the present invention.

Example 1

The mixture prepared by mixing red phosphorus and carbon in a weight ratio of 7: 3 was immersed with a ball in a cylindrical vial and milled for 20 hours after mounting on a high energy ball mill. Carbon black was used. The weight ratio of the ball and the mixture was maintained in a ratio of 10 to 30 to 1, and was carried out in a glove box of argon gas atmosphere to prepare a phosphorus-carbon composite anode active material.

Example 2

A phosphorus-carbon composite anode active material was prepared in the same manner as in Example 1 except that the mixture was prepared by mixing red phosphorus and carbon in a weight ratio of 5: 5.

Example 9

A phosphorus-carbon composite anode active material was prepared in the same manner as in Example 1 except that carbon was used as graphite.

Comparative Example 1

Red phosphorus (Aldrich) was used as the negative electrode active material instead of the mixture.

Comparative Example 5

Red phosphorus and graphite were prepared in a mixture only without a ball milling process at a mass ratio of 1: 1.

Experiment 1 X-ray Diffraction Experiment and Observation of Particle Shape

For the negative electrode active materials according to Examples 1, 2, 9 and Comparative Examples 1, 5, X-ray diffraction analysis was performed to determine crystallinity, and the shape of the particles was confirmed by observation with a transmission electron microscope and a scanning electron microscope. .

The cathode active material according to Example 9 was processed by using a focused ion beam (FIB), and the elements were analyzed using a scanning electron microscope and an energy dispersive X-ray spectrometer.

In addition, the regularity of the structure of the negative electrode active material according to Example 9 and Comparative Examples 1 and 5 was analyzed using Raman spectroscopy.

X-ray diffraction analysis results and the particle shape observed by transmission electron microscope of Example 1 are shown in Figs. 2a and 2b, respectively. Phosphorus and carbon of the phosphorus-carbon composite anode active material of Example 1 both appeared to be in an amorphous phase, and it can be seen that the average particle diameter is 0.1 to 3 μm in size.

X-ray diffraction analysis results and the particle shape observed with a scanning electron microscope of Example 2 are shown in Figs. 3a and 3b, respectively. As in Example 1, Example 2 also appeared in both the phosphorus and carbon of the phosphorus-carbon composite anode active material in an amorphous phase, it can be seen that the average particle size is 0.1 to 3㎛ size.

X-ray diffraction analysis of Comparative Example 1 and the particle shape observed by transmission electron microscope are shown in Figs. 4a and 4b, respectively. Comparative Example 1 was also amorphous, but the average particle diameter was widely distributed in the range of 0.01 to 10 µm. That is, in the case of red phosphorus, red phosphorus itself is not suitable as an active material due to its low electrical conductivity, and the average particle diameter may be wide so that diffusion of sodium ions may be difficult, making it difficult to use as a negative electrode active material.

X-ray diffraction analysis results of Example 9 and the particle shape observed by scanning electron microscopy prepared by scanning electron microscope and focused ion beam are shown in Figure 14 and 15, respectively.

Hundreds of nanometers of particles joined together to form secondary microparticles of several micrometers in size. In addition, the results of the energy dispersive X-ray spectroscopy in the cross section shows that phosphorus and carbon are uniformly mixed up to the inside of the active material to prepare a phosphorus-carbon composite anode active material.

X-ray diffraction analysis results for Example 9 and Comparative Examples 1 and 5 are shown in FIG. 16. In the graph of Example 9, it can be seen that the characteristic peaks shown in Comparative Examples 1 and 5 were synthesized in the disappeared amorphous state.

Raman spectroscopic analysis results of Example 9 and Comparative Example 1 are shown in FIG. 17. X-ray diffraction analysis showed that the negative electrode active material of Example 9, which did not show any peak, was regular in a short period. The peak appears at a wavenumber of 1582 cm ^-1 corresponding to the graphite structure of carbon, which is larger than the peak at 1332 cm ^-1 at the diamond structure.

Next, in order to proceed with the sodium secondary battery charge and discharge experiment, the electrode was prepared for the sample prepared above.

Example 3

An electrode was prepared using the phosphorus-carbon composite anode active material prepared in Example 1 above. The paste prepared by mixing and stirring a phosphorus-carbon composite anode active material, carbon black as a conductive material, and polyacrylic acid as a binder in a weight ratio of 70:10:20 was stirred on a copper current collector and dried at 120 ° C. to remove moisture. The dried electrode was pressed using a roll press, cut into a required size, and dried in a vacuum oven at 120 ° C. for at least 12 hours to remove residual moisture. Using this electrode, a 2032 size coin cell was fabricated inside an argon glove box. At this time, sodium metal foil was used as the counter electrode, and an electrochemical cell was prepared using 0.8 mol of NaClO ₄ / ethylene carbonate (EC): diethyl carbonate (DEC) (volume ratio 1: 1) as the electrolyte. It was.

Example 4

An electrode was manufactured in the same manner as in Example 3, except that the electrode was manufactured using the phosphorus-carbon composite anode active material prepared in Example 2, and an electrochemical cell was prepared in the same manner.

Example 5

The mixture prepared by mixing red phosphorus and carbon in a weight ratio of 9: 1 was immersed with a ball in a cylindrical vial and milled for 20 hours after mounting in a high energy ball mill. Carbon black was used. The weight ratio of the ball and the mixture was maintained in a ratio of 10 to 30 to 1, the same method as in Example 3 except that the electrode was prepared using a phosphorous-carbon composite anode active material by performing in a glove box of argon gas atmosphere An electrode was prepared, and an electrochemical cell was prepared in the same manner.

Example 6

The mixture prepared by mixing red phosphorus and carbon in a weight ratio of 8: 2 was immersed with a ball in a cylindrical vial and milled for 20 hours after mounting in a high energy ball mill. Carbon black was used. The weight ratio of the ball and the mixture was maintained in a ratio of 10 to 30 to 1, the same method as in Example 3 except that the electrode was prepared using a phosphorous-carbon composite anode active material by performing in a glove box of argon gas atmosphere An electrode was prepared, and an electrochemical cell was prepared in the same manner.

Example 7

Red phosphorus, carbon, and graphene were mixed in a weight ratio of 70: 30: 5, dispersed in distilled water, and dried in an oven to remove moisture to prepare a mixture. An electrode was manufactured in the same manner as in Example 3, except that the electrode was manufactured using the composite anode active material, and an electrochemical cell was prepared in the same manner.

Example 8

An electrode was prepared in the same manner as in Example 3, except that polyvinylidenedifluoride (PVdF) dissolved in N-methylpyrrolidone was used as a binder, and an electrochemical cell was prepared in the same manner.

Example 10

An electrode was manufactured in the same manner as in Example 3, except that the electrode was manufactured using the phosphorus-carbon composite anode active material prepared in Example 9, and an electrochemical cell was prepared in the same manner.

Example 11

An electrode was prepared in the same manner as in Example 10, and an electrochemical cell was prepared in the same manner as in Example 10 except that 5 wt% of ethylene carbonate was added to the electrolyte.

Example 12

An electrode was manufactured in the same manner as in Example 10. An electrochemical cell was prepared in the same manner as in Example 10, except that 1.0 mol of NaPF ₆ was used instead of 0.8 mol of NaClO _{4 for the} electrolyte.

Comparative Example 2

An electrode was prepared using red phosphorus according to Comparative Example 1 as a negative electrode active material. The negative electrode active material, carbon black as a conductive material, and polyacrylic acid as a binder were mixed at a weight ratio of 70:10:20 and stirred to coat a paste prepared on a copper current collector and dried at 120 ° C. to remove moisture. The dried electrode was pressed using a roll press, cut into a required size, and dried in a vacuum oven at 120 ° C. for at least 12 hours to remove residual moisture. Using this electrode, a 2032 size coin cell was fabricated inside an argon glove box. At this time, sodium metal foil was used as the counter electrode, and an electrochemical cell was prepared using 0.8 mol of NaClO ₄ / ethylene carbonate (EC): diethyl carbonate (DEC) (volume ratio 1: 1) as the electrolyte. It was.

Comparative Example 3

The mixture prepared by mixing red phosphorus and carbon in a weight ratio of 2.5: 7.5 was infiltrated with a ball in a cylindrical vial and milled for 20 hours after mounting on a high energy ball mill. Carbon black was used. The weight ratio of the ball and the mixture was maintained at a ratio of 10 to 30 to 1, it was carried out in a glove box of argon gas atmosphere to prepare a phosphorus-carbon composite anode active material. The paste prepared by mixing and stirring a phosphorus-carbon composite anode active material, carbon black as a conductive material, and polyacrylic acid as a binder in a weight ratio of 70:10:20 was stirred on a copper current collector and dried at 120 ° C. to remove moisture. The dried electrode was pressed using a roll press, cut into a required size, and dried in a vacuum oven at 120 ° C. for at least 12 hours to remove residual moisture. Using this electrode, a 2032 size coin cell was fabricated inside an argon glove box. In this case, sodium metal foil was used as the counter electrode, and an electrochemical cell was prepared using 0.8 mol of NaClO ₄ / ethylene carbonate (EC): diethyl carbonate (DEC) (volume ratio 1: 1) as the electrolyte. It was.

Comparative Example 4

An electrode was prepared using carbon as a negative electrode active material. The carbon negative electrode active material, carbon black as a conductive material, and polyacrylic acid as a binder were mixed in a weight ratio of 70:10:20 and stirred to coat a paste prepared on a copper current collector and dried at 120 ° C. to remove moisture. The dried electrode was pressed using a roll press, cut into a required size, and dried in a vacuum oven at 120 ° C. for at least 12 hours to remove residual moisture. Using this electrode, a 2032 size coin cell was fabricated inside an argon glove box. In this case, sodium metal foil was used as the counter electrode, and an electrochemical cell was prepared using 0.8 mol of NaClO ₄ / ethylene carbonate (EC): diethyl carbonate (DEC) (volume ratio 1: 1) as the electrolyte. It was.

<Experiment 2> Confirmation of reaction voltage and capacity of material

Charge and discharge experiments were performed under the constant current conditions of the electrochemical cells prepared in Examples 3 to 8, 11 to 13, and Comparative Example 2. A current density of 143 mA / g or 286 mA / g was used based on the weight of the active material.

The constant current charge and discharge curves of Example 3 are shown in FIG. 5. As shown in FIG. 5, the charge capacity of the first cycle is 1557 mAh / g and the discharge capacity is 1323 mAh / g, which is very large and has an initial efficiency of 85%. The second cycle is charging and discharging with a value similar to the first discharge capacity. In terms of the discharge capacity compared to the green, it can be seen that the 1890mAh / g has a high reversibility corresponding to 73% of the theoretical capacity of the phosphorus (P). In addition, it can be seen that most of the charge and discharge occurs in the range of 0.3 to 0.8V, which is a desirable characteristic as the negative electrode of the sodium secondary battery. In other words, if the charging voltage is too low as the negative electrode, the electroplating of sodium occurs during charging, which causes a fatal problem in the safety of the battery. If the discharge voltage is too high as the negative electrode, the output voltage of the battery is low. Therefore, in the case of Example 4, it can be seen that the charge-discharge voltage is in the range of 0.3 to 0.8V, so that there is no problem of electrodeposition of sodium and a problem of decreasing the output voltage of the complete cell.

The constant current charge and discharge curves of Example 4 are shown in FIG. 6. As shown in FIG. 6, the charge capacity of the first cycle is 903 mAh / g, and the discharge capacity is 683 mAh / g, showing a gentle slope curve. In Example 5, the content of red phosphorus was lower than that of Example 4, so the capacity and initial efficiency appeared to be somewhat lower, but the initial efficiency reached 75%, and the charge / discharge voltage was in the range of 0.3 to 0.8V.

In Example 6, when the battery was charged and discharged at a constant current of 286 mA / g, the discharge capacity was 1117 mAh / g, which is not sufficient for the phosphorus content because the electric conductivity is not high due to the lack of carbon, but the capacity is not high. Shows capacity. In addition, in the case of Example 5, when the charge and discharge at a constant current of 286mA / g, the discharge capacity was the highest to 1428mAh / g, because the electrical conductivity is higher than in Example 6 and the phosphorus content is higher than in Examples 3 and 4 to be.

The constant current charge and discharge curves of Example 7 are shown in FIG. 7. As shown in FIG. 7, the charge capacity of the first cycle is 1208 mAh / g, and the discharge capacity is 1016 mAh / g. Compared to Example 4, graphene was added to the electrode to decrease the capacity per weight, and the initial efficiency was 84%, which is similar to that of Example 4.

The constant current charge and discharge curves of Example 8 are shown in FIG. 8. The charge capacity of the first cycle is 1698 mAh / g and the discharge capacity is 1473 mAh / g, which shows an excellent effect with an initial efficiency of 86%. Capacity retention in the second cycle was also excellent.

The constant current charge and discharge curves of Example 10 are shown in FIG. 18. The first cycle had a charge capacity of 1730 mAh / g and a discharge capacity of 1350 mAh / g, which showed a high capacity despite the high phosphorus content and a relatively high initial efficiency of 78%.

The constant current charge / discharge curve of Example 11 is shown in FIG. 20. The charge capacity of the first cycle was 1870mAh / g and the discharge capacity was 1492mAh / g, indicating a high capacity, and the initial efficiency was 80%, and it can be seen that the initial capacity is increased when ethylene carbonate is added.

The constant current charge and discharge curves of Example 12 are shown in FIG. 22. In the first cycle, the charging capacity was 1670mAh / g and the discharge capacity was 1100mAh / g, which was a high capacity, and the initial efficiency was 66%, which was somewhat lower than that in Example 10.

The constant current charge and discharge curves of Example 13 are shown in FIG. 24. In the first cycle, the charge capacity was 1730mAh / g and the discharge capacity was 1520mAh / g, showing a high capacity, and the initial efficiency was also very high at 88%. When using tetraethylene glycol dimethyl ether (TEGDME) as a solvent, It can be seen that the performance is improved.

The constant current charge and discharge curves of Comparative Example 2 are shown in FIG. 9. As shown in Fig. 9, the charge capacity of the first cycle is 1718mAh / g, the discharge capacity is 250mAh / g, and the efficiency is very low, which is 15%. From the second cycle it can be seen that the charge and discharge capacity is drastically reduced. Comparative Example 2 seems to have a low initial efficiency because the volume is expanded and contracted during the initial charging and discharging process, and some phosphorus (P) is electrically isolated so that the stored sodium does not escape. This is because the electrical isolation becomes serious when phosphorus is not complexed with carbon. The reversible capacity of Comparative Example 3 was 347 mAh / g, and the reversible capacity of Comparative Example 4 was 115 mAh / g, since the phosphorus content mainly responsible for storing sodium in the phosphorus-carbon composite was low or absent. It can be seen that the discharge and storage capacity of sodium ions is significantly lowered and has a very low value capacity.

Therefore, by forming a composite of phosphorus and carbon with a cathode active material as in the present invention, while ensuring the content of phosphorus to store sodium, it is possible to discharge all stored sodium by suppressing the electrical isolation phenomenon, high capacity, high efficiency Implementation is possible.

Experiment 3 Life Characteristics of Materials

The electrochemical cell prepared in Example 3 was charged by the constant current and constant voltage method and discharged by the constant current method to measure the life characteristics of the battery, and the results are shown in FIG. 10.

During constant current charging, charging was performed from a current of 143 mA / g to a 0 V (vs. Na / Na ⁺ ) voltage region based on the weight of the phosphorus-carbon composite anode active material. The constant current discharge was discharged to 1.5 V (vs. Na / Na ⁺ ) under a current of 143 mA / g based on the weight of the active material to confirm the decrease in capacity. As a result of the experiment, there was almost no reduction in capacity up to 30 cycles, and more than 2 moles of sodium ions per mole of red were reversibly stored / exhausted and showed a high reversible capacity of about 1250 mAh / g or more.

The electrochemical cell prepared in Example 10 was charged in a constant current / constant voltage method and discharged in a constant current method to measure the life characteristics of the battery, and the results are shown in FIG. 19. There is a slight decrease in capacity up to the first 10 cycles, but there is no decrease in capacity even after 60 cycles. Rather, all of the initially reduced capacity is recovered to maintain a stable capacity. In view of this, it can be seen that the use of graphite in the preparation of the phosphorus-carbon composite anode active material can realize the excellent initial capacity and ensure a stable lifetime.

The electrochemical cell prepared in Example 11 was charged by the constant current and constant voltage method and discharged by the constant current method to measure the life characteristics of the battery, and the results are shown in FIG. 21. Not only did the initial capacity increase than that of Example 10, but the portion where the capacity decreases initially disappears and then the capacity continuously increases, and after 30 cycles, a capacity of 1700 mAh / g or more appears. When ethylene carbonate is added to the electrolyte, it can be seen that more stable and superior performance can be achieved.

The electrochemical cell prepared in Example 12 was charged by the constant current and constant voltage method and discharged by the constant current method to measure the life characteristics of the battery, and the results are shown in FIG. 23. Although the initial dose was somewhat low, all of the samples prepared in Example 9 had a stable cycle, and when NaPF ₆ salt was used, the initial capacity was still excellent even though the initial dose was somewhat low.

The electrochemical cell prepared in Example 13 was charged by the constant current and constant voltage method and discharged by the constant current method to measure the life characteristics of the battery, and the results are shown in FIG. 25. High initial efficiency and stable capacity are shown without decreasing initial capacity or gradual change of capacity. Therefore, it is stable when tetraethylene glycol dimethyl ether is used as solvent in electrolyte.

Experiment 4 Characteristics of Structural Change due to Charge and Discharge of Materials

The electrochemical cell prepared in Example 3 was charged and discharged with a constant current, and X-ray diffraction analysis was performed by ex-situ method. A current of 143 mA / g was used in the 0.0-1.5 V (vs. Na / Na ⁺ ) voltage range. In the X-ray diffraction analysis, when the first cycle charging was stopped at 0.2V and 0.0V, the electrodes were stopped at 1.5V, and each electrode was prepared by decomposing an electrochemical cell in an argon glove box to obtain an electrode. This electrode was performed by adhering Kapton tape to a beryllium (Be) window.

The experimental results are shown in FIG. 11. The phosphorus-carbon composite, which was in an amorphous phase before charging, showed no peak due to the charging progressing to 0.2V, but specific peaks corresponding to Na ₃ P were observed in the diffraction pattern obtained by X-ray diffraction analysis after stopping charging at 0.0V. It was confirmed to be amorphous again in the X-ray diffraction pattern measured after discharging this to 1.5V. This result confirms that the phosphorus-carbon composite is changed to the crystalline Na ₃ P phase which was amorphous during the charging process, and then restored to the amorphous phosphor again during the discharge process.

Experiment 5 Charge and Discharge Characteristics According to Current Rate of Materials-1

The rate characteristic results of the electrochemical cell prepared in Example 3 are shown in FIG. Charging and discharging experiments were carried out in the voltage range of 0.0 ~ 1.5V (vs. Na / Na ⁺ ), and the current was charged while changing the magnitude of 143mA / g, 286mA / g, 571mA / g, 1430mA / g, 2860mA / g. Over discharge was performed. 12 shows very high reversible capacity despite increasing charge and discharge currents, 91% capacity at 1430mA / g current compared to capacity at 143mA / g current, and 82 at 2860mA / g. A dose of% is shown.

In addition, the capacity according to the charge and discharge current in Examples 3 to 6 is shown in comparison with FIG. This shows that the capacity is advantageous in that the higher the content of phosphorus and the higher the content of carbon, the higher the capacity and the higher the carbon content. In the charge and discharge characteristics according to, it was found that the most excellent effect appears.

Experiment 6 Charge and Discharge Characteristics According to Current Rate of Materials-2

Velocity characteristic results of the electrochemical cell prepared in Example 10 are shown in FIG. Charging and discharging experiments were conducted in the voltage range of 0.0 ~ 1.5V (vs. Na / Na ⁺ ), and the magnitude of current was 50mA / g, 100mA / g, 200mA / g, 300mA / g, 500mA / g, 1000mA / g Charging and discharging were performed while changing to 2000 mA / g and 50 mA / g. According to FIG. 26, despite the increase in the charge and discharge currents, it exhibits a very high reversible capacity and a capacity of about 1000 mAh / g even at 300 mA / g current, representing 65% of the capacity at a low current of 50 mA / g. .

Velocity characteristic results of the electrochemical cell prepared in Example 11 are shown in FIG. 27. Experimental conditions were performed in the same manner as in Example 10 above. It can be seen that the use of ethylene fluoride carbonate as an additive to the electrolyte improves the rate characteristic. Even at a current of 500 mA / g, a capacity of 1200 mAh / g or more is shown, indicating a capacity of 80% or more of the capacity at a low current of 50 mA / g.

Velocity characteristic results of the electrochemical cell prepared in Example 12 are shown in FIG. Experimental conditions were performed in the same manner as in Example 10 above. It can be seen that the rate characteristic can be improved when NaPF ₆ salt is used in the electrolyte by showing a large capacity even at higher current conditions than in Example 10.

Velocity characteristic results of the electrochemical cell prepared in Example 13 are shown in FIG. 29. Experimental conditions were performed in the same manner as in Example 10 above. This shows little reduction in capacity even at a current of 500mA / g and a capacity of more than 1100mAh / g at a current of 1000mA / g. In addition, even at a current of 2000 mA / g, a large capacity of 800 mAh / g or more is expressed, indicating a capacity of 60% or more compared to the capacity at a low current of 50 mA / g. When tetraethylene glycol dimethyl ether was used as the solvent of the electrolyte, the most excellent speed characteristics could be achieved.

Through this, it can be seen that the output material of the phosphorus-carbon composite is very excellent as the anode active material of the sodium secondary battery capable of rapid charging.

The scope of the present invention is not limited to the above-described embodiment, but may be embodied in various forms of embodiments within the scope of the appended claims. Without departing from the gist of the present invention as claimed in the claims, any person having ordinary skill in the art to which the present invention pertains is considered to be within the scope of the claims described in the present invention to various extents which can be modified.

It is possible to implement a sodium secondary battery having a large reversible capacity per weight and a low charge / discharge voltage by increasing the reactivity with sodium by using the cathode active material for sodium secondary battery according to the present invention.

Claims (27)

1. Comprising a phosphorus-carbon composite, the phosphorus in the phosphorus-carbon composite is at least one of red phosphorus, black phosphorus, white phosphorus or sulfur phosphorus active material for sodium secondary battery.
2. The method of claim 1,

   The weight ratio of the phosphorus and carbon of the phosphorus-carbon composite is 1: 0.1 to 1: 2.5 negative electrode active material for sodium secondary battery.
3. The method of claim 1,

   The average particle diameter of the phosphorus-carbon composite is 0.01 to 10㎛, the primary particle size is 5 to 500nm of the negative electrode active material for sodium secondary battery.
4. The method of claim 1,

   The phosphorus-carbon composite is a cathode active material for sodium secondary battery further comprising graphene.
5. The method of claim 1,

   Carbon of the phosphorus-carbon composite is a negative electrode active material for sodium secondary battery having a specific surface area of 10 to 3000 m 2 / g.
6. The method of claim 1,

   Carbon of the phosphorus-carbon composite is a cathode active material for sodium secondary battery containing graphite.
7. The method of claim 1,

   Phosphorus of the phosphorus-carbon composite is red phosphorus, wherein the red phosphorus is in an amorphous phase.
8. The method of claim 7, wherein

   The amorphous phase has a signal-to-noise ratio of less than 50 compared to the noise appearing at the baseline when X-ray diffraction analysis is performed at a scanning speed of 1 ^o / min to 16 ^o / min per minute and 20 ^o to 70 ^o at 0.01 ^o intervals. Anode active material for sodium secondary battery.
9. The method of claim 1,

   The negative electrode active material is a cathode active material for sodium secondary battery that the peak is present in the wave number of 1582cm ^-1 in Raman spectroscopy.
10. The method of claim 1,

    The cathode material is a cathode active material for a sodium secondary battery having a peak at a wavenumber of 1582 cm ^-1 measured by Raman spectroscopy is larger than a peak at a wave number of 1332 cm ^-1 .
11. The method of claim 1,

    The negative electrode active material is a cathode active material for sodium secondary battery operating in the voltage range of 0.2 to 1.0V in preparation for the reduction potential of sodium.
12. The method of claim 1,

    The negative electrode active material is a negative electrode active material for sodium secondary battery having a reversible capacity of 650mAh / g or more.
13. A paste preparation step of preparing a paste by mixing a negative active material powder, a binder, and a dispersion composed of a phosphorus-carbon composite;

    An application step of applying the paste to an electrode current collector; And

    The method of manufacturing an electrode for a sodium secondary battery comprising a drying step of drying the paste at a temperature of 50 to 200 ℃.
14. The method of claim 13,

    In the paste preparation step, with respect to 100 parts by weight of the negative electrode active material, the dispersion is 10 to 200 parts by weight, the binder is 3 to 50 parts by weight of the method for producing a sodium secondary battery electrode.
15. The method of claim 13,

    In the paste preparation step, the dispersion is a method of manufacturing an electrode for a sodium secondary battery comprising at least one of N-methylpyrrolidone, isopropyl alcohol, acetone or water.
16. The method of claim 13,

    In the paste preparation step, the binder is polytetrafluoroethylene, polyvinylidene fluoride, cellulose styrene-butadiene rubber, polyimide, polyacrylic acid, polyacrylic acid alkali salt, polymethyl methacrylate or polyacrylonitrile A method of manufacturing an electrode for sodium secondary battery comprising at least one of reels.
17. The method of claim 13,

    In the paste preparation step, the paste further comprises a powdery conductive material, wherein the conductive material comprises at least one of carbon black, vapor-grown carbon fiber or graphite.
18. The method of claim 17,

    The conductive material is a sodium secondary battery electrode manufacturing method of 1 to 30 parts by weight based on 100 parts by weight of the negative electrode active material.
19. A negative electrode comprising the negative electrode active material according to claim 1;

    An anode comprising at least one of sodium metal oxide, sodium metal phosphate, sodium metal fluoride or sodium metal fluoride;

    A separator existing between the cathode and the anode; And

    Sodium secondary battery comprising an electrolyte.
20. The method of claim 19,

    The sodium metal oxide is Na _x CoO ₂ , Na _x Co _2/3 Mn _1/3 O ₂ , Na _x Fe _1/2 Mn _1/2 O ₂ , NaCrO ₂ , NaLi _0.2 Ni _0.25 Mn _0.75 O _2.35 , Na _0.44 Sodium secondary battery comprising at least one of MnO ₂ , NaMnO ₂ , Na _0.7 VO ₂ , Na _0.33 V ₂ O ₅ .

    Where 0 <x≤1
21. The method of claim 19,

    The sodium metal phosphate is at least one of Na ₃ V ₂ (PO ₄ ) ₃ , NaFePO ₄ , NaMn _0.5 Fe _0.5 PO ₄ , Na ₃ V ₂ (PO ₄ ) ₃ .
22. The method of claim 19,

    The sodium metal fluorophosphate is sodium secondary battery comprising at least one of Na ₂ FePO ₄ F, Na ₃ V ₂ (PO ₄ ) ₃ .
23. The method of claim 19,

    The sodium metal fluoride oxide is NaFeSO ₄ F Sodium secondary battery.
24. The method of claim 19,

    The electrolyte is sodium in which a sodium salt comprising at least one of NaClO ₄ , NaAsF ₆ , NaBF ₄ , NaPF ₆ , NaSbF ₆ , NaCF ₃ SO ₃ or NaN (SO ₂ CF ₃ ) ₂ is dissolved in an organic solvent. Secondary battery.
25. The method of claim 24,

    The organic solvent is ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, isopropylmethyl carbonate, vinylene carbonate, ethylene fluoride, 1,2-dimethoxyethane, 1,2-diethoxyethane, at least one of γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxene, 4-methyl-1,3-dioxene, diethyl ether, tetraethylene glycol dimethyl ether or sulfolane Sodium secondary battery comprising one.
26. The method of claim 24,

    The sodium salt is sodium secondary battery of 0.1 to 2 molar concentration.
27. The method of claim 24,

    The electrolyte is sodium secondary battery containing 0.1 to 10% by weight of ethylene fluoride as an additive.

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