KR20100133879A - Positive electrode comprising additive material and metal sulfide, fabrication method thereof, and battery comprising the positive electrode - Google Patents

Abstract

PURPOSE: A positive electrode is provided to suppress the overcharging and to minimize the reduction of discharge capacity in high speed charging/discharging. CONSTITUTION: A positive electrode(110) used for a sodium battery generating electrical energy through sodium ion transfer comprises additive consisting of transition metal or catalyst, and metal sulfide forming an electrode by mixing with the additive. A method for manufacturing the positive electrode comprises the steps of: mixing additive and metal sulfide through a ball milling method; and drying the mixed additive and metal sulfide in a specific condition to prepare a positive electrode.

Description

Positive electrode comprising additive material and metal sulfide, fabrication method etc, and battery comprising the positive electrode}

The present invention relates to an electrode for a positive electrode and a sodium battery using the same, and more particularly to an electrode for a positive electrode including an additive and a metal sulfide and a sodium battery using the same.

With the development of electronic technology, various types of electronic devices are gradually being developed. Since electronic devices basically use electrical energy, efforts have been made to develop batteries suitable for the type of electronic devices.

Typically, secondary batteries may be classified into lithium batteries and sodium batteries according to the negative electrode material. At present, a lot of lithium (ion) batteries are used, and accordingly, research on lithium batteries has been progressing. On the other hand, research on sodium cells operating at room temperature is relatively insignificant.

However, the recent direction of secondary battery research has focused on the development of materials having high capacity and high efficiency characteristics, and thus, research on sodium batteries has attracted attention.

As the electrode material for the positive electrode used in the sodium battery, Ni ₃ S ₂ may be conventionally used. 1 is a graph measuring charge and discharge characteristics of a battery using Ni ₃ S ₂ as a cathode material and Na as a cathode material.

In FIG. 1, upper graphs (a) are charge curves showing voltage changes when charged at a constant current density, and lower graphs (b) show discharge curves corresponding to discharges. Specifically, a and b graphs are graphs of the discharge capacity of a conventional battery when a current is applied at a discharge rate of 1 C at a current density of 450 mA / g. The 1C discharge rate means the rate of charging for 1 hour and discharging once.

In the state where the end voltage of charging is set to 2.6 V and the end voltage of discharge is set to 0.4 V, according to FIG. 1, the charging end voltage is reached to 2.6 V after the proper capacity charging at the first and second charge and discharge stages. However, it can be seen that after 28 charge / discharge cycles, the battery does not reach 2.6V and is in an overcharge state where the charge continues. In addition, it can be seen that the capacity at the time of 28 charge / discharge cycles is only about 360 mAh / g.

Meanwhile, the graph c in FIG. 1 shows initial discharge characteristics when measured at a 2C discharge rate. When a current is applied at a 2C discharge rate, the capacity is only about 70 mAh / g. Accordingly, it can be seen that the capacity drops more rapidly than the capacity of 450 mAh / g when applied at a 1C discharge rate.

As described above, the current sodium battery configuration has a problem in that an overcharge phenomenon occurs even in a state where charge and discharge do not occur several times. Overcharging may adversely affect the structure of the battery. Therefore, there is a problem that it is difficult to apply the product to the conventional sodium battery structure.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a positive electrode and a sodium battery using the same, which is capable of high-speed charging and discharging, and suppressing the overcharge phenomenon by adding an additive. .

Electrode for a positive electrode according to an embodiment of the present invention for achieving the above object includes an additive consisting of a transition metal or a catalyst and a metal sulfide mixed with the additive to form an electrode.

Here, the additive is Ni, the metal sulfide may be Ni ₃ S ₂ .

In addition, the additive and the metal sulfide may be mixed in one ratio of 1: 4, 1: 1, and 4: 1 ratios.

The transition metal may be Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Lr, Rf, Db, Sg, Bh, Hs, Mt, Ds, Rg, Uub may be one, the catalyst is PtCo, Ag / C It may be one of CuO, NiO, FeO, Co (OH) ₂ , Pt / C, PT.

And, the metal sulfide is Ag ₂ S, As ₂ S ₃ , CdS, CuS, Cu ₂ S, FeS, FeS ₂ , HgS, MoS ₂ , Ni ₃ S ₂ , NiS, NiS ₂ , PbS, TiS ₂ , MnS , Sb ₂ S ₃ It can be one.

On the other hand, the manufacturing method of the electrode for the positive electrode according to an embodiment of the present invention, the step of mixing the additives and metal sulfides by a ball milling method and drying the mixed additives and metal sulfides under specific conditions to produce an electrode for the positive electrode Steps.

Here, the additive is Ni, the metal sulfide may be Ni ₃ S ₂ .

According to another embodiment of the present invention, a method of manufacturing an electrode for a cathode includes coating an additive on a metal sulfide surface by an electroless plating method, washing and drying the additive-coated metal sulfide, and the additive-coated metal. Preparing a sulfide in the form of an electrode.

Here, the additive is Ni, the metal sulfide may be Ni ₃ S ₂ .

On the other hand, the battery according to an embodiment of the present invention, an additive made of a transition metal or a catalyst, the electrode for the positive electrode mixed with a metal sulfide, the electrode for the negative electrode made of sodium material and the positive electrode and the negative electrode between And an electrolyte that is disposed to transfer sodium ions to generate electrical energy.

Here, the additive is Ni, the metal sulfide may be Ni ₃ S ₂ .

On the other hand, the electrode manufacturing method for a positive electrode according to an embodiment of the present invention, the step of mixing the additive with a metal sulfide by a quenching solidification method, pulverizing the mixture to prepare a powder, and producing the powder in the form of an electrode Steps.

According to various embodiments of the present disclosure as described above, an overcharge phenomenon can be suppressed as much as possible, and a cathode electrode for minimizing the reduction of the discharge capacity during high-speed charging and discharging can be realized. Thereby, the sodium battery using the electrode for positive electrodes can be manufactured. Therefore, development and dissemination of electronic products using sodium batteries can be promoted.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the present invention.

2 is a view showing the configuration of a battery according to an embodiment of the present invention.

According to FIG. 2, the battery 100 includes a cathode electrode 110, an electrolyte 120, and an anode electrode 130. The negative electrode 130 used in the battery 100 may be formed of Na. Therefore, the battery 100 corresponds to a sodium battery (Na battery). Specifically, this corresponds to a Na-S battery.

The electrolyte 120 serves to transfer ions between the anode electrode 110 and the cathode electrode 130. The electrolyte 120 may be made of a solid electrolyte or a liquid electrolyte. As an example of the electrolyte 120, TEGDME may be used in the battery 100, but is not necessarily limited thereto, and may be implemented as another electrolyte that is commonly used.

In FIG. 2, the anode electrode 110, the electrolyte 120, and the cathode electrode 130 are manufactured in a film form and are sequentially stacked, but this is merely an example, and the shape and shape of each component may be described. The location is not necessarily limited to FIG. 2. That is, each of the positive electrode 110, the electrolyte 120, and the negative electrode 130 may have a thread shape instead of a film shape. For example, when the positive electrode 110 or the negative electrode 130 is manufactured in a thread form, the electrolyte 120 is formed to cover the surface thereof, and the remaining electrodes 130 or 110 are again in the form of electrolyte 120. It may be formed in a form covering the surface, it may be implemented as a battery of the seal form.

The anode electrode 110 of FIG. 2 includes an additive and a metal sulfide. The additive functions to suppress the overcharge phenomenon and the discharge capacity decrease by mixing the metal sulfide to form the electrode 110 for the positive electrode.

As the additive, a transition metal or a catalyst may be used.

The transition metals listed in the periodic table are Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Lu Since, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Lr, Rf, Db, Sg, Bh, Hs, Mt, Ds, Rg, Uub, one of these may be used as an additive.

Examples of the catalyst include PtCo, Ag / C, CuO, NiO, FeO, Co (OH) ₂ , PT, Pt / C, and the like, and one of them may be used as the additive 111.

In the following specification, a case of using Ni is described as an example, and the experimental results described below also show the results when Ni is used as the additive 111, but is not limited thereto.

On the other hand, the metal sulfide may be made of a conventional electrode material containing sulfur. For example, Ag ₂ S, As ₂ S ₃ , CdS, CuS, Cu ₂ S, FeS, FeS ₂ , HgS, MoS ₂ , Ni ₃ S ₂ , NiS, NiS ₂ , PbS, TiS ₂ , MnS, Sb ₂ S One of various metal sulfides such as ₃ may be used as the metal sulfide. In the following description, a case where Ni ₃ S ₂ is used is described as an example, but is not limited thereto. The performance of suppressing overcharge and discharge capacity reduction due to the additive will be described later.

On the other hand, the mixing method of Ni and Ni ₃ S _{2 as} the additive 111 has a simple mixing method of each powder, Ni ₃ S ₂ A method of depositing Ni powder on the surface of the powder, a method of dissolving and cooling the two powders (quench coagulation method) and the like can be used.

3 is a view showing the configuration of an electrode for a positive electrode according to an embodiment of the present invention. According to FIG. 3, the anode electrode 110 may be formed of a mixture of the additive 111 and the metal sulfide 112. The additive 111 of FIG. 3 may be Ni, and the metal sulfide 112 may be Ni ₃ S ₂ . As shown in FIG. 3, the additive 111 and the metal sulfide particles 112 may be mixed in a form separated from each other in the electrode 110 for the positive electrode.

The additive 111 and the metal sulfide 112 may be mixed by ball milling or electroless plating.

The ball milling method is a method in which electrodes are manufactured by mixing respective materials using a ball milling machine. Specifically, a conductive agent, a binder, a solvent, and the like are put together with the additive 111 and the metal sulfide 112 into a ball milling machine, and mixing is performed. Then, the mixed resultant is dried under specific conditions to prepare an anode electrode 110 in which the additive 111, the metal sulfide 112, and the like are mixed. Drying conditions may be determined in various ways, for example, it can be treated under conditions that dry for about a day at room temperature (vacuum) room temperature.

The electroless plating method refers to a surface treatment method of causing a chemical reduction reaction on the surface of the metal sulfide 112 by using an electroless plating solution including the additive 111 to deposit the additive 111. Specifically, the metal sulfide 112 is added to the electroless plating solution including the additive 111, the stirring is carried out under specific conditions, and the resultant is washed and dried, whereby the additive 111 is a metal sulfide. Precipitates on the surface 112 to obtain a coated metal sulfide 112. By using this, the anode electrode 110 may be manufactured.

4 is a diagram illustrating an example of a form of the metal sulfide 112 to which the additive 111 is attached through an electroless plating method or the like. As shown in FIG. 4, at least one additive 111, that is, Ni, may be attached to the surface of the metal sulfide 112, that is, Ni ₃ S ₂ . When the anode electrode 110 is manufactured in such a state, it may be shaped as shown in FIG. 5.

5 is a view showing the shape of the anode electrode 110 according to another embodiment of the present invention. Referring to FIG. 5, the anode electrode 110 may further include a conductive agent 113, a binder 114, and the like in addition to the metal sulfide 112 and the additive 111. The additive 111 and the conductive agent 113 may be attached to the surface of the metal sulfide 112, and the binder 114 may form the metal sulfides 112 to be bonded to each other. In FIG. 5, the distance between the metal sulfides 112 is shown to be somewhat spaced apart, but this is for convenience of description and may actually be tightly coupled to each other. The positive electrode 110 as shown in FIG. 5 may be formed when manufactured through an electroless plating method.

Since the ball milling method or the electroless plating method is already known, further detailed description and illustration are omitted.

Meanwhile, the mixing ratio of the additive 111 and the metal sulfide 112 may be adaptively set in consideration of battery characteristics. For example, the ratio may be set to 1: 4, 1: 1, 4: 1, and the like, but the mixing ratio is not limited thereto, and other mixing ratios not described may be adopted. As the inclusion ratio of the additive 111 increases, the overcharge phenomenon is further weakened, but the inclusion ratio of the metal sulfide 112 is relatively low, thereby reducing the capacity to volume. Therefore, it is preferable to set the mixing ratio appropriately in consideration of the degree of suppression of overcharge phenomenon and the capacity to volume ratio.

FIG. 6 is a graph showing charge and discharge characteristics measured under the same conditions as those of FIG. 1 for a battery using a positive electrode according to an embodiment of the present invention. 6 is a case using Ni as an additive 111, Ni ₃ S ₂ as the metal sulfide 112, the mixing ratio was set to Ni ₃ S ₂ : Ni = 4: 1: A current density of 1C discharge rate was used.

According to FIG. 6, it can be seen that overcharging does not occur since charging is performed to 2.6 V without change even during the 35th charge / discharge. As such, it can be confirmed that the overcharge phenomenon is improved by adding the additive 111 to the electrode.

7 shows a charge / discharge graph charged and discharged at a 2C charge / discharge rate with respect to a battery using an electrode for a positive electrode manufactured at a mixing ratio of Ni ₃ S ₂ : Ni = 4: 1. In FIG. 7, as in FIG. 6, even when the 35th charge / discharge is performed, the overcharge phenomenon does not occur at all. In particular, it can be seen that the discharge capacity at the first discharge at 2C discharge rate is about 330mAh / g, which is much higher than the discharge capacity of 70mAh / g in the graph c of FIG. 1. That is, it can be seen that at the time of 2C fast charging and discharging, much better performance can be obtained than conventional sodium batteries. This performance is not only limited to 2C fast charge and discharge, but can also be expected at higher speed charge and discharge.

FIG. 8 is a graph of charge and discharge characteristics measured at a current density of 3C charge and discharge rates for a battery using a positive electrode prepared at a mixing ratio of Ni ₃ S ₂ : Ni = 4: 1. Likewise, in FIG. 8, even when the 35th charge / discharge is performed, the overcharge phenomenon does not occur at all.

FIG. 9 is a graph of charge / discharge characteristics measured at a current density of 3C charge / discharge rate in a state where the Ni content is increased compared to FIGS. 6 to 8. _{Specifically, Ni 3 S 2: Ni =} 1: A is the measurement results for the positive electrode cell using the electrode 4 made of a mixing ratio of. According to FIG. 9, it can be seen that the overcharge phenomenon does not occur until the 100th charge / discharge is continued.

As such, various charging and discharging characteristics can be obtained according to the mixing ratio of the additive 111 and the metal sulfide 112, and therefore, it is preferable to set an appropriate ratio according to the use purpose of the battery, thereby manufacturing the positive electrode 110. Do. Although the above drawings refer to the specific number of charge / discharge cycles in which an overcharge phenomenon does not occur, this is merely an example of a numerical value provided for convenience of description, and does not necessarily mean that overcharge does not occur until such times.

10 is a graph showing charge and discharge characteristics according to the cycle number. Referring to FIG. 10, Ni is added as an additive 111, and the charge and discharge repeatability according to C-rate of the anode electrode 110 having the metal sulfide 112 Ni ₃ S ₂ may be confirmed. That is, although a high current is applied, it can be seen that the charge and discharge characteristics of the anode electrode 110 are excellent (2C).

11 and 12 are diagrams for explaining a method of manufacturing an electrode for a positive electrode using a quench solidification method. Referring to FIG. 11, the additive 111 is mixed with the metal sulfide 112 by a quench coagulation method.

Specifically, Ni as the additive 111 and Ni ₃ S ₂ as the metal sulfide 112 are injected into the chamber 1110. The additive 111 and the metal sulfide 112 may be melted by the induction coil 1130 heated according to the application of electricity while the additive 111 and the metal sulfide 112 move to the bottom of the tube 1120. have. In this case, the additive 111 and the metal sulfide 112 are heated above the melting point.

The molten additive 111 and the metal sulfide 112 are sprayed on the surface of the cooled rotating body 1140 through the bottom of the tube 1120, so that the molten additive 111 and the metal sulfide 112 are Can be cooled at high speed. In addition, when the rotating body 1140 rotates, the additive 111 and the metal sulfide 112 cooled on the surface of the rotating body 1140 may be separated from the rotating body 1140 using the ribbon 1150. Accordingly, the mixture 1160 having a thin plate shape may be generated on the surface of the ribbon 1150.

The mixture 1160 has a structure in which the additive 111 is added to the metal sulfide 112 as shown. Here, the additive 111 and the metal sulfide 112 are preferably mixed in a weight ratio of 20:80, but are not limited thereto. In addition, the rotating body 1140 is made of a copper wheel, and may rotate at 22 m / s.

Thereafter, the mixture in which the additive 111 and the metal sulfide 112 are mixed is ground to prepare a powder, and as shown in FIG. 12, the powder is prepared in the form of an electrode. Specifically, by grinding the metal sulfide 112 by ball milling, an electrode material in which Ni powder is formed inside and outside of the Ni ₃ S ₂ powder may be manufactured.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the invention as defined by the appended claims. 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 invention.

1 is a view showing the charge and discharge characteristics of a conventional sodium battery,

2 is a view showing the configuration of a battery according to an embodiment of the present invention;

3 to 5 are views showing the configuration of an electrode for a positive electrode according to various embodiments of the present invention, and

6 to 10 are measurements of charge and discharge characteristics of a battery using an electrode for a positive electrode according to various embodiments of the present disclosure under various conditions.

11 and 12 are diagrams for explaining a method of manufacturing an electrode for a positive electrode using a quench solidification method.

Explanation of symbols on the main parts of the drawing

110: anode electrode

120: electrolyte

130: cathode electrode

111: Additive

112: metal sulfide

Claims (12)

In the electrode for the positive electrode used in the sodium battery that generates electrical energy through sodium ion transfer, Additives consisting of transition metals or catalysts; And, And a metal sulfide mixed with the additive to form an electrode. The method of claim 1, The additive is Ni, and the metal sulfide is Ni ₃ S _{2 Is} an electrode for a positive electrode. The method of claim 1, Wherein the additive and the metal sulfide is an electrode for a positive electrode, characterized in that mixed in the ratio of one of 1: 4, 1: 1, 4: 1 ratio. The method of claim 1, The transition metal is Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Lu, Hf, Ta , W, Re, Os, Ir, Pt, Au, Hg, Lr, Rf, Db, Sg, Bh, Hs, Mt, Ds, Rg, Uub, The catalyst is positive electrode, characterized in that one of PtCo, Ag / C, CuO, NiO, FeO, Co (OH) ₂ , Pt / C, PT. The method of claim 1, The metal sulfide is Ag ₂ S, As ₂ S ₃ , CdS, CuS, Cu ₂ S, FeS, FeS ₂ , HgS, MoS ₂ , Ni ₃ S ₂ , NiS, NiS ₂ , PbS, TiS ₂ , MnS, Sb _It is one of ₂ S ₃ electrode for the anode. Mixing the additive and the metal sulfide in a ball milling manner; And And drying the mixed additive and the metal sulfide under specific conditions to prepare an electrode for a cathode. The method of claim 6, The additive is Ni, and the metal sulfide is Ni ₃ S _{2 The} method for producing a positive electrode. Coating the additive on the metal sulfide surface by electroless plating; Washing and drying the additive-coated metal sulfide; And Producing the additive-coated metal sulfide in the form of an electrode; electrode manufacturing method for a positive electrode comprising a. The method of claim 8, The additive is Ni, and the metal sulfide is Ni ₃ S _{2 The} method for producing a positive electrode. Additives consisting of transition metals or catalysts; An electrode for a cathode in which a metal sulfide is mixed; An electrode for a cathode made of a sodium material; And And an electrolyte disposed between the anode electrode and the cathode electrode to transfer sodium ions to generate electrical energy. The method of claim 10, The additive is Ni, and the metal sulfide is Ni ₃ S ₂ . Mixing the additive with the metal sulfide by quench coagulation; Grinding the mixture to prepare a powder; And Producing the powder in the form of an electrode; Manufacturing method for a positive electrode comprising a.

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