KR101296789B1 - Zinc based negative Active Material, Manufacturing Method thereof And Lithium Secondary Battery Comprising The Same - Google Patents

Abstract

The present invention is a method for producing a zinc-based negative electrode active material comprising ZnO of the present invention
(1) Zn-In-Ni composite is prepared by uniformly mixing zinc acetate, indium acetate and nickel acetate by the sol-gel chemical method, but after mixing zinc acetate, indium acetate and nickel acetate, acrylamide and methylene bisacryl Zn-In-Ni composite manufacturing step of stirring and mixing the amide at 70 ~ 80 ℃ 12 hours at 100 ~ 120 ℃,
(2) The heat treatment of the Zn-In-Ni composite, wherein the heat treatment is the first heat treatment at 300 ℃ for 5 hours, the temperature is raised to 5 ℃ / min and the second heat treatment for 3 hours at 550 ~ 750 ℃ Zn- In-Ni oxide composite is prepared.

Description

Zinc based negative active material, manufacturing method, and lithium secondary battery computing method

The present invention relates to a method of manufacturing a zinc-based negative active material for a high capacity lithium secondary battery, and in particular, to manufacture a zinc-based negative electrode active material including a Zn-In-Ni oxide composite including ZnO by using a sol-gel method. It is about a method.

Many researches are being conducted to promote the dissemination of electric vehicles and to develop high-performance secondary batteries as their energy sources. The negative electrode active material of the currently commercialized lithium secondary battery uses graphite and lithium transition metal oxide, which can insert and desorb lithium ions, and in addition, an insulating film that prevents direct contact between the electrodes and an organic solvent electrolyte in which lithium ions are dissociated. Or a polymer electrolyte.

In the future, the large secondary battery market, such as electric vehicles, requires high capacity and high output technology of lithium secondary batteries. Accordingly, in order to increase the capacity of the negative electrode, development of a non-carbon negative electrode active material based on silicon or tin, which has a much higher theoretical capacity than the carbonaceous material, is being actively conducted.

Since lithium secondary batteries were commercialized in 1991, carbon materials such as graphite have been mainly used as negative electrode active materials. From the beginning of commercialization to the present, battery capacity has more than doubled, and this improvement in battery performance is accompanied by an increase in battery charging voltage at the positive electrode, and a specific amount of negative active material of 360 mAh / g in amorphous hard carbon with 170 mAh / g. This is due to the development of high specific capacity graphite.

In order to satisfy the long operation time due to the weight reduction and miniaturization of portable devices to which a lithium secondary battery is applied, power consumption of the device must be reduced and the energy density of the battery as the power source must be improved. However, since graphite has been commercialized to date, the theoretical storage capacity of lithium (LiC6 basis) is limited to 372 mAh / g, and thus, an anode active material having a larger lithium storage capacity is required to overcome this problem. In addition to graphite, a high-capacity cathode active material may include silicon and tin, which may react with lithium to form an alloy, and various alloys and composites related to such metals have been actively researched and developed. Pure silicon and tin react with lithium to produce lithium-silicon alloys and lithium-tin alloys, with energy densities of about 10 and 3 times greater than graphite, respectively. However, repetitive shrinkage and expansion of the alloy during charge and discharge acts as a cause of lowering the electrochemical reversible reaction of the battery, which has not yet reached commercialization.

Do Chil-Hoon et al. (Korea Patent Application No. 10-2009-0135084, filed Dec. 31, 2009) filed a patent for the application of lithium secondary battery negative electrode active material of pure zinc powder electrode, 300 mAh / Specific amount of g or less was expressed, and it was reported that discharge specific amount shows 20 mAh / g or less at normal temperature.

According to a paper report by Kaila Selby et al. (N. Jayaprakash, K. Sathiyanarayanan, N. Kalaiselvi. Electrochimica Acta 52 (2007) 2453-2460), a zinc-based alloy was developed through a sol-gel method and a 500 ° C. heat treatment, and a lithium secondary battery As a negative electrode active material, the primary discharge cost was 450 to 650 mAh / g, and the discharge capacity of 25 charge / discharge cycles was 490 mAh / g.

In the papers of Suunun Yoon, Cheol-Min Park, Hansu Kim, Hun-Joon Sohn, Journal of Power Sources 167 (2007) 520-523, the characteristics of zinc carbon composite electrodes were reported. It is about 200 mAh / g and it is reported that Li2ZnSi is formed of an intermetallic compound.

Hou et al. (Xianghui HOU, Qiang Cheng, Ying Bai, WF Zhang., Solid State Ionics 181 (2010) 631-634) studied the characteristics of lithium secondary batteries of Zn2SnO4 materials and reported 850 mAh / g at 25 charge / discharge cycles. It was.

The present invention was created in view of the above matters, and synthesized a zinc-based anode active material using a sol-gel method, and includes a ZnO for a lithium secondary battery as a novel material to surpass the specific capacity and capacity density of existing graphite materials. An object of the present invention is to provide a Zn-In-Ni oxide composite.

Zinc is a light metal, has no problem of environmental pollution of heavy metals, and has a large amount of low cost, which is inexpensive and has been widely used as an active material such as alkaline manganese batteries and air zinc batteries.

In the present invention, a zinc-based oxide composite including ZnO is developed and applied as a lithium secondary battery anode active material to provide a high efficiency, high energy lithium secondary battery.

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Zinc-based negative electrode active material manufacturing method comprising ZnO of the present invention for achieving the above object
(1) Zn-In-Ni composite is prepared by uniformly mixing zinc acetate, indium acetate, and nickel acetate by the sol-gel chemical method, but after mixing zinc acetate, indium acetate and nickel acetate, acrylamide and methylene bisacryl Zn-In-Ni composite manufacturing step of stirring and mixing the amide at 70 ~ 80 ℃ 12 hours at 100 ~ 120 ℃,
(2) The heat treatment of the Zn-In-Ni composite, the heat treatment is the first heat treatment at 300 ℃ for 5 hours, the temperature is raised to 5 ℃ / min and the second heat treatment for 3 hours at 550 ~ 750 ℃ Zn- In-Ni oxide composite is prepared.

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A zinc-based oxide composite anode active material comprising ZnO prepared from a metal ion complex of the sol-gel method according to the present invention and a lithium secondary battery using the same, and the physical and electrochemical characteristics thereof were analyzed. The characteristics have been improved and excellent cycle characteristics, specific capacity, charge and discharge rate characteristics can be used as a negative electrode active material of a lithium secondary battery.

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1 is a FE-SEM photograph of a Zn-In-Ni oxide composite according to an embodiment of the present invention.
Figure 2 is an XRD diffraction analysis results according to the temperature-specific heat treatment of one embodiment of the present invention.
Figure 3 is a comparison of the constant current / constant voltage charging specific capacity of the lithium secondary battery using a Zn-In-Ni oxide composite according to an embodiment of the present invention.
Figure 4 is a comparison of the constant current / constant voltage discharge capacity of a lithium secondary battery using a Zn-In-Ni oxide composite according to an embodiment of the present invention

Hereinafter, the present invention will be described in more detail. Description of the following manufacturing method also includes a description of the negative electrode active material.

 First, the negative electrode active material will be described in the present invention.

 Method for preparing a negative electrode active material according to the present invention comprises the steps of preparing a composite by mixing zinc acetate, indium acetate, nickel acetate (Zn acetate, In acetate, Ni acetate) by the sol-gel method, heat treatment the prepared Zn-In-Ni composite Thus, a Zn-In-Ni oxide composite containing ZnO is prepared.

 It is preferable to heat-treat the composite prepared by the sol-gel method in an inert gas atmosphere, and argon (Ar) was used as the inert gas. It is good to control the particle size by grinding the resultant heat treatment. The method for preparing a Zn-In-Ni oxide composite including ZnO, which is a zinc-based composite of the present invention, is uniformly mixed by a sol-gel chemical method.

In the sol-gel method, zinc acetate (Zn acetate), indium acetate (In acetate), and nickel acetate (Ni acetate) are mixed in a molar ratio composition of 90: 7.5: 2.5, followed by acryl amide and methylene bis acrylamide ( N, N-methylene-bis-acryl amide) is preferably stirred at 70-80 ° C. and mixed for 12 hours at 100-120 ° C.

Next, heat treatment is preferable to stabilize the zinc composite mixed by the sol-gel method. The heat treatment is gradually heated to a first heat treatment for 5 hours at 300 ℃. After the primary heat treatment, the particles are pulverized and classified to control the particle size.

 Next, after the first heat treatment, the supplied Zn-In-Ni composite may be subjected to a second heat treatment for 3 hours at 550-750 ° C. at a heating rate of 5 ° C./min. Even after the above step (secondary heat treatment), it is good to finely grind and classify the obtained material.

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In the present invention, indium may be replaced or added to Sb, Te, Se, Sn, Ge, Si, or P or nickel may be replaced or added to Co, Fe, Mn, or Cu.

Physical properties of the Zn-In-Ni oxide composite anode active material including ZnO of the present invention prepared through the above process were measured.

 Hereinafter, a lithium secondary battery having a Zn-In-Ni oxide composite anode active material including ZnO according to the present invention will be described in detail.

 Except for the Zn-In-Ni oxide composite including ZnO, the remaining components may be selected and applied without limitation to those known in the art. Preferably, the negative electrode may further include carbon black (Super P Black) as a conductive material, and the negative electrode may further include a polyvinylidene fluoride (PVDF) as a binder and a current collector. In addition, the ion conductor may be an electrolyte solution or a polymer electrolyte.

 The present invention for achieving the above object is a negative electrode active material, a conductive material, and a negative electrode comprising a binder in a weight ratio of 70:15:15; The present invention provides a negative electrode active material for a high capacity lithium secondary battery including a negative electrode having a negative electrode active material including a Zn90In7.5Ni2.5 (molar ratio) composite and having an initial discharge cost of 909 mAh / g.

 In addition, the negative electrode active material provides a high capacity lithium secondary battery, wherein the conductive material is carbon black (Super P Black).

 In addition, the binder provides polyvinylidene fluoride (PVDF) to provide a high voltage lithium secondary battery.

 In addition, the ion conductor provides a high capacity lithium secondary battery, characterized in that the non-aqueous electrolyte solution in which LiPF6 is dissolved.

 In addition, the non-aqueous electrolyte provides a high capacity lithium secondary battery, characterized in that the EC, EMC, VC is included.

 In addition, the Zn-In-Ni oxide composite has an average particle size of 15 ~ 17 ㎛, provides a high capacity lithium secondary battery, characterized in that the size of the secondary particles is 3 ㎛.

In addition, the weight ratio of the negative electrode active material: conductive material: binder is 70:15:15 provides a negative electrode for a high capacity lithium secondary battery.

Preferably, an electrolyte solution in which vinylene carbonate (VC) additive is dissolved in a solvent in which ethylene carbonate (EC) and ethyl-methyl carbonate (EMC) are dissolved in a volume ratio of 1: 1 in a solute of LiPF6 is used.

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.

Example  One

end. Zn90In7 .5 Ni2 .5-500 Anode active material  Produce

Zinc acetate (Zn acetate), Indium acetate (Ni acetate) powder (98 +% pure, Sigma Aldrich) was 3.95 g, 0.43 g, 0.12 g with a molar ratio of 90: 7.5: 2.5, respectively. After 20 g of distilled water was sufficiently mixed in a water bath at 80 ° C., 1.42 g and 0.061 g of acryl amide and N, N-methylene-bis-acryl amide were used as catalysts. Was added and mixed.

The composite prepared using the sol-gel method was dried at 100 ° C. for 12 hours, and 32 g of Zn-In-Ni composite was obtained.

The Zn-In-Ni composite prepared by the sol-gel method was placed in an aluminum crucible and sintered for 5 hours in an argon atmosphere at 300 ° C. After the first heat-treated material was ground, the Zn-In-Ni composite was ground, and the composite was secondly sintered at 500 ° C. The temperature increase rate of an electric furnace was 5 degreeC / min, and it hold | maintained for 3 hours. The secondary heat-treated material was ground and classified to adjust the particle size of the material to obtain a Zn-In-Ni oxide composite anode active material containing ZnO having an average particle diameter of 16 µm or less.

I. Lithium secondary battery assembly using Zn-In-Ni oxide composite anode active material

 A slurry was prepared to assemble the lithium secondary battery. Zn-In-Ni oxide composite prepared in the above, carbon black (Super P Black) as a conductive material, polyvinylidene fluoride (Polyvinylidene fluoried (PVDF)) as a binder in a weight ratio of 70:15:15 composition Prepared. First, 0.3 g of a binder and 12 ml of N-methyl-2-pyrrolidone (NMP), a dispersion solvent, were put in a thinky bowl and stirred with a thinky mixer (Kurabo AR-250) for 5 minutes. 1.4 g of Zn-In-Ni composite and 0.3 g of conductive material were mixed using a mortar and put in a thin bowl, followed by mixing for 25 minutes. The prepared slurry was applied to a copper current collector at about 70 μm, dried at 100 ° C. for 5 hours, and then compressed to prepare an electrode. The densities of the prepared electrodes were 0.515, 0.391, 0.218 and 0.219 g / ml, respectively, of the 500, 550, 750 and 950 ° C materials.

 Lithium metal was used as the counter electrode, a separator was placed between the anode and the cathode, and vinylene carbonate was added to the solute in which ethylene carbonate (EC) and ethyl-methyl carbonate (EMC) were dissolved in a volume ratio of 1: 1 in 1.2M LiPF6. A 2025 round battery was assembled using the electrolyte solution to which 2% of (VC) was added.

Example  2

end. Zn90In7 .5 Ni2 .5-550 Anode active material  Produce

 Except for changing the second heat treatment temperature from 500 ° C to 550 ° C in Example 1-A.

I. Lithium secondary battery assembly using Zn-In-Ni oxide composite anode active material

 As shown in Example 1-b.

Example  3

end. Zn90In7 .5 Ni2 .5-750 Anode active material  Produce

 Except for changing the second heat treatment temperature from 500 ° C to 750 ° C in Example 1-A.

I. Lithium secondary battery assembly using Zn-In-Ni oxide composite anode active material

 As shown in Example 1-b.

Example  4

end. Zn90In7 .5 Ni2 .5-950 Anode active material  Produce

 Except for changing the secondary heat treatment temperature from 500 ° C to 950 ° C in Example 1-A.

I. Lithium secondary battery assembly using Zn-In-Ni oxide composite anode active material

As shown in Example 1-b.

Experimental Example  One

end. Zn - In - Ni  Physical property analysis of composite material

The crystal structure of the material was measured by X-rayt diffractometer from X-pert PRO MPD Philips, using Cu Kradiation (λ = 1.5406 Å), scanning rate was 0.04 / sec, and measured 2θ range. Was 20-80.

Surface shape of the material was used SEM (Scanning Electron Microscope, Jeol S-300H). Particle size analysis was performed using Malvern Hydro 2000MU.

Experimental Example  2

I. Electrochemical Characterization of Cells

 After stabilizing the battery prepared according to each Example for 24 hours to evaluate the charge and discharge characteristics and rate characteristics using Toyo's TOSCAT 3100.

 Specifically, after charging the constant current mode to 0.005V at a current density of 0.2C at room temperature, the battery was charged in a constant voltage mode so that the current density was 0.02C, and the constant current mode discharge was completed to 1.5V at a current density of 0.2C. Constant current / constant voltage charging / discharging was repeated 25 times under the same conditions, and the rate characteristic test was completed by charging and discharging five times at a rate of 0.5C, 1C, 2C, 3C, 5C, 10C, and 0.2C.

The experimental results are as follows.

1 is a SEM photograph of a Zn-In-Ni oxide composite prepared by the sol-gel method. It can be seen that the size of the secondary particles is 3 μm in size.

Figure 2 shows the XRD diffraction pattern of the zinc-based composite synthesized with each starting material. Zinc-based composites fired at 500, 550, 750 ℃ was confirmed by ZnO (see Figure 2). In addition, it was confirmed that at the heat treatment temperature of 950 ℃ ZnO disappeared and a new intermetallic composite of In3Ni2 was formed. As the heat treatment temperature increases, the peak strength also increases to increase the crystallinity.

Figure 3 shows the charge specific capacity change according to the charge and discharge of the lithium secondary battery prepared using the zinc-based oxide composite for each heat treatment temperature. Example 1 (500 ° C-firing) is 1508 mAh / g, Example 2 (550 ° C-firing) is 2036 mAh / g, Example 3 (750 ° C-firing) is 1373 mAh / g, Example 4 (950 ° C-firing) was 1508 mAh / g. In addition, the initial charging cost of the electrode made of the material obtained by heat treatment at 550 ° C. was the highest, and the electrode made of the material obtained by heat treatment at 950 ° C. had excellent cycle characteristics.

4 shows a change in discharge capacity according to charge and discharge of a lithium secondary battery manufactured using a zinc-based oxide composite according to heat treatment temperature. Example 1 (500 ° C-firing) is 682 mAh / g, Example 2 (550 ° C-firing) is 909 mAh / g, Example 3 (750 ° C-firing) is 568 mAh / g, Example 4 (950 ° C-firing) was 503 mAh / g. In addition, the initial discharge specific capacity of the electrode made of the material obtained by heat treatment at 550 ° C. was the highest, and the electrode made of the material obtained by heat treatment at 950 ° C. had excellent cycle characteristics.

Table 1 summarizes the lithium secondary battery negative electrode characteristics of the zinc-based oxide composite negative electrode active material prepared according to Example 1 to Example 4.

Heat treatment temperature 1st
Charge capacity
(mAh / g) 1st
Discharge capacity
(mAh / g) 1st
Ah efficiency
(%) 65th
Charge capacity
(mAh / g) 65th
Discharge capacity
(mAh / g) 65th
Ah efficiency
(%) 3C
Discharge capacity
(mAh / g) 3C
Discharge capacity
(%) ^* 500 1527.12 682.44 44.68 37 273.82 739.93 86.8 76.6 550 2036.17 909.92 44.68 49.34 635.09 739.93 115.73 76.6 750 1373.59 568.62 41.39 135.91 381.59 280.77 248.46 88.13 950 1508.93 503.14 33.34 237.96 361.03 151.71 286.79 91.42

* Compared with 62 times discharge capacity charged and discharged at 0.2C rate

Example 3 (750 ° C.-calcined anode active material) has a specific specific capacity compared to the cathode active materials prepared in Example 1 (500 ° C.-fired cathode active material) and Example 2 (550 ° C.-fired cathode active material). The theoretical specific capacity of phosphorous graphite was 372 mAh / g, which was higher than that of the graphite, showing superior characteristics to cycle characteristics.

In the specific capacity, cycle and rate characteristic tests of the charge and discharge shown in FIGS. 3 and 4, the material heat-treated at 750 ° C. showed 568 mAh / g as the primary discharge capacity, and the 3C rate discharge capacity was 250 mAh / As g, the discharge specific capacity of 62.5% was shown as compared with the specific capacity of 400 times 0.2mAh rate discharge of 62 mAh / g.
As confirmed in Figure 2, the zinc-based composite obtained in the heat treatment at 550 ~ 750 ℃ can confirm that ZnO is confirmed to obtain a Zn-In-Ni oxide composite, as shown in Figure 4, the heat treatment at 550 ℃ Since the initial discharge specific amount of the electrode prepared by the oxide composite obtained by the highest, the secondary heat treatment temperature is most preferably 550 ~ 750 ℃.

Claims (12)

(1) Zn-In-Ni composite is prepared by uniformly mixing zinc acetate, indium acetate and nickel acetate by the sol-gel chemical method, but after mixing zinc acetate, indium acetate and nickel acetate, acrylamide and methylene bisacryl Zn-In-Ni composite manufacturing step of stirring and mixing the amide at 70 ~ 80 ℃ 12 hours at 100 ~ 120 ℃,
(2) The heat treatment of the Zn-In-Ni composite, wherein the heat treatment is the first heat treatment at 300 ℃ for 5 hours, the temperature is raised to 5 ℃ / min and the second heat treatment for 3 hours at 550 ~ 750 ℃ ZnO Method for producing a zinc-based negative electrode active material, characterized in that for preparing a Zn-In-Ni oxide composite comprising.

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