Additive for secondary battery electrolyte containing magnesium silicate and method for producing same

Abstract

The present invention relates to an additive for secondary battery electrolytes containing magnesium silicate and a manufacturing method thereof, and more particularly to an additive for secondary battery electrolytes containing magnesium silicate that can reversibly improve the absorption and release of lithium ions in secondary battery electrodes and promote the formation of a solid electrolyte interphase (SEI) without affecting charge / discharge capacity by suppressing electrochemical side reactions, and a manufacturing method thereof.

Description

[Technical Field]

[0001] The present invention relates to an additive for secondary battery electrolytes containing magnesium silicate and a manufacturing method thereof, and more particularly to an additive for secondary battery electrolytes containing magnesium silicate that can reversibly improve the absorption and release of lithium ions in secondary battery electrodes and promote the formation of a solid electrolyte interphase (SEI) by suppressing electrochemical side reactions without affecting charge / discharge capacity, and a manufacturing method thereof. [Background technology]

[0002] Nanoporous materials, which have large specific surface areas and uniform pores, are widely used as adsorbents, catalyst supports, separation and purification processes, and ion exchange media. In particular, the synthesis of new nanostructured materials with controlled porosity is a topic of ongoing research in the field of new materials.

[0003] Magnesium silicate is a porous inorganic chemical substance synthesized by the precipitation reaction of water-soluble aluminum salts and sodium silicate. Due to its strong adsorption properties, it can be used in industrial applications, food refining, cosmetics, and other fields.

[0004] In most of the silica and silicate-related literature reported to date, silica has been synthesized using tetraethyl orthosilicate (TEOS) as a silica precursor. TEOS's high reactivity makes it possible to synthesize silica at a pH level, and its low impurity content makes it possible to synthesize high-purity inorganic compounds, which is a major advantage. However, its high unit price makes it difficult to ensure price competitiveness in the global market.

[0005] Silicate-based inorganic compounds can be synthesized using the sol-gel method, whereby particle shape, size, and surface properties can be adjusted by adjusting various variables (e.g., pH, surfactant, temperature, and concentration), but there has been little research into the exact mechanism behind this. Furthermore, magnesium silicate is difficult to control due to its particle size and wide pH range, so most of its development has been limited to adjusting its porosity.

[0006] On the other hand, lithium secondary batteries are used at high voltages after undergoing high-voltage activation to increase energy density. However, at high voltages, side reactions occur between the active material and the electrolyte, which leads to further deterioration of battery performance. In addition, there is a problem of the active material dissolving into the electrolyte during charging and discharging, which ultimately leads to battery deterioration.

[0007] To alleviate these drawbacks, electrolyte additives for protecting the positive electrode are used, which oxidize before other electrolytes when the lithium secondary battery is charged, forming a protective film on the surface of the positive electrode. However, most existing additives are organic compounds that are not environmentally friendly and are unable to suppress the deterioration of battery performance to a satisfactory level, hindering the development of high-performance (high-power) lithium secondary batteries.

[0008] Therefore, the present inventors recognized that there is an urgent need to develop an electrolyte additive for lithium secondary batteries that can improve the capacity decrease in high voltage cycles and improve the life stability of lithium secondary batteries in order to solve the above problems, and have completed the present invention. Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide an additive for secondary battery electrolytes containing magnesium silicate, which can reversibly improve the absorption and release of lithium ions in secondary battery electrodes and promote the formation of a solid electrolyte interphase (SEI) by suppressing electrochemical side reactions without affecting charge / discharge capacity.

[0010] Another object of the present invention is to provide a method for preparing an additive for secondary battery electrolytes containing magnesium silicate, which can reversibly improve the absorption and release of lithium ions in secondary battery electrodes and promote the formation of a solid electrolyte interphase (SEI) by suppressing electrochemical side reactions without affecting charge / discharge capacity.

[0011] The technical problems that the present invention aims to achieve are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the art from the description of the present invention. [Means for solving the problem]

[0012] In order to achieve the above object, the present invention provides a method for producing an additive for secondary battery electrolytes containing magnesium silicate.

[0013] The present invention will be described in further detail below.

[0014] The present invention provides an additive for secondary battery electrolytes containing magnesium silicate.

[0015] In the present invention, the magnesium silicate is characterized by having a particle size of 50 nm to 800 nm.

[0016] In the present invention, the magnesium silicate is characterized by having a mass ratio of 50 to 70 wt % of oxygen (O), 5 to 20 wt % of magnesium (Mg), and 15 to 35 wt % of silicon (Si).

[0017] In the present invention, the magnesium silicate is 50 to 500 m 2 It is characterized by having a specific surface area of 1 / g.

[0018] In the present invention, the magnesium silicate is characterized by having a pore size of 0.1 to 20 nm.

[0019] The present invention also provides (A1) preparing a silicate precursor; (A2) mixing a magnesium precursor and an ammonium salt to prepare a mixture; (A3) adding the silicate precursor to the mixture to prepare a secondary battery electrolyte additive containing magnesium silicate; The present invention provides a method for producing a magnesium silicate-containing additive for secondary battery electrolytes, the method comprising the steps of:

[0020] In the present invention, the step (A1) comprises: (A1a) mixing alcohol, water, and aqueous ammonia (NH3H2O, ammonia-water) to prepare a mixed solution; (A1b) adding tetraethyl orthosilicate (TEOS) to the mixed solution to prepare a silicate precursor having nano-sized particles.

[0021] In the present invention, the step (A3) comprises: (A3a) adding the silicate precursor to the mixture; (A3b) heating the mixture to which the silicate precursor has been added at 100 to 200°C; (A3c) filtering the mixture after the heating to prepare an additive for a secondary battery electrolyte containing magnesium silicate.

[0022] The present invention also provides a secondary battery electrolyte containing the additive for secondary battery electrolytes containing the magnesium silicate.

[0023] In the present invention, the secondary battery electrolyte is characterized in that it contains the additive for secondary battery electrolytes in an amount of 0.1 to 2.0% by weight relative to the total weight of the secondary battery electrolyte.

[0024] The present invention also provides a secondary battery comprising the secondary battery electrolyte.

[0025] All matters mentioned in the secondary battery electrolyte additive containing magnesium silicate, the manufacturing method thereof, the secondary battery electrolyte containing the same, and the secondary battery containing the secondary battery electrolyte are equally applicable unless inconsistent. [Effects of the Invention]

[0026] The additive for secondary battery electrolytes containing magnesium silicate and the manufacturing method thereof according to the present invention can suppress electrochemical side reactions, thereby reversibly improving the absorption and release of lithium ions in secondary battery electrodes and promoting the formation of a solid electrolyte interphase (SEI) without affecting the charge / discharge capacity.

[0027] The effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a scanning electron microscope (SEM) image showing the particle size of magnesium silicate for use as a secondary battery additive according to the present invention. [Figure 2]1 is a dynamic light scattering (DLS) graph showing the average particle size of magnesium silicate for use as a secondary battery additive according to the present invention; [Figure 3] 1 is an image of energy dispersive X-ray spectroscopy (EDS) confirming the structure of magnesium silicate for use as a secondary battery additive according to the present invention. [Figure 4] 2 is a graph showing the specific surface area of the magnesium silicate for use as a secondary battery additive according to the present invention and the size of pores present on the surface of the magnesium silicate. [Figure 5] 1 is a graph showing galvanostatic charge-discharge cycles to confirm whether the application of magnesium silicate according to the present invention as an additive affects the positive electrode of a secondary battery. [Figure 6] 1 is a graph of electrochemical impedance spectroscopy (EIS) for confirming whether the magnesium silicate according to the present invention has an effect on the positive electrode of a secondary battery when used as an additive. [Figure 7] 1 is a graph showing the discharge capacity retention characteristics that change with the progress of charge-discharge cycles, which confirms whether the application of magnesium silicate according to the present invention as an additive affects the positive electrode of a secondary battery. [Figure 8] 1 is a graph showing galvanostatic charge-discharge cycles to determine whether the magnesium silicate according to the present invention has an effect on the negative electrode of a secondary battery when used as an additive. [Figure 9] 1 is a graph of electrochemical impedance spectroscopy (EIS) for confirming whether the magnesium silicate according to the present invention has an effect on the negative electrode of a secondary battery when used as an additive. [Figure 10] 1 is a graph showing the discharge capacity retention characteristics that change with the progress of charge-discharge cycles, which confirms whether the application of magnesium silicate according to the present invention as an additive affects the negative electrode of a secondary battery. DETAILED DESCRIPTION OF THE INVENTION

[0029] The terms used in this specification are currently selected as widely used and general terms as possible, taking into consideration the functions of the present invention. However, they may differ depending on the intentions of those skilled in the art, precedents, or the emergence of new technologies. In addition, in certain cases, the applicant may arbitrarily select terms, and in such cases, their meanings will be described in detail in the description of the invention. Therefore, the terms used in this specification must be defined based on the meanings of the terms and the overall content of the present invention, rather than simply by the names of the terms.

[0030] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms as defined in commonly used dictionaries should be interpreted to have a meaning consistent with the meaning they have in the context of the relevant art, and should not be interpreted as having an idealized or overly formal meaning unless expressly defined in this application.

[0031] Numerical ranges are inclusive of the numerical values defined in the range. Every maximum numerical limitation given herein includes every lower numerical limitation, as if such lower numerical limitation were expressly stated. Every minimum numerical limitation given herein includes every higher numerical limitation, as if such higher numerical limitation were expressly stated. Every numerical limitation given herein includes every finer numerical range within a broader numerical range, as if such narrower numerical limitations were expressly stated.

[0032] Hereinafter, embodiments of the present invention will be described in detail, but it is obvious that the present invention is not limited to the following embodiments.

[0033] Additive for secondary battery electrolyte containing magnesium silicate and method for producing same The present invention provides an additive for secondary battery electrolytes containing magnesium silicate.

[0034] The magnesium silicate may have a particle size of 50 nm to 800 nm. The magnesium silicate may be present in nano-size.

[0035] The magnesium silicate may be composed of 50 to 70 wt% oxygen (O), 5 to 20 wt% magnesium (Mg), and 15 to 35 wt% silicon (Si) in a mass ratio, and preferably 55 to 65 wt% oxygen (O), 10 to 15 wt% magnesium (Mg), and 20 to 30 wt% silicon (Si).

[0036] The magnesium silicate is 50 to 500 m 2 / g, and preferably 100 to 450 m 2 / g, and most preferably 120 to 420 m 2 / g specific surface area.

[0037] The magnesium silicate may have a pore size of 0.1 to 20 nm, preferably 0.5 to 15 nm, and most preferably 1.0 to 13 nm.

[0038] The present invention also provides (A1) preparing a silicate precursor; (A2) mixing a magnesium precursor and an ammonium salt to prepare a mixture; (A3) adding the silicate precursor to the mixture to prepare a secondary battery electrolyte additive containing magnesium silicate; The present invention provides a method for producing a magnesium silicate-containing additive for secondary battery electrolytes, comprising:

[0039] The step (A1) is a step of preparing a silicate precursor, (A1a) mixing alcohol, water, and aqueous ammonia (NH3H2O, ammonia-water) to prepare a mixed solution; (A1b) adding tetraethyl orthosilicate (TEOS) to the mixed solution to prepare a silicate precursor having nano-sized particles.

[0040] The alcohol may be a C1 to C4 lower alcohol, for example, methanol, ethanol, propanol or n-butanol.

[0041] The silicate precursor may be at least one selected from the group consisting of silica (SiO), sodium silicate, tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, triethoxyethylsilane (TEES), and 1,2-bis(triethoxysilyl)ethane (BTSE), and is preferably at least one selected from the group consisting of nanoparticle-sized silica, sodium silicate, tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, triethoxyethylsilane, and 1,2-bis(triethoxysilyl)ethane.

[0042] The silicate precursor prepared in step (A1) may be a silicate precursor having nano-sized particles.

[0043] Step (A2) may be a step of preparing a mixture by mixing a magnesium precursor and an ammonium salt.

[0044] The magnesium precursor may be one or more selected from the group consisting of magnesium nitrate, magnesium sulfate, and magnesium chloride, and the magnesium precursor may be a single precursor or a mixed precursor.

[0045] The ammonium salt is at least one selected from the group consisting of ammonium chloride (NH4Cl), ammonium nitrate (NH4NO3), and ammonium sulfate ((NH4)2SO4).

[0046] The ammonium salt added in step (A2) serves to suppress side reactions of the magnesium precursor and induce the reaction between magnesium ions and silicate ions, thereby producing uniform spherical magnesium silicate.

[0047] After step (A2), aqueous ammonia (NH4OH) may be further added to the mixture of the magnesium precursor and the ammonium salt.

[0048] The step (A3) is a step of adding the silicate precursor to the mixture to prepare the additive for a secondary battery electrolyte containing magnesium silicate according to the present invention, (A3a) adding the silicate precursor to the mixture; (A3b) heating the mixture to which the silicate precursor has been added at 100 to 200°C; (A3c) filtering the mixture after the heating to prepare a secondary battery electrolyte additive containing magnesium silicate.

[0049] The step (A3a) may be a step of adding the silicate precursor to the mixture, more specifically, a step of dispersing the silicate precursor in water (H2O) and adding the solution in which the silicate precursor is dispersed to the mixture.

[0050] After completion of step (A3a), the mixture may be mixed with stirring until homogeneous.

[0051] The step (A3b) may be a step of heating the mixture to which the silicate precursor has been added at 100 to 200°C, more specifically, a step of transferring the mixture to which the silicate precursor has been added to an autoclave and reacting the mixture at 100 to 200°C for 1 to 36 hours.

[0052] Step (A3c) may be a step of filtering the mixture after the heating to prepare the additive for a secondary battery electrolyte containing magnesium silicate according to the present invention. More specifically, the mixture after the heating is cooled to room temperature, and then the magnesium silicate produced by the reaction is filtered, washed, and dried at 50 to 150°C to prepare the additive for a secondary battery electrolyte containing magnesium silicate according to the present invention.

[0053] Secondary battery electrolyte containing additive for secondary battery electrolyte containing magnesium silicate and secondary battery containing the same The present invention provides a secondary battery electrolyte containing the additive for secondary battery electrolytes containing the magnesium silicate.

[0054] The secondary battery electrolyte may contain the additive for secondary battery electrolytes in an amount of 0.1 to 2.0% by weight relative to the total weight of the secondary battery electrolyte.

[0055] The present invention also provides a secondary battery containing the secondary battery electrolyte.

[0056] The secondary battery contains the secondary battery electrolyte in an optimal weight amount, thereby suppressing side reactions and electrolyte decomposition occurring in the secondary battery electrodes, thereby extending the life of the secondary battery and improving its efficiency.

[0057] The advantages and features of the present invention, as well as methods for achieving them, will become apparent from the following detailed examples. However, the present invention is not limited to the following examples, and can be embodied in various different forms. These examples are provided solely for the purpose of making the disclosure complete and fully conveying the scope of the invention to those skilled in the art. The present invention is defined only by the scope of the claims.

[0058] Example 1. Preparation of magnesium silicate for use as a secondary battery additive 1.1. Preparation of silicate precursor To produce magnesium silicate with nano-sized particles, spherical nanosilica (SiO2) was prepared as a silicate precursor by carrying out the Stober process on a silicate precursor with nano-sized particles.

[0059] More specifically, ethanol, distilled water, and aqueous ammonia (NH3H2O, ammonia-water) were mixed homogeneously, tetraethyl orthosilicate (TEOS) was added to the mixture, and the mixture was stirred at 250 rpm for 2 hours at room temperature. After the stirring was completed, the mixture was centrifuged at high speed to separate the solid layer, which was washed with distilled water and ethanol and then dried at 80°C to produce nanosilica (SiO2), a silicate precursor with nano-sized particles.

[0060] 1.2. Production of magnesium silicate for secondary battery additives Magnesium chloride (MgCl2, 0.75 mmol) and ammonium chloride (NH4Cl, 10 mmol) were dissolved in distilled water (30 mL), followed by the addition and mixing of 28% aqueous ammonia (NH4OH, 1 mL). Next, the prepared sodium silicate having nano-sized particles (0.1 g) was dispersed in distilled water (20 mL), and the dispersion was added to the mixture and mixed until homogeneous. The mixed solution was transferred to an autoclave and reacted at 140°C for 12 hours to release Si ions from the silicate precursor, spherical silica (SiO2), and allow the released Si ions to interact with magnesium ions. The reaction mixture was then cooled to room temperature, and the magnesium silicate produced by the reaction was filtered, washed with distilled water, and dried in a dryer at 100°C to produce the magnesium silicate for use as a secondary battery additive according to the present invention.

[0061] Example 2. Secondary battery electrolyte 1 containing magnesium silicate as an additive Ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a weight ratio of 1:1, and the mixture was mixed with LiPF to prepare a liquid electrolyte LiPF-EC / DEC. 0.003 g (0.3 wt % of the total weight of the liquid electrolyte) of the magnesium silicate prepared in Example 1 was added to 1 g of the liquid electrolyte (LiPF-EC / DEC) to prepare a secondary battery electrolyte 1 containing magnesium silicate as an additive according to the present invention.

[0062] Example 3. Secondary battery electrolyte 2 containing magnesium silicate as an additive 0.01 g (1.0 wt % of the total weight of the liquid electrolyte) of the magnesium silicate prepared in Example 1 was added to 1 g of the liquid electrolyte (LiPF-EC / DEC) prepared in Example 2 to prepare secondary battery electrolyte 2 containing magnesium silicate as an additive according to the present invention.

[0063] Comparative Example 1: Comparative secondary battery electrolyte 1 containing no magnesium silicate as an additive Ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a weight ratio of 1:1, and the mixture was mixed with LiPF to prepare a comparative secondary battery electrolyte 1 consisting of a liquid electrolyte LiPF-EC / DEC.

[0064] Comparative Example 2: Comparative secondary battery electrolyte 2 containing magnesium silicate as an additive 0.03 g (3.0 wt % of the total weight of the liquid electrolyte) of magnesium silicate prepared in Example 1 was added to 1 g of the liquid electrolyte (LiPF-EC / DEC) prepared in Example 2 to prepare a comparative secondary battery electrolyte 2 containing magnesium silicate as an additive.

[0065] Experimental Example 1. Analysis of magnesium silicate material for secondary battery additives 1.1. Magnesium silicate particle size analysis In order to confirm whether the particles of the magnesium silicate for use as a secondary battery additive according to the present invention are nano-sized, the silicate precursor, spherical silica (SiO2), and the magnesium silicate for use as a secondary battery additive prepared in Example 1 were subjected to scanning electron microscope (SEM) and dynamic light scattering (DLS) measurements, and the results are shown in Table 1, FIGS. 1 and 2 below.

[0066] [Table 1]

[0067] Referring to Table 1, FIGS. 1 and 2, it can be seen that (a) spherical silica, which is a silicate precursor, and (b) magnesium silicate for use as a secondary battery additive, which were prepared in Example 1 according to the present invention, have a particle size range of 200 nm to 500 nm.

[0068] 1.2. Composition analysis of magnesium silicate In order to confirm the constitution of the magnesium silicate for a secondary battery additive according to the present invention, the magnesium silicate for a secondary battery additive prepared in Example 1 was subjected to energy dispersive X-ray spectroscopy (EDS) measurement, and the results are shown in Table 2 and FIG. 3 below.

[0069] [Table 2]

[0070] Referring to Table 2 and FIG. 3, it can be seen that the magnesium silicate for secondary battery additive according to the present invention (Example 1) is a magnesium silicate composed of oxygen, magnesium, and silicon.

[0071] 1.3. Analysis of specific surface area and pore size of magnesium silicate In order to confirm the specific surface area of the magnesium silicate for use as a secondary battery additive according to the present invention and the size of the pores present on the surface of the magnesium silicate, the specific surface area and the pore size of the magnesium silicate for use as a secondary battery additive prepared in Example 1 were measured using a BET specific surface area analyzer, and the results are shown in FIG. 4.

[0072] Referring to FIG. 4, the magnesium silicate for secondary battery additive according to the present invention (Example 1) was 399.10 m 2 It can be seen that the magnesium silicate has a specific surface area of 7.00 nm / g and that pores of 7.00 nm are formed on the surface of the magnesium silicate.

[0073] From the above results, it can be said that the magnesium silicate for use as a secondary battery additive according to the present invention can contribute to suppressing electrolyte decomposition and improving the capacity retention rate of secondary batteries by adsorbing impurities that may be generated during the use of secondary batteries.

[0074] Experimental Example 2. Analysis of the effect of secondary battery electrolyte containing magnesium silicate as an additive - Application to the positive electrode 2.1. Galvanostatic charge-discharge cycles with additives In order to confirm whether the application of the magnesium silicate according to the present invention as an additive affects the efficiency of the secondary battery, positive electrode half-cells (NCM62) of lithium secondary batteries containing the secondary battery electrolytes containing magnesium silicate as an additive prepared in Examples 2 and 3 and the comparative secondary battery electrolytes prepared in Comparative Examples 1 and 2 were used. 2) Galvanostatic charge-discharge cycles were measured for the above materials, and the results are shown in Table 3 below and FIG.

[0075] [Table 3]

[0076] Referring to Table 3 and FIG. 5, it can be seen that the lithium secondary batteries including the secondary battery electrolytes (Examples 2 and 3) containing magnesium silicate as an additive according to the present invention do not affect the charge / discharge capacity and initial charge / discharge efficiency (ICE) despite the use of magnesium silicate as the electrolyte.

[0077] From the above results, it can be confirmed that the magnesium silicate for use as an additive in secondary batteries according to the present invention can be used as an additive in secondary batteries.

[0078] 2.2. Confirmation of Additives by Electrochemical Impedance Spectroscopy (EIS) In order to confirm whether the application of the magnesium silicate according to the present invention as an additive has an effect on the secondary battery, the positive electrode half-cell (NCM62) of the lithium secondary battery containing the electrolyte for the secondary battery containing the magnesium silicate as an additive prepared in Examples 2 and 3 was used. 2) Electrochemical Impedance Spectroscopy (EIS) was performed on the cathode half-cells of the lithium secondary batteries containing the secondary battery electrolytes prepared in Comparative Examples 1 and 2, and in order to compare the results, EIS was also performed on the cathode half-cells of the lithium secondary batteries containing the secondary battery electrolytes prepared in Comparative Examples 1 and 2. The results are shown in Table 4 and FIG. 6 below.

[0079] [Table 4]

[0080] Table 4 and Referring to FIG. 6, when magnesium silicate is added as an additive, the bulk resistance is reliably small, and R SEI On the other hand, when 3 wt% of magnesium silicate is added as an additive, R SEI It can be seen that the resistance becomes very high, causing a high interface resistance.

[0081] From the above results, when the magnesium silicate for use as a secondary battery additive according to the present invention is contained at a specific capacity, R SEI It was confirmed that the resistance was reduced and a solid electrolyte interphase (SEI) that facilitates lithium ion transport was formed.

[0082] 2.3.Charge-discharge cycle confirmation with additives In order to confirm whether the application of the magnesium silicate according to the present invention as an additive has an effect on the secondary battery, the positive electrode half-cell (NCM62) of the lithium secondary battery containing the electrolyte for the secondary battery containing the magnesium silicate as an additive prepared in Examples 2 and 3 was used. 2)It was confirmed that the discharge capacity retention characteristics of the positive electrode half-cells of the lithium secondary batteries containing the secondary battery electrolytes prepared in Comparative Examples 1 and 2 change with the progress of charge-discharge cycles. To compare this, it was confirmed that the discharge capacity retention characteristics of the positive electrode half-cells of the lithium secondary batteries containing the secondary battery electrolytes prepared in Comparative Examples 1 and 2 change with the progress of charge-discharge cycles. The results are shown in FIG. 7.

[0083] 7, it can be seen that the positive electrode half-cells of the lithium secondary batteries containing the secondary battery electrolyte containing magnesium silicate as an additive, manufactured in Example 2 (red line) and Example 3 (blue line), exhibit higher capacity retention rates than Comparative Example 1 (black line), which does not contain magnesium silicate as an additive. In particular, it can be seen that the cycle characteristics of Comparative Example 2 (pink line), which contains an excess amount of 3 wt% magnesium silicate additive, are significantly reduced.

[0084] From the above results, it can be confirmed that the magnesium silicate additive according to the present invention should be added only in the optimum weight ratio.

[0085] Experimental Example 3. Analysis of the effect of secondary battery electrolyte containing magnesium silicate as an additive - Application to negative electrode 3.1. Galvanostatic charge-discharge cycles with additives

[0086] In order to confirm whether the application of the magnesium silicate according to the present invention as an additive affects the efficiency of the secondary battery, negative electrode half cells of lithium secondary batteries containing the secondary battery electrolytes containing magnesium silicate as an additive prepared in Examples 2 and 3 and the comparative secondary battery electrolytes prepared in Comparative Examples 1 and 2 were used. To Galvanostatic charge-discharge cycles were measured on the battery, and the results are shown in Table 5 below and FIG.

[0087] [Table 5]

[0088] 8, it can be seen that the lithium secondary batteries including the secondary battery electrolytes (Examples 2 and 3) containing magnesium silicate as an additive according to the present invention did not affect the charge / discharge capacity and initial charge / discharge efficiency (ICE) despite the use of magnesium silicate as the electrolyte. However, in the case of Comparative Example 2 (green dot line) containing an excess amount of 3 wt% magnesium silicate additive, the cell rapidly deteriorated and could not be measured.

[0089] From the above results, it can be seen that the magnesium silicate for use as a secondary battery additive according to the present invention can be used only when the additive for the secondary battery is applied in an optimum weight ratio.

[0090] 3.2. Confirmation of Additives by Electrochemical Impedance Spectroscopy (EIS) In order to confirm whether the application of the magnesium silicate according to the present invention as an additive has an effect on the secondary battery, the negative electrode half cell of the lithium secondary battery containing the electrolyte for the secondary battery containing the magnesium silicate as an additive prepared in Examples 2 and 3 was used. To Electrochemical Impedance Spectroscopy (EIS) was performed on the negative electrode half-cells of the lithium secondary batteries containing the comparative secondary battery electrolytes prepared in Comparative Examples 1 and 2 for comparison, and the electrochemical impedance spectroscopy was also performed on the negative electrode half-cells of the lithium secondary batteries containing the comparative secondary battery electrolytes prepared in Comparative Examples 1 and 2. The results are shown in Table 6 and FIG. 9 below.

[0091] [Table 6]

[0092] Referring to Table 6 and FIG. 9, when magnesium silicate is added as an additive, the bulk resistance is reliably small, and R SEI On the other hand, when 3 wt% of magnesium silicate is added as an additive, R SEI It can be seen that the resistance becomes very high.

[0093] From the above results, when the magnesium silicate for a secondary battery additive according to the present invention is contained in a specific weight ratio, R SEI It was confirmed that a solid electrolyte interphase (SEI) was formed, which reduced resistance and facilitated lithium ion transport.

[0094] 3.3. Confirmation of charge-discharge cycle with additives In order to confirm whether the application of the magnesium silicate according to the present invention as an additive has an effect on the secondary battery, the negative electrode half cell of the lithium secondary battery containing the electrolyte for the secondary battery containing the magnesium silicate as an additive prepared in Example 2 was used. To In contrast, to confirm and compare the change in discharge capacity retention characteristics as the charge-discharge cycle progresses, the lithium secondary battery containing the secondary battery electrolyte prepared in Comparative Example 1 was negative For the polar half-cell, we confirmed that the discharge capacity retention characteristics change as the charge-discharge cycle progresses, and the results are shown in Figure 10.

[0095] Referring to FIG. 10, the lithium secondary battery including the secondary battery electrolyte containing magnesium silicate as an additive, which was manufactured in Example 2 (red line), negative It can be seen that the polar half-cell exhibits a higher capacity retention rate than Comparative Example 1 (black line) which does not contain magnesium silicate as an additive.

[0096] From the above description, it will be understood by those skilled in the art that the present invention can be embodied in other specific forms without changing the technical spirit or essential features of the present invention. In this regard, the above-described embodiments are illustrative in all respects and are not limiting.

Claims

1. Contains magnesium silicate, the magnesium silicate has a particle size of 50 nm to 800 nm; The magnesium silicate has a mass ratio of 50 to 70 wt % of oxygen (O), 5 to 20 wt % of magnesium (Mg), and 15 to 35 wt % of silicon (Si); The magnesium silicate has a specific surface area of 50 to 500 m 2 / g, The magnesium silicate has a pore size of 0.1 to 20 nm.

1. An additive for a secondary battery electrolyte comprising:

2. (A1) preparing a silicate precursor; (A2) mixing a magnesium precursor and an ammonium salt to prepare a mixture; (A3) adding the silicate precursor to the mixture to prepare a secondary battery electrolyte additive containing magnesium silicate; the magnesium silicate has a particle size of 50 nm to 800 nm; The magnesium silicate has a mass ratio of 50 to 70 wt % of oxygen (O), 5 to 20 wt % of magnesium (Mg), and 15 to 35 wt % of silicon (Si); The magnesium silicate has a specific surface area of 50 to 500 m 2 / g, The magnesium silicate has a pore size of 0.1 to 20 nm. A method for producing an additive for a secondary battery electrolyte containing magnesium silicate, comprising:

3. The step (A1) is (A1a) Alcohol, water and aqueous ammonia (NH ３ H ２ O, ammonia-water) to prepare a mixed solution; (A1b) adding tetraethyl orthosilicate (TEOS) to the mixed solution to prepare a silicate precursor having nano-sized particles. The method for producing the additive for a secondary battery electrolyte according to claim 2 .

4. The step (A3) is (A3a) adding the silicate precursor to the mixture; (A3b) heating the mixture to which the silicate precursor has been added at 100 to 200°C; (A3c) filtering the mixture after the heating to prepare a secondary battery electrolyte additive containing magnesium silicate. The method for producing the additive for a secondary battery electrolyte according to claim 2 .

5. A secondary battery electrolyte comprising the additive for secondary battery electrolytes containing the magnesium silicate according to claim 1, The secondary battery electrolyte contains the additive for secondary battery electrolyte in an amount of 0.1 to 2.0 wt % based on the total weight % of the secondary battery electrolyte. A secondary battery electrolyte characterized by:

6. A secondary battery comprising the electrolyte of claim 5. A secondary battery characterized by:

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