Electrolyte for secondary battery and secondary battery containing same

Abstract

The present invention relates to a non-aqueous electrolyte for a secondary battery and a secondary battery including the same. By adding a compound of Chemical Formula 1 or Chemical Formula 2 to the non-aqueous electrolyte for a secondary battery according to the present invention, it is possible to improve thermal stability characteristics and high-temperature storage characteristics at room temperature and high temperature.

Description

[Technical Field]

[0001] The present invention relates to an electrolyte for a secondary battery and a secondary battery including the same, and more particularly to a non-aqueous electrolyte for a secondary battery that has the effect of improving the stability of the non-aqueous electrolyte by adding a compound of Chemical Formula 1 or Chemical Formula 2 to the non-aqueous electrolyte for a lithium ion secondary battery, and a secondary battery including the same. [Background technology]

[0002] Recently, portable electronic devices have become widespread, and as a result, these devices have become thinner, smaller, and lighter. Accordingly, efforts are being made to improve the high-rate charge / discharge characteristics of secondary batteries used as power sources for these devices, which are small and lightweight yet capable of long-term charge / discharge.

[0003] Secondary batteries are classified into lead-acid batteries, nickel-cadmium (Ni-Cd) batteries, nickel-metal hydride (Ni-MH) batteries, and lithium batteries, depending on the anode and cathode materials. The potential and energy density are determined by the inherent characteristics of the electrode materials. Among these, lithium secondary batteries are widely used as power sources for portable electronic devices such as laptops, camcorders, and mobile phones due to their high energy density, resulting from lithium's low redox potential and molecular weight. However, lithium secondary batteries face a major problem of reduced battery safety during continuous charging. One of the factors affecting battery stability is heat generation due to structural collapse of the positive electrode. The stability of secondary batteries, particularly nonaqueous electrolyte secondary batteries, based on their operating principles can be explained as follows: The positive electrode active material of nonaqueous electrolyte secondary batteries is composed of lithium-containing metal oxides capable of absorbing and releasing lithium and / or lithium ions. However, when overcharged, large amounts of lithium are released from these positive electrode active materials, resulting in a thermally unstable structure. In this overcharged state, if the battery temperature reaches a critical temperature due to an external physical impact, such as exposure to high temperatures, oxygen is released from the unstable positive electrode active material. The released oxygen undergoes an exothermic decomposition reaction with the electrolyte solvent. In particular, the oxygen released from the positive electrode further accelerates the combustion of the electrolyte, leading to thermal runaway and subsequent exothermic reactions, resulting in battery ignition and explosion. Furthermore, the positive electrode transition metal deposited on the negative electrode acts as a catalyst to promote the decomposition of the non-aqueous electrolyte, generating gas inside the battery. Furthermore, the SEI layer of the negative electrode impedes the movement of lithium ions as charging and discharging progresses, significantly reducing the performance and efficiency of the battery.

[0004] On the other hand, in batteries that use high-capacity Ni-rich cathodes, residual lithium (LiOH, Li2CO3) and residual moisture can promote side reactions of lithium salts in the non-aqueous electrolyte. By-products are generated through the side reactions of lithium salts in the non-aqueous electrolyte, which can cause discoloration of the electrolyte and impair battery performance.

[0005] To solve the above problems, Japanese Patent Publication No. 2013-157305 discloses an electrolyte solution containing a compound having two isocyanate groups, and Korean Patent Registration No. 10-0412522 proposes electrolyte solutions containing di-tert-butylsilylbis(trifluoromethanesulfonate), trimethylsilylmethanesulfonate, trimethylsilylbenzenesulfonesulfonate, trimethylsilyltrifluoromethanesulfonesulfonate, triethylsilyltrifluoromethanesulfonesulfonate, etc. However, there is still a need to research electrolyte solutions that have excellent thermal stability at room temperature and high temperature and high-temperature storage properties. Currently, there is a need to develop additives that can improve the thermal stability and high-temperature storage characteristics of secondary batteries.

[0006] Therefore, the inventors have made extensive efforts to solve the above problems and have found that adding a compound of Formula 1 or 2 to a non-aqueous electrolyte stabilizes the non-aqueous electrolyte, thereby suppressing the generation of by-products in the electrolyte, preventing discoloration due to decomposition of the electrolyte itself, improving the resistance characteristics within the battery, and improving high-temperature storage efficiency (capacity retention / recovery rate), which led to the completion of the present invention. Furthermore, the present invention has a differentiated structure and superior performance compared to conventional electrolyte stabilizing additives. Summary of the Invention

[0007] An object of the present invention is to provide a non-aqueous electrolyte for a secondary battery which has improved thermal stability at room temperature and high temperature and high-temperature storage characteristics. Another object of the present invention is to provide a secondary battery having excellent thermal stability at room temperature and high temperature and high temperature storage characteristics. To achieve the above object, there is provided a non-aqueous electrolyte solution for a secondary battery, comprising (A) a lithium salt, (B) a non-aqueous organic solvent, and (C) one or more additives selected from the group consisting of a compound represented by Chemical Formula 1 and a compound represented by Chemical Formula 2. [ka] In formula 1, R1's are each independently alkyl having 1 to 3 carbon atoms. [ka] In formula 2, R1 and R2 are each independently a hydrogen atom or alkyl having 1 to 9 carbon atoms.

[0008] The present invention also provides a secondary battery comprising: (a) a positive electrode including a positive electrode active material capable of absorbing and desorbing lithium; (b) a negative electrode including a negative electrode active material capable of absorbing and desorbing lithium; (c) the above secondary battery electrolyte; and (d) a separator. BEST MODE FOR CARRYING OUT THE INVENTION

[0009] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Generally, the nomenclature used herein is that which is well known and commonly used in the art.

[0010] In the present invention, it has been confirmed that by adding an additive of the compound of Chemical Formula 1 or Chemical Formula 2, which is a compound represented by Chemical Formula 1, to the non-aqueous electrolyte of a secondary battery, the non-aqueous electrolyte can be stabilized, thereby suppressing the generation of by-products in the electrolyte, preventing discoloration due to decomposition of the electrolyte itself, and improving the resistance characteristics inside the battery and the high-temperature storage efficiency (capacity retention / recovery rate).

[0011] Therefore, in one aspect, the present invention relates to a non-aqueous electrolyte solution for a secondary battery, comprising (A) a lithium salt, (B) a non-aqueous organic solvent, and (C) one or more additives selected from the group consisting of a compound represented by Chemical Formula 1 and a compound represented by Chemical Formula 2. [ka] In formula 1, R1's are each independently alkyl having 1 to 3 carbon atoms. [ka] In formula 2, R1 and R2 are each independently a hydrogen atom or alkyl having 1 to 9 carbon atoms.

[0012] From another viewpoint, the present invention relates to a secondary battery including: (a) a positive electrode including a positive electrode active material capable of absorbing and desorbing lithium; (b) a negative electrode including a negative electrode active material capable of absorbing and desorbing lithium; (c) the above-mentioned electrolyte for the secondary battery; and (d) a separator. The present invention will be described in detail below.

[0013] The non-aqueous electrolyte for a secondary battery according to the present invention may include (A) a lithium salt, (B) a non-aqueous organic solvent, and (C) one or more additives selected from the group consisting of a compound represented by Chemical Formula 1 and a compound represented by Chemical Formula 2. [ka] In the above Chemical Formula 1, R1's are each independently alkyl having 1 to 3 carbon atoms. [ka] In the above Chemical Formula 2, R1 and R2 are each independently a hydrogen atom or alkyl having 1 to 9 carbon atoms.

[0014] In the present invention, the compound represented by Chemical Formula 1 is preferably 2-imidazolidinethione, which is a compound represented by Chemical Formula 1-1. [ka] In the present invention, the compound represented by Chemical Formula 2 is preferably thiourea, which is a compound represented by Chemical Formula 2-1. [ka]

[0015] In the present invention, the battery may further include one or more life performance improving additives or anode film forming additives selected from the group consisting of vinyl carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, and tetrahydrofuro[3,2-b]furan-2,5-dione (also called muconic lactone).

[0016] In the present invention, 1,3-propane sultone, 1,3-propene-1,3-sultone, ethyl sulfate, 1,4-butane sultone, 1,3-propanediol cyclic sulfate, The composition may further comprise one or more high temperature performance enhancing additives selected from the group consisting of 4,4'-bi-1,3,2-dioxathiolane-2,2,2',2'-tetraoxide, 1,3-divinyltetramethyldisiloxane, and 2,4,8,10-Tetraoxa-3,9-dithiaspiro[5.5]undecane (or 3,3,9,9-tetraoxide).

[0017] In the present invention, the lubricant may further contain one or more power performance improving additives selected from the group consisting of bis(triethylsilyl)sulfate, bis(trimethylsilyl)sulfate, trimethylsilyl ethylenesulfonate, triethylsilyl ethylenesulfonate, and aromatic phosphate compounds such as tetraphenyl(propane-2,2-diylbis(4,1-phenylene)) bis(phosphate).

[0018] In the present invention, lithium difluorophosphate, lithium bis(oxalato)borate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, cesium hexafluorophosphate, cesium bis(fluorosulfonyl)imide, cesium bis(trifluoromethanesulfonyl)imide, lithium difluoro(oxalato)borate, lithium tetrafluorooxalate phosphate, lithium difluoro bis(oxalato)phosphate, The lubricating oil may further comprise one or more high temperature and power performance enhancing additives selected from the group consisting of lithium bis(phosphorodifluoridate) triethylammonium ethylenesulfonate and lithium bis(phosphorodifluoridate) triethylammonium ethylenesulfonate.

[0019] In the present invention, the lithium salt used as the solute of the electrolyte is at least one selected from the group consisting of LiPF, LiBF, LiSbF, LiAsF, LiClO, LiN(C2F5SO2)2, LiN(CF3SO2)2, CF3SO3Li, and LiC(CF3SO2)3. The lithium salt concentration is preferably between 0.1 M and 2.0 M, more preferably between 0.7 M and 1.6 M. If the concentration is less than 0.1 M, the conductivity of the electrolyte solution decreases, resulting in a decrease in performance. If the concentration is more than 2.0 M, the viscosity of the electrolyte solution increases, resulting in a decrease in lithium ion mobility. These lithium salts act as a source of lithium ions within the battery, enabling basic lithium secondary battery operation.

[0020] In the present invention, the non-aqueous organic solvent is at least one selected from the group consisting of linear carbonates, cyclic carbonates, linear esters, and cyclic esters, the linear carbonates being at least one carbonate selected from the group consisting of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, ethyl methyl carbonate, and mixtures thereof, and the cyclic carbonates being at least one carbonate selected from the group consisting of ethylene carbonate (ethyl carbonate, EC), propylene carbonate (propylene carbonate, PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, vinylene carbonate, The non-aqueous organic solvent may be one or more carbonates selected from the group consisting of methyl methylpropionate, ethyl propionate, propyl acetate, butyl acetate, and ethyl acetate, and the cyclic ester may be one or more esters selected from the group consisting of gamma butyrolactone, caprolactone, and valerolactone. In the electrolyte according to one embodiment of the present invention, when the non-aqueous organic solvent is a mixed solvent of a linear carbonate solvent and a cyclic carbonate solvent, the volume ratio of the linear carbonate solvent to the cyclic carbonate solvent is 1:9 to 9:1, and preferably 1.5:1 to 4:1.

[0021] In the present invention, the content of one or more additives selected from the group consisting of the compounds represented by Chemical Formula 1 or the compounds represented by Chemical Formula 2 can be added to the secondary battery electrolyte solution in an amount of 10 to 100,000 ppm, preferably 20 to 80,000 ppm, and more preferably 50 to 50,000 ppm. If the content is less than 10 ppm, there is a problem of reduced high-temperature battery characteristics, and if it exceeds 100,000 ppm, there is a problem of reduced ionic conductivity.

[0022] The electrolyte solution of the lithium ion secondary battery of the present invention generally maintains stable characteristics in a temperature range of −20 to 50° C. The electrolyte solution of the present invention can be applied to lithium ion secondary batteries, lithium ion polymer batteries, and the like.

[0023] In the present invention, the positive electrode material of the lithium secondary battery is LiCoO2, LiNiO2, LiMnO2, LiMn2O4, or LiNi 1-x-y Co x M y Lithium metal oxides such as O2 (0≦x≦1, 0≦y≦1, 0≦x+y≦1, M is a metal such as Al, Sr, Mg, or La) are used, and crystalline or amorphous carbon, carbon composites, lithium metal, or lithium alloys are used as the anode material. The active material is applied to a thin current collector with an appropriate thickness and length, or the active material itself is applied in film form and then wound or laminated with an insulating separator to form an electrode group. This is then placed in a can or similar container and a non-aqueous electrolyte containing trialkylsilyl sulfate and a phosphate-based stabilizer is poured into it to manufacture a lithium-ion secondary battery. Resins such as polyethylene and polypropylene can be used as the separator.

[0024] The present invention will be described in more detail below with reference to examples. It will be obvious to those skilled in the art that these examples are merely for the purpose of illustrating the present invention and that the scope of the present invention is not limited by these examples. [Example]

[0025] Example 1 LiNi as the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2 was mixed with polyvinylidene fluoride (PVdF) as a binder and carbon black as a conductive material in a weight ratio of 95.6:2.2:2.2, and then dispersed in N-methyl-2-pyrrolidone to prepare a cathode slurry. This slurry was then coated onto a 20 μm thick aluminum foil, dried, and rolled to prepare a cathode.

[0026] Anode active material slurry was prepared by mixing natural graphite as the anode active material, acetylene black as the conductive material, and polyvinylidene fluoride (PVdF) as the binder in a weight ratio of 85:8:7 and dispersing the mixture in N-methyl-2-pyrrolidone. This slurry was then coated onto a 15 μm thick copper foil, dried, and rolled to prepare an anode.

[0027] A 20 μm thick polyethylene (PE) film separator was stacked between the prepared electrodes, and then wound and compressed to form a pouch measuring 6 mm thick x 35 mm wide x 60 mm long. A non-aqueous electrolyte solution (described below) was injected to prepare a lithium secondary battery (NCM811 / AG (890 mAh)).

[0028] The electrolyte solution was prepared by dissolving LiPF6 in a mixed solvent of ethylene carbonate (EC):ethyl methyl carbonate (EMC) (1:1 (v / v)) to a concentration of 1.0 M, and then adding 0.02 wt% of 2-imidazolidinethione. Examples 2 to 28

[0029] The same procedure as in Example 1 was carried out, except that the electrolyte solution and the content of 2-imidazolidinethione or thiourea added were as shown in Tables 1 to 5 below.

[0030] [Table 1]

[0031] [Table 2]

[0032] [Table 3]

[0033] [Table 4]

[0034] [Table 5] Comparative Examples 1 to 7 As shown in Table 6, lithium secondary batteries were produced in the same manner except that 2-imidazolidinethione was not added to each secondary battery electrolyte solution.

[0035] [Table 6] Examples 29 to 73

[0036] In Example 2, the same procedure as in Example 2 was carried out, except that a life performance improving additive, a high temperature performance improving additive, a power improving additive, or a high temperature performance and power improving additive was further added in the amounts shown in Tables 7 to 9 below.

[0037] [Table 7]

[0038] [Table 8]

[0039] [Table 9]

[0040] [Table 10]

[0041] [Table 11]

[0042] [Table 12]

[0043] [Table 13]

[0044] [Table 14] Comparative Examples 8 to 29

[0045] Comparative Example 1 was carried out in the same manner as Comparative Example 1, except that a life performance improving additive, a high temperature performance improving additive, a power improving additive, or a high temperature performance and power improving additive was further added in the amounts shown in Tables 15 to 18 below.

[0046] [Table 15]

[0047] [Table 16]

[0048] [Table 17]

[0049] [Table 18] Note) Chemical formula A-1: ​​vinyl carbonate Chemical formula A-2: vinyl ethylene carbonate Chemical formula A-3: Fluoroethylene carbonate

[0050] Chemical Formula A-4: Muconic lactone or tetrahydrofuro[3,2-b]furan-2,5-dione Chemical formula B-1: 1,3-propane sultone Chemical formula B-2: 1,3-propene-1,3-sultone Chemical Formula B-3: Ethylene sulfate Chemical formula B-4:1,4-butane sultone(1,4-butane sultone) Chemical Formula B-5: 1,3-propanediol cyclic sulfate

[0051] Chemical Formula B-6: 4,4'-bi-1,3,2-dioxathiolane-2,2,2',2'-tetraoxide

[0052] Chemical Formula B-7: 2,4,8,10-Tetraoxa-3,9-dithiaspiro[5.5]undecane (or 3,3,9,9-tetraoxide) Chemical formula C-1: bis(triethylsilyl)sulfate Chemical formula C-2: bis(trimethylsilyl)sulfate Chemical formula C-3: Trimethylsilyl ethenesulfonate Chemical formula C-4: Triethylsilyl ethenesulfonate

[0053] Chemical Formula C-5: Tetraphenyl (propane-2,2-diylbis(4,1-phenylene)) bis(phosphate) Chemical formula D-1: Lithium difluorophosphate Chemical formula D-2: lithium-bis(oxalato)borate Chemical Formula D-3: Lithium bis(fluorosulfonyl)imide Chemical Formula D-4: Lithium difluoro(oxalato)borate Chemical formula D-5: lithium tetrafluorooxalate phosphate Chemical Formula D-6: Lithium difluorobis(oxalato) phosphate Physical property evaluation 1: Room temperature thermal stability evaluation The thermal stability of the fabricated batteries was measured using a colorimeter (G&B Tech) at 25°C every week for one month. The APHA values ​​at the initial and one-month intervals were recorded. Physical property evaluation 2: High temperature thermal stability evaluation The thermal stability was measured at 60°C every day for one week using a colorimeter (GNB Tech). The APHA values ​​at the initial and one-week intervals were recorded. Physical property evaluation 3: High temperature storage evaluation

[0054] 1) Internal resistance (AC-IR): After charging the manufactured battery at 1C to 4.2V, the internal resistance (AC-IR) was measured using a resistance meter (HIOKI, Japan). After charging at 1C to 4.2V and storing at high temperature (70℃) for 7 days, the battery was charged at 1C to 4.2V and discharged at 1C twice, and then stored at high temperature (70℃) using a resistance meter (HIOKI, Japan) to measure the internal resistance (AC-IR).

[0055] 2) Retention and recovery capacity: After charging at 1C up to 4.2V, the battery was stored at high temperature (70℃) for 7 days, and then discharged at 1C, 2.75V to measure the retention capacity (discharge capacity). After charging again at 1C, 4.2V and discharging at 1C, 2.75V, the recovery capacity (discharge capacity) was measured and expressed as a percentage of the initial discharge capacity.

[0056] As shown in Tables 1 to 18, the electrolyte solutions of Examples 1 to 71 of the present invention have improved life evaluation and high-temperature storage evaluation compared to Comparative Examples 1 to 28 in room temperature and high-temperature thermal stability evaluation and high-temperature storage evaluation.

[0057] Through the examples of the present invention, it has been confirmed that the additive of the present invention has a stabilizing effect on the non-aqueous electrolyte, and through the stabilization of the non-aqueous electrolyte, it suppresses the generation of by-products in the electrolyte, (1) prevents discoloration due to decomposition of the electrolyte itself, and (2) improves the resistance characteristics inside the battery and the high-temperature storage efficiency (capacity retention / recovery rate).

[0058] As shown in Tables 1 to 4, the non-aqueous electrolytes containing 2-imidazolidinethione according to Examples 1 to 21 of the present invention showed less or almost no color change at room temperature and high temperature compared to the non-aqueous electrolytes containing no 2-imidazolidinethione according to Comparative Examples 1 to 7 of Table 6. It was also confirmed that the color change rate significantly decreased as the content of 2-imidazolidinethione increased.

[0059] Furthermore, as shown in Table 5, the non-aqueous electrolytes containing thiourea according to Examples 22 to 28 of the present invention showed less or almost no color change at room temperature and high temperature compared to the non-aqueous electrolytes containing no thiourea according to Comparative Examples 1 to 7 of Table 6.

[0060] As shown in Table 7, the electrolyte of Example 2 of the present invention, to which 0.1 wt% of 2-imidazolidinethione was added, showed significantly lower color change rates at room temperature and high temperature than Comparative Example 1 in Table 15, and exhibited excellent performance in the evaluation of battery internal resistance and high-temperature storage efficiency. When a life performance improving additive, a high-temperature performance improving additive, a power improving additive, or a high-temperature performance and power improving additive was further added as in Examples 29 to 50, battery performance was further improved. The electrolytes of Examples 29 to 50 showed significantly lower color change rates at room temperature and high temperature than Comparative Examples 8 to 29, to which 2-imidazolidinethione was not added, and showed an improvement in battery internal resistance of about 5 to 45%, and an improvement in capacity retention and recovery rate after high-temperature storage of about 3 to 15%.

[0061] Similarly, as shown in Table 11, the electrolyte of Example 51 of the present invention, to which 0.1 wt % thiourea was added, exhibited significantly lower color change rates at room temperature and high temperature than Comparative Example 1 in Table 15, and exhibited excellent performance in the evaluation of battery internal resistance and high-temperature storage efficiency. When a life performance improving additive, a high-temperature performance improving additive, a power improving additive, or a high-temperature performance and power improving additive was additionally added as in Examples 52 to 73, battery performance was further improved. The electrolytes of Examples 52 to 73 exhibited significantly lower color change rates at room temperature and high temperature than Comparative Examples 8 to 29 to which thiourea was not added, and the battery internal resistance was improved by about 2 to 45%, and the capacity retention rate and recovery rate after high-temperature storage were improved by about 3 to 15%. [Industrial Applicability]

[0062] The non-aqueous electrolyte according to the present invention stabilizes the non-aqueous electrolyte by adding the compound of Chemical Formula 1 or Chemical Formula 2, thereby suppressing the generation of by-products in the electrolyte, preventing discoloration due to decomposition of the electrolyte itself, improving the resistance characteristics inside the battery, and enhancing the high-temperature storage efficiency (capacity retention / recovery rate).

[0063] Although certain parts of the present invention have been described in detail above, it will be apparent to those skilled in the art that these specific techniques are merely preferred embodiments and do not limit the scope of the present invention. Therefore, the true scope of the present invention can be defined by the claims and their equivalents.

Claims

1. (A) lithium salts, (B) a non-aqueous organic solvent; (C) one or more additives of compounds represented by the following chemical formula 1, and (D) one or more additives selected from the group consisting of life performance improving additives; high temperature performance improving additives; power performance improving additives; and high temperature and power performance improving additives. A non-aqueous electrolyte solution for a secondary battery comprising: the life performance enhancing additive is selected from the group consisting of vinyl carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, and tetrahydrofuro[3,2-b]furan-2,5-dione; The high temperature performance enhancing additive is selected from the group consisting of 1,3-propane sultone, 1,3-propene-1,3-sultone, ethylene sulfate, 1,4-butane sultone, 1,3-propanediol cyclic sulfate, sulfate, 4,4'-bi-1,3,2-dioxathiolane-2,2,2',2'-tetraoxide, 1,3-divinyltetramethyldisiloxane, and 2,4,8,10-tetraoxa-3,9-dithiaspiro[5.5]undecane; the power performance enhancing additive is selected from the group consisting of bis(triethylsilyl) sulfate, bis(trimethylsilyl) sulfate, trimethylsilyl ethenesulfonate, triethylsilyl ethylenesulfonate, and tetraphenyl(propane-2,2-diylbis(4,1-phenylene)) bis(phosphate); The high temperature and power performance improving additive is selected from the group consisting of lithium difluorophosphate, lithium bis(oxalato)borate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, cesium hexafluorophosphate, cesium bis(fluorosulfonyl)imide, cesium bis(trifluoromethanesulfonyl)imide, lithium difluoro(oxalato)borate, lithium tetrafluorooxalate phosphate, and lithium difluorobis(oxalato)phosphate. The non-aqueous electrolyte for the secondary battery is selected from the group consisting of lithium bis(phosphorodifluoridate) triethylammonium ethylenesulfonate and lithium bis(phosphorodifluoridate) triethylammonium ethylenesulfonate. 【Chemistry 1】 In Chemical Formula 1, R 1 are each independently alkyl having 1 to 3 carbon atoms.

2. 2. The nonaqueous electrolyte for a secondary battery according to claim 1, wherein the compound represented by Chemical Formula 1 is a compound represented by Chemical Formula 1-1. 【Chemistry 1-1】

3. The lithium salt is LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiClO 4 , LiN(C 2 F 5 SO 2 ) 2 , LiN(CF 3 SO 2 ) 2 , CF 3 SO 3 Li and LiC(CF 3 SO 2 ) 3 2. The electrolyte solution for a secondary battery according to claim 1, wherein the electrolyte solution is one or more selected from the group consisting of:

4. 4. The electrolyte for a secondary battery according to claim 3, wherein the lithium salt is contained in the non-aqueous organic solvent at a concentration of 0.1 to 2.0M.

5. 2. The electrolyte solution for a secondary battery according to claim 1, wherein the non-aqueous organic solvent is at least one selected from the group consisting of linear carbonates, cyclic carbonates, linear esters, and cyclic esters.

6. the linear carbonate is one or more carbonates selected from the group consisting of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, ethyl methyl carbonate, and mixtures thereof; the cyclic carbonate is one or more carbonates selected from the group consisting of ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, vinylene carbonate, vinylethylene carbonate, and fluoroethylene carbonate; 6. The electrolyte solution for a secondary battery according to claim 5, wherein the linear ester is one or more esters selected from the group consisting of methyl propionate, ethyl propionate, propyl acetate, butyl acetate, and ethyl acetate, and the cyclic ester is one or more esters selected from the group consisting of gamma butyrolactone, caprolactone, and valerolactone.

7. 6. The electrolyte for a secondary battery according to claim 5, wherein the non-aqueous organic solvent is a mixture of linear carbonate and cyclic carbonate in a volume ratio of 1:9 to 9:

1.

8. 10. The electrolyte for a secondary battery according to claim 1, wherein the content of the compound represented by Formula 1 is 10 to 100,000 ppm based on the electrolyte for a secondary battery.

9. Secondary lithium batteries, including: (a) a positive electrode including a positive electrode active material capable of absorbing and releasing lithium; (b) a negative electrode including a negative electrode active material capable of absorbing and releasing lithium; (c) the electrolyte solution for a secondary battery according to any one of claims 1 to 8, and (d) Separation membrane.

Images