Electrolyte additive, battery electrolyte containing same, and secondary battery

Abstract

The present invention relates to an electrolyte additive, a battery electrolyte containing same, and a secondary battery. According to the present invention, the electrolyte additive, the battery electrolyte containing same, a secondary battery comprising same, and the like can be provided, the electrolyte additive suppressing side reactions inside various lithium secondary batteries including high-nickel, Si anode, LFP, lithium manganese-rich (LMR) or cobalt-free batteries, so as to lower the internal resistance of a battery, and being capable of providing a secondary battery that has a low charging resistance so as to have improved charging efficiency and output and that can suppress, even if stored for a long time under high-temperature conditions, an increase in battery resistance and the generation of gas, thereby having excellent long-term life and high-temperature capacity retention.

Description

Electrolyte additive, battery electrolyte containing the same, and secondary battery

[0001] The present invention relates to an electrolyte additive, an electrolyte for a battery containing the same, and a secondary battery. More specifically, the invention relates to an electrolyte additive capable of suppressing side reactions within various lithium secondary batteries, including high-nickel, Si anode, LFP, LMR (lithium manganese-rich), or cobalt-free batteries, thereby lowering the internal resistance of the battery and reducing the charging resistance to improve charging efficiency and output, and suppressing the increase in resistance and gas generation of the battery even when stored for a long time under high-temperature conditions, thereby providing a secondary battery with excellent long-term lifespan and high-temperature capacity retention rate, an electrolyte for a battery containing the same, and a secondary battery containing the same.

[0002] Lithium secondary batteries enable the smooth movement of lithium ions by placing an electrolyte between the positive and negative electrodes, and facilitate the utilization of electrical energy through a method in which electricity is generated or consumed by oxidation-reduction reactions resulting from insertion and extraction at the positive and negative electrodes.

[0003] Meanwhile, as environmental concerns grow due to the recent tightening of global regulations, interest in eco-friendly vehicles capable of replacing fossil fuel vehicles, which are one of the main causes of air pollution, is also increasing. Consequently, the domestic and international battery industries are actively developing automotive batteries.

[0004] To use batteries in automobiles, not only must their output and capacity be significantly increased, but issues regarding improved output at high and low temperatures and increased resistance must also be resolved to suit operating environments such as weather changes. Particularly in the case of electric vehicles, where output and driving range performance are critical, research is being conducted to lower internal resistance and increase remaining capacity. Therefore, there is a need to develop batteries that suppress internal side reactions and ensure low resistance and long lifespan performance, even when stored for extended periods under high-temperature conditions.

[0005] [Prior Art Literature]

[0006] [Patent Literature]

[0007] Korean Patent Publication No. 2024-0052530

[0008] In order to solve the problems of the prior art as described above, the present invention aims to provide a novel electrolyte for batteries and a secondary battery containing the same.

[0009] Furthermore, the present invention aims to provide a secondary battery that suppresses internal side reactions to lower the internal resistance of the battery and reduces charging resistance, thereby improving the output of the battery, enhances recovery capacity at high temperatures to enable long-term storage, and maintains an excellent lifespan at high temperatures.

[0010] The above and other objectives of the present invention can all be achieved by the present invention described below.

[0011] To achieve the above objective, the present invention provides an electrolyte additive characterized by comprising a compound having a halogen terminal group, which simultaneously includes carbon-carbon unsaturated bonds and a sulfonyl structural group.

[0012]

[0013] The above compound may be one or more selected from substances represented by the following chemical formulas 1 to 3.

[0014] [Chemical Formulas 1 to 3]

[0015]

[0016] (In the above chemical formulas 1 to 3, X is independently fluorine (F), chlorine (Cl), or bromine (Br).)

[0017]

[0018] The above compound may include one or more selected from substances represented by the following chemical formulas 1-1 to 1-9.

[0019] [Chemical Formulas 1-1 to 1-9]

[0020]

[0021] (In the chemical formulas described herein, lines represent bonds, and where no separate element is specified, the point where bonds meet is carbon, and the number of hydrogen atoms satisfying the valence of the carbon is omitted.)

[0022]

[0023] The above electrolyte additive may be included in an amount of 0.01 to 10 weight percent based on 100 weight percent of the total components constituting the battery electrolyte.

[0024] The above electrolyte additive may include one or more selected from cyclic sulfone compounds, phosphoric compounds, and carbonate compounds.

[0025] The above cyclic sulfone compound may be one or more selected from compounds represented by the following chemical formulas 2-1 to 2-6.

[0026] [Chemical Formulas 2-1 to 2-6]

[0027]

[0028] The above phosphorus compound may be one or more selected from the compounds represented by the following chemical formulas 3-1 to 3-3.

[0029] [Chemical Formulas 3-1 to 3-3]

[0030]

[0031] The above carbonate-based compound may be one or more selected from the compounds represented by the following chemical formulas 4-1 to 4-4.

[0032] [Chemical Formulas 4-1 to 4-4]

[0033]

[0034] One or more compounds selected from the above cyclic sulfone compounds, phosphoric compounds, and carbonate compounds may be included in a range of 0.1 to 10 weight percent of the total 100 weight percent of the electrolyte.

[0035] One or more compounds selected from the above chemical formulas 1 to 3; and one or more compounds selected from cyclic sulfone compounds, phosphoric compounds and carbonate compounds may be included in a weight ratio of 1:0.1 to 5.

[0036]

[0037] In addition, the present invention provides a battery electrolyte characterized by comprising the aforementioned electrolyte additive as an electrolyte for a secondary battery.

[0038] The above electrolyte additive may be included in an amount of 0.01 to 10 weight percent based on 100 weight percent of the total components constituting the battery electrolyte.

[0039]

[0040] The above-mentioned electrolyte for the battery may include a lithium salt.

[0041] The above lithium salts are LiPF6, LiF4, LiCl, LiBr, LiI, LiClO4, LiBF4, and LiB 10 Cl 10 , LiSbF6, LiAsF6, LiN(SO2C2F5)2, LiCF3SO3, LiCF3CO2, Li(CF3SO2)2N, LiN(SO3C2F5)2, Li(FSO2)2N, LiC4F9SO3, LiClO4, LiFePO4, LiAlO2, LiAlCl4, LiN(C x F 2x +1SO2)(C y F 2y+1SO2)(where x and y are natural numbers, for example, integers from 1 to 20), LiAsF6, LiSbF6, LiAlCl4, LiB(C2O4)2 (can include one or more selected from the group consisting of lithium bis(oxalato) borate (LiBOB), CH3SO3Li, CF3SO3Li, and (CF3SO2)2NLi.

[0042] The above-mentioned electrolyte for the battery may include an organic solvent.

[0043] The above organic solvent may include one or more selected from the group consisting of ethylene carbonate (EC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), dimethyl carbonate (DMC), propylene carbonate (PC), dipropyl carbonate (DPC), butylene carbonate, methylpropyl carbonate, and ethylpropyl carbonate.

[0044]

[0045] In addition, the present invention comprises an electrode assembly including an anode, a cathode, and a separator separating the anode and the cathode; a case for housing the electrode assembly; and an electrolyte that is housed in the case and immerses the electrode assembly.

[0046] The above electrolyte provides a secondary battery characterized by including the aforementioned electrolyte additive.

[0047]

[0048] In addition, the present invention comprises an electrode assembly including an anode, a cathode, and a separator separating the anode and the cathode; a case for housing the electrode assembly; and an electrolyte that is housed in the case and immerses the electrode assembly.

[0049] The above electrolyte provides a secondary battery characterized by including the above-described electrolyte for a battery.

[0050] The above secondary battery may be an NCM, NCA, LFP, LMFP, LMR, or cobalt-free lithium battery.

[0051] A secondary battery comprising an electrolyte according to the present invention has the effect of providing a secondary battery with excellent long-term lifespan and high-temperature capacity retention rate, which can improve charging efficiency and output by suppressing side reactions within the battery to lower the internal resistance and charging resistance, and can suppress the increase in resistance of the battery even when stored for a long time under high-temperature conditions.

[0052]

[0053] The present invention will be described in detail below, but the invention is not limited thereto.

[0054]

[0055] While researching a secondary battery capable of producing a battery usable as an automobile battery, in which internal side reactions are suppressed to lower internal resistance and thus output is improved, and the increase in resistance is suppressed even when stored for a long time under high-temperature conditions, thereby providing excellent high-temperature recovery capacity and lifespan characteristics, the inventors confirmed that using a compound of a specific structure in the electrolyte of the secondary battery can achieve all of the above objectives, and based on this, completed the present invention.

[0056]

[0057] The electrolyte additive according to the present invention is characterized by comprising a compound having a halogen as a terminal group, which simultaneously contains carbon-carbon unsaturated bonds and sulfonyl structural groups. In this case, internal side reactions of the battery are suppressed, thereby lowering the internal resistance of the battery and reducing the charging resistance of the secondary battery, which can improve charging efficiency and output. Additionally, even when stored for a long time under high-temperature conditions, the increase in resistance of the battery can be suppressed, resulting in excellent long-term lifespan and high-temperature capacity retention rates.

[0058] The above compound may be one or more selected from substances represented by the following chemical formulas 1 to 3, for example.

[0059] [Chemical Formulas 1 to 3]

[0060]

[0061] (In the above chemical formulas 1 to 3, X is independently fluorine (F), chlorine (Cl), or bromine (Br).)

[0062]

[0063] In the chemical formulas described herein, lines represent bonds, and where no separate element is specified, the points where bonds meet are carbons, and a number of hydrogens satisfying the valence of the carbons are omitted.

[0064]

[0065] The compounds represented by the above chemical formulas 1 to 3 may be provided, for example, by a bonding reaction between a compound containing an unsaturated bond structure between carbons and a compound containing a sulfonyl structure. The bonding reaction may be a condensation reaction, a elimination reaction, an oxidation reaction, a reduction reaction, or a dimerization reaction.

[0066] The compounds represented by the above chemical formulas 1 to 3 may, as another example, be provided by a bonding reaction between a compound containing both an unsaturated carbon-carbon bond structure and a sulfonyl structure, and a compound containing a sulfonyl structure. The bonding reaction may be a condensation reaction, a elimination reaction, an oxidation reaction, a reduction reaction, or a dimerization reaction.

[0067]

[0068] Specifically, the compounds of Chemical Formulas 1 to 3 may be one or more selected from the substances represented by Chemical Formulas 1-1 to 1-9 below.

[0069] [Chemical Formulas 1-1 to 1-9]

[0070]

[0071] In the compounds represented by the above chemical formulas 1 to 3, electrons are localized toward the halogen atom due to the electronegativity difference between the S element directly connected to the halogen atom, and furthermore, due to the overall asymmetric structure of the chemical formula, the S element becomes electron-poor (e- poor, δ+), thereby inducing an oxidation reaction in an electrolyte containing lithium ions, and as a specific example, a stable film is formed on the electrode.

[0072] Due to the stability of the aforementioned film, the decomposition of the electrolyte can be prevented, thereby improving cycle characteristics. In particular, since it does not decompose at high temperatures, it offers an excellent effect of significantly improving high-temperature storage performance compared to conventional electrode films, which decompose at high temperatures and consequently experience reduced high-temperature storage performance. Furthermore, the prevention of increased resistance improves charging efficiency and output, and the suppression of gas generation caused by chemical reactions within the battery enhances battery safety. Additionally, by preventing the structural collapse of the active materials of the positive and negative electrodes at high temperatures, the capacity retention rate is improved, which in turn extends the battery's lifespan.

[0073] The compounds represented by the above chemical formulas 1 to 3 may be included in an amount of 0.01 to 10 weight% based on 100 weight% of the total electrolyte for the battery described below, preferably 0.1 to 5 weight%, more preferably 0.1 to 2.0 weight%, even more preferably 0.1 to 1.0 weight%, and most preferably 0.1 to 0.5 weight%. Within the above range, the effect of improving the charging efficiency and high-temperature life of the battery may be the best.

[0074]

[0075] The above electrolyte additive may include one or more selected from cyclic sulfone compounds, phosphoric compounds, and carbonate compounds.

[0076] The above-mentioned cyclic sulfonate compound may be a compound containing one or more sulfonyl groups in a symmetric or asymmetric form.

[0077] The above cyclic sulfone compound may be one or more selected from compounds represented by the following chemical formulas 2-1 to 2-6.

[0078] [Chemical Formulas 2-1 to 2-6]

[0079]

[0080] The above cyclic sulfone compound may be one or more compounds selected from 2,4,8,10-tetraoxa-3,9-dithiaspiro[5.5]undecane, 3,3,9,9-tetraoxide), 1,5,2,4-dioxaditian 2,2,4,4-tetraoxide, 3-fluoro-1,3-propanesulfone, ethylene sulfate, 1-propene-1,3-sulfone, 1,3-propanesulfone, 1,3-propylene sulfate, 1,4-butanesulfone, and sulforene.

[0081] The above-mentioned cyclic sulfone compound may be included in an amount of 0.1 to 10 weight% based on 100 weight% of the total electrolyte, preferably 0.1 to 5 weight%, more preferably 0.1 to 4.0 weight%, even more preferably 0.1 to 3.0 weight%, and most preferably 0.1 to 2.5 weight%. When the content of the compound satisfies the above range, it is desirable in terms of the effect of improving the high-temperature characteristics and cycle characteristics of the battery.

[0082] The aforementioned compound must be additionally included in the compound represented by the aforementioned chemical formulas 1-1 to 1-9, and if used alone without the compound represented by the chemical formulas 1-1 to 1-9, the improvement effect on long-term lifespan and low resistance may be poor.

[0083] The electrolyte additive represented by the above chemical formulas 1-1 to 1-9; and the cyclic sulfone compound may be included in a weight ratio of 1:1 to 1:0.1 to 5.0. In this case, internal side reactions of the battery are suppressed, thereby lowering the internal resistance of the battery and lowering the charging resistance of the secondary battery, which can improve charging efficiency and output, and have excellent long-term lifespan and high-temperature capacity retention rate.

[0084]

[0085] The above phosphoric compounds may be one or more compounds selected from LDFP (LiPO2F2, (Lithium difluorophosphate)), diethyl(difluoromethyl)phosphonate, TMSP (Tris(trimethylsilyl) Phosphite), TFPi (Tris(trifluoro Phosphite)), tripropagyl phosphate, TPP (Triphenyl phosphine), tetrapropagyl pyrophosphate, lithium difluorobis(oxalato)phosphate (LDFBOP), and lithium tetrafluorooxalatophosphate (LTFOP). In this case, a stable film is formed on the positive and negative electrodes of various lithium secondary batteries, including high-nickel full-cell batteries, mid-nickel full-cell batteries, lithium iron phosphate batteries, or lithium manganese-rich batteries, thereby suppressing side reactions inside the battery and lowering charge / discharge resistance, which has the effect of improving charging efficiency and output.

[0086] The above phosphorus compound may be one or more selected from the compounds represented by the following chemical formulas 3-1 to 3-3.

[0087] [Chemical Formulas 3-1 to 3-3]

[0088]

[0089] The above phosphoric compound may be included in an amount of 0.1 to 10 weight% based on 100 weight% of the total electrolyte, preferably 0.1 to 5 weight%, more preferably 0.1 to 4.0 weight%, even more preferably 0.1 to 3.0 weight%, and most preferably 0.1 to 2.5 weight%. When the content of the compound satisfies the above range, it is desirable in terms of the effect of improving the high-temperature characteristics and cycle characteristics of the battery.

[0090] The aforementioned compound must be additionally included in the compound represented by the aforementioned chemical formulas 1-1 to 1-9, and if used alone without the compound represented by the chemical formulas 1-1 to 1-9, the improvement effect on long-term lifespan and low resistance may be poor.

[0091] The electrolyte additive represented by the above chemical formulas 1-1 to 1-9; and the phosphoric compound may be included in a weight ratio of 1:1 to 1:0.1 to 5.0. In this case, internal side reactions of the battery are suppressed, thereby lowering the internal resistance of the battery and lowering the charging resistance of the secondary battery, which can improve charging efficiency and output, and have excellent long-term lifespan and high-temperature capacity retention rate.

[0092]

[0093] The above carbonate-based compound may be one or more compounds selected from vinylene carbonate, vinylene ethylene carbonate, fluoroethylene carbonate, ethyl propionate, and propyl propionate. In this case, a stable film is formed on the positive and negative electrodes of various lithium secondary batteries, including high-nickel full-cell batteries, mid-nickel full-cell batteries, lithium iron phosphate batteries, or lithium manganese-rich batteries, thereby suppressing side reactions inside the battery and lowering charge / discharge resistance, which has the effect of improving charging efficiency and output.

[0094] The above carbonate-based compound may be one or more compounds selected from the compounds represented by the following chemical formulas 4-1 to 4-4.

[0095] [Chemical Formulas 4-1 to 4-4]

[0096]

[0097] The above carbonate-based compound may be included in an amount of 0.1 to 10 weight% based on 100 weight% of the total electrolyte, preferably 0.1 to 5 weight%, more preferably 0.1 to 4.0 weight%, even more preferably 0.1 to 3.0 weight%, and most preferably 0.1 to 2.5 weight%. When the content of the compound satisfies the above range, it is desirable in terms of the effect of improving the high-temperature characteristics and cycle characteristics of the battery.

[0098] The aforementioned compound must be additionally included in the compound represented by the aforementioned chemical formulas 1-1 to 1-9, and if used alone without the compound represented by the chemical formulas 1-1 to 1-9, the improvement effect on long-term lifespan and low resistance may be poor.

[0099] The electrolyte additives represented by the above chemical formulas 1-1 to 1-9; and the carbonate-based compounds may be included in a weight ratio of 1:1 to 1:0.1 to 5.0. In this case, internal side reactions of the battery are suppressed, thereby lowering the internal resistance of the battery and lowering the charging resistance of the secondary battery, which can improve charging efficiency and output, and have excellent long-term lifespan and high-temperature capacity retention rate.

[0100]

[0101] One or more compounds selected from the above cyclic sulfone compounds, phosphoric compounds, and carbonate compounds may be included in a range of 0.1 to 10 weight percent of the total 100 weight percent of the electrolyte.

[0102] One or more compounds selected from the above chemical formulas 1 to 3; and one or more compounds selected from cyclic sulfone compounds, phosphoric compounds and carbonate compounds may be included in a weight ratio of 1:0.1 to 5.

[0103]

[0104] In addition to the compound described above, the electrolyte of the present invention may further include compound(s) that can generally be used in an electrolyte for purposes such as suppressing internal side reactions of the battery, improving the lifespan characteristics of the battery, suppressing the reduction of battery capacity, and improving the discharge capacity of the battery.

[0105] Preferred embodiments include ethyl propionate (EP), propyl propionate (PP), succinic anhydride, tetravinyl silane, 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether, 1,2-bis((difluorophosphanyl)oxy)ethane, 1,3,6-hexanetricarbonitrile, succinonitrile, 1-ethyl-3-methylimidazolium dicyanamide, lithium tetrafluoro(oxalato)phosphate, lithium difluoro(bisoxalato)phosphate, lithium difluorophosphate, diethyl (difluoromethyl)phosphonate, tris(trimethylsilyl)phosphite, tripropagyl phosphate, 2,4,8,10-tetraoxa-3,9-dithiaspiro[5.5]undecane 3,3,9,9-tetraoxide, dimethyl sulfate, and ethylene. It may be one or more selected from the group consisting of dimethanesulfonate, methylene methyl disulfonate, lithium bis(fluorosulfonyl)imide, lithium fluorosulfate, lithium bis(trifluoromethanesulfonyl)imide, 3-fluoro-1,3-propanesulfone, 1,4-butanesulfone, sulfonene, biphenyl, cyclohexylbenzene, 4-fluorotoluene, triphenyl phosphate, fluorobenzene, and 2-fluoro-biphenyl.

[0106] Among the aforementioned types, one or more metal phosphate compounds selected from the group consisting of lithium difluoro(bisoxalato) phosphate (LiDFOP), lithium tetrafluorooxalato phosphate (LiTFOP), lithium difluorophosphate, and lithium trioxalato phosphate are components added to improve the performance of lithium secondary batteries, lithium-ion capacitors, etc., suppress internal side reactions of the battery, and improve resistance and lifespan, and may be included in the electrolyte in, for example, 0.3 to 2.5 weight%, preferably 0.5 to 1.5 weight%. When the aforementioned electrolyte content satisfies the above range, it is desirable in terms of the effect of improving the high-temperature characteristics and cycle characteristics of the battery.

[0107] The above compounds may be included in the aforementioned electrolyte for batteries in an amount equal to the total content of all components used, for example, 0.1 to 10.0 wt%, 0.1 to 8.0 wt%, 0.1 to 7 wt%, 0.1 to 6 wt%, 0.1 to 5 wt%, or 0.5 to 5 wt%. It is more preferable when the usage amount satisfies the above ranges in terms of the effect of improving the high-temperature characteristics and cycle characteristics of the battery.

[0108]

[0109] The above-mentioned electrolyte for the battery may include a lithium salt.

[0110] The above lithium salts are LiPF6, LiF4, LiCl, LiBr, LiI, LiClO4, LiBF4, and LiB 10 Cl 10 , LiSbF6, LiAsF6, LiN(SO2C2F5)2, LiCF3SO3, LiCF3CO2, Li(CF3SO2)2N, LiN(SO3C2F5)2, Li(FSO2)2N, LiC4F9SO3, LiClO4, LiFePO4, LiAlO2, LiAlCl4, LiN(C x F 2x +1SO2)(C y F 2y+1SO2)(where x and y are natural numbers, for example, integers from 1 to 20), LiAsF6, LiSbF6, LiAlCl4, LiB(C2O4)2 (can include one or more selected from the group consisting of lithium bis(oxalato) borate (LiBOB), CH3SO3Li, CF3SO3Li, and (CF3SO2)2NLi.

[0111] When the lithium salt is dissolved in the electrolyte, the lithium salt functions as a source of lithium ions within the lithium secondary battery and can promote the movement of lithium ions between the positive and negative electrodes. Accordingly, it is preferable that the lithium salt be included in the electrolyte at a concentration of approximately 0.6 mol% to 2 mol%. If the concentration of the lithium salt is less than 0.6 mol%, the conductivity of the electrolyte may decrease, leading to reduced electrolyte performance, and if it exceeds 2 mol%, the viscosity of the electrolyte may increase, resulting in reduced lithium ion mobility. Considering the conductivity of the electrolyte and the mobility of lithium ions, the lithium salt may be included in the electrolyte preferably at 0.7 mol% to 1.6 mol%, and more preferably at 0.8 mol% to 1.5 mol%.

[0112]

[0113] The above-mentioned electrolyte for the battery may include an organic solvent.

[0114] The above organic solvent may include one or more selected from the group consisting of ethylene carbonate (EC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), dimethyl carbonate (DMC), propylene carbonate (PC), dipropyl carbonate (DPC), butylene carbonate, methylpropyl carbonate, and ethylpropyl carbonate.

[0115] The above organic solvent may be, for example, one or two or more mixed solvents, and preferably, a high dielectric constant organic solvent having high ionic conductivity to improve the charge / discharge performance of the battery and a low viscosity organic solvent that can be adjusted to have a viscosity suitable for application to the battery may be mixed and used as a mixed solvent.

[0116] Examples of the above high dielectric constant organic solvents include EC and PC, and examples of the above low viscosity organic solvents include EMC, DMC, and DEC. It is preferable to use the above high dielectric constant and low viscosity organic solvents mixed in a volume ratio of 2:8 to 8:2. More specifically, it may be a ternary mixed solvent of EC, EMC, and DEC, and the ratio of EC, EMC, and DEC may be, for example, a volume ratio of 1 to 3 : 2 to 5 : 2 to 5 (EC:EMC:DEC), and as a specific example, a volume ratio of 1 to 3 : 3 to 5 : 3 to 5 (EC:EMC:DEC).

[0117] Since the above organic solvent may cause lithium ions in the electrolyte to hydrolyze if it contains water, it is desirable that the water content in the organic solvent be controlled to 150 ppm or less, preferably 100 ppm or less, and more preferably 50 ppm.

[0118]

[0119] In addition, the present invention provides a secondary battery comprising: an electrode assembly including a positive electrode, a negative electrode, and a separator separating the positive electrode and the negative electrode; a case for housing the electrode assembly; and the aforementioned electrolyte additive for housing the electrode assembly and immersing the electrode assembly.

[0120] Furthermore, the present invention provides a secondary battery comprising: an electrode assembly including a positive electrode, a negative electrode, and a separator separating the positive electrode and the negative electrode; a case for housing the electrode assembly; and the aforementioned electrolyte for a battery that is housed in the case and immersed in the electrode assembly.

[0121] The above anode can be manufactured, for example, by mixing an anode active material, a binder, and optionally a conductive agent to prepare a composition for forming an anode active material layer, and then applying this to an anode current collector such as aluminum foil.

[0122] As the above-mentioned positive electrode active material, a compound capable of reversible intercalation and deintercalation of lithium (a lithated intercalation compound) may be used.

[0123] The above-mentioned positive active material may, for example, use a conventional NCM (lithium nickel manganese cobalt oxide, LiNiMnCoO2) positive active material used in lithium secondary batteries, and specifically, the chemical formula Li[Ni x Co y Mn z ]O2(here 0 <x<98, 0<y<35, 0<z<35, 단 x+y+z=100이다.) 형태의 리튬 복합금속 산화물일 수 있으나 이에 제한되는 것은 아니다.

[0124] The variables x, y, and z of the chemical formula Li[NixCoyMnz]O2 of the above lithium composite metal oxide are, for example, 0.0001 <x<98, 0.0001<y<35, 0.0001<z<35일 수 있고, 바람직하게는 1≤x≤93, 1≤y≤30, 1≤z≤30일 수 있으며, 보다 바람직하게는 5≤x≤91, 3≤y≤25, 3≤z≤25일 수 있다. 이때 x+y+z는 100을 만족한다.

[0125] Other examples of the above lithium composite metal oxides include LiCoO2, LiMnO2, LiMn2O4, LiNiO2, and LiNi x Mn (1-x) O2(where 0 <x<1), 및 LiM1 x M2y It may be one or more selected from the group consisting of O2 (wherein 0≤x≤1, 0≤y≤1, 0≤x+y≤1, M1 and M2 are each independently selected from the group consisting of Al, Sr, Mg and La), and in this case, the capacity characteristics and stability of the battery can be improved.

[0126] It may be used to have a coating layer on the surface of the above compound, or a mixture of the above compound and a compound having a coating layer may be used. The coating layer may comprise at least one coating element compound selected from the group consisting of oxides of coating elements, hydroxides of coating elements, oxyhydroxides of coating elements, oxycarbonates of coating elements, and hydroxycarbonates of coating elements. The compounds forming these coating layers may be amorphous or crystalline.

[0127] The coating elements included in the above coating layer may be Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. For the coating layer formation process, any coating method may be used as long as the compound can be coated using these elements in a manner that does not adversely affect the physical properties of the cathode active material (e.g., spray coating, immersion method, etc.). Since this is a known practice in the art, a detailed explanation is omitted.

[0128] The content of the above positive active material may be, for example, 90 weight% or more, or 90 to 98 weight% with respect to the total weight of the positive active material layer.

[0129] In one embodiment of the present invention, the positive active material layer may include a binder and a conductive material. In this case, the content of the binder and the conductive material may each be 1 weight% or more, or 1 to 5 weight%, based on the total weight of the positive active material layer.

[0130] The above binder serves to adhere the positive active material particles well to each other and also to adhere the positive active material well to the current collector. Examples include polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers including ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc.

[0131] The above conductive material is used to impart conductivity to the electrode, and in the battery being constructed, any electronically conductive material that does not cause chemical changes can be used. Examples include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber; metal-based materials such as metal powder or metal fiber such as copper, nickel, aluminum, silver; conductive polymers such as polyphenylene derivatives; or conductive materials including mixtures thereof.

[0132] Al can be used as the current collector, but is not limited to it.

[0133]

[0134] The above cathode can be manufactured, for example, by mixing a cathode active material, a binder, and optionally a conductive agent to prepare a composition for forming a cathode active material layer, and then applying this to a cathode current collector such as a copper foil.

[0135] The surface of the above cathode may further include a solid electrolyte interface (SEI) film.

[0136] The above-mentioned negative electrode active material includes a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0137] As a carbon material capable of reversibly intercalating / deintercalating the above lithium ions, any carbon-based negative electrode active material commonly used in lithium-ion secondary batteries can be used.

[0138] Specific examples of the above-mentioned negative electrode active material may be carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon. In addition, in addition to the above-mentioned carbonaceous materials, metallic compounds capable of alloying with lithium, or composites comprising metallic compounds and carbonaceous materials may also be used as negative electrode active materials, and for example, graphite may be used.

[0139] In addition, a metallic lithium thin film may be used as the above-mentioned negative electrode active material. As the above-mentioned negative electrode active material, one or more selected from the group consisting of crystalline carbon, amorphous carbon, carbon composites, lithium metal, and alloys containing lithium may be used in terms of high stability.

[0140] As for the metals capable of alloying with the above lithium, at least one of Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy may be used.

[0141] Materials capable of doping and undoping the above lithium include Si, Si-C composites, SiOx (0 < x < 2), Si-Q alloys (wherein Q is an element selected from the group consisting of alkali metals, alkaline earth metals, group 13 elements, group 14 elements, group 15 elements, group 16 elements, transition metals, rare earth elements, and combinations thereof, and is not Si), Sn, SnO2, Sn-R (wherein R is an element selected from the group consisting of alkali metals, alkaline earth metals, group 13 elements, group 14 elements, group 15 elements, group 16 elements, transition metals, rare earth elements, and combinations thereof, and is not Sn), and at least one of these may also be mixed with SiO2.

[0142] The above elements Q and R may be selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof.

[0143] Examples of the above transition metal oxides include vanadium oxide, lithium vanadium oxide, or lithium titanium oxide.

[0144] The content of the negative electrode active material in the above negative electrode active material layer may be, for example, 95 weight% or more, or 95 to 99 weight% with respect to the total weight of the negative electrode active material layer.

[0145] The content of the binder in the above-mentioned negative electrode active material layer may be, for example, 1 weight% or more, or 1 to 5 weight% with respect to the total weight of the negative electrode active material layer.

[0146] In the case of including a conductive material, the negative electrode active material can be used in the range of 90 to 98 weight%, the binder in the range of 1 to 5 weight%, and the conductive material in the range of 1 to 5 weight%.

[0147] The above binder serves to effectively bond the negative electrode active material particles to each other and also to effectively bond the negative electrode active material to the current collector. As the binder, a water-insoluble binder, a water-soluble binder, or a combination thereof may be used.

[0148] Examples of the above-mentioned water-insoluble binders include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers including ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or combinations thereof.

[0149] Examples of the above-mentioned water-soluble binders include rubber-based binders or polymer resin binders.

[0150] The above rubber-based binder may be selected from styrene-butadiene rubber, acrylated styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, and combinations thereof.

[0151] The above polymer resin binder may be selected from polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene copolymer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, ethylene-propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0152] When a water-soluble binder is used as the above-mentioned cathode binder, it may further include a cellulose-based compound capable of imparting viscosity.

[0153] The above cellulose-based compounds may be used by mixing one or more of, for example, carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or alkali metal salts thereof.

[0154] Na, K, or Li may be used as the alkali metal. The amount of such thickener used may be, for example, 0.1 to 5 parts by weight or 0.1 to 3 parts by weight per 100 parts by weight of the negative electrode active material.

[0155] The above conductive material is used to impart conductivity to the electrode, and any electronically conductive material that does not cause chemical changes can be used in the battery being constructed. Examples include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber; metal-based materials such as metal powder or metal fiber such as copper, nickel, aluminum, silver; conductive polymers such as polyphenylene derivatives; or conductive materials including mixtures thereof.

[0156] The above current collector may be selected from the group consisting of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof.

[0157]

[0158] Depending on the type of lithium secondary battery, a separator may be present between the positive and negative electrodes. As such a separator, polyethylene, polypropylene, polyvinylidene fluoride, or multilayer films of two or more layers thereof may be used, and of course, mixed multilayer films such as polyethylene / polypropylene two-layer separators, polyethylene / polypropylene / polyethylene three-layer separators, and polypropylene / polyethylene / polypropylene three-layer separators may be used.

[0159]

[0160] The secondary battery of the present invention has the effect of further improving battery characteristics, such as battery charge resistance measured by the HPPC (Hybrid Pulse Power Characterization) method, output characteristics, capacity recovery characteristics, and lifespan characteristics even when stored for a long period of 8 weeks or more at a high temperature of 60°C or higher, by using the electrolyte in addition to the conventional compound added to the electrolyte to improve battery performance.

[0161] Specifically, the secondary battery of the present invention may have an HPPC charging resistance value of 82Ω or less measured after storage at 60℃ for 8 weeks, and preferably 80Ω or less.

[0162]

[0163] In this description, the HPPC charging resistance value can be measured by the method specified in the document "Battery test manual for plug-in hybrid electric vehicles" (2010, Idaho National Laboratory for the US Department of Energy), and is an important indicator representing battery characteristics such as battery output. Furthermore, charging resistance is a resistance value measured during battery charging; the lower the charging resistance, the less energy loss occurs, which can lead to faster charging speeds and improved battery output. The secondary battery of the present invention exhibits a low HPPC charging resistance value as described above, resulting in excellent charging speed and output, making it suitable for use, for example, as an automotive battery.

[0164] The above secondary battery may have a recovery capacity of 960 mAh or more, preferably 970 mAh or more, measured after storage at 60°C for 8 weeks.

[0165]

[0166] In this description, the recovery capacity represents the capacity preservation characteristics of a battery that has been left unused for a long time. It involves measuring the discharged electrical capacity when the battery left unused for a long time is discharged to the discharge cutoff voltage, and the discharged electrical capacity when the discharged battery is recharged and discharged again to the discharge cutoff voltage, and comparing the two capacity values. A higher recovery capacity means that the amount of natural discharge due to battery preservation (storage) is smaller, which implies that the battery can be preserved for a long period. In particular, since the rate of natural discharge increases as the storage temperature of the battery increases, the recovery capacity at high temperatures is a very important characteristic for automotive batteries. When using the electrolyte of the present invention, the recovery capacity is improved by, for example, up to 12%, or specifically, 1.5 to 12% compared to conventional methods, thereby providing the effect of enabling longer storage with a single charge.

[0167]

[0168] The lifespan maintenance efficiency measured after storing the above secondary battery at 60°C for 8 weeks may be 90% or more, preferably 93% or more, and more preferably 95% or more.

[0169]

[0170] Therefore, when the battery of the present invention is used as an automotive battery, it can exhibit excellent performance as an automotive battery by ensuring stability even when a high-content nickel cathode material is applied to achieve high capacity, along with improvements in output, which becomes important depending on the size of the vehicle, and improvements in performance at low and high temperatures, which are problematic due to the characteristics of the vehicle being exposed to sunlight for most of the time while driving or parked and due to climate change.

[0171] The above secondary battery may be an NCM, NCA, LFP, LMFP, LMR, or cobalt-free lithium battery, etc.

[0172]

[0173] Hereinafter, preferred embodiments are presented to aid in understanding the present invention; however, the following embodiments are merely illustrative of the invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and spirit of the invention, and that such variations and modifications fall within the scope of the appended claims.

[0174]

[0175] [Example]

[0176] Example 1

[0177] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 2:4:4 as the organic solvent and adding 0.2 wt% of a compound represented by Chemical Formula 1-1 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt.

[0178] [Chemical Formula 1-1]

[0179]

[0180]

[0181] Example 2

[0182] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 2:4:4 as the organic solvent and adding 0.5 wt% of a compound represented by Chemical Formula 1-1 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt.

[0183]

[0184] Example 3

[0185] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 2:4:4 as the organic solvent and adding 1.0 wt% of a compound represented by Chemical Formula 1-1 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt.

[0186]

[0187] Comparative Example 1

[0188] A battery electrolyte was prepared using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 2:4:4 as the organic solvent and a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt, without using the compound represented by Chemical Formula 1-1.

[0189]

[0190] Evaluation experiment

[0191] Batteries were fabricated using the electrolytes obtained in Examples 1 to 3 and Comparative Example 1, and the initial discharge, high-temperature storage DC-IR increase rate (%), high-temperature storage recovery capacity retention rate (%), and lifespan efficiency (%) were measured and are shown together in Table 1 below.

[0192] Specifically, an electrolyte was prepared by adding additives of the types and amounts shown in Table 1 above to 100% by weight of an electrolyte obtained by dissolving 1.5M LiPF6 in a solvent mixed with ethylene carbonate (EC):ethylmethyl carbonate (EMC):dimethyl carbonate (DMC) in a volume ratio of 20:10:70.

[0193] Next, a Pouch cell was prepared as follows.

[0194] A cathode active material slurry was prepared by mixing 96 wt% of artificial graphite (shanshan, FSNC-4) and silicon (SiO (Osaka Titanium, CC grage), 1 wt% of conductive material (denka black Li250), 1.5 wt% of styrene-butadiene rubber (SBR) binder (ZEON), and 1.5 wt% of carboxymethylcellulose (CMC, Sigma-Aldrich), adding the mixture to distilled water, and stirring for 60 minutes using a mechanical stirrer.

[0195] The above slurry was applied to a copper current collector with a thickness of about 60 μm using a doctor blade, dried in a 100°C hot air dryer for 1 hour, dried again for 8 hours under vacuum conditions, and then rolled to manufacture a cathode plate.

[0196] LiNi 0.8 Mn 0.1 Co 0.1 A cathode active material slurry was prepared by mixing 294 wt% O, 3 wt% denka black (Li250) as a conductive material, and 3% polyvinylidene fluoride (PVdF, Sigma-Aldrich), adding the mixture to an N-methyl-2-pyrrolidone solvent, and stirring for 30 minutes using a mechanical stirrer.

[0197] The above slurry was applied to a thickness of 60 μm on a 20 μm thick aluminum current collector using a doctor blade, dried in a 100℃ hot air dryer for 1 hour, dried again for 8 hours under vacuum conditions, and rolled to manufacture an anode plate.

[0198] A lithium battery (hereinafter referred to as NCM 811) was manufactured using a 14 μm thick polypropylene separator and the above electrolyte.

[0199] Then, room temperature life performance was evaluated using a lithium battery manufactured with the prepared electrolyte. Specifically, the lithium battery was charged at a constant current rate of 10 C-rate to 4.2 V under constant current / constant voltage (CC / CV) conditions at 25°C, then cut off at 0.05 C-rate while maintaining 4.2 V in constant voltage mode, and then discharged at 1.0 C-rate to 2.7 V. The above charge and discharge conditions were performed as one cycle and repeated up to 200 cycles.

[0200]

[0201] The specific performance evaluation method using lithium batteries is summarized as follows.

[0202] [HPPC Charging Resistance Evaluation]

[0203] Measurements were taken according to the method prescribed in the "Battery test manual for plug-in hybrid electric vehicles," (2010, Idaho National Laboratory for the US Department of Energy.).

[0204] After storing at 60℃ for 8 weeks, the measured voltage value, the charge / discharge current value corresponding to the C-rate, the change in current (△I), the change in discharge voltage (△V), the change in charge voltage (△V), the discharge resistance, and the charge resistance were measured. The resistance increase rate was calculated using the slope value obtained from the change in current and voltage by briefly flowing the charge / discharge current for a certain period of time for each C-rate, and this was shown as the high-temperature storage DC_IR increase rate in Table 1 below.

[0205] [High-temperature recovery capacity evaluation]

[0206] The charging conditions were performed by charging at a constant current of 0.5C and a voltage of 4.2V until the charging current became 1 / 10C. The discharging conditions were performed by charging and discharging to 3.0V with a constant current of 0.5C, after which the discharge capacity was measured and shown as the initial discharge in Table 1 below.

[0207] After charging under the same charge-discharge conditions and storing at 60°C for 8 weeks, the change in remaining capacity was measured after discharging to a discharge voltage of 3V under the same conditions, and the high-temperature recovery capacity retention rate was shown in Table 1 below.

[0208] [Thickness Evaluation]

[0209] The pouch cell to be measured was placed in the thickness gauge, pressure was applied using the top plate weight, and the difference in space between the bottom plate and the top plate was measured using a digital gauge.

[0210] [High Temperature Life Evaluation]

[0211] The above secondary battery was charged at a constant current rate of 1C at 60°C until the voltage reached 4.20V (vs. Li), and then cut off at a current rate of 0.1C while maintaining 4.20V in constant voltage mode. Subsequently, it was discharged at a constant current rate of 1C until the voltage reached 3.0V (vs. Li) during discharge (1st cycle). After repeating the above cycle 500 times, the battery was stored for 8 weeks, and then the resistance, capacity, and thickness were measured, and the results are shown in Table 1 below.

[0212] Electrolyte Composition Resistance Before / After High-Temperature Storage (Initial / After 8 weeks DCIR, Ω) Recovery Capacity Before / After High-Temperature Storage (Initial / After 8 weeks, mAh) Thickness Before / After High-Temperature Storage (Initial / After 8 weeks, mm) Initial Capacity (mAh) / 500 Cycle Efficiency (%) Example 1: 81.1 / 119.5 (47.3%) 925.7 / 705.9 (76.3%) 2.75 / 2.80 85.7 (81.9%) Example 2: 80.8 / 118.4 (46.6%) 928.1 / 706.9 (76.2%) 2.74 / 2.80 92.1 (82.1%) Example 3: 85.2 / 127.5 (49.6%) 902.1 / 699.8 (77.6%) 2.80 / 2.90880.1 (81.4%) Comparative Example 184.4 / 143.4 (69.9%) 912.5 / 610.3 (66.9%) 2.73 / 2.90877.6 (83.2%)

[0213] As shown in Table 1 above, in Examples 1 to 3 which included the compound represented by Chemical Formula 1-1 as an electrolyte additive, it was confirmed that the initial discharge, the increase rate of high-temperature storage DC-IR, the retention rate of high-temperature storage recovery capacity, thickness, and lifespan efficiency were significantly improved compared to Comparative Example 1, which did not use the compound represented by Chemical Formula 1-1.

[0214]

[0215] Example 4

[0216] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 2:4:4 as the organic solvent and adding 1.5 wt% of a compound represented by the following chemical formula 4-1 and 0.2 wt% of a compound represented by chemical formula 1-1 to a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M.

[0217] [Chemical Formula 4-1]

[0218]

[0219] Example 5

[0220] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 2:4:4 as the organic solvent and adding 1.5 wt% of the compound represented by Chemical Formula 4-1 and 0.5 wt% of the compound represented by Chemical Formula 1-1 to a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M.

[0221]

[0222] Example 6

[0223] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 2:4:4 as the organic solvent and adding 1.5 wt% of the compound represented by Chemical Formula 4-1 and 1.0 wt% of the compound represented by Chemical Formula 1-1 to a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M.

[0224]

[0225] Comparative Example 2

[0226] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:CEC = 2:4:4 as the organic solvent and adding 1.5 wt% of the compound represented by Chemical Formula 4-1 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt.

[0227]

[0228] Comparative Example 3

[0229] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:CEC = 2:4:4 as the organic solvent and adding 1.5 wt% of the compound represented by Chemical Formula 4-1 and 0.5 wt% of the compound represented by Chemical Formula 2-3 below to a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M.

[0230] [Chemical Formula 2-3]

[0231]

[0232] Comparative Example 4

[0233] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:CEC = 2:4:4 as the organic solvent and adding 1.5 wt% of the compound represented by Chemical Formula 4-1 and 0.5 wt% of 1-propene-1,3-sulfone to a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M.

[0234]

[0235] Comparative Example 5

[0236] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:CEC = 2:4:4 as the organic solvent and adding 1.5 wt% of the compound represented by Chemical Formula 4-1 and 0.5 wt% of the compound represented by Chemical Formula 2-4 below to a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M.

[0237] [Chemical Formula 2-4]

[0238]

[0239] Comparative Example 6

[0240] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:CEC = 2:4:4 as the organic solvent and adding 1.5 wt% of the compound represented by Chemical Formula 4-1 and 1.0 wt% of the compound represented by Chemical Formula 3-1 to a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M.

[0241] [Chemical Formula 3-1]

[0242]

[0243] NCM 811 batteries were fabricated in the same manner as above using the electrolytes of Examples 4 to 6 and Comparative Examples 2 to 6, and after repeating the cycle 500 times and storing for 8 weeks, the resistance, capacity, thickness, etc. were measured and the results are shown in Table 2 below.

[0244] Electrolyte Composition Resistance Before / After High-Temperature Storage (Initial / After 8 weeks DCIR, Ω) Recovery Capacity Before / After High-Temperature Storage (Initial / After 8 weeks, mAh) Thickness Before / After High-Temperature Storage (Initial / After 8 weeks, mm) Initial Capacity (mAh) / 300 Cycle Efficiency (%) Example 4 10 1.9 / 149.1 (46.3%) 9 27.1 / 798.1 (86.1%) 2.61 / 2.75 851.1 (84.8%) Example 5 10 0.1 / 147.2 (47.1%) 9 34.1 / 805.1 (86.2%) 2.61 / 2.79 853.5 (85.0%) Example 6 10 6.9 / 161.1 (50.7%) 8 99.0 / 761.1 (84.7%) 2.70 / 2.81849.1 (83.5%) Comparative Example 299.1 / 152.4 (53.8%) 943.2 / 781.8 (82.9%) 2.64 / 2.75869.1 (85.9%) Comparative Example 3102.5 / 153.5 (49.8%) 933.7 / 805.7 (86.3%) 2.63 / 2.70857.6 (85.8%) Comparative Example 4108.2 / 155.7 (43.9%) 928.1 / 809.7 (87.2%) 2.64 / 2.72852.9 (86.9%) Comparative Example 5105.1 / 167.5 (59.4%) 930.5 / 802.9 (86.3%) 2.64 / 2.75851.1 (85.2%) Comparative Example 6101.2 / 165.9 (64.0%) 932.4 / 794.7 (85.2%) 2.64 / 2.72853.1 (83.1%)

[0245] As shown in Table 2 above, in Examples 4 to 6, which included a compound commonly used in the compound represented by Chemical Formula 1-1 as an electrolyte additive, it was confirmed that the initial discharge, the increase rate of high-temperature storage DC-IR, the retention rate of high-temperature storage recovery capacity, thickness, and lifespan efficiency were improved compared to Comparative Examples 2 to 6, which did not use the compound represented by Chemical Formula 1-1.

[0246]

[0247] Example 7

[0248] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC 20:60:20 as the organic solvent and adding 2.5 wt% of the compound represented by Chemical Formula 4-1 and 0.2 wt% of the compound represented by Chemical Formula 1-1 to a solution containing LiPF6 as the lithium salt at a concentration of 1.10 M.

[0249] [Chemical Formula 1-1]

[0250]

[0251] Example 8

[0252] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC 20:60:20 as the organic solvent and adding 2.5 wt% of the compound represented by Chemical Formula 4-1 and 0.5 wt% of the compound represented by Chemical Formula 1-1 to a solution containing LiPF6 as the lithium salt at a concentration of 1.10 M.

[0253]

[0254] Example 9

[0255] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC 20:60:20 as the organic solvent and adding 2.5 wt% of the compound represented by Chemical Formula 4-1 and 1.0 wt% of the compound represented by Chemical Formula 1-1 to a solution containing LiPF6 as the lithium salt at a concentration of 1.10 M.

[0256]

[0257] Example 10

[0258] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC 20:60:20 was used as the organic solvent, and a solution containing LiPF6 at a concentration of 1.10 M as the lithium salt was prepared by adding 2.5 wt% of the compound represented by Chemical Formula 4-1, 2.0 wt% of the compound represented by Chemical Formula 4-3, and 0.5 wt% of the compound represented by Chemical Formula 1-1.

[0259] [Chemical Formula 4-3]

[0260]

[0261] Comparative Example 7

[0262] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC 20:60:20 as the organic solvent and adding 1.5 wt% of the compound represented by Chemical Formula 4-1 to a solution containing LiPF6 at a concentration of 1.10 M as the lithium salt.

[0263]

[0264] Comparative Example 8

[0265] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC 20:60:20 was used as the organic solvent, and a lithium salt containing LiPF6 at a concentration of 1.10 M was used, to which 1.5 wt% of the compound represented by Chemical Formula 4-1 and 0.5 wt% of lithium bis(fluorosulfonylmide)imide (LiFSI) were added to prepare an electrolyte for a battery.

[0266]

[0267] Comparative Example 9

[0268] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC 20:60:20 was used as the organic solvent, and a lithium salt containing LiPF6 at a concentration of 1.10 M was used to prepare an electrolyte for a battery by adding 2.5 wt% of the compound represented by Chemical Formula 4-1 and 2.0 wt% of the compound represented by Chemical Formula 4-3.

[0269]

[0270] Comparative Example 10

[0271] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC 20:60:20 was used as the organic solvent, and a lithium salt containing LiPF6 at a concentration of 1.10 M was used to prepare a battery electrolyte by adding 2.5 wt% of the compound represented by Chemical Formula 4-1, 2.0 wt% of the compound represented by Chemical Formula 4-3, and 1.5 wt% of lithium bis(fluorosulfonyl)imide (LiFSI).

[0272]

[0273] LFP batteries were fabricated using the electrolytes of Examples 7 to 10 and Comparative Examples 7 to 10, and after repeating the cycle 300 times, they were stored for 8 weeks, and then the resistance, capacity, thickness, etc. were measured and the results are shown in Table 3 below.

[0274]

[0275] Specifically, the above LFP battery was manufactured in the following manner.

[0276] Manufacturing of LFP batteries

[0277] A cathode mixture slurry was prepared by adding 492 wt% of LiFePO4 as a cathode active material, 4 wt% of carbon black as a conductive agent, and 4 wt% of polyvinylidene fluoride (PVdF) as a binder to N-methyl-2-pyrrolidone (NMP) as a solvent. The cathode mixture slurry was coated onto an aluminum (Al) thin film, which is a cathode current collector, with a thickness of about 20 μm, dried to produce a cathode, and then subjected to a roll press to produce a cathode.

[0278] A cathode mixture slurry was prepared by adding carbon powder as the cathode active material, PVdF as the binder, and carbon black as the conductive agent to NMP as the solvent in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively. The cathode mixture slurry was coated onto a copper (Cu) thin film, which is a cathode current collector with a thickness of 10 μm, and dried to produce a cathode, and then a roll press was performed to produce a cathode.

[0279] After manufacturing a pouch-type battery using a conventional method with the positive and negative electrodes prepared as described above and a separator composed of three layers of polypropylene / polyethylene / polypropylene (PP / PE / PP) (operating voltage 3.65V, 3.66V, 3.67V), the manufacturing of a lithium secondary battery was completed by injecting each electrolyte prepared in Examples 7 to 10 and Comparative Examples 7 to 10.

[0280] Electrolyte Composition Resistance Before / After High-Temperature Storage (Initial / After 8 weeks DCIR, Ω) Recovery Capacity Before / After High-Temperature Storage (Initial / After 8 weeks, mAh) Thickness Before / After High-Temperature Storage (Initial / After 8 weeks, mm) Initial Capacity (mAh) / 300 Cycle Efficiency (%) Example 7 62.1 / 112.7 (81.5%) 100 1.1 / 83 2.1 (83.1%) 2.2 / 2.39 71.1 (82.9%) Example 8 61.3 / 110.6 (80.5%) 101 8.2 / 845.4 (83.0%) 2.2 / 2.39 78.3 (83.6%) Example 9 65.4 / 119.2 (82.3%) 956.3 / 755.1 (79.0%) 2.2 / 2.395 1.1 (82.2%) Example 1068.0 / 112.7 (65.6%) 973.3 / 836.0 (85.9%) 2.1 / 2.392 6.4 (86.4%) Comparative Example 765.1 / 119.7 (83.8%) 989.4 / 829.9 (83.9%) 2.2 / 2.397 7.2 (84.3%) Comparative Example 865.6 / 120.6 (84.0%) 991.1 / 830.7 (83.8%) 2.2 / 2.398 0.9 (83.8%) Comparative Example 964.4 / 126.4 (96.3%) 1016.5 / 808.0 (79.5%) 2.1 / 2.399 0.1 (78.8%) Comparative Example 1065.0 / 124.4 (91.4%) 1018.8 / 810.3 (79.5%) 2.1 / 2.3989.8 (75.6%)

[0281] As shown in Table 3 above, in Examples 7 to 10 which included compounds commonly used for the compound represented by Chemical Formula 1-1 as electrolyte additives, it was confirmed that the initial discharge, the increase rate of high-temperature storage DC-IR, the retention rate of high-temperature storage recovery capacity, thickness, and lifespan efficiency were improved compared to Comparative Examples 7 to 10 which did not use the compound represented by Chemical Formula 1-1.

[0282]

[0283] Therefore, when the electrolyte according to the embodiments of the present invention is applied to a secondary battery, it is found that not only is the internal resistance of the battery reduced and the amount of gas generated reduced by suppressing internal side reactions of the battery, but the charging resistance, output, recovery capacity, and lifespan efficiency are also improved even when stored for a long time at high temperatures, making it suitable for use as a secondary battery for automobiles.

Claims

1. An electrolyte additive characterized by comprising a compound having a halogen terminal group, which simultaneously contains carbon-carbon unsaturated bonds and a sulfonyl structural group.

2. In Paragraph 1, An electrolyte additive characterized in that the above compound is one or more selected from substances represented by the following chemical formulas 1 to 3. [Chemical Formulas 1 to 3] (In the above chemical formulas 1 to 3, X is independently fluorine (F), chlorine (Cl), or bromine (Br).) 3. In Paragraph 1, An electrolyte additive characterized in that the above compound is one or more selected from substances represented by the following chemical formulas 1-1 to 1-9. [Chemical Formulas 1-1 to 1-9] (In the chemical formulas described herein, lines represent bonds, and where no separate element is specified, the point where bonds meet is carbon, and the number of hydrogen atoms satisfying the valence of the carbon is omitted.) 4. In Paragraph 1, The electrolyte additive is characterized by being included in a range of 0.01 to 10 weight percent with respect to 100 weight percent of the total components constituting the electrolyte for a battery.

5. In Paragraph 1, The above electrolyte additive is characterized by comprising one or more selected from cyclic sulfone compounds, phosphoric compounds, and carbonate compounds.

6. In Paragraph 5, The above cyclic sulfone compound is one or more selected from compounds represented by the following chemical formulas 2-1 to 2-6, and The above phosphorus compound is one or more selected from compounds represented by the following chemical formulas 4-1 to 4-4, and An electrolyte for a battery characterized in that the above carbonate-based compound is one or more compounds selected from the compounds represented by the following chemical formulas 4-1 to 4-4. [Chemical Formulas 2-1 to 2-6] [Chemical Formulas 3-1 to 3-3] [Chemical Formulas 4-1 to 4-4] 7. In Paragraph 5, An electrolyte additive characterized by including one or more compounds selected from the above-mentioned cyclic sulfone compounds, phosphoric compounds, and carbonate compounds in an amount of 0.1 to 10 weight% based on 100 weight% of the total electrolyte.

8. An electrolyte for a battery characterized by comprising the electrolyte additive of claim 1 as an electrolyte for a secondary battery.

9. In Paragraph 8, A battery electrolyte characterized by containing the above electrolyte additive in an amount of 0.01 to 10 weight% based on 100 weight% of the total components constituting the battery electrolyte.

10. In Paragraph 8, The above-mentioned electrolyte for a battery is characterized by comprising a lithium salt and an organic solvent.

11. In Paragraph 10, The above lithium salts are LiPF6, LiF4, LiCl, LiBr, LiI, LiClO4, LiBF4, and LiB 10 Cl 10 , LiSbF6, LiAsF6, LiN(SO2C2F5)2, LiCF3SO3, LiCF3CO2, Li(CF3SO2)2N, LiN(SO3C2F5)2, Li(FSO2)2N, LiC4F9SO3, LiClO4, LiFePO4, LiAlO2, LiAlCl4, LiN(C x F 2x +1SO2)(C y F 2y An electrolyte for a battery characterized by comprising one or more selected from the group consisting of +1SO2)(where x and y are natural numbers, for example, integers from 1 to 20), LiAsF6, LiSbF6, LiAlCl4, LiB(C2O4)2 (lithium bis(oxalato) borate (LiBOB), CH3SO3Li, CF3SO3Li, and (CF3SO2)2NLi).

12. In Paragraph 10, The electrolyte for a battery is characterized by comprising one or more organic solvents selected from the group consisting of ethylene carbonate, diethyl carbonate, ethylmethyl carbonate, dimethyl carbonate, propylene carbonate, dipropyl carbonate, butylene carbonate, methylpropyl carbonate, and ethylpropyl carbonate.

13. An electrode comprising an anode, a cathode, and a separator separating the anode and the cathode. A secondary battery comprising: an assembly; a case for housing the electrode assembly; and an electrolyte for housing the electrode assembly within the case and immersing the electrode assembly, wherein the electrolyte comprises an electrolyte additive according to claim 1.

14. An electrode comprising an anode, a cathode, and a separator separating the anode and the cathode. A secondary battery comprising: an assembly; a case for housing the electrode assembly; and an electrolyte for housing the electrode assembly within the case and immersing the electrode assembly, wherein the electrolyte comprises the electrolyte according to claim 8.

15. In Paragraph 13 or 14, The above secondary battery is characterized as being an NCM, NCA, LFP, LMFP, LMR, or cobalt-free lithium battery.

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