Electrolyte additive, battery electrolyte comprising same, and secondary battery comprising same

Abstract

The present invention relates to an electrolyte additive, and an electrolyte and a secondary battery that comprise same. According to the present invention, a stable film is formed on anodes and cathodes of various lithium secondary batteries including high-nickel, Si anodes, LFP batteries, lithium-manganese-rich (LMR) batteries, or cobalt-free batteries. As a result, side reactions inside a battery are suppressed, charging efficiency and output may be enhanced due to low charge / discharge resistance, an increase in battery resistance may be suppressed even during long-term storage under high-temperature conditions, gas generation due to decomposition of electrolyte components may also be significantly suppressed, resulting in excellent long-term lifespan and high-temperature capacity retention while simultaneously improving low-temperature performance and output. Hydrofluoric acid among side reaction products caused by instability of a battery cathode may be effectively scavenged to suppress an increase in acidity of the electrolyte and elution of transition metal ions from the cathode, and thus secondary batteries having excellent battery characteristics and an excellent lifespan may be provided.

Description

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

[0001] The present invention relates to an electrolyte additive, a battery electrolyte containing the same, and a secondary battery containing the same. More specifically, it relates to a stable film formed on the anode and cathode of various lithium secondary batteries, including high-nickel, mid-nickel, Si anode, LFP (lithium iron phosphate), NMX (nickel-manganese, Co free), LMR (lithium-manganese-rich), LMX (lithium-manganese-rich, Co free), OLO (over-lithiated layered oxide), LCO (lithium cobalt oxide), or DRX (disordered rocksalt), thereby suppressing side reactions within the battery and lowering charge / discharge resistance, which can improve charging efficiency and output. Furthermore, even when stored for a long time under high-temperature conditions, the increase in battery resistance and gas generation can be suppressed, resulting in excellent long-term lifespan and high-temperature capacity retention rate, while simultaneously improving low-temperature performance and output. Additionally, it effectively scavenges hydrofluoric acid among the side reaction products caused by the instability of the battery anode, thereby suppressing the increase in electrolyte acidity and the leaching of transition metal ions from the anode. This invention relates to an electrolyte additive capable of providing a secondary battery with excellent battery characteristics, including output, and lifespan.

[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. Accordingly, 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] In addition, there is a need to develop a battery that can improve charging efficiency and output by forming a stable film on the anodes and cathodes of various lithium secondary batteries, including high-nickel, Si anodes, LFP, LMR (lithium manganese-rich) batteries, or cobalt-free batteries, thereby suppressing side reactions inside the battery and lowering charge / discharge resistance. That is, there is a need to develop a battery with excellent battery characteristics, including output, and lifespan by effectively scavenging hydrofluoric acid among the side reaction products caused by the instability of the battery anode to suppress the increase in electrolyte acidity and the leaching of transition metal ions from the anode.

[0006] [Prior Art Literature]

[0007] [Patent Literature]

[0008] Korean Patent Publication No. 10-2023-0168034

[0009] In order to solve the problems of the prior art as described above, the present invention aims to provide a novel electrolyte additive for batteries, a battery electrolyte containing the same, and a secondary battery containing the same.

[0010] Furthermore, the present invention aims to provide a secondary battery that suppresses internal side reactions and reduces charging resistance to improve battery output, enhances recovery capacity at high temperatures to enable long-term storage, maintains a high-temperature lifespan, and simultaneously improves low-temperature performance and output.

[0011] The above and other objectives of the present invention can all be achieved by the present invention described below.

[0012] To achieve the above objective, the present invention provides an electrolyte additive for a secondary battery electrolyte, characterized by comprising two or more compounds selected from dioxaphosphorane compounds, carbonate compounds, acid anhydride compounds, silane compounds, amine compounds, ether compounds, fluorophosphorane compounds, nitrile compounds, boron compounds, phosphorus compounds, sulfur compounds, and aromatic compounds.

[0013]

[0014] In addition, the present invention provides an electrolyte additive for a secondary battery electrolyte, characterized by comprising: a dioxaphosphorane-based compound; and one or more compounds selected from carbonate-based compounds, acid anhydride-based compounds, silane-based compounds, amine-based compounds, ether-based compounds, fluorophosphorane-based compounds, nitrile-based compounds, boron-based compounds, phosphorus-based compounds, sulfur-based compounds, and aromatic compounds.

[0015]

[0016] The above-mentioned dioxaphosphorane compound may be a compound represented by the following chemical formula 1.

[0017] [Chemical Formula 1]

[0018]

[0019] (In the above Chemical Formula 1, the lines represent bonds, and where no separate element is specified, the points where bonds meet are carbons, and A1, A2, and A3 are independently oxygen (O), nitrogen (N), or sulfur (S).)

[0020]

[0021] The above carbonate-based compound may be a compound selected from one or more of vinylene carbonate, fluoroethylene carbonate, vinylethylene carbonate, ethyl propionate, and propyl propionate.

[0022] The above acid anhydride compound may be succinic acid anhydride, etc.

[0023] The above silane compound may be tetravinyl silane, etc.

[0024] The above amine-based compound may be hexamethyleneterlamine, etc.

[0025] The above ether-based compound may be a compound selected from one or more of 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether.

[0026] The above fluorophosphorane compound may be one or more compounds selected from 1,2-bis((difluorophosphanyl)oxy)ethane, 2-fluoro-4-methyl-[1,3,2]-dioxaphosphorane, and difluoro((4-methylpentane-2-yl)oxy)phosphane.

[0027] The above nitrile compound may be one or more compounds selected from 1,3,6-hexanetricarbonitrile, succinonitrile, adiponitrile, and 1-ethyl-3-methylimidazolium dicyanamide.

[0028] The above boron-based compound may be one or more compounds selected from lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium tetrafluoroborate, tris(trimethylsilyl)borate, triisopropyl borate, and trimethoxyboroxine.

[0029] The above-mentioned phosphorus compound may be one or more compounds selected from lithium tetrafluoro(oxalato)phosphate, lithium difluoro(bisoxalato)phosphate, lithium difluorophosphate, diethyl(difluoromethyl)phosphonate, tris(trimethylsilyl)phosphite, tripropargyl phosphate, and triphenyl phosphate.

[0030] The above sulfur compounds may be one or more compounds selected from butadiene sulfone, dimethyl sulfate, ethylene dimethanesulfonate, lithium bis(fluorosulfonyl)imidazole, 1,3-propylene sulfate, ethylene sulfate, 1,-propene-1,3-sulfone, 1,3-propanesulfone, 2,4,8,10-tetraoxa-3,9-dithiaspiro[5,5[undecane, 3,3,9,9-tetraoxide, methylene methyl disulfonate, 3-fluoro-1,3-propanesulfone and 1,4-butanesulfone.

[0031] The above aromatic compound may be one or more compounds selected from biphenyl, cyclohexylbenzene, 4-fluorotoluene, fluorobenzene, and 2-fluorobiphenyl.

[0032]

[0033] The compound represented by the above chemical formula 1 may be a compound represented by the following chemical formulas 1-1 to 1-5.

[0034] [Chemical Formulas 1-1 to 1-5]

[0035]

[0036] One or more compounds selected from the above carbonate compounds, acid anhydride compounds, silane compounds, amine compounds, ether compounds, fluorophosphorane compounds, nitrile compounds, boron compounds, phosphorus compounds, sulfur compounds, and aromatic compounds may be selected from the following chemical formulas 2-1 to 2-45.

[0037] [Chemical Formulas 2-1 to 2-45]

[0038]

[0039]

[0040] The above electrolyte additive may comprise 0.1 to 10 weight% of the above-mentioned dioxaphosphorane compound; and 0.1 to 10 weight% of one or more compounds selected from carbonate compounds, acid anhydride compounds, silane compounds, amine compounds, ether compounds, fluorophosphorane compounds, nitrile compounds, boron compounds, phosphorus compounds, sulfur compounds, and aromatic compounds.

[0041] The above-mentioned dioxaphosphorane compound; and two or more compounds selected from carbonate compounds, acid anhydride compounds, silane compounds, amine compounds, ether compounds, fluorophosphorane compounds, nitrile compounds, boron compounds, phosphorus compounds, sulfur compounds, and aromatic compounds may be included in a weight ratio of 1:1 to 1:10.

[0042]

[0043] In addition, the present invention provides an electrolyte comprising an organic solvent, a lithium salt, and an electrolyte additive, wherein the electrolyte additive comprises an electrolyte additive.

[0044] 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, ethylpropyl carbonate, and 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether.

[0045] The above lithium salts are LiPF6, LiF4, LiCl, LiBr, LiI, LiClO4, and LiB 10 Cl 10It may include one or more selected from the group consisting of LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, (FSO2)2NLi and (CF3SO2)2NLi.

[0046]

[0047] In addition, the present invention provides a secondary battery comprising a negative electrode, a positive electrode, a separator interposed between the negative electrode and the positive electrode, and an electrolyte, wherein the electrolyte is the aforementioned electrolyte.

[0048] The above secondary battery may be a high-nickel full-cell battery, a mid-nickel full-cell battery, a lithium iron phosphate battery, an NMX (Nickel-Manganese, Co-free) battery, an LMR (Lithium-Manganese-Rich) battery, an LMX (Lithium-Manganese-Rich, Co-free) battery, an OLO (Over-Lithiated Layered Oxide) battery, an LCO (Lithium Cobalt Oxide) battery, a DRX (Disordered Rocksalt) battery, etc.

[0049] A secondary battery comprising an electrolyte containing an electrolyte additive according to the present invention can form a stable film on the positive and negative electrodes of various lithium secondary batteries, including high nickel, mid nickel, Si anode, LFP (lithium iron phosphate), NMX (Nickel-Manganese, Co free), LMR (Lithium-Manganese-Rich), LMX (Lithium-Manganese-Rich, Co free), OLO (Over Lithiated layered Oxide), LCO (Lithium Cobalt Oxide), or DRX (Disordered Rocksalt), thereby suppressing side reactions inside the battery and lowering charge / discharge resistance, so that charge efficiency and output can be improved.

[0050] In addition, a secondary battery comprising an electrolyte containing an electrolyte additive according to the present invention can suppress the increase in resistance of the battery even when stored for a long time under high temperature conditions, thereby providing excellent long-term lifespan and high-temperature capacity retention rate, while simultaneously improving low-temperature performance and output. Furthermore, by effectively scavenging hydrofluoric acid among the by-products caused by the instability of the battery anode, it suppresses the increase in acidity of the electrolyte and the leaching of transition metal ions from the anode, thereby providing a secondary battery with excellent battery characteristics, including output, and lifespan.

[0051] The present invention will be described in detail below, but the invention is not limited thereto.

[0052]

[0053] In order to manufacture a specific secondary battery suitable for use as an automobile battery, the inventors were researching a secondary battery in which internal side reactions are suppressed to improve output, 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, while simultaneously improving low-temperature performance and output. During this research, they confirmed that all of the above objectives can be achieved by adding an additive of a specific structure to the electrolyte of the secondary battery, and based on this, they completed the present invention.

[0054]

[0055] The electrolyte additive included in the secondary battery electrolyte according to the present invention is characterized by comprising two or more compounds selected from dioxaphosphorane compounds, carbonate compounds, acid anhydride compounds, silane compounds, amine compounds, ether compounds, fluorophosphorane compounds, nitrile compounds, boron compounds, phosphorus compounds, sulfur compounds, and aromatic compounds. In this case, a stable film is formed on the positive and negative electrodes of various lithium secondary batteries, including high nickel, mid nickel, Si anode, LFP (lithium iron phosphate), NMX (Nickel-Manganese, Co free), LMR (Lithium-Manganese-Rich), LMX (Lithium-Manganese-Rich, Co free), OLO (Over Lithiated layered Oxide), LCO (Lithium Cobalt Oxide), or DRX (Disordered Rocksalt), thereby suppressing side reactions inside the battery and lowering charge / discharge resistance, resulting in improved charging efficiency and output.

[0056] The electrolyte additive included in the secondary battery electrolyte according to the embodiments of the present invention is characterized by comprising: a dioxaphosphorane-based compound; and one or more compounds selected from carbonate-based compounds, acid anhydride-based compounds, silane-based compounds, amine-based compounds, ether-based compounds, fluorophosphorane-based compounds, nitrile-based compounds, boron-based compounds, phosphorus-based compounds, sulfur-based compounds, and aromatic compounds; in this case, internal side reactions of the battery are suppressed and the charging resistance of the secondary battery is lowered, thereby improving charging efficiency and output; and even if stored for a long time under high temperature conditions, the increase in resistance of the battery can be suppressed, so that long-term lifespan and high-temperature capacity retention rate are excellent, while low-temperature performance and output are improved; and by effectively scavenging hydrofluoric acid among the side reaction products caused by the instability of the battery anode, the increase in acidity of the electrolyte and the leaching of transition metal ions from the anode are suppressed, thereby providing excellent effects such as output, battery characteristics, and lifespan.

[0057] The dioxaphosphorane-based compound included in the secondary battery electrolyte according to the embodiments of the present invention is characterized as being a compound represented by the following chemical formula 1.

[0058] For reference, LiPF6, a representative lithium salt used in secondary batteries, is Li due to dissociation. + It needs to decompose into PF6-, but Li + + PF5- + F - When incomplete dissociation occurs, it reacts with moisture in the battery to form hydrofluoric acid (HF). The hydrofluoric acid generated in this way attacks the anode, particularly high-nickel, causing metal to leach out and move to the cathode, where it is deposited and acts as a catalyst to cause side reactions, thereby degrading cell performance. Additionally, the generated hydrofluoric acid destroys the composition of the SEI (solid electrolyte interphase) of the cathode and converts it into LiF, an inorganic composition, which increases the impedance within the cell and reduces the battery life.

[0059] The dioxaphosphorane compound represented by Chemical Formula 1 above is capable of resolving these problems; specifically, the PO3 lone pair of electrons can act as a Lewis base to stabilize the PF5- (acting as a Lewis acid) and suppress side reactions caused by PF5- reacting with water. Furthermore, the P lone pair of electrons effectively scavenges hydrofluoric acid to increase the acidity of the electrolyte, and not only performs a stabilizing role by converting the phosphite into a phosphate type through interaction with the P element and water, but also possesses the reactive oxygen species scavenging function of P-containing molecules along with OH -By reacting with it, the stability of the secondary battery can be improved through the formation of stable compounds such as H2O capture and LiOH control, and the amount of gas generated is reduced by absorbing oxygen produced by the decomposition of the Li2MnO3 component, as well as by forming a CEI film (anode SEI film) to prevent the decomposition of the electrolyte and reduce hydrofluoric acid, thereby promoting improved stability.

[0060] As a result, a stable film is formed on the positive and negative electrodes of various lithium secondary batteries, including high nickel, mid nickel, Si anode, LFP (lithium iron phosphate), NMX (Nickel-Manganese, Co free), LMR (Lithium-Manganese-Rich), LMX (Lithium-Manganese-Rich, Co free), OLO (Over Lithiated layered Oxide), LCO (Lithium Cobalt Oxide), or DRX (Disordered Rocksalt), thereby suppressing side reactions inside the battery and lowering charge / discharge resistance, which has the effect of improving charging efficiency and output.

[0061] [Chemical Formula 1]

[0062]

[0063] (In the above Chemical Formula 1, the lines represent bonds, and where no separate element is specified, the points where bonds meet are carbons, and A1, A2, and A3 are independently oxygen (O), nitrogen (N), or sulfur (S).)

[0064]

[0065] Specifically, the results of the Density Functional Theory (DFT) calculation for this compound showed a HOMO of -9.87 eV and a LUMO of 1.32 eV compared to ethylene carbonate (EC), which had a HOMO of -10.92 eV and a LUMO of 1.41 eV. Judging from the high HOMO and low LUMO values, it is predicted that it can act on both the anode and the cathode. In fact, the interface between the electrode and the electrolyte can be stabilized by forming a P-based inorganic film after the middle of the reaction along with the organic film components of the initial series. Specifically, an organic-inorganic composite film is formed by reducing the acetate ester fraction (functional group) to form an organic-based film in the form of Li2CO3 and / or ROCO2Li, and by oxidizing the cyclic phosphite fraction (functional group) to form a lithium phosphate-based inorganic layer (LixPOyFz, where x is an integer from 1 to 3, y is 1, z is an integer from 2 to 6, and y+z is an integer within the range of a lower limit of 2 and an upper limit of 6). The compound forms SEI (Solid Electrolyte Interphase) and CEI (Cathode Electrolyte Interphase) on the cathode and anode, thereby providing effects of electrode stabilization, resistance reduction, and long-term cycle stabilization, as well as an effect of improving high-voltage stability. In addition, it provides effects of suppressing metal leaching and reducing gas generation.

[0066] Furthermore, the electronic stability and planar structure of the ring are adsorbed onto the electrode surface, thereby securing a uniform decomposition reaction pathway. In particular, the heteroatoms contained in the ring act as electron absorbers to lower the HOMO energy of the additive molecules, thereby inducing them to be preferentially reduced. This enables the formation of a uniform SEI with low resistance characteristics, which significantly reduces the internal resistance (DC-IR) of the battery during the initial cycle. Additionally, since the ring does not decompose even under high temperature conditions, it maintains the electrode surface as a protective layer with heat dissipation, electronic insulation, and ion permeability, thereby enabling the maintenance of excellent electrical conductivity and output without an increase in resistance even after high-temperature storage.

[0067] It is desirable to use oxygen (O), nitrogen (N), or sulfur (S) independently as heteroelements with a large electronegativity difference from phosphorus (P) for the above A1, A2, and A3, as this suppresses internal side reactions of the battery, thereby improving output and preventing an increase in resistance even when stored for a long time under high temperature conditions, thus providing a secondary battery with excellent high-temperature recovery capacity and lifespan characteristics; in particular, it is even more desirable to use oxygen (O) or nitrogen (N), which can act as strong electron absorbers.

[0068] It is preferable that at least one of the above A1, A2, and A3 contains oxygen (O), it is more preferable that two or more contain oxygen (O), and most preferable that all three contain oxygen (O).

[0069] When the electrolyte additive represented by the above chemical formula 1 is added to the electrolyte of a battery, electrons are localized toward the P element due to the electronegativity difference between the (P) element and the heteroelement directly connected to it (e.g., oxygen (O) element), and furthermore, due to the overall asymmetric structure of the chemical formula, the P element is electron-deficient (e - poor, δ +) In this state, an oxidation reaction is induced in an electrolyte containing lithium ions, forming a stable film on the electrode, specifically, as an example, the cathode.

[0070] 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 resistance increase improves charge / discharge efficiency and output, and the suppression of gas generation caused by chemical reactions within the battery enhances battery safety. Additionally, a chemically stable residual film can be maintained even during long-term, repeated charge / discharge cycles. In addition, by preventing the structural collapse of the electrode active materials of the anode and cathode at high temperatures, the capacity retention rate is improved, thereby extending the lifespan. Furthermore, the hydrofluoric acid generated by reacting with residual moisture in the electrolyte among the by-products of the instability of the battery anode is effectively captured or neutralized by the acidity control ability of the phosphite group, thereby suppressing the increase in the acidity of the electrolyte and the leaching and deposition of transition metal ions (Mn, Ni, etc.) of the anode, and delaying the mechanical collapse of the electrode and interfacial oxidation reaction, thereby improving long-term lifespan characteristics and Coulombic Efficiency.

[0071] Furthermore, the inorganic-centered SEI generated after decomposition maintains a balance of electronic insulation and ion permeability; in particular, the LixPOyFz-based inorganic layer acts as an electron insulator and inhibits redox reactions, thereby stabilizing the interface. This CEI layer blocks contact between the anode surface and the electrolyte, thereby inhibiting electrolyte decomposition and suppressing the leaching of transition metals (TM) such as Ni, Mn, and Co. Additionally, the oxygen negative charge and Lewis base functions of the phosphate structure capture PF5 and HF, further inhibiting decomposition. The phosphite core structure reduces electrolyte oxidation byproducts such as CO2 and O2, thereby suppressing gas generation. High-temperature stability is enhanced through the formation of an inorganic layer with high thermal stability, and the formation of a uniform thin film can suppress the rise in initial and long-term resistance.

[0072] Meanwhile, while the viscosity of the electrolyte typically increases and the diffusion of Li ions is restricted in low-temperature environments, maintaining a thin and dense inorganic SEI even at low temperatures can provide the effect of not hindering the passage of Li ions across the interface. In particular, while efficiency often drops due to a rapid decrease in reactivity during cycling or non-uniform SEI growth at low temperatures, this structure can form a film of stable SEI components (Li2CO3, ROCO2Li) that is reduced relatively quickly to form a uniform film and does not degrade in electrochemical properties during subsequent cycles. Since it is a structure that ensures decomposition reactivity even at low temperatures, it is advantageous for securing initial charge efficiency (ICE) and can stabilize capacity retention and efficiency over the long term.

[0073]

[0074] The electrolyte additive represented by the above chemical formula 1 may be selected from among the compounds represented by the following chemical formulas 1-1 to 1-5 as specific examples.

[0075] [Chemical Formulas 1-1 to 1-6]

[0076]

[0077] The compound represented by the above chemical formula 1 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 2.0 weight%, even more preferably 0.1 to 1.0 weight%, and most preferably 0.15 to 1.0 weight%. Within the above range, the effect of improving the charging efficiency and high-temperature life of the battery may be the best.

[0078]

[0079] It is preferable to add the compound represented by the above chemical formula 1 together with one or more compounds selected from carbonate compounds, acid anhydride compounds, silane compounds, amine compounds, ether compounds, fluorophosphorane compounds, nitrile compounds, boron compounds, phosphorus compounds, sulfur compounds, and aromatic compounds, as this can provide a predetermined synergistic effect without adversely affecting the components constituting the battery.

[0080] One or more compounds selected from these carbonate compounds, acid anhydride compounds, silane compounds, amine compounds, ether compounds, fluorophosphorane compounds, nitrile compounds, boron compounds, phosphorus compounds, sulfur compounds, and aromatic compounds may be included in a total amount of 0.1 to 20 weight% based on 100 weight% of the total electrolyte, and may be included in an amount of 0.1 to 20 weight%, specifically 0.2 to 10 weight%, and preferably 0.5 to 5 weight%. When the content of the above compounds satisfies the above range, it is desirable in terms of the effect of improving the high-temperature characteristics and cycle characteristics of the battery.

[0081] A compound represented by the above chemical formula 1; and one or more compounds selected from the group consisting of carbonate compounds, acid anhydride compounds, silane compounds, amine compounds, ether compounds, fluorophosphorane compounds, nitrile compounds, boron compounds, phosphorus compounds, sulfur compounds, and aromatic compounds may be used in a weight ratio of 1:0.5 to 1:20, or a weight ratio of 1:1 to 1:15, or a weight ratio of 1:1.5 to 1:15. Within the above range, the effect of improving the charging efficiency and high-temperature life of the battery may be the best.

[0082]

[0083] The carbonate-based compound included in the electrolyte according to the present invention is characterized by being selected from one or more of vinylene carbonate, fluoroethylene carbonate, vinylethylene 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, mid nickel, Si anode, LFP (lithium iron phosphate), NMX (Nickel-Manganese, Co free), LMR (Lithium-Manganese-Rich), LMX (Lithium-Manganese-Rich, Co free), OLO (Over Lithiated layered Oxide), LCO (Lithium Cobalt Oxide), or DRX (Disordered Rocksalt), thereby suppressing side reactions inside the battery and lowering charge / discharge resistance, resulting in improved charging efficiency and output.

[0084] The above carbonate-based compound may be included in an amount of 0.1 to 10 weight% based on 100 weight% of the total secondary battery electrolyte, 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 0.2 to 1.0 weight%. Within the above range, the effect of improving the charging efficiency and high-temperature life of the battery may be the best.

[0085]

[0086] The acid anhydride compound included in the electrolyte according to the present invention may be succinic anhydride, etc. In this case, a stable film is formed on the positive and negative electrodes of various lithium secondary batteries including high nickel, mid nickel, Si anode, LFP (lithium iron phosphate), NMX (Nickel-Manganese, Co free), LMR (Lithium-Manganese-Rich), LMX (Lithium-Manganese-Rich, Co free), OLO (Over Lithiated layered Oxide), LCO (Lithium Cobalt Oxide), or DRX (Disordered Rocksalt), thereby suppressing side reactions inside the battery and lowering charge / discharge resistance, resulting in improved charging efficiency and output.

[0087] The above acid anhydride compound may be included in an amount of 0.1 to 10 weight% based on 100 weight% of the total secondary battery electrolyte, 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 0.2 to 1.0 weight%. Within the above range, the effect of improving the charging efficiency and high-temperature life of the battery may be the best.

[0088]

[0089] The silane-based compound included in the electrolyte according to the present invention may be tetravinyl silane, etc. In this case, a stable film is formed on the positive and negative electrodes of various lithium secondary batteries including high nickel, mid nickel, Si anode, LFP (lithium iron phosphate), NMX (Nickel-Manganese, Co free), LMR (Lithium-Manganese-Rich), LMX (Lithium-Manganese-Rich, Co free), OLO (Over Lithiated layered Oxide), LCO (Lithium Cobalt Oxide), or DRX (Disordered Rocksalt), thereby suppressing side reactions inside the battery and lowering charge / discharge resistance, resulting in improved charging efficiency and output.

[0090] The above silane compound may be included in an amount of 0.1 to 10 weight% based on 100 weight% of the total secondary battery electrolyte, 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 0.2 to 1.0 weight%. Within the above range, the effect of improving the charging efficiency and high-temperature life of the battery may be the best.

[0091]

[0092] The amine-based compound included in the electrolyte according to the present invention may be hexamethyleneterramine, etc. In this case, a stable film is formed on the positive and negative electrodes of various lithium secondary batteries including high nickel, mid nickel, Si anode, LFP (lithium iron phosphate), NMX (Nickel-Manganese, Co free), LMR (Lithium-Manganese-Rich), LMX (Lithium-Manganese-Rich, Co free), OLO (Over Lithiated layered Oxide), LCO (Lithium Cobalt Oxide), or DRX (Disordered Rocksalt), thereby suppressing side reactions inside the battery and lowering the charge / discharge resistance, resulting in improved charging efficiency and output.

[0093] The above amine-based compound may be included in an amount of 0.1 to 10 weight% based on 100 weight% of the total secondary battery electrolyte, 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 0.2 to 1.0 weight%. Within the above range, the effect of improving the charging efficiency and high-temperature life of the battery may be the best.

[0094]

[0095] The ether-based compound included in the electrolyte according to the present invention is characterized by being selected from one or more of 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoroethyl ether. In this case, a stable film is formed on the positive and negative electrodes of various lithium secondary batteries, including high nickel, mid nickel, Si cathode, LFP (lithium iron phosphate), NMX (Nickel-Manganese, Co free), LMR (Lithium-Manganese-Rich), LMX (Lithium-Manganese-Rich, Co free), OLO (Over Lithiated layered Oxide), LCO (Lithium Cobalt Oxide), or DRX (Disordered Rocksalt), thereby suppressing side reactions inside the battery and lowering charge / discharge resistance, resulting in improved charging efficiency and output.

[0096] The above ether-based compound may be included in an amount of 0.1 to 10 weight% based on 100 weight% of the total secondary battery electrolyte, 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 0.2 to 1.0 weight%. Within the above range, the effect of improving the charging efficiency and high-temperature life of the battery may be the best.

[0097]

[0098] The fluorophosphorane-based compound included in the electrolyte according to the present invention is characterized by being selected from one or more of 1,2-bis((difluorophosphanyl)oxy)ethane, 2-fluoro-4-methyl-[1,3,2]-dioxaphosphorane, and difluoro((4-methylpentane-2-yl)oxy)phosphane. In this case, a stable film is formed on the positive and negative electrodes of various lithium secondary batteries, including high nickel, mid nickel, Si anode, LFP (lithium iron phosphate), NMX (Nickel-Manganese, Co free), LMR (Lithium-Manganese-Rich), LMX (Lithium-Manganese-Rich, Co free), OLO (Over Lithiated layered Oxide), LCO (Lithium Cobalt Oxide), or DRX (Disordered Rocksalt), thereby suppressing side reactions inside the battery and lowering charge / discharge resistance, resulting in improved charging efficiency and output.

[0099] The above fluorophosphorane compound may be included in an amount of 0.1 to 10 weight% based on 100 weight% of the total secondary battery electrolyte, 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 0.2 to 1.0 weight%. Within the above range, the effect of improving the charging efficiency and high-temperature life of the battery may be the best.

[0100]

[0101] The nitrile-based compound included in the electrolyte according to the present invention is characterized by being selected from one or more of 1,3,6-hexanetricarbonitrile, succinonitrile, adiponitrile, and 1-ethyl-3-methylimidazolium dicyanamide, and in this case, a stable film is formed on the positive and negative electrodes of various lithium secondary batteries including high nickel, mid nickel, Si anode, LFP (lithium iron phosphate), NMX (Nickel-Manganese, Co free), LMR (Lithium-Manganese-Rich), LMX (Lithium-Manganese-Rich, Co free), OLO (Over Lithiated layered Oxide), LCO (Lithium Cobalt Oxide), or DRX (Disordered Rocksalt), thereby suppressing side reactions inside the battery and lowering charge / discharge resistance, resulting in improved charging efficiency and output.

[0102] The above nitrile-based compound may be included in an amount of 0.1 to 10 weight% based on 100 weight% of the total secondary battery electrolyte, 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 0.2 to 1.0 weight%. Within the above range, the effect of improving the charging efficiency and high-temperature life of the battery may be the best.

[0103]

[0104] The boron-based compound included in the electrolyte according to the present invention is characterized by being selected from one or more of lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium tetrafluoroborate, tris(trimethylsilyl)borate, triisopropyl borate, and trimethoxyboroxine. In this case, a stable film is formed on the positive and negative electrodes of various lithium secondary batteries, including high nickel, mid nickel, Si anode, LFP (lithium iron phosphate), NMX (Nickel-Manganese, Co free), LMR (Lithium-Manganese-Rich), LMX (Lithium-Manganese-Rich, Co free), OLO (Over Lithiated layered Oxide), LCO (Lithium Cobalt Oxide), or DRX (Disordered Rocksalt), thereby suppressing side reactions inside the battery and lowering charge / discharge resistance, resulting in improved charging efficiency and output.

[0105] The above boron-based compound may be included in an amount of 0.1 to 10 weight% based on 100 weight% of the total secondary battery electrolyte, 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 0.2 to 1.0 weight%. Within the above range, the effect of improving the charging efficiency and high-temperature life of the battery may be the best.

[0106]

[0107] The phosphorus-containing compound included in the electrolyte according to the present invention is characterized by being selected from one or more of lithium tetrafluoro(oxalato)phosphate, lithium difluoro(bisoxalato)phosphate, lithium difluorophosphate, diethyl(difluoromethyl)phosphonate, tris(trimethylsilyl)phosphite, tripropargyl phosphate, and triphenyl phosphate. In this case, a stable film is formed on the positive and negative electrodes of various lithium secondary batteries, including high nickel, mid nickel, Si anode, LFP (lithium iron phosphate), NMX (Nickel-Manganese, Co free), LMR (Lithium-Manganese-Rich), LMX (Lithium-Manganese-Rich, Co free), OLO (Over Lithiated layered Oxide), LCO (Lithium Cobalt Oxide), or DRX (Disordered Rocksalt), thereby suppressing side reactions inside the battery and lowering charge / discharge resistance, resulting in improved charging efficiency and output.

[0108] The above phosphorus-containing compound may be included in an amount of 0.1 to 10 weight% based on 100 weight% of the total secondary battery electrolyte, 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 0.2 to 1.0 weight%. Within the above range, the effect of improving the charging efficiency and high-temperature life of the battery may be the best.

[0109]

[0110] The sulfur-based compound included in the electrolyte according to the present invention is characterized by being selected from one or more of butadiene sulfone, dimethyl sulfate, ethylene dimethanesulfonate, lithium bis(fluorosulfonyl)imidazole, 1,3-propylene sulfate, ethylene sulfate, 1,-propene-1,3-sulfone, 1,3-propanesulfone, 2,4,8,10-tetraoxa-3,9-dithiaspiro[5,5[undecane, 3,3,9,9-tetraoxide, methylene methyl disulfonate, 3-fluoro-1,3-propanesulfone, and 1,4-butanesulfone, and in this case, high nickel, mid nickel, Si cathode, LFP (lithium iron phosphate), NMX (Nickel-Manganese, Co free), LMR (Lithium-Manganese-Rich), LMX (Lithium-Manganese-Rich, Co free), By forming a stable film on the positive and negative electrodes of various lithium secondary batteries, including OLO (Over Lithiated layered Oxide), LCO (Lithium Cobalt Oxide), or DRX (Disordered Rocksalt), side reactions inside the battery are suppressed, and the charge / discharge resistance is lowered, which has the effect of improving charging efficiency and output.

[0111] The above sulfur-based compound may be included in an amount of 0.1 to 10 weight% based on 100 weight% of the total secondary battery electrolyte, 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 0.2 to 1.0 weight%. Within the above range, the effect of improving the charging efficiency and high-temperature life of the battery may be the best.

[0112]

[0113] The aromatic compound included in the electrolyte according to the present invention is characterized by being selected from one or more of biphenyl, cyclohexylbenzene, 4-fluorotoluene, fluorobenzene, and 2-fluorobiphenyl. In this case, a stable film is formed on the positive and negative electrodes of various lithium secondary batteries, including high nickel, mid nickel, Si anode, LFP (lithium iron phosphate), NMX (Nickel-Manganese, Co free), LMR (Lithium-Manganese-Rich), LMX (Lithium-Manganese-Rich, Co free), OLO (Over Lithiated layered Oxide), LCO (Lithium Cobalt Oxide), or DRX (Disordered Rocksalt), thereby suppressing side reactions inside the battery and lowering charge / discharge resistance, resulting in improved charging efficiency and output.

[0114] The above aromatic compound may be included in an amount of 0.1 to 10 weight% based on 100 weight% of the total secondary battery electrolyte, 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 0.2 to 1.0 weight%. Within the above range, the effect of improving the charging efficiency and high-temperature life of the battery may be the best.

[0115]

[0116] The above electrolyte additive may be included in an amount of 0.1 to 10 weight% based on 100 weight% of the total secondary battery electrolyte, preferably 0.1 to 5 weight%, and more preferably 0.1 to 3.0 weight%. Within the above range, the effect of improving the charging efficiency and high-temperature life of the battery may be the best.

[0117] The above electrolyte additive may be included in an amount of 0.1 to 10 weight% of the above-mentioned dioxaphosphorane compound based on 100 weight% of the total secondary battery electrolyte, preferably 0.1 to 5 weight%, more preferably 0.1 to 2.0 weight%, even more preferably 0.1 to 1.0 weight%, most preferably 0.2 to 1.0 weight%; and may be included in an amount of 0.1 to 10 weight% of one or more compounds selected from carbonate compounds, acid anhydride compounds, silane compounds, amine compounds, ether compounds, fluorophosphorane compounds, nitrile compounds, boron compounds, phosphorus compounds, sulfur compounds, and aromatic compounds, preferably 0.1 to 5 weight%, more preferably 0.1 to 2.0 weight%, even more preferably 0.1 to 1.0 weight%, most preferably 0.2 to 1.0 weight%. Within the above range, the effect of improving battery charging efficiency and high-temperature life can be the best.

[0118] The above electrolyte additive may be a dioxaphosphorane compound; and one or more compounds selected from carbonate compounds, acid anhydride compounds, silane compounds, amine compounds, ether compounds, fluorophosphorane compounds, nitrile compounds, boron compounds, phosphorus compounds, sulfur compounds, and aromatic compounds, in a weight ratio of 1:1 to 1:10, preferably in a weight ratio of 1:1 to 1:8, and more preferably in a weight ratio of 1:2 to 1:7. Within the above range, the effect of improving the charging efficiency and high-temperature life of the battery may be the best.

[0119]

[0120] The electrolyte additives additionally included in the above-mentioned dioxaphosphorane-based compound may be, for example, one or more selected from the following chemical formulas 2-1 to 2-45.

[0121] [Chemical Formulas 2-1 to 2-45]

[0122]

[0123]

[0124] The electrolyte of the present invention may, for example, include additional additives that can generally be used in electrolytes 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, in addition to the electrolyte additives mentioned above.

[0125]

[0126] The above electrolyte additive may be included in the aforementioned electrolyte in an amount equal to the total content of all components used, for example, 0.1 to 20.1 wt%, 0.1 to 18.0 wt%, 0.1 to 17 wt%, 0.3 to 17 wt%, 0.5 to 13 wt%, or 0.5 to 10 wt%. When the electrolyte additive content satisfies the above ranges, it is desirable in terms of the effect of improving the high-temperature characteristics and cycle characteristics of the battery.

[0127]

[0128] It is more preferable that the aforementioned additive component be additionally included in the aforementioned dioxaphosphorane-based compound, as it was confirmed through the experimental examples described below that when other additive components are injected alone without the aforementioned dioxaphosphorane-based compound, the improvement effect on long-term lifespan and low resistance is poor.

[0129]

[0130] The present invention also provides an electrolyte comprising the electrolyte additive of the present invention. The electrolyte is an electrolyte for a non-aqueous lithium secondary battery and comprises the electrolyte additive, an organic solvent, and a lithium salt.

[0131] The above organic solvent may be, for example, a carbonate-based organic solvent, and specifically, may be an organic solvent comprising 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, ethylpropyl carbonate, and 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether.

[0132] 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.

[0133] Examples of the above high dielectric constant organic solvents may include EC and PC, and examples of the above low viscosity organic solvents may include EMC, DMC, and DEC, and 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 or PC and EMC and DEC, and the ratio (volume ratio) of EC or PC and EMC and DEC may be, for example, 1:0.1 to 1:2 to 5, or 1:0.2 to 0.5:3 to 5, or 1:0.2 to 0.3:3 to 4.

[0134] Since the above organic solvent may hydrolyze lithium ions in the electrolyte if it contains water, it is desirable to control the water content in the organic solvent to 150 ppm or less, preferably 100 ppm or less.

[0135] The above lithium salt may be used without special restrictions as long as it is a compound capable of providing lithium ions used in lithium secondary batteries, and specifically, LiPF6, LiBF4, LiCl, LiBr, LiI, LiClO4, LiB 10 Cl 10 It may include one or more selected from the group consisting of LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, (FSO2)2NLi, and (CF3SO2)2NLi. Preferably, it may be LiPF6.

[0136] 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%.

[0137] The above electrolyte additive may be included in the electrolyte in an amount of, for example, 0.1 to 10.1 wt%, 0.1 to 8.0 wt%, 0.1 to 7 wt%, 0.3 to 7 wt%, 0.5 to 6 wt%, or 0.5 to 5 wt%. It is desirable for the above electrolyte additive content to satisfy the above ranges in terms of the effect of improving the high-temperature characteristics and cycle characteristics of the battery.

[0138]

[0139] The secondary battery of the present invention is characterized by comprising a negative electrode, a positive electrode, a separator interposed between the negative electrode and the positive electrode, and the electrolyte.

[0140] 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.

[0141] 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.

[0142] The above-mentioned positive electrode active material may be a conventional NCM (lithium nickel manganese cobalt oxide, LiNiMnCoO2) positive electrode active material used in lithium secondary batteries, and for example, the chemical formula Li[Ni x Co y M z ]O2(where M is Mn and / or Al, 0 <x<98, 0<y<35, 0<z<35, 단 x+y+z=100이다.) 형태의 리튬 복합금속 산화물일 수 있으나 이에 제한되는 것은 아니다.

[0143] The chemical formula of the above lithium complex metal oxide is Li[NixCoyM z The variables x, y, and z of ]O2 are, for example, 0.0001 <x<98, 0.0001<y<35, 0.0001<z<35일 수 있고, 구체적으로는 1≤x≤93, 1≤y≤30, 1≤z≤30일 수 있으며, 보다 바람직하게는 5≤x≤91, 3≤y≤25, 3≤z≤25일 수 있고, 이때 x+y+z는 100을 만족한다.

[0144] The above variables x, y, and z can provide a high-nickel cathode material by satisfying 80≤x≤91, 3≤y≤25, and 1≤z≤25, and can provide a mid-nickel cathode material by satisfying 50≤x≤80, 0.5≤y≤35, and 0.5≤z≤35.

[0145] Unless otherwise specified, the above high-nickel cathode material contains 80 mol% or more of Ni, preferably 80 to 95 mol%, more preferably 80 to 93 mol%, and even more preferably 80 to 91 mol% based on 100 mol% of the total remaining metals excluding Li, and within this range, the initial discharge capacity, output performance, capacity characteristics, and resistance characteristics of the lithium-ion battery have excellent effects.

[0146] For example, high-nickel batteries with an operating voltage in the range of 2.0 to 4.3 V are applicable, and specific examples include NCM811 (nickel 80%, cobalt 10%, manganese 10%) and NCA (nickel 80% or more, cobalt 15%, aluminum 5%), which have the effect of very high energy density required in high-performance applications such as electric vehicles.

[0147] Unless otherwise specified, the above mid-nickel cathode material contains 50 to 79 mol%, preferably 50 to 75 mol%, and more preferably 50 to 70 mol% of Ni based on 100 mol% of the total metals excluding Li, and within this range, the initial discharge capacity, output performance, capacity characteristics, and resistance characteristics of the lithium-ion battery are excellent. For example, mid-nickel batteries with an operating voltage in the range of 2.0 to 4.5 V are applicable, and specific examples include NCM523 (nickel 50%, cobalt 20%, manganese 30%), NCM613 (nickel 60%, cobalt 10%, manganese 30%), NCM622 (nickel 60%, cobalt 20%, manganese 20%), etc., which have excellent stability and lifespan, and there are also high-voltage NCM products, etc., as they have lower energy density compared to high-nickel.

[0148] The above lithium-ion battery cathode material may be, for example, a high-nickel cathode material, a mid-nickel cathode material, or a lithium iron phosphate cathode material.

[0149] As another example of the above lithium complex metal oxide, a compound with an olivine structure can be used.

[0150] The compound with the above olivine structure may be, for example, a compound represented by the following chemical formula 2, and in this case, it has the advantages of excellent high-temperature stability and lifespan characteristics and excellent economic efficiency.

[0151] [Chemical Formula 2]

[0152]

[0153] (In the above chemical formula 2, M comprises one or more elements selected from the group consisting of Al, Mg, Ni, Co, Mn, Ti, Ga, Cu, V, Nb, Zr, Ce, In, Zn, and Y, X comprises one or more elements selected from the group consisting of F, S, and N, and a, b, and c are each -0.5≤a≤0.5, 0≤b≤0.5, and 0≤c≤0.1.)

[0154] The above-mentioned compound having an olivine structure may preferably include LiFePO4 having an olivine structure, and for example, an LFP (lithium iron phosphate) battery or LMFP battery having an operating voltage in the range of 2.0 to 4.0 V is applicable, and as a specific example, in this case, there are advantages such as excellent high-temperature stability and lifespan characteristics and excellent economic efficiency.

[0155] 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.

[0156] 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.

[0157]

[0158] 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.

[0159] 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.

[0160]

[0161] In addition, the above-mentioned positive active material can be used in NMX (Nickel-Manganese, Co-free) batteries with an operating voltage range of 2.0 to 4.6 V, LMR (Lithium-Manganese-Rich) batteries with an operating voltage of 2.0 to 4.8 V, LMX (Lithium-Manganese-Rich, Co-free) batteries with an operating voltage of 2.0 to 4.8 V, OLO (Over Lithiated layered Oxide) batteries with an operating voltage of 2.0 to 4.8 V, LCO (Lithium Cobalt Oxide) batteries with an operating voltage of 2.0 to 4.8 V, DRX (Disordered Rocksalt) batteries with an operating voltage of 2.0 to 4.8 V, etc.

[0162] As a specific example, the above NMX (Nickel-Manganese, Co-free) battery has the chemical formula Li[NixCoyM of the above lithium composite metal oxide. z As variables x, y, and z of ]O2, for example, 0.001 <x<0.999, y=0, 0.001<z<0.999일 수 있고, 구체적으로는 0.01≤x≤0.97, y=0, 0.03≤z≤0.99일 수 있고 이때 x+z는 1을 만족한다.

[0163] The above LCO (Lithium Cobalt Oxide) battery may have the chemical formula LiCoO2 of the above lithium composite metal oxide.

[0164] The above LMR (Lithium-Manganese-Rich, OLO) battery is a lithium composite metal oxide with the chemical formula xLi2MnO3·(1-x)LiNi a Co b Mn c As variables x, a, b, and c of O2, for example, 0.1 <x<0.99이고, a+b+c는 1을 만족하는 범위 내에서 a, b, c 값을 가질 수 있다.

[0165] The above LMX (Lithium-Manganese-Rich, Co-free) battery is a lithium composite metal oxide with the chemical formula xLi2MnO3·(1-x)LiNi a Mn c As variables x, a, and c of O2, for example, 0.1 <x<0.99, a+c는 1을 만족하는 범위 내에서 a, c 값을 가질 수 있다.

[0166]

[0167] 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.

[0168] 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.

[0169] 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.

[0170] 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.

[0171] Al can be used as the current collector, but is not limited to it.

[0172]

[0173] 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.

[0174] The surface of the above cathode may further include a solid electrolyte interface (SEI) film.

[0175] 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.

[0176] 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.

[0177] 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.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] Examples of the above transition metal oxides include vanadium oxide, lithium vanadium oxide, or lithium titanium oxide.

[0183] 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.

[0184] 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.

[0185] 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%.

[0186] 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.

[0187] 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.

[0188] Examples of the above-mentioned water-soluble binders include rubber-based binders or polymer resin binders.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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.

[0193] 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.

[0194] 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.

[0195] 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.

[0196]

[0197] 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.

[0198]

[0199] The secondary battery of the present invention has the effect of significantly improving battery characteristics, such as battery charge resistance, output characteristics, capacity recovery characteristics, and lifespan characteristics, even when stored for more than 28 days at a high temperature of 60°C or higher, by adding the electrolyte additive together with the conventional compound added to the electrolyte to improve battery performance, thereby effectively scavenging hydrofluoric acid among the by-products caused by the instability of each high-nickel / mid-nickel / lithium iron phosphate anode compared to when only the conventional electrolyte additive is added, thereby suppressing the increase in acidity of the electrolyte and the leaching of transition metal ions from the anode.

[0200] Specifically, the secondary battery of the present invention may have an HPPC discharge resistance value of 60 mΩ or less, preferably 55 mΩ or less, measured after storage at 60°C for 28 days.

[0201] In this description, the HPPC charge (discharge) resistance value can be measured by the method specified in the literature “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, charge (discharge) resistance refers to the resistance value measured during the charging (discharging) of a battery; the lower the charge (discharge) 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 discharge resistance value as described above, resulting in excellent charging speed and output, making it suitable for use, for example, as an automotive battery.

[0202] The above secondary battery exhibits a recovery capacity retention rate of 75% or more, 77% or more, and 80 to 94% when measured after storage at 60°C for 28 days.

[0203] 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 indicates that the amount of natural discharge due to battery preservation (storage) is smaller, meaning 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 the electrolyte additive of the present invention is added to the electrolyte, the recovery capacity is improved by, for example, up to 11%, and specifically, by 9 to 11% compared to when only conventional additives are used, thereby providing the effect of enabling longer storage with a single charge.

[0204] The above secondary battery may have a lifespan efficiency of 80% or more, 83% or more, or 83.1 to 97.4% when measured after being stored at 60°C for 28 days.

[0205] The above secondary battery may have a volume (thickness) increase rate of 52% or less, 48.5% or less, 3 to 41.5%, or 3.5 to 40.2% at 60°C.

[0206] In the case where the above secondary battery is a high-nickel full-cell battery, the resistance increase rate at 60°C may be 70% or less, 60% or less, 5 to 50%, or 3 to 40%.

[0207] In the case where the above secondary battery is a mid-nickel full-cell battery, the resistance increase rate at 60°C may be 70% or less, 60% or less, 5 to 50%, or 3 to 40%.

[0208] If the above secondary battery is an LFP battery or an LMFP battery, the resistance increase rate at 60°C may be 105% or less, 103% or less, 1 to 103%, or 3 to 103%.

[0209] If the secondary battery is an LMR(OLO) battery, an LMX battery, or an LCO battery, the resistance increase rate at 60°C may be 80% or less, 70% or less, 1 to 60%, or 3 to 50%.

[0210]

[0211] Therefore, when the battery of the present invention is used as an automotive battery, even if a high-content nickel cathode material is applied to improve output, which becomes important depending on the size of the vehicle, and to improve performance at low and high temperatures, which is problematic due to the characteristics of the vehicle being exposed to sunlight during driving or parking due to climate change, it is possible to effectively scavenge hydrofluoric acid among the by-products caused by the instability of each cathode of various secondary batteries, including high-nickel / mid-nickel / lithium iron phosphate, thereby suppressing the increase in acidity of the electrolyte and the leaching of transition metal ions from the cathode to ensure stability, so that it can exhibit excellent performance as an automotive battery.

[0212]

[0213] 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.

[0214]

[0215] Example 1-1

[0216] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1 and 1.0 wt% of a carbonate-based compound represented by Chemical Formula 2-1.

[0217]

[0218] Examples 1-2

[0219] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1 and 1.0 wt% of a carbonate-based compound represented by Chemical Formula 2-2.

[0220]

[0221] Comparative Example 1-1

[0222] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 as the organic solvent and adding 1.0 wt% of a carbonate-based compound represented by Chemical Formula 2-1 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt. For reference, Comparative Example 1-1 corresponds to an experiment in which no dioxaphosphorane-based compound represented by Chemical Formula 1-1 was used.

[0223]

[0224] Comparative Example 1-2

[0225] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 as the organic solvent and adding 1.0 wt% of a carbonate-based compound represented by Chemical Formula 2-2 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt. For reference, Comparative Example 1-2 corresponds to an experiment in which no dioxaphosphorane-based compound represented by Chemical Formula 1-1 was used.

[0226]

[0227] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 as the organic solvent and adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt. For reference, the control group corresponds to an experiment in which no carbonate-based compound represented by Chemical Formula 2-1 or 2-2 was used.

[0228]

[0229] Manufacturing of NCM batteries

[0230] Li(Ni as a positive electrode active material 0.6 Co 0.1 Mn 0.3 An anode mixture slurry was prepared by adding 292 wt% of )O, 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 anode mixture slurry was applied to an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0231] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0232] After fabricating 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), the lithium secondary battery was manufactured by injecting each electrolyte prepared in Examples 1-1 to 1-2, Comparative Examples 1-1 to 1-2, and the Control Example.

[0233]

[0234] Test Example 1

[0235] To evaluate the performance of the NCM-based secondary battery manufactured above, the performance was evaluated using the following method, and the results are summarized in Table 1 below.

[0236]

[0237] [HPPC Charge (Discharge) Resistance Evaluation]

[0238] 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.).

[0239] After storing at 60℃ for 28 days, 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 charge resistance, and the discharge 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.

[0240] For reference, the initial discharge DC-IR value measured in the control example was 63.8 mΩ.

[0241]

[0242] [High-temperature storage DC-IR, recovery capacity evaluation]

[0243] The charging conditions were performed by charging at a constant current of 0.5C and a voltage of 4.4V until the charging current became 1 / 10C. The discharging conditions were performed by charging and discharging at a constant current of 0.5C to 3.0V, after which the discharge capacity was measured.

[0244] After charging under the same charge-discharge conditions and storing at 60°C for 28 days, the change in remaining capacity was measured after discharging to a discharge voltage of 3V under the same conditions, and the high-temperature storage DC-IR increase rate and recovery capacity retention rate are shown in Table 1 below.

[0245] For reference, the high-temperature storage DC-IR growth rate measured in the control example was 52.6%, and the high-temperature storage recovery capacity retention rate was 93.0%.

[0246]

[0247] [Volume (Thickness) Increase Rate]

[0248] After measuring the initial thickness of the above secondary battery after formation, the thickness was measured after high-temperature storage, and the volume (thickness) increase rate was measured according to the following mathematical formula 1.

[0249] [Mathematical Formula 1]

[0250] Volume (Thickness) Increase Rate (%) = Thickness (After High-Temperature Storage) - Thickness (Before Test) / Thickness (Before Test) X 100

[0251] For reference, the volume increase rate after high-temperature storage measured in the control example was 17.0%.

[0252]

[0253] [High Temperature Life Evaluation]

[0254] The above secondary battery was charged at a constant current rate of 1C at 60°C until the voltage reached 4.4V (vs. Li), and then cut off at a current rate of 0.1C while maintaining 4.4V 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 300 times, the changes in capacity and retention rate were measured, and the lifespan efficiency was measured.

[0255] For reference, the lifespan efficiency measured in the control example was 88.8%.

[0256] Classification Initial Discharge DC-IR (mΩ) High-Temperature Storage DC-IR Growth Rate (%) High-Temperature Storage Recovery Capacity Retention Rate (%) Volume Increase Rate After High-Temperature Storage (%) Lifetime Efficiency (%) Example 1-17 1.26 4.59 0.81 8.98 8.9 Example 1-26 5.95 8.99 3.52 0.28 9.1 Comparative Example 1-18 0.275 98 8.42 7.88 1.4 Comparative Example 1-275 28 0.59 1.23 2.58 2.2

[0257] As shown in Table 1 above, in the case of Examples 1-1 to 1-2, which are electrolyte additives of the present invention, it was confirmed that the initial discharge resistance, resistance growth rate, high-temperature recovery capacity, thickness growth rate, and high-temperature life capacity efficiency in NCM batteries were all improved compared to Comparative Examples 1-1 to 1-2, which did not use a dioxaphosphorane-based compound. In particular, a significant difference was observed in the resistance growth rate of the battery before and after high-temperature storage. It was confirmed that the improvement was significant in Examples 1-1 to 1-2 according to the present invention, with an improvement of 15.0 to 26.8% compared to Comparative Examples 1-1 to 1-2. In addition, a significant difference was observed in the recovery capacity growth rate after high-temperature storage. It was confirmed that the improvement was significant in Examples 1-1 to 1-2 according to the present invention, with an improvement of 2.7 to 5.8% compared to Comparative Examples 1-1 to 1-2.

[0258] Differences were also observed in lifespan efficiency. It was confirmed that Examples 1-1 to 1-2 according to the present invention showed a significant improvement of 8.2 to 9.5% compared to Comparative Examples 1-1 to 1-2.

[0259] Furthermore, as a result of measuring the change in thickness of the battery before and after high-temperature storage, it was confirmed that the electrolyte additive of the present invention significantly suppresses the oxidation / reduction decomposition of the electrolyte and also has the effect of reducing the amount of gas generated. It was confirmed that Examples 1-1 to 1-2 according to the present invention showed a significant improvement of 27.3 to 41.8% compared to Comparative Examples 1-1 to 1-2.

[0260]

[0261] Example 2-1

[0262] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1 and 1.0 wt% of a nitrile-based compound represented by Chemical Formula 2-45.

[0263]

[0264] Example 2-2

[0265] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1 and 1.0 wt% of a nitrile-based compound represented by Chemical Formula 2-13.

[0266]

[0267] Examples 2-3

[0268] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1 and 1.0 wt% of a nitrile-based compound represented by Chemical Formula 2-12.

[0269]

[0270] Comparative Example 2-1

[0271] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 as the organic solvent and adding 1.0 wt% of a nitrile-based compound represented by the above chemical formula 2-45 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt. For reference, Comparative Example 2-1 corresponds to an experiment in which no dioxaphosphorane-based compound represented by the above chemical formula 1-1 was used.

[0272]

[0273] Comparative Example 2-2

[0274] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 as the organic solvent and adding 1.0 wt% of a nitrile-based compound represented by Chemical Formula 2-13 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt. For reference, Comparative Example 2-2 corresponds to an experiment in which the dioxaphosphorane-based compound represented by Chemical Formula 1-1 was not used at all.

[0275]

[0276] Comparative Example 2-3

[0277] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 as the organic solvent and adding 1.0 wt% of a nitrile-based compound represented by Chemical Formula 2-12 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt. For reference, Comparative Example 2-3 corresponds to an experiment in which the dioxaphosphorane-based compound represented by Chemical Formula 1-1 was not used at all.

[0278]

[0279] Manufacturing of NCM batteries

[0280] Li(Ni as a positive electrode active material 0.6 Co 0.1 Mn 0.3 An anode mixture slurry was prepared by adding 292 wt% of )O, 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 anode mixture slurry was applied to an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0281] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0282] 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), the manufacturing of a lithium secondary battery was completed by injecting each electrolyte prepared in Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-3.

[0283]

[0284] Test Example 2

[0285] To evaluate the performance of the NCM-based secondary battery manufactured above, the performance was evaluated using the method described above, and the results are summarized in Table 2 below.

[0286] Classification Initial Discharge DC-IR (mΩ) High-Temperature Storage DC-IR Growth Rate (%) High-Temperature Storage Recovery Capacity Retention Rate (%) Volume Increase Rate After High-Temperature Storage (%) Lifetime Efficiency (%) Example 2-1 56.3 78.5 90.1 22.5 83.9 Example 2-2 55.5 60.5 89.5 20.2 85.6 Example 2-3 57.9 58.5 92.1 18.2 87.5 Comparative Example 2-16 4.2 204.6 55.2 25.2 78.9 Comparative Example 2-26 3.8 117.8 47.1 20.8 77.8 Comparative Example 2-3 65.9 77.6 80.6 18.7 80.1

[0287] As shown in Table 2 above, in the case of Examples 2-1 to 2-3, which are electrolyte additives of the present invention, it was confirmed that the initial discharge resistance, resistance growth rate, high-temperature recovery capacity, thickness growth rate, and high-temperature life capacity efficiency in NCM batteries were all improved compared to Comparative Examples 2-1 to 2-3, which did not use a dioxaphosphorane-based compound. In particular, a significant difference was observed in the resistance growth rate of the battery before and after high-temperature storage. It was confirmed that the improvement was significant in Examples 2-1 to 2-3 according to the present invention, with an improvement of 24.6 to 61.6% compared to Comparative Examples 2-1 to 2-3. In addition, a significant difference was observed in the recovery capacity growth rate after high-temperature storage. It was confirmed that the improvement was significant in Examples 2-1 to 2-3 according to the present invention, with an improvement of 14.2 to 90.0% compared to Comparative Examples 2-1 to 2-3.

[0288] Differences were also observed in lifespan efficiency. It was confirmed that Examples 2-1 to 2-3 according to the present invention showed a significant improvement of 6.3 to 10.0% compared to Comparative Examples 2-1 to 2-3.

[0289] Furthermore, as a result of measuring the change in thickness of the battery before and after high-temperature storage, it was confirmed that the electrolyte additive of the present invention significantly suppresses the oxidation / reduction decomposition of the electrolyte and also has the effect of reducing the amount of gas generated. It was confirmed that Examples 2-1 to 2-3 according to the present invention showed a significant improvement of 2.7 to 10.7% compared to Comparative Examples 2-1 to 2-3.

[0290]

[0291] Example 3-1

[0292] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1 and 0.5 wt% of a boron-based compound represented by Chemical Formula 2-15.

[0293]

[0294] Example 3-2

[0295] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1 and 0.5 wt% of a boron-based compound represented by Chemical Formula 2-16.

[0296]

[0297] Comparative Example 3-1

[0298] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 as the organic solvent and adding 0.5 wt% of a boron-based compound represented by Chemical Formula 2-15 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt. For reference, Comparative Example 3-1 corresponds to an experiment in which no dioxaphosphorane-based compound represented by Chemical Formula 1-1 was used.

[0299]

[0300] Comparative Example 3-2

[0301] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 as the organic solvent and adding 0.51 wt% of a boron-based compound represented by Chemical Formula 2-16 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt. For reference, Comparative Example 3-2 corresponds to an experiment in which the dioxaphosphorane-based compound represented by Chemical Formula 1-1 was not used at all.

[0302]

[0303] Manufacturing of NCM batteries

[0304] Li(Ni as a positive electrode active material 0.6 Co 0.1 Mn 0.3 An anode mixture slurry was prepared by adding 292 wt% of )O, 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 anode mixture slurry was applied to an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0305] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0306] 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), the manufacturing of a lithium secondary battery was completed by injecting each electrolyte prepared in Examples 3-1 to 3-2 and Comparative Examples 3-1 to 3-2.

[0307]

[0308] Test Example 3

[0309] To evaluate the performance of the NCM-based secondary battery manufactured above, the performance was evaluated using the method described above, and the results are summarized in Table 3 below.

[0310] Classification Initial Discharge DC-IR (mΩ) High-Temperature Storage DC-IR Growth Rate (%) High-Temperature Storage Recovery Capacity Retention Rate (%) Volume Increase Rate After High-Temperature Storage (%) Lifetime Efficiency (%) Example 3-16 3.8 40.4 87.5 18.9 87.5 Example 3-26 1.2 60.2 89.2 17.5 89.1 Comparative Example 3-16 5.9 128.4 77.7 23.0 85.4 Comparative Example 3-26 2.4 10 3.1 82.2 20.8 86.9

[0311] As shown in Table 3 above, in the case of Examples 3-1 to 3-2, which are electrolyte additives of the present invention, it was confirmed that the initial discharge resistance, resistance growth rate, high-temperature recovery capacity, thickness growth rate, and high-temperature life capacity efficiency in NCM batteries were all improved compared to Comparative Examples 3-1 to 3-2, which did not use dioxaphosphorane-based compounds. In particular, a significant difference was observed in the resistance growth rate of the battery before and after high-temperature storage. It was confirmed that the improvement was significant in Examples 3-1 to 3-2 according to the present invention, with an improvement of 41.6 to 68.5% compared to Comparative Examples 3-1 to 3-2. In addition, a significant difference was also observed in the recovery capacity growth rate after high-temperature storage. It was confirmed that the improvement was significant in Examples 3-1 to 3-2 according to the present invention, with an improvement of 8.5 to 12.6% compared to Comparative Examples 3-1 to 3-2.

[0312] Differences were also observed in lifespan efficiency. It was confirmed that Examples 3-1 to 3-2 according to the present invention showed a significant improvement of 2.5% compared to Comparative Examples 3-1 to 3-2.

[0313] Furthermore, as a result of measuring the change in thickness of the battery before and after high-temperature storage, it was confirmed that the electrolyte additive of the present invention significantly suppresses the oxidation / reduction decomposition of the electrolyte and also has the effect of reducing gas generation. It was confirmed that Examples 3-1 to 3-2 according to the present invention showed a significant improvement of 15.9 to 17.8% compared to Comparative Examples 3-1 to 3-2.

[0314]

[0315] Example 4-1

[0316] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1 and 1.0 wt% of a phosphorus-based compound represented by Chemical Formula 2-23.

[0317]

[0318] Comparative Example 4-1

[0319] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 as the organic solvent and adding 1.0 wt% of a phosphorus-based compound represented by Chemical Formula 2-23 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt. For reference, Comparative Example 4-1 corresponds to an experiment in which no dioxaphosphorane-based compound represented by Chemical Formula 1-1 was used.

[0320]

[0321] Manufacturing of NCM batteries

[0322] Li(Ni as a positive electrode active material 0.6 Co0.1 Mn 0.3 An anode mixture slurry was prepared by adding 292 wt% of )O, 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 anode mixture slurry was applied to an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0323] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0324] After fabricating 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), the lithium secondary battery was manufactured by injecting each electrolyte prepared in Example 4-1 and Comparative Example 4-1.

[0325]

[0326] Test Example 4

[0327] To evaluate the performance of the NCM-based secondary battery manufactured above, the performance was evaluated using the method described above, and the results are summarized in Table 4 below.

[0328] Classification Initial Discharge DC-IR (mΩ) High-Temperature Storage DC-IR Growth Rate (%) High-Temperature Storage Recovery Capacity Retention Rate (%) Volume Increase Rate After High-Temperature Storage (%) Lifetime Efficiency (%) Example 4-16 1.24 9.29 2.81 7.29 0.2 Comparative Example 4-16 4.25 5.48 5.72 0.18 7.8

[0329] As shown in Table 4 above, in the case of Example 4-1, which contains the electrolyte additives of the present invention, it was confirmed that the initial discharge resistance, resistance growth rate, high-temperature recovery capacity, thickness growth rate, and high-temperature life capacity efficiency were all improved in the NCM battery compared to Comparative Example 4-1, which did not use a dioxaphosphorane-based compound. In particular, a significant difference was observed in the resistance growth rate of the battery before and after high-temperature storage. It was confirmed that the improvement was significant in Example 4-1 according to the present invention, with an improvement of 11.2% compared to Comparative Example 4-1. In addition, a significant difference was observed in the recovery capacity growth rate after high-temperature storage. It was confirmed that the improvement was significant in Example 4-1 according to the present invention, with an improvement of 8.3% compared to Comparative Example 4-1.

[0330] Differences were also observed in lifespan efficiency. It was confirmed that Example 4-1 according to the present invention was significantly improved to 2.7% compared to Comparative Example 4-1.

[0331] Furthermore, as a result of measuring the change in thickness of the battery before and after high-temperature storage, it was confirmed that the electrolyte additive of the present invention significantly suppresses the oxidation / reduction decomposition of the electrolyte and also has the effect of reducing gas generation. In Example 4-1 according to the present invention, it was confirmed to be significantly improved at 14.4% compared to Comparative Example 4-1.

[0332]

[0333] Example 5-1

[0334] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1 and 1.0 wt% of a sulfur-based compound represented by Chemical Formula 2-31.

[0335]

[0336] Comparative Example 5-1

[0337] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 as the organic solvent and adding 1.0 wt% of a sulfur-based compound represented by Chemical Formula 2-31 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt. For reference, Comparative Example 5-1 corresponds to an experiment in which no dioxaphosphorane-based compound represented by Chemical Formula 1-1 was used.

[0338]

[0339] Manufacturing of NCM batteries

[0340] Li(Ni as a positive electrode active material 0.6 Co 0.1 Mn 0.3 An anode mixture slurry was prepared by adding 292 wt% of )O, 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 anode mixture slurry was applied to an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0341] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0342] 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), the manufacturing of a lithium secondary battery was completed by injecting each electrolyte prepared in Example 5-1 and Comparative Example 5-1.

[0343]

[0344] Test Example 5

[0345] To evaluate the performance of the NCM-based secondary battery manufactured above, the performance was evaluated using the method described above, and the results are summarized in Table 5 below.

[0346] Classification Initial Discharge DC-IR (mΩ) High-Temperature Storage DC-IR Growth Rate (%) High-Temperature Storage Recovery Capacity Retention Rate (%) Volume Increase Rate After High-Temperature Storage (%) Lifetime Efficiency (%) Example 5-16 5.9 5.8 9 2.7 18.6 89.1 Comparative Example 5-17 2.7 7 7.1 8 7.7 22.6 83.9

[0347] As shown in Table 5 above, in the case of Example 5-1, which contains the electrolyte additives of the present invention, it was confirmed that the initial discharge resistance, resistance growth rate, high-temperature recovery capacity, thickness growth rate, and high-temperature life capacity efficiency were all improved in the NCM battery compared to Comparative Example 5-1, which did not use a dioxaphosphorane-based compound. In particular, a significant difference was observed in the resistance growth rate of the battery before and after high-temperature storage. It was confirmed that the improvement was significant in Example 5-1 according to the present invention, with an improvement of 21.3% compared to Comparative Example 5-1. In addition, a significant difference was also observed in the recovery capacity growth rate after high-temperature storage. It was confirmed that the improvement was significant in Example 5-1 according to the present invention, with an improvement of 4.5 to 5.7% compared to Comparative Example 5-2.

[0348] Differences were also observed in lifespan efficiency. It was confirmed that in Examples 4-5 according to the present invention, the efficiency was significantly improved to 6.2% compared to Comparative Example 5-1.

[0349] Furthermore, as a result of measuring the change in thickness of the battery before and after high-temperature storage, it was confirmed that the electrolyte additive of the present invention significantly suppresses the oxidation / reduction decomposition of the electrolyte and also has the effect of reducing gas generation. In Example 5-1 according to the present invention, it was confirmed to be significantly improved to 17.7% compared to Comparative Example 5-1.

[0350]

[0351] Example 6-1

[0352] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1 and 0.5 wt% of a sulfur-based compound represented by Chemical Formula 2-22.

[0353]

[0354] Example 6-2

[0355] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1 and 0.5 wt% of a sulfur-based compound represented by Chemical Formula 2-34.

[0356]

[0357] Example 6-3

[0358] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1 and 0.5 wt% of a sulfur-based compound represented by Chemical Formula 2-35.

[0359]

[0360] Comparative Example 6-1

[0361] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 as the organic solvent and adding 0.5 wt% of a sulfur-based compound represented by Chemical Formula 2-22 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt. For reference, Comparative Example 6-1 corresponds to an experiment in which no dioxaphosphorane-based compound represented by Chemical Formula 1-1 was used.

[0362]

[0363] Comparative Example 6-2

[0364] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 as the organic solvent and adding 0.5 wt% of a sulfur-based compound represented by Chemical Formula 2-34 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt. For reference, Comparative Example 6-2 corresponds to an experiment in which no dioxaphosphorane-based compound represented by Chemical Formula 1-1 was used.

[0365]

[0366] Comparative Example 6-3

[0367] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 as the organic solvent and adding 0.5 wt% of a sulfur-based compound represented by the above chemical formula 2-35 to a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M. For reference, Comparative Example 6-3 corresponds to an experiment in which the dioxaphosphorane-based compound represented by the above chemical formula 1-1 was not used at all.

[0368]

[0369] Manufacturing of NCM batteries

[0370] Li(Ni as a positive electrode active material 0.6 Co 0.1 Mn0.3 An anode mixture slurry was prepared by adding 292 wt% of )O, 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 anode mixture slurry was applied to an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0371] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0372] 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), the manufacturing of a lithium secondary battery was completed by injecting each electrolyte prepared in Examples 6-1 to 6-3 and Comparative Examples 6-1 to 6-3.

[0373]

[0374] Test Example 6

[0375] To evaluate the performance of the NCM-based secondary battery manufactured above, the performance was evaluated using the method described above, and the results are summarized in Table 6 below.

[0376] Classification Initial Discharge DC-IR (mΩ) High-Temperature Storage DC-IR Growth Rate (%) High-Temperature Storage Recovery Capacity Retention Rate (%) Volume Increase Rate After High-Temperature Storage (%) Lifetime Efficiency (%) Example 6-169.566.493.618.685.9 Example 6-271.251.294.117.986.9 Example 6-365.867.590.116.485.6 Comparative Example 6-172.584.489.423.879.1 Comparative Example 6-271.370.587.822.580.2 Comparative Example 6-369.472.688.218.980.3

[0377] As shown in Table 6 above, in the case of Examples 6-1 to 6-3, which are electrolyte additives of the present invention, it was confirmed that the initial discharge resistance, resistance growth rate, high-temperature recovery capacity, thickness growth rate, and high-temperature life capacity efficiency in NCM batteries were all improved compared to Comparative Examples 6-1 to 6-3, which did not use a dioxaphosphorane-based compound. In particular, a significant difference was observed in the resistance growth rate of the battery before and after high-temperature storage. It was confirmed that the improvement was significant in Examples 6-1 to 6-3 according to the present invention, with an improvement of 7.0 to 27.4% compared to Comparative Examples 6-1 to 6-3. In addition, a significant difference was also observed in the recovery capacity growth rate after high-temperature storage. It was confirmed that the improvement was significant in Examples 6-1 to 6-3 according to the present invention, with an improvement of 4.7 to 7.2% compared to Comparative Examples 6-1 to 6-3.

[0378] Differences were also observed in lifespan efficiency. It was confirmed that Examples 6-1 to 6-3 according to the present invention showed a significant improvement of 6.6 to 8.6% compared to Comparative Examples 6-1 to 6-3.

[0379] Furthermore, as a result of measuring the change in thickness of the battery before and after high-temperature storage, it was confirmed that the electrolyte additive of the present invention significantly suppresses the oxidation / reduction decomposition of the electrolyte and also has the effect of reducing gas generation. It was confirmed that Examples 6-1 to 6-3 according to the present invention showed a significant improvement of 13.2 to 21.8% compared to Comparative Examples 6-1 to 6-3.

[0380]

[0381] Example 7-1

[0382] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1 and 0.5 wt% of a sulfur-based compound represented by Chemical Formula 2-39.

[0383]

[0384] Comparative Example 7-1

[0385] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 as the organic solvent and adding 0.5 wt% of a sulfur-based compound represented by the above chemical formula 2-39 to a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M. For reference, Comparative Example 7-1 corresponds to an experiment in which no dioxaphosphorane-based compound represented by the above chemical formula 1-1 was used.

[0386]

[0387] Manufacturing of NCM batteries

[0388] Li(Ni as a positive electrode active material 0.6 Co 0.1 Mn 0.3An anode mixture slurry was prepared by adding 292 wt% of )O, 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 anode mixture slurry was applied to an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0389] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0390] After fabricating 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), the respective electrolytes prepared in Example 7-1 and Comparative Example 7-1 were injected to complete the manufacture of a lithium secondary battery.

[0391]

[0392] Test Example 7

[0393] To evaluate the performance of the NCM-based secondary battery manufactured above, the performance was evaluated using the method described above, and the results are summarized in Table 7 below.

[0394] Classification Initial Discharge DC-IR (mΩ) High-Temperature Storage DC-IR Growth Rate (%) High-Temperature Storage Recovery Capacity Retention Rate (%) Volume Increase Rate After High-Temperature Storage (%) Lifetime Efficiency (%) Example 7-16 1.5 49.8 92.4 14.3 89.4 Comparative Example 7-16 5.2 93.4 78.5 13.0 81.6

[0395] As shown in Table 7 above, in the case of Example 7-1, which contains the electrolyte additives of the present invention, it was confirmed that the initial discharge resistance, resistance growth rate, high-temperature recovery capacity, thickness growth rate, and high-temperature life capacity efficiency were all improved in the NCM battery compared to Comparative Example 7-1, which did not use a dioxaphosphorane-based compound. In particular, a significant difference was observed in the resistance growth rate of the battery before and after high-temperature storage. It was confirmed that the improvement was significant in Example 7-1 according to the present invention, with a 46.7% improvement compared to Comparative Example 7-1. In addition, a significant difference was also observed in the recovery capacity growth rate after high-temperature storage. It was confirmed that the improvement was significant in Example 7-1 according to the present invention, with a 17.7% improvement compared to Comparative Example 7-1.

[0396] Differences were also observed in lifespan efficiency. In Example 7-5 according to the present invention, it was confirmed to be significantly improved at 9.6% compared to Comparative Example 7-1.

[0397] Furthermore, as a result of measuring the change in thickness of the battery before and after high-temperature storage, it was confirmed that the electrolyte additive of the present invention significantly suppresses the oxidation / reduction decomposition of the electrolyte and also has the effect of reducing gas generation. In Example 7-1 according to the present invention, it was confirmed to be significantly improved by 10% compared to Comparative Example 7-1.

[0398]

[0399] Example 8-1

[0400] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1 and 1.0 wt% of a phosphorus-based compound represented by Chemical Formula 2-11.

[0401]

[0402] Comparative Example 8-1

[0403] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 as the organic solvent and adding 1.0 wt% of a phosphorus-based compound represented by Chemical Formula 2-11 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt. For reference, Comparative Example 7-1 corresponds to an experiment in which no dioxaphosphorane-based compound represented by Chemical Formula 1-1 was used.

[0404]

[0405] Manufacturing of NCM batteries

[0406] Li(Ni as a positive electrode active material 0.6 Co 0.1 Mn 0.3 An anode mixture slurry was prepared by adding 292 wt% of )O, 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 anode mixture slurry was applied to an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0407] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0408] 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), the manufacturing of a lithium secondary battery was completed by injecting each electrolyte prepared in Example 8-1 and Comparative Example 8-1.

[0409]

[0410] Test Example 8

[0411] To evaluate the performance of the NCM-based secondary battery manufactured above, the performance was evaluated using the method described above, and the results are summarized in Table 8 below.

[0412] Classification Initial Discharge DC-IR (mΩ) High-Temperature Storage DC-IR Growth Rate (%) High-Temperature Storage Recovery Capacity Retention Rate (%) Volume Increase Rate After High-Temperature Storage (%) Lifetime Efficiency (%) Example 8-16 5.9 50.2 91.2 15.4 89.5 Comparative Example 8-17 3.4 13 8.2 78.5 12.5 85.2

[0413] As shown in Table 8 above, in the case of Example 8-1, which contains the electrolyte additives of the present invention, it was confirmed that the initial discharge resistance, resistance growth rate, high-temperature recovery capacity, thickness growth rate, and high-temperature life capacity efficiency were all improved in the NCM battery compared to Comparative Example 8-1, which did not use a dioxaphosphorane-based compound. In particular, a significant difference was observed in the resistance growth rate of the battery before and after high-temperature storage. It was confirmed that the improvement was significant in Example 8-1 according to the present invention, with a 63.7% improvement compared to Comparative Example 8-1. In addition, a significant difference was also observed in the recovery capacity growth rate after high-temperature storage. It was confirmed that the improvement was significant in Example 8-1 according to the present invention, with a 4.5 to 16.2% improvement compared to Comparative Example 8-2.

[0414] Differences were also observed in lifespan efficiency. It was confirmed that Example 8-1 according to the present invention was significantly improved to 5.0% compared to Comparative Example 8-1.

[0415]

[0416] Example 9-1

[0417] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1 and 5.0 wt% of an ether-based compound represented by Chemical Formula 2-8.

[0418]

[0419] Comparative Example 9-1

[0420] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 as the organic solvent and adding 5.0 wt% of an ether-based compound represented by Chemical Formula 2-8 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt. For reference, Comparative Example 9-1 corresponds to an experiment in which no dioxaphosphorane-based compound represented by Chemical Formula 1-1 was used.

[0421]

[0422] Manufacturing of NCM batteries

[0423] Li(Ni as a positive electrode active material 0.6 Co 0.1 Mn 0.3 An anode mixture slurry was prepared by adding 292 wt% of )O, 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 anode mixture slurry was applied to an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0424] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0425] After fabricating 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), the respective electrolytes prepared in Example 9-1 and Comparative Example 9-1 were injected to complete the manufacture of a lithium secondary battery.

[0426]

[0427] Test Example 9

[0428] To evaluate the performance of the NCM-based secondary battery manufactured above, the performance was evaluated using the method described above, and the results are summarized in Table 9 below.

[0429] Classification Initial Discharge DC-IR (mΩ) High-Temperature Storage DC-IR Growth Rate (%) High-Temperature Storage Recovery Capacity Retention Rate (%) Volume Increase Rate After High-Temperature Storage (%) Lifetime Efficiency (%) Example 9-16 1.45 3.79 2.017 29 1.5 Comparative Example 9-17 0.16 4.59 0.32 2.09 0.1

[0430] As shown in Table 9 above, in the case of Example 9-1, which contains the electrolyte additives of the present invention, it was confirmed that the initial discharge resistance, resistance growth rate, high-temperature recovery capacity, thickness growth rate, and high-temperature life capacity efficiency in the NCM battery were all improved compared to Comparative Example 9-1, which did not use a dioxaphosphorane-based compound. In particular, a significant difference was observed in the resistance growth rate of the battery before and after high-temperature storage. It was confirmed that the improvement was significant in Example 9-1 according to the present invention, with an improvement of 16.7% compared to Comparative Example 9-1. In addition, a difference was also observed in the recovery capacity growth rate after high-temperature storage. It was confirmed that the improvement was 1.9% in Example 9-1 according to the present invention compared to Comparative Example 9-1.

[0431] Differences were also observed in lifespan efficiency. In Example 9-1 according to the present invention, an improved result of 1.6% was confirmed compared to Comparative Example 9-1.

[0432] Furthermore, as a result of measuring the change in thickness of the battery before and after high-temperature storage, it was confirmed that the electrolyte additive of the present invention significantly suppresses the oxidation / reduction decomposition of the electrolyte and also has the effect of reducing gas generation. In Example 9-1 according to the present invention, it was confirmed to be significantly improved at 21.8% compared to Comparative Example 9-1.

[0433]

[0434] Example 10-1

[0435] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1, 1.0 wt% of a carbonate-based compound represented by Chemical Formula 2-2, and 0.5 wt% of a carbonate-based compound represented by Chemical Formula 2-1.

[0436]

[0437] Example 10-2

[0438] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1, 1.0 wt% of a carbonate-based compound represented by Chemical Formula 2-2, and 1.0 wt% of a phosphorus-based compound represented by Chemical Formula 2-23.

[0439]

[0440] Example 10-3

[0441] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1, 1.0 wt% of a phosphorus-based compound represented by Chemical Formula 2-23, and 0.5 wt% of a sulfur-based compound represented by Chemical Formula 2-35.

[0442]

[0443] Example 10-4

[0444] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt was prepared by adding 0.5 wt% of a dioxaphosphorane compound represented by Chemical Formula 1-1, 0.5 wt% of a dioxaphosphorane compound represented by Chemical Formula 1-1, 1.0 wt% of a carbonate-based compound represented by Chemical Formula 2-2, and 0.5 wt% of a sulfur-based compound represented by Chemical Formula 2-35.

[0445]

[0446] Example 10-5

[0447] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt was prepared by adding 0.5 wt% of a dioxaphosphorane compound represented by Chemical Formula 1-1, 0.5 wt% of a dioxaphosphorane compound represented by Chemical Formula 1-1, 1.0 wt% of a phosphorus-based compound represented by Chemical Formula 2-23, and 0.5 wt% of a carbonate-based compound represented by Chemical Formula 2-1.

[0448]

[0449] Examples 10-6

[0450] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1, 0.5 wt% of a sulfur-based compound represented by Chemical Formula 2-34, and 0.5 wt% of a sulfur-based compound represented by Chemical Formula 2-35.

[0451]

[0452] Examples 10-7

[0453] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 0.5 wt% of a dioxaphosphorane-based compound represented by Chemical Formula 1-1, 1.0 wt% of a phosphorus-based compound represented by Chemical Formula 2-23, and 0.5 wt% of a sulfur-based compound represented by Chemical Formula 2-34.

[0454]

[0455] Example 10-8

[0456] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DEC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt was prepared by adding 0.5 wt% of a dioxaphosphorane compound represented by Chemical Formula 1-1, 0.5 wt% of a dioxaphosphorane compound represented by Chemical Formula 1-1, 1.0 wt% of a carbonate-based compound represented by Chemical Formula 2-2, and 0.5 wt% of a sulfur-based compound represented by Chemical Formula 2-34.

[0457]

[0458] Comparative Example 10-1

[0459] A battery electrolyte was prepared by using a carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 as the organic solvent and adding 1.0 wt% of a carbonate-based compound represented by Chemical Formula 2-2 and 0.5 wt% of a carbonate-based compound represented by Chemical Formula 2-1 to a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt. For reference, Comparative Example 10-1 corresponds to an experiment in which no dioxaphosphorane-based compound represented by Chemical Formula 1-1 was used.

[0460]

[0461] Comparative Example 10-2

[0462] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 1.0 wt% of a carbonate-based compound represented by Chemical Formula 2-2 and 1.0 wt% of a phosphorus-based compound represented by Chemical Formula 2-23. For reference, Comparative Example 10-2 corresponds to an experiment in which the dioxaphosphorane-based compound represented by Chemical Formula 1-1 was not used at all.

[0463]

[0464] Comparative Example 10-3

[0465] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 was used as the organic solvent, and a battery electrolyte was prepared by adding 1.0 wt% of a phosphorus-based compound represented by Chemical Formula 2-23 and 0.5 wt% of a sulfur-based compound represented by Chemical Formula 2-35 to a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M. For reference, Comparative Example 10-3 corresponds to an experiment in which the dioxaphosphorane-based compound represented by Chemical Formula 1-1 was not used at all.

[0466]

[0467] Comparative Example 10-4

[0468] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt was prepared by adding 1.0 wt% of a carbonate-based compound represented by Chemical Formula 2-2 and 0.5 wt% of a sulfur-based compound represented by Chemical Formula 2-35. For reference, Comparative Example 10-4 corresponds to an experiment in which the dioxaphosphorane-based compound represented by Chemical Formula 1-1 was not used at all.

[0469]

[0470] Comparative Example 10-5

[0471] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt was prepared by adding 0.5 wt% of a dioxaphosphorane compound represented by Chemical Formula 1-1, 1.0 wt% of a phosphorus compound represented by Chemical Formula 2-23, and 0.5 wt% of a carbonate-based compound represented by Chemical Formula 2-1. For reference, Comparative Example 10-5 corresponds to an experiment in which the dioxaphosphorane compound represented by Chemical Formula 1-1 was not used at all.

[0472]

[0473] Comparative Example 10-6

[0474] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 at a concentration of 1.15 M as the lithium salt was prepared by adding 0.5 wt% of a sulfur compound represented by Chemical Formula 2-34 and 0.5 wt% of a sulfur compound represented by Chemical Formula 2-35. For reference, Comparative Example 10-6 corresponds to an experiment in which the dioxaphosphorane compound represented by Chemical Formula 1-1 was not used at all.

[0475]

[0476] Comparative Example 10-7

[0477] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 was used as the organic solvent, and a battery electrolyte was prepared by adding 1.0 wt% of a phosphorus-based compound represented by Chemical Formula 2-23 and 0.5 wt% of a sulfur-based compound represented by Chemical Formula 2-34 to a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M. For reference, Comparative Example 10-7 corresponds to an experiment in which the dioxaphosphorane-based compound represented by Chemical Formula 1-1 was not used at all.

[0478]

[0479] Comparative Example 10-8

[0480] A carbonate-based mixed solvent having a volume ratio of EC:EMC:DMC = 20:40:40 was used as the organic solvent, and a solution containing LiPF6 as the lithium salt at a concentration of 1.15 M was prepared by adding 1.0 wt% of a carbonate-based compound represented by Chemical Formula 2-2 and 0.5 wt% of a sulfur-based compound represented by Chemical Formula 2-34. For reference, Comparative Example 10-8 corresponds to an experiment in which the dioxaphosphorane-based compound represented by Chemical Formula 1-1 was not used at all.

[0481]

[0482] Manufacturing of NCM batteries

[0483] Li(Ni as a positive electrode active material 0.6 Co 0.1 Mn 0.3 An anode mixture slurry was prepared by adding 292 wt% of )O, 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 anode mixture slurry was applied to an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0484] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0485] After fabricating 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), the manufacturing of a lithium secondary battery was completed by injecting each electrolyte prepared in Examples 10-1 to 10-8 and Comparative Examples 10-1 to 10-8.

[0486]

[0487] Test Example 10

[0488] To evaluate the performance of the NCM-based secondary battery manufactured above, the performance was evaluated using the method described above, and the results are summarized in Table 10 below.

[0489] Classification Initial Discharge DC-IR (mΩ) High-Temperature Storage DC-IR Growth Rate (%) High-Temperature Storage Recovery Capacity Retention Rate (%) Volume Increase Rate After High-Temperature Storage (%) Lifetime Efficiency (%) Example 10-169.155.492.122.589.5 Example 10-265.758.291.219.590.2 Example 10-365.257.291.517.289.2 Example 10-468.861.290.518.189.1 Example 10-565.753.590.019.190.5 Example 10-666.260.890.419.586.1 Example 10-764.158.790.817.089.5 Example 10-868.261.189.915.690.2 Comparative Example 10-176.776.889.528.281.5 Comparative Example 10-267.565.788.924.685.4 Comparative Example 10-367.262.586.819.284.7 Comparative Example 10-473.275.889.525.883.8 Comparative Example 10-571.860.288.719.888.9 Comparative Example 10-670.171.288.520.781.5 Comparative Example 10-766.961.188.718.988.5 Comparative Example 10-874.775.889.115.785.4

[0490] As shown in Table 10 above, in the case of Examples 10-1 to 10-8, which are electrolyte additives of the present invention, it was confirmed that the initial discharge resistance, resistance growth rate, high-temperature recovery capacity, thickness growth rate, and high-temperature life capacity efficiency in NCM batteries were all improved compared to Comparative Examples 10-1 to 10-8, which did not use a dioxaphosphorane-based compound. In particular, a significant difference was observed in the resistance growth rate of the battery before and after high-temperature storage. It was confirmed that the improvement was significant in Examples 10-1 to 10-8 according to the present invention, with an improvement of 3.9 to 27.9% compared to Comparative Examples 10-1 to 10-8. In addition, a significant difference was also observed in the recovery capacity growth rate after high-temperature storage. It was confirmed that the improvement was significant in Examples 10-1 to 10-8 according to the present invention, with an improvement of 0.9 to 5.4% compared to Comparative Examples 10-1 to 10-8.

[0491] Differences were also observed in lifespan efficiency. It was confirmed that Examples 10-1 to 10-8 according to the present invention were significantly improved to 1.1 to 9.8% compared to Comparative Examples 10-1 to 10-8.

[0492] Furthermore, as a result of measuring the change in thickness of the battery before and after high-temperature storage, it was confirmed that the electrolyte additive of the present invention significantly suppresses the oxidation / reduction decomposition of the electrolyte and also has the effect of reducing the amount of gas generated. It was confirmed that Examples 10-1 to 10-8 according to the present invention showed a significant improvement of 3.5 to 29.8% compared to Comparative Examples 10-1 to 10-8.

[0493]

[0494] Manufacturing of high-nickel NCM batteries

[0495] Li(Ni as a positive electrode active material 0.8 Co 0.1 Mn 0.1 An anode mixture slurry was prepared by adding 292 wt% of )O, 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 anode mixture slurry was applied to an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0496] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0497] 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), the manufacturing of a lithium secondary battery was completed by injecting each electrolyte prepared in Examples 1-1 to 10-8 and Comparative Examples 1-1 to 10-8.

[0498]

[0499] Manufacturing of high-nickel NCM batteries (Ni 90%)

[0500] Li(Ni as a positive electrode active material 0.9 Co 0.05 Mn 0.05 An anode mixture slurry was prepared by adding 292 wt% of )O, 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 anode mixture slurry was applied to an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0501] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0502] 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 4.3V, 4.4V, 4.5V, 4.6V, 4.7V, 4.8V, 4.9V, 4.10V), the manufacturing of a lithium secondary battery was completed by injecting each electrolyte prepared in Examples 1-1 to 10-8 and Comparative Examples 1-1 to 10-8.

[0503]

[0504] Manufacture of NCA batteries (Ni 90%)

[0505] Li(Ni as a positive electrode active material 0.9 Co 0.09 Al 0.02 An anode mixture slurry was prepared by adding 292 wt% of )O, 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 anode mixture slurry was applied to an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0506] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0507] After manufacturing a pouch-type battery using a conventional method with the positive and negative electrodes prepared as described above together with a separator composed of three layers of polypropylene / polyethylene / polypropylene (PP / PE / PP) (operating voltage 2.0 to 4.3 V), the manufacturing of a lithium secondary battery was completed by injecting each electrolyte prepared in Examples 1-1 to 10-8 and Comparative Examples 1-1 to 10-8.

[0508]

[0509] Manufacturing of Mid-Nickel NCM Batteries

[0510] Li(Ni as a positive electrode active material 0.6 Co 0.2 Mn 0.2 An anode mixture slurry was prepared by adding 292 wt% of )O, 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 anode mixture slurry was applied to an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0511] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0512] After manufacturing a pouch-type battery (operating voltage 4.5V) 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), the manufacturing of a lithium secondary battery was completed by injecting each electrolyte prepared in Examples 1-1 to 10-8 and Comparative Examples 1-1 to 10-8.

[0513]

[0514] Manufacturing of NMX batteries

[0515] Li(Ni as a positive electrode active material 0.7 Mn 0.3 An anode mixture slurry was prepared by adding 292 wt% of )O, 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 anode mixture slurry was applied to an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0516] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0517] 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 2.0 to 4.6 V), the manufacturing of a lithium secondary battery was completed by injecting each electrolyte prepared in Examples 1-1 to 10-8 and Comparative Examples 1-1 to 10-8.

[0518]

[0519] Manufacturing of LFP batteries

[0520] 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.

[0521] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0522] 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 1-1 to 10-8 and Comparative Examples 1-1 to 10-8.

[0523]

[0524] Manufacturing of LMFP batteries

[0525] An anode mixture slurry was prepared by adding 492 wt% of LiMnFePO4 as an anode 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 anode mixture slurry was coated onto an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0526] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0527] 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 2.0 to 4.0 V), the manufacturing of a lithium secondary battery was completed by injecting each electrolyte prepared in Examples 1-1 to 10-8 and Comparative Examples 1-1 to 10-8.

[0528]

[0529] Manufacturing of LMR(OLO) batteries

[0530] xLi2MnO3·(1-x)LiNi as the positive active material a Co b Mn c O2(x=0.1~0.9, a+b+c=1) An anode mixture slurry was prepared by adding 92 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 anode mixture slurry was applied to an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0531] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0532] 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 4.6 V), the manufacturing of a lithium secondary battery was completed by injecting each electrolyte prepared in Examples 1-1 to 10-8 and Comparative Examples 1-1 to 10-8.

[0533]

[0534] Manufacturing of LMX batteries

[0535] xLi2MnO3·(1-x)LiNi as the positive active material a Mn CAn anode mixture slurry was prepared by adding 92 wt% of O2 (x=0.1~0.9, a+c=1), 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 anode mixture slurry was applied to an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0536] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0537] 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 4.6 V), the manufacturing of a lithium secondary battery was completed by injecting each electrolyte prepared in Examples 1-1 to 10-8 and Comparative Examples 1-1 to 10-8.

[0538]

[0539] Manufacturing of LCO batteries

[0540] An anode mixture slurry was prepared by adding 92 wt% of LiCoO2 as an anode 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 anode mixture slurry was coated onto an aluminum (Al) thin film, which is an anode current collector, with a thickness of about 20 μm, dried to produce an anode, and then subjected to a roll press to produce an anode.

[0541] 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 in amounts of 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as the solvent. 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.

[0542] 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 2.0 to 4.8 V), the manufacturing of a lithium secondary battery was completed by injecting each electrolyte prepared in Examples 1-1 to 10-8 and Comparative Examples 1-1 to 10-8.

[0543]

[0544] As a result, the secondary batteries of Examples 1-1 to 10-8 using the electrolyte additive of the present invention showed positive performance improvements in initial resistance, high-temperature durability, rate characteristics, retention capacity, and recovery capacity compared to comparative examples that did not use the electrolyte additive and conventional electrolyte additives at all, and comparative examples that used only conventional electrolyte additives. This can be seen as contributing to maximizing the efficiency and lifespan of the battery at high and low temperatures and improving electrical characteristics.

[0545]

[0546] Accordingly, when an electrolyte additive comprising two or more compounds selected from dioxaphosphorane compounds, carbonate compounds, acid anhydride compounds, silane compounds, amine compounds, ether compounds, fluorophosphorane compounds, nitrile compounds, boron compounds, phosphorus compounds, sulfur compounds, and aromatic compounds according to the present invention, and an electrolyte containing the same are applied to a secondary battery, not only does it provide an effect of reducing gas generation by suppressing internal side reactions of the battery, but also improves charge resistance, discharge resistance, output, recovery capacity, and lifespan efficiency even when stored for a long period at high temperatures, thereby enabling a secondary battery for automobiles, particularly a high-nickel full-cell battery with a basic capacity of 0.1 to 100 Ah, a mid-nickel full-cell battery with a basic capacity of 0.1 to 100 Ah, an LFP battery with a basic capacity of 0.1 to 100 Ah, an LMR (lithium manganese-rich) battery with a basic capacity of 0.1 to 100 Ah, or a battery with a basic capacity of 0.1 to 100 Ah It can be seen that it is suitable for use in cobalt-free batteries, etc.

Claims

1. As an electrolyte additive for secondary battery electrolytes, An electrolyte additive characterized by comprising two or more compounds selected from dioxaphosphorane compounds, carbonate compounds, acid anhydride compounds, silane compounds, amine compounds, ether compounds, fluorophosphorane compounds, nitrile compounds, boron compounds, phosphorus compounds, sulfur compounds, and aromatic compounds.

2. As an electrolyte additive for secondary battery electrolytes, An electrolyte additive characterized by comprising: a dioxaphosphorane compound; and one or more compounds selected from carbonate compounds, acid anhydride compounds, silane compounds, amine compounds, ether compounds, fluorophosphorane compounds, nitrile compounds, boron compounds, phosphorus compounds, sulfur compounds, and aromatic compounds.

3. In Paragraph 1 or 2, The above-mentioned dioxaphosphorane compound is a compound represented by the following chemical formula 1, and The above-mentioned carbonate-based compound, acid anhydride-based compound, silane-based compound, amine-based compound, ether-based compound, fluorophosphorane-based compound, nitrile-based compound, boron-based compound, phosphorus-based compound, sulfur-based compound, and aromatic compound are compounds selected from one or more of the following chemical formulas 2-1 to 2-45, characterized as an electrolyte additive. [Chemical Formula 1] (In the above Chemical Formula 1, the lines represent bonds, and where no separate element is specified, the points where bonds meet are carbons, and A1, A2, and A3 are independently oxygen (O), nitrogen (N), or sulfur (S).) [Chemical Formulas 2-1 to 2-45] 4. In Paragraph 1, An electrolyte additive characterized in that the above-mentioned dioxaphosphorane compound is a compound represented by the following chemical formulas 1-1 to 1-5. [Chemical Formulas 1-1 to 1-5] 5. In Paragraph 1, The electrolyte additive is characterized by comprising: 0.1 to 10 weight% of the dioxaphosphorane compound based on 100 weight% of the total electrolyte of the secondary battery; and 0.1 to 10 weight% of one or more compounds selected from carbonate compounds, acid anhydride compounds, silane compounds, amine compounds, ether compounds, fluorophosphorane compounds, nitrile compounds, boron compounds, phosphorus compounds, sulfur compounds, and aromatic compounds.

6. In Paragraph 1, An electrolyte additive characterized by comprising: the above-mentioned dioxaphosphorane compound; and one or more compounds selected from carbonate compounds, acid anhydride compounds, silane compounds, amine compounds, ether compounds, fluorophosphorane compounds, nitrile compounds, boron compounds, phosphorus compounds, sulfur compounds, and aromatic compounds in a weight ratio of 1:1 to 1:

10.

7. An electrolyte comprising an organic solvent, a lithium salt, and an electrolyte additive, The electrolyte is characterized by comprising the electrolyte additive of claim 1 or 2.

8. In Paragraph 7, The electrolyte is characterized by comprising one or more organic solvents 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, ethylpropyl carbonate, and 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether.

9. In Paragraph 7, The above lithium salts are LiPF6, LiF4, LiCl, LiBr, LiI, LiClO4, and LiB 10 Cl 10 An electrolyte characterized by comprising one or more selected from the group consisting of LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, (FSO2)2NLi, and (CF3SO2)2NLi.

10. A secondary battery comprising a negative electrode, a positive electrode, a separator interposed between the negative electrode and the positive electrode, and an electrolyte, wherein A secondary battery characterized in that the above electrolyte is the electrolyte of claim 7.

11. In Paragraph 10, The above secondary battery is characterized by being a high-nickel full-cell battery, a mid-nickel full-cell battery, a lithium iron phosphate battery, an NMX (Nickel-Manganese, Co-free) battery, an LMR (Lithium-Manganese-Rich) battery, an LMX (Lithium-Manganese-Rich, Co-free) battery, an OLO (Over-Lithiated Layered Oxide) battery, an LCO (Lithium Cobalt Oxide) battery, or a DRX (Disordered Rocksalt) battery.

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