Electrolyte additive for secondary battery, non-aqueous electrolyte for lithium secondary battery comprising same, and lithium secondary battery comprising same

Abstract

The present invention relates to a novel electrolyte additive, a non-aqueous electrolyte for a lithium secondary battery comprising the novel electrolyte additive, and a lithium secondary battery comprising the non-aqueous electrolyte. More specifically, the present invention relates to a non-aqueous electrolyte for a lithium secondary battery, which comprises an additive capable of forming a coordinate bond on the cathode surface. In addition, the present invention relates to a lithium secondary battery, wherein the inclusion of the non-aqueous electrolyte prevents deterioration of the high-temperature lifespan of the lithium secondary battery, suppresses gas generation during storage of the lithium secondary battery at a high temperature, improves the capacity retention rate and the capacity recovery rate, and enhances the performance of suppressing the volume (thickness) expansion of the secondary battery during storage of the lithium secondary battery at a high temperature.

Description

Electrolyte additive for secondary batteries, non-aqueous electrolyte for lithium secondary batteries containing the same, and lithium secondary batteries containing the same

[0001] The present invention relates to an electrolyte additive for secondary batteries. More specifically, the present invention relates to a non-aqueous electrolyte additive that prevents electrolyte decomposition and gas generation at the interface between the positive electrode and the electrolyte, and a non-aqueous electrolyte for a lithium secondary battery comprising the same. The present invention relates to a non-aqueous electrolyte additive that can form a robust cathode electrolyte interphase layer (CEI layer), and a non-aqueous electrolyte for a lithium secondary battery comprising the same. More specifically, the present invention relates to a non-aqueous electrolyte for a lithium secondary battery comprising a phosphorus compound of the fluorinated phosphazene series that can form a cathode electrolyte interphase layer (CEI layer) on the surface of the positive electrode. The phosphorus compound coordinates with a transition metal of the positive electrode to enhance the stability of the metal and the positive electrode active material, and further suppresses side reactions between the positive electrode and the electrolyte. The present invention also relates to a lithium secondary battery comprising such a non-aqueous electrolyte. The lithium secondary battery of the present invention has improved high-temperature performance by including the non-aqueous electrolyte.

[0002] Lithium secondary batteries are not only used as portable power sources for mobile phones, laptops, and other devices, but their applications are also expanding to medium- to large-scale power sources for electric bicycles and electric vehicles (EVs). This expansion of applications is driving the demand for lithium secondary batteries that can maintain superior performance not only at room temperature but also in harsher environments, such as high and low temperatures.

[0003] The lithium secondary batteries widely used today are generally composed of a carbon-based negative electrode that allows the insertion and deintercalation of lithium ions, a transition metal oxide-based positive electrode containing lithium, a non-aqueous electrolyte in which a lithium salt is dissolved in a mixed carbonate-based organic solvent, and a separator that prevents contact between the positive and negative electrodes. When a lithium secondary battery is charged, the lithium atoms in the positive electrode are ionized into lithium ions and electrons, and the electrons move to the negative electrode through an external circuit. The lithium ions then cross the non-aqueous electrolyte and the separator to the negative electrode and are intercalated into the carbon negative electrode. When discharging, the electrons move to the positive electrode through an external circuit, and at the same time, the lithium ions are deintercalated from the carbon negative electrode and cross the non-aqueous electrolyte and the separator to the positive electrode, where the lithium ions and electrons meet to form lithium atoms in a stable state. Lithium secondary batteries generate electrical energy by repeating this charging and discharging cycle.

[0004] Demand for large-scale devices such as electric vehicles (EVs) and energy storage systems (ESS) is increasing. Large-scale devices require longer driving and operating times. Therefore, active research is being conducted to develop materials that can increase the energy density of lithium-ion secondary batteries. Among these materials, lithium nickel cobalt manganese oxide (Li(Ni)) with a layered structure with a high nickel content is x Co y Mn z )O2) is attracting attention. Lithium nickel cobalt manganese oxide (Li(Ni x Co y Mn z )O2) is commonly referred to as NCM. Generally, when the nickel content is 60% or higher, it is called high nickel content NCM.

[0005] However, NCM materials with high nickel content suffer from poor cycle characteristics due to poor interfacial stability. The high reactivity of nickel accelerates the electrochemical decomposition of the electrolyte at the interface between the cathode and the electrolyte. This leads to the accumulation of by-products resulting from the decomposition of the electrolyte on the surface of the cathode. These by-products hinder the movement of lithium ions between the cathode and the electrolyte, increasing the interfacial resistance between the cathode and the electrolyte. Consequently, the cycle characteristics of the secondary battery deteriorate significantly. The electrochemical decomposition of the electrolyte generates gas, which causes the secondary battery to swell.

[0006] One way to prevent electrolyte decomposition on the nickel-rich NCM electrode surface is to add a special additive to the electrolyte. This additive forms a cathode-electrolyte interface (CEI) layer on the surface of the nickel-rich NCM cathode through an electrochemical reaction. The CEI layer allows lithium ions to move between the electrode and the electrolyte, but prevents electrons from moving. Thus, the CEI layer effectively minimizes electrolyte decomposition.

[0007] In addition to using NCM with a high nickel content to achieve high-capacity secondary batteries, increasing the operating voltage is also a method. However, using NCM with a high nickel content or using high voltage causes the layered structure of the cathode to collapse, generating reactive oxygen species. These reactive oxygen species react with the electrolyte solvent to generate gas. Regardless of the type of gas generated, this gas increases the internal pressure of the lithium secondary battery, acts as a resistance to lithium movement, expands the volume (thickness) of the secondary battery, poses a significant challenge to weight reduction, and degrades the battery's performance. These factors, along with the collapse of the cathode's layered structure and the electrochemical oxidation that decomposes the electrolyte, degrade the performance of the secondary battery. In order to suppress such performance degradation, a technology is being developed to add an additive capable of forming a coordination bond to the metal oxide of the anode to the electrolyte so that a stable anode-electrolyte interface film (CEI layer) is formed on the surface of the anode, the additive provides a coordination bond to the anode so that the charging structure of the anode does not collapse, and prevents the generation of active oxygen at the anode according to this mechanism, thereby increasing the structural stability of the anode and preventing the electrolyte from oxidizing by suppressing contact between the electrolyte and the anode.

[0008] Additives that can be coordinated to the positive electrode can form a coordination bond with the positive electrode metal and donate electrons to the positive electrode metal, thereby strengthening the bond between the positive electrode metal and oxygen, i.e., the bonding strength of the metal oxide. Therefore, additives that can be coordinated to the positive electrode can suppress the generation of reactive oxygen species due to the collapse of the layered structure, thereby reducing gas generation. Furthermore, additives that can be coordinated to the positive electrode can inhibit the contact between the solvent and the positive electrode, thereby reducing the electrochemical decomposition of the solvent and suppressing gas generation. Thus, the high-temperature storage characteristics and lifespan characteristics of secondary batteries can be improved.

[0009] Therefore, in order to improve the high-temperature storage characteristics and lifespan characteristics of lithium secondary batteries, there is a continuous need for the development of additives that can form coordination bonds to the positive electrode to prevent the collapse of the layered structure of the positive electrode, suppress the generation of active oxygen, suppress side reactions between the positive electrode and electrolyte, and suppress the generation of gas within the secondary battery.

[0010] In order to solve the above problems, the present invention aims to provide a non-aqueous electrolyte for a lithium secondary battery including an additive capable of forming a coordination bond on the surface of a positive electrode.

[0011] A non-aqueous electrolyte for a lithium secondary battery according to one embodiment of the present invention

[0012] A compound containing phosphorus of the phosphazene series treated with fluorination as an additive;

[0013] lithium salt;

[0014] Additional additives; and

[0015] Contains non-aqueous organic solvents.

[0016] A non-aqueous electrolyte for a lithium secondary battery according to one embodiment of the present invention

[0017] A compound containing a fluorinated phosphazene series phosphorus represented by the following chemical formula 1 as an additive;

[0018] lithium salt;

[0019] Additional additives; and

[0020] Contains non-aqueous organic solvents.

[0021]

[0022] (n is an integer from 0 to 5)

[0023] A non-aqueous electrolyte for a lithium secondary battery according to one embodiment of the present invention

[0024] A compound containing a fluorinated phosphazene series phosphorus represented by the following chemical formula 2 as an additive;

[0025] lithium salt;

[0026] Additional additives; and

[0027] Contains non-aqueous organic solvents.

[0028]

[0029] In one embodiment of the present invention, a lithium secondary battery is provided, which includes a non-aqueous electrolyte, a positive electrode, a negative electrode, and a separator for a lithium secondary battery of the present invention.

[0030] The above positive electrode includes a current collector and a positive electrode active material layer formed on the current collector. The positive electrode active material layer may include a binder and a conductive material.

[0031] As the positive electrode active material, a compound capable of reversibly intercalating and deintercalating lithium can be used. Specifically, an oxide of cobalt and lithium, i.e., lithium cobalt oxide (LCO), can be used. An oxide of manganese and lithium, i.e., lithium manganese oxide (LMO), can be used. At least one type of a composite oxide of nickel, cobalt, manganese, or a combination of these metals with lithium, i.e., lithium nickel cobalt manganese oxide (LNCMO), can be used. At least one type of a composite oxide of nickel, cobalt, aluminum, or a combination of these metals with lithium, i.e., lithium nickel cobalt aluminum oxide (LNCAO), can be used. At least one type of a composite oxide of nickel, cobalt, manganese, aluminum, or a combination of these metals with lithium, i.e., lithium nickel cobalt manganese aluminum oxide (LNCMAO), can be used. Lithium iron phosphate (LiFePO4), which is composed of lithium (Li), iron (Fe), and phosphoric acid (PO4), can be used.

[0032] Specifically, a compound represented by any one of the following chemical formulas may be used as the positive electrode active material: Li a A 1-b R b D2 (where 0.90≤a≤1.8, 0≤b≤0.5); Li a E1-b R b O 2-c D c (where 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiE 2-b R b O 4-c D c (where 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b R c D a (Here, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0 <a≤2이다); Li a Ni 1-b-c Co b R c O 2-a Z a (Here, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0 <a<2이다); Li a Ni 1-b-c Co b R c O 2-a Z2 (where, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0 <a<2이다); Li a Ni 1-b-c Mn b R c D a (Here, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0 <a≤2이다); Li a Ni 1-b-c Mn b R c O 2-a Z a (Here, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0 <a<2이다); Li a Ni 1-b-c Mn b R c O 2-a Z2 (where, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0 <a<2이다); Li a Ni b E c G dO2 (where 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1); Li a Ni b Co c Mn d G e O2 (where 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1); Li a NiG b O2 (where 0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2 (where 0.90≤a≤1.8, 0.001≤b≤0.1); Li a MnG b O2 (where 0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4 (where 0.90≤a≤1.8, 0.001≤b≤0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiTO2; LiNiVO4; Li (3-f) J2(PO4)3(0≤f≤2); Li (3-f) Fe2(PO4)3(0≤f≤2); and LiFePO4.

[0033] In the above chemical formula, A is Ni, Co, Mn or a combination thereof; R is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element or a combination thereof; D is O, F, S, P or a combination thereof; E is Co, Mn or a combination thereof; Z is F, S, P or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof; Q is Ti, Mo, Mn or a combination thereof; T is Cr, V, Fe, Sc, Y or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu or a combination thereof.

[0034] The above positive electrode active material is Li[Ni x Coy Mn z ]O2(0.5≤x<1, 0≤y≤0.5, 0≤z≤0.5, x+y+z=1), NCM cathode material, Li[Ni x Co y Al z ]O2(0.5≤x<1, 0≤y≤0.5, 0≤z≤0.5, x+y+z=1), NCA cathode material, Li[Ni x Co y M z ] It is preferable to use a lithium metal oxide cathode material represented by O2(0.5≤x<1, 0≤y≤0.5, 0≤z≤0.5, x+y+z=1, M is Al, Sr, Mg, Mn or La).

[0035] The above-mentioned positive electrode active material may be used as one having a coating layer on the surface of the compound, or a compound having a coating layer may be mixed and used. The coating layer may include a coating element compound, such as an oxide, a hydroxide, an oxyhydroxide of the coating element, an oxycarbonate of the coating element, or a hydroxycarbonate of the coating element. The compounds forming these coating layers may be amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer forming process may use any coating method as long as it can coat the compound with these elements by a method (e.g., spray coating, dipping, etc.) that does not adversely affect the physical properties of the positive electrode active material.

[0036] The above binder serves to adhere the positive electrode active material particles well to each other and also to adhere the positive electrode active material well to the current collector. Representative examples of the binder include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc.

[0037] The above conductive material is used to impart conductivity to the electrode. Any material that does not cause chemical changes and is electronically conductive can be used. Examples of the conductive material include natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, metal powders such as copper, nickel, aluminum, and silver, and metal fibers. Additionally, one or a mixture of one or more conductive materials, such as polyphenylene derivatives, can be used as the conductive material.

[0038] Al may be used as the above current collector, but is not limited thereto.

[0039] The above negative electrode includes a current collector and a negative electrode active material layer formed on the current collector, and the negative electrode active material layer includes a negative electrode active material. The negative electrode active material layer may include a binder and optionally further include a conductive material.

[0040] As the negative electrode active material, a material capable of reversibly intercalating and deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide can be used.

[0041] Any carbon-based negative electrode active material commonly used in lithium-ion secondary batteries can be used as the material capable of reversibly intercalating and deintercalating lithium ions. Representative examples include crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite in an amorphous, plate-like, flake-like, spherical, or fibrous form, and examples of the amorphous carbon include soft carbon (low-temperature calcined carbon), hard carbon, mesophase pitch carbide, calcined coke, etc.

[0042] As the above lithium metal alloy, an alloy of lithium and a metal such as Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al or Sn can be used.

[0043] Materials capable of doping and dedoping the above lithium include Si, SiO x(0 <x<2), Si-C 복합체, Si-Q 합금(상기 Q는 알칼리 금속, 알칼리 토금속, 13족 내지 16족 원소, 전이금속, 희토류 원소 또는 이들의 조합이며, Si은 아님), Sn, SnO2, Sn-C 복합체, Sn-R(상기 R은 알칼리 금속, 알칼리 토금속, 13족 내지 16족 원소, 전이금속, 희토류 원소 또는 이들의 조합이며, Sn은 아님) 등을 들 수 있다. 상기 Q와 R의 구체적인 원소로는, 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, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po 또는 이들의 조합을 들 수 있다.

[0044] Examples of the above transition metal oxides include vanadium oxide, lithium vanadium oxide, etc.

[0045] The above binder serves to adhere the negative electrode active material particles well to each other and also to adhere the negative electrode active material well to the current collector. Representative examples of the binder include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc.

[0046] The conductive material described above is used to impart conductivity to the electrode. Any material that does not cause chemical changes and is electronically conductive can be used. Examples of the conductive material include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, and carbon fiber; metal-based materials such as metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; or conductive materials comprising mixtures thereof.

[0047] The above-mentioned current collector may be a copper foil, a nickel foil, a stainless steel foil, a titanium foil, a nickel foam, a copper foam, a polymer substrate coated with a conductive metal, or a combination thereof.

[0048] The above negative electrode may include a carbon-based negative electrode active material and a silicon-based negative electrode active material.

[0049] The above negative electrode may include a carbon-based negative electrode active material and a silicon-based negative electrode active material in a weight ratio of 100:0 to 50:50.

[0050] The above negative electrode may include a carbon-based negative electrode active material and a silicon-based negative electrode active material in a weight ratio of 97:3 to 50:50.

[0051] The above negative electrode may include a carbon-based negative electrode active material and a silicon-based negative electrode active material in a weight ratio of 90:10 to 60:40.

[0052] The fluorinated phosphazene functional group represented by Chemical Formula 1 provided as an additive in the non-aqueous electrolyte of the present invention can improve the high-temperature storage characteristics and lifespan characteristics of lithium-ion secondary batteries, and can stably operate the lithium-ion secondary batteries. The present invention can improve the stability and reliability of lithium-ion secondary batteries, which are becoming larger and have higher capacities, by protecting the positive electrode through a small amount of electrolyte additive.

[0053] The additive included in the non-aqueous electrolyte of the secondary battery of the present invention has the above-mentioned effects, so that even when the lithium secondary battery is exposed to high temperatures, the lifespan is not deteriorated, and when stored at high temperatures, the generation of gas is suppressed, thereby reducing volume expansion, thereby enabling the realization of a secondary battery with improved performance.

[0054] Hereinafter, the present invention will be described in more detail through examples. These examples are intended solely to illustrate the present invention, and therefore, the scope of the present invention should not be construed as being limited by these examples.

[0055] The terms "includes" and "has" used in this specification should be understood as open-ended terms that imply the possibility of including other components, unless specifically stated otherwise in the phrase or sentence in which the expression is included.

[0056] In this specification, “%” means weight percent unless explicitly indicated otherwise.

[0057] Hereinafter, the electrolyte additive for a lithium secondary battery, the non-aqueous electrolyte for a lithium secondary battery, and the lithium secondary battery including the non-aqueous electrolyte of the present invention will be described in detail.

[0058] Electrolyte additives for lithium secondary batteries

[0059] The present invention provides a compound including phosphorus of the fluorinated phosphazene series as an additive for an electrolyte for a lithium secondary battery, and in particular, a compound including phosphorus of the fluorinated phosphazene series represented by the following chemical formula 1.

[0060] [Chemical Formula 1]

[0061]

[0062] (n is an integer from 0 to 5)

[0063] The present invention provides a compound including phosphorus of the fluorinated phosphazene series as an additive for an electrolyte for a lithium secondary battery, and in particular, a compound including phosphorus of the fluorinated phosphazene series represented by the following chemical formula 2.

[0064] [Chemical Formula 2]

[0065]

[0066] Electrolyte for lithium secondary batteries

[0067] The present invention

[0068] A compound containing phosphorus of the fluorinated phosphazene series;

[0069] Additional additives;

[0070] lithium salt; and

[0071] An electrolyte for a lithium secondary battery containing a non-aqueous organic solvent is provided.

[0072] The present invention

[0073] A compound containing a fluorinated phosphazene series phosphorus represented by the above chemical formula 1;

[0074] Additional additives;

[0075] lithium salt; and

[0076] An electrolyte for a lithium secondary battery containing a non-aqueous organic solvent is provided.

[0077] The present invention

[0078] A compound containing a fluorinated phosphazene series phosphorus represented by the above chemical formula 2;

[0079] Additional additives;

[0080] lithium salt; and

[0081] An electrolyte for a lithium secondary battery containing a non-aqueous organic solvent is provided.

[0082] The compound containing the phosphorus of the fluorinated phosphazene series may be included in an amount of 0.05 to 20 wt% based on the total weight of the electrolyte for the lithium secondary battery.

[0083] The compound containing the fluorinated phosphazene series may preferably be included in an amount of 0.05 to 10 wt% based on the total weight of the electrolyte for the lithium secondary battery.

[0084] The compound including the phosphorus of the fluorinated phosphazene series may more preferably be included in an amount of 0.05 to 5 wt%, 0.05 to 3 wt%, or 0.05 to 2 wt% based on the total weight of the electrolyte for the lithium secondary battery.

[0085] The compound containing the fluorinated phosphazene series may be included in an amount of 0.1 to 20 wt% based on the total weight of the electrolyte for the lithium secondary battery.

[0086] The compound containing the phosphorus of the fluorinated phosphazene series may preferably be included in an amount of 0.1 to 10 wt% based on the total weight of the electrolyte for the lithium secondary battery.

[0087] The compound including the phosphorus of the fluorinated phosphazene series may more preferably be included in an amount of 0.1 to 5 wt%, 0.1 to 3 wt%, or 0.1 to 2 wt% based on the total weight of the electrolyte for the lithium secondary battery.

[0088] If the compound including the phosphorus of the fluorinated phosphazene series is included in an amount of less than 0.05 wt% based on the total weight of the electrolyte for the lithium secondary battery, the high-temperature storage characteristics or life characteristics of the lithium secondary battery are not sufficient, and conversely, if the compound including the phosphorus of the fluorinated phosphazene series is included in an amount exceeding 20 wt% based on the total weight of the electrolyte for the lithium secondary battery, the problem of deterioration of the high-temperature storage characteristics or life characteristics occurs due to an increase in the internal resistance and a decrease in the capacity of the secondary battery.

[0089] The above-mentioned electrolyte for a lithium secondary battery may additionally include at least one additional additive selected from the group consisting of a halogen-substituted or unsubstituted carbonate-based compound, a nitrile-based compound, a borate-based compound, a lithium salt-based compound, a phosphate-based compound, a sulfite-based compound, a sulfone-based compound, a sulfate-based compound, and a sultone-based compound.

[0090] Representative examples of the above-mentioned additional additives include lithium difluorophosphate, lithium tetrafluoro(oxalate)phosphate, lithium bis(fluorosulfonyl)imide, 1,3-propane sultone, 1,3-propene sultone, fluoroethylene carbonate, vinylene carbonate, and vinyl ethylene carbonate.

[0091] The above-mentioned additional additive may be included in an amount of 0.05 to 20 wt% based on the total weight of the electrolyte for the lithium secondary battery.

[0092] The above-mentioned additional additive may preferably be included in an amount of 0.05 to 10 wt% based on the total weight of the electrolyte for the lithium secondary battery.

[0093] The above-mentioned additional additive may more preferably be included in an amount of 0.05 to 5 wt%, specifically 0.05 to 3 wt%, based on the total weight of the electrolyte for the lithium secondary battery.

[0094] If the above-mentioned additional additive is included in an amount of less than 0.05 wt% based on the total weight of the electrolyte for lithium secondary batteries, the effect of forming a film on the electrode is minimal, and thus the effect of suppressing side reactions between the electrode and the electrolyte may be reduced. If the above-mentioned electrolyte additive is included in an amount exceeding 20 wt% based on the total weight of the electrolyte for lithium secondary batteries, an excessively thick film may be formed on the electrode surface, increasing the interfacial resistance and causing problems such as reduced capacity.

[0095] The above lithium salt may include at least one selected from the group consisting of LiPF6, LiClO4, LiAsF6, LiBF4, LiBF6, LiSbF6, LiAl04, LiAlCl4, LiClO4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, and LiB(C2O4)2.

[0096] It is preferable to use a lithium salt having a high lattice energy dissociation degree, excellent ionic conductivity, and superior thermal stability and oxidation resistance. The lithium salt acts as a passage for lithium ions within the secondary battery, thereby enabling the basic operation of the lithium secondary battery.

[0097] The concentration of the lithium salt may be included in a range of 0.1 to 2.5 M (mol / L) based on the total amount of the electrolyte for the lithium secondary battery.

[0098] The concentration of the lithium salt may be preferably included at 0.3 to 2.5 M (mol / L) with respect to the total amount of the electrolyte for the lithium secondary battery, taking into consideration properties related to electrical conductivity and viscosity related to the mobility of lithium ions.

[0099] The concentration of the lithium salt may be more preferably comprised at 0.7 to 1.6 M (mol / L), taking into account properties related to electrical conductivity and viscosity related to mobility of lithium ions.

[0100] If the concentration of the lithium salt is less than 0.1 M, the electrical conductivity of the electrolyte for the lithium secondary battery decreases, thereby reducing the performance of the non-aqueous electrolyte for rapidly transferring ions between the positive and negative electrodes of the lithium secondary battery. If the concentration of the lithium salt exceeds 2.5 M, the viscosity of the electrolyte for the lithium secondary battery increases, thereby reducing the mobility of lithium ions and causing a problem in that the performance of the secondary battery deteriorates at low temperatures.

[0101] The above non-aqueous organic solvent may be a linear carbonate solvent, a cyclic carbonate solvent, an ester solvent, or a mixed solvent thereof.

[0102] The linear carbonate solvent may include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl propyl carbonate (EPC), ethyl methyl carbonate (EMC), and methyl propyl carbonate (MPC).

[0103] In addition, the cyclic carbonate solvent may include at least one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate (BC), vinylene carbonate (VC), and fluoroethylene carbonate (FEC).

[0104] The above ester solvent may include at least one selected from the group consisting of methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), and butyl propionate (BP).

[0105] It may be desirable to use a mixture of a high-dielectric constant cyclic carbonate organic solvent having high ionic conductivity that can improve the charge / discharge performance of a secondary battery and a low-viscosity linear carbonate organic solvent that can appropriately control the viscosity of the high-dielectric constant carbonate organic solvent.

[0106] Specifically, a high-dielectric constant carbonate organic solvent selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), and mixtures thereof, which are cyclic carbonate solvents, and a low-viscosity carbonate organic solvent selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and mixtures thereof, which are linear carbonate solvents, can be used in combination.

[0107] The above cyclic carbonate solvent has a large polarity and can sufficiently dissociate lithium ions, but has a large viscosity and thus has a disadvantage of low ion conductivity. Therefore, by mixing and using a linear carbonate solvent with a small polarity but low viscosity with the above cyclic carbonate solvent, the characteristics of a lithium secondary battery can be optimized.

[0108] Therefore, it may be desirable to use a mixture of at least one solvent selected from the cyclic carbonate solvent and at least one solvent selected from the linear carbonate solvent as the non-aqueous organic solvent.

[0109] The mixed solvent of the linear carbonate solvent and the cyclic carbonate solvent can be used by mixing the linear carbonate solvent and the cyclic carbonate solvent in a volume ratio of 9:1 to 1:9.

[0110] In terms of the life characteristics and storage characteristics of a secondary battery, it may be more preferable to use a mixed solvent of the linear carbonate solvent and the cyclic carbonate solvent in a volume ratio of 2:8 to 8:2.

[0111] The non-aqueous organic solvent may include ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC).

[0112] The non-aqueous organic solvent may include 5 to 40 wt% of the ethylene carbonate (EC), 5 to 20 wt% of the propylene carbonate (PC), 10 to 70 wt% of the ethyl methyl carbonate (EMC), and 10 to 60 wt% of the diethyl carbonate (DEC).

[0113] Specifically, among the cyclic carbonate solvents, ethylene carbonate (EC) or propylene carbonate (PC) having a high dielectric constant can be used. When artificial graphite is used as the negative electrode active material, it is preferable to use the ethylene carbonate (EC). Among the linear carbonate solvents, it is preferable to use dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), or diethyl carbonate (DEC) having a low viscosity.

[0114] The non-aqueous organic solvent may be included in an amount of 5% to 80% of the total amount of the electrolyte for the lithium secondary battery. The non-aqueous organic solvent may be included in an amount of 5% to 70% of the total amount of the electrolyte for the lithium secondary battery.

[0115] Lithium secondary battery

[0116] A lithium secondary battery including the above non-aqueous electrolyte does not deteriorate in life characteristics at high temperatures, does not increase in resistance when stored at high temperatures, and has superior performance in suppressing expansion of the volume (thickness) of the secondary battery.

[0117] Hereinafter, the lithium secondary battery of the present invention will be described in detail.

[0118] The lithium secondary battery of the present invention

[0119] anode;

[0120] cathode;

[0121] membrane;

[0122] and non-aqueous electrolytes.

[0123] The above cathode is LiCoO2, LiFePO4, LiMnO2, LiMn2O4, LiNiO2, Li[Ni x Co y Mn z ]O2(0.5≤x<1, 0≤y≤0.5, 0≤z≤0.5, x+y+z=1), and Li[Ni x Co y M z ]O2(0.5≤x<1, 0≤y≤0.5, 0≤z≤0.5, x+y+z=1, M is Al, Sr, Mg, Mn or La) and may include at least one positive electrode active material selected from the group consisting of lithium metal oxides. The positive electrode may include high nickel NMC.

[0124] The above negative electrode may include at least one negative electrode active material selected from the group consisting of silicon, silicon compounds, tin, tin compounds, lithium titanate, crystalline carbon, amorphous carbon, artificial graphite, natural graphite, and a mixture of artificial graphite and natural graphite.

[0125] The above separator may be composed solely of a porous polymer film made of at least one polyolefin polymer selected from among ethylene polymers, propylene polymers, ethylene / butene copolymers, and ethylene / hexene copolymers, or may be composed of a laminate thereof. The above separator may include a coating film coated with a ceramic or polymer material.

[0126] The above non-aqueous electrolyte comprises a compound containing phosphorus of the fluorinated phosphazene series, particularly a compound represented by the following chemical formula 1;

[0127] Additional additives;

[0128] lithium salt; and

[0129] May contain non-aqueous organic solvents.

[0130] [Chemical Formula 1]

[0131]

[0132] (n is an integer from 0 to 5)

[0133] The above non-aqueous electrolyte comprises a compound containing phosphorus of the fluorinated phosphazene series, particularly a compound represented by the following chemical formula 2;

[0134] Additional additives;

[0135] lithium salt; and

[0136] May contain non-aqueous organic solvents.

[0137] [Chemical Formula 2]

[0138]

[0139] Examples of the above lithium secondary battery include, but are not limited to, a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.

[0140] To explain in more detail, it is preferable that the positive electrode active material is a composite metal oxide of at least one material selected from cobalt, manganese, and nickel and lithium, or a composite metal oxide of at least one material selected from cobalt, aluminum, and nickel and lithium. The solid solution rate between cobalt, manganese, and nickel metals of the composite metal oxide or the solid solution rate between cobalt, aluminum, and nickel metals can be varied. In addition to the cobalt, manganese, and nickel metals, an element selected from the group consisting of Mg, Al, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As, Zr, Cr, Fe, Sr, V, and rare earth elements may be further included. In addition to the cobalt, aluminum, and nickel metals, an element selected from the group consisting of Mg, Mn, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As, Zr, Cr, Fe, Sr, V, and rare earth elements may be further included.

[0141] Specifically, the positive electrode active materials include LiCoO2, LiFePO4, LiMnO2, LiMn2O4, and LiNiO. 2, Li[Ni x Co y Mnz ]O2(0.5≤x<1, 0≤y≤0.5, 0≤z≤0.5, x+y+z=1), or Li[Ni x Co y M z ]O2(0.5≤x<1, 0≤y≤0.5, 0≤z≤0.5, x+y+z=1, M is Al, Sr, Mg, Mn or La) or a lithium intercalation compound such as a lithium chalcogenide compound can be used, but is not limited thereto and any material usable as a positive electrode active material in a secondary battery can be used. The positive electrode active material may be high nickel NMC.

[0142] The above positive electrode includes a current collector and a positive electrode active material layer formed on the current collector. The positive electrode active material layer may include a positive electrode active material capable of absorbing and releasing lithium, a binder, a conductive material, and the like.

[0143] The above negative electrode includes a current collector and a negative electrode active material layer formed on the current collector. The negative electrode active material layer may include a negative electrode active material capable of inserting and de-inserting lithium, a binder, a conductive material, etc. As the negative electrode active material, crystalline carbon, amorphous carbon, a carbon composite, carbon fiber, lithium metal, a lithium alloy, or a carbon-silicon composite may be used, but is not limited thereto, and any material usable as a negative electrode active material in a secondary battery may be used.

[0144] The above positive and / or negative electrodes can be manufactured by dispersing an electrode active material, a binder, a conductive agent, and, if necessary, a thickener in a solvent to prepare an electrode slurry composition, and then applying the slurry composition to an electrode current collector. Aluminum or an aluminum alloy can commonly be used as the positive current collector, and copper or a copper alloy can commonly be used as the negative current collector.

[0145] Examples of the form of the positive electrode current collector and the negative electrode current collector include foil or mesh forms.

[0146] The above binder is a material that plays a role in pasting the active material, mutual adhesion of the active material, adhesion with the current collector, and cushioning effect for expansion and contraction of the active material, and any binder that can be used by a person skilled in the art can be used. For example, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride (PVdF), polyhexafluoropropylene-polyvinylidene fluoride copolymer (PVdF / HFP), poly(vinylacetate), alkylated polyethylene oxide, polyvinyl ether, poly(methyl methacrylate), poly(ethyl acrylate), polyacrylonitrile, polyvinylpyridine, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, epoxy resin, nylon, etc. can be used, but are not limited thereto.

[0147] The conductive material is used to provide conductivity to the electrode, and any electrically conductive material that does not cause a chemical change in the secondary battery to be formed can be used. The conductive material may include at least one selected from the group consisting of a graphite-based conductive material, a carbon black-based conductive material, and a metal or metal compound-based conductive material. Examples of the graphite-based conductive material include artificial graphite, natural graphite, etc., examples of the carbon black-based conductive material include acetylene black, ketjen black, denka black, thermal black, channel black, etc., and examples of the metal-based or metal compound-based conductive material include perovskite materials such as tin, tin oxide, tin phosphate (SnPO4), titanium oxide, potassium titanate, LaSrCoO3, and LaSrMnO3. However, the present invention is not limited to the conductive materials listed above.

[0148] The above thickener is not particularly limited as long as it can play a role in controlling the viscosity of the active material slurry, and examples thereof include carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose.

[0149] As a solvent in which the electrode active material, binder, conductive material, etc. are dispersed, a non-aqueous solvent or an aqueous solvent may be used. Examples of the non-aqueous solvent include N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, N,N-dimethylaminopropylamine, ethylene oxide, or tetrahydrofuran. Examples of the aqueous solvent include water.

[0150] The above lithium secondary battery may include a separator that prevents short circuits between the positive and negative electrodes and provides a passage for lithium ions to move. As the separator, a polyolefin-based polymer film such as polypropylene, polyethylene, polyethylene / polypropylene, polyethylene / polypropylene / polyethylene, polypropylene / polyethylene / polypropylene, or a multi-film thereof, a microporous film, a woven fabric, or a non-woven fabric may be used. In addition, a film in which a porous polyolefin film is coated with a resin having excellent stability may be used as the separator.

[0151] In addition, the lithium secondary battery can be made into various shapes such as square, cylindrical, pouch or coin shape.

[0152] [Example]

[0153] Hereinafter, the present invention will be described in more detail through examples. The scope of the present invention should not be construed as being limited by these examples.

[0154] <Method for producing a compound of chemical formula 1>

[0155] <1,3-Bis((2,4,4,6,6-pentafluoro-1,3,5,2λ 5 ,4λ 5 ,6λ 5 -triazatriphosphinin-2-yl)oxy)propane(1,3-bis((2,4,4,6,6-pentafluoro-1,3,5,2λ 5 ,4λ 5 ,6λ 5 Synthesis example of -triazatriphosphinin-2-yl)oxy)propane)

[0156] A 500 mL three-necked flask was equipped with a N2 purge line and a dropping funnel, and 0.14 mol of hexachlorocyclotriphosphazene and 200 mL of acetonitrile were added at room temperature, followed by the addition of 1.43 mol of sodium fluoride. The inside of the reactor was made into a nitrogen atmosphere, and 10 w% of 1-ethyl-3-methylimidazolium tetrafluoroborate was slowly added, the reaction temperature was changed to 40°C, and the mixture was stirred for 14 hours. Afterwards, the reactant was filtered to remove the white solid, and the filtrate was poured into a 500 mL flask. Then, 0.07 mol of 1,3-propanediol and 0.07 mol of tripotassium phosphate were rapidly added, and the inside of the reactor was made into a nitrogen atmosphere and stirred at room temperature for 16 hours. After the reaction was completed, the reactant was filtered to remove the white solid, and the solvent was concentrated and purified by column chromatography under the condition of heptane: dichloromethane (8:1). Afterwards, it was dried in a vacuum oven to obtain the desired substance, 1,3-bis((2,4,4,6,6-pentafluoro-1,3,5,2λ) 5 ,4λ 5 ,6λ 5 -Triazatriphosphinin-2-yl)oxy)propane(1,3-Bis((2,4,4,6,6-pentafluoro-1,3,5,2λ 5 ,4λ 5 ,6λ 5 -triazatriphosphinin-2-yl)oxy)propane) was obtained.

[0157] 1 H NMR CDCl3δ = 2.18 (m, 2H), 4.35 (m, 4H)

[0158] <1,3-Bis((2,4,4,6,6-pentafluoro-1,3,5,2λ 5 ,4λ 5 ,6λ 5 -triazatriphosphinin-2-yl)oxy)propane(1,3-bis((2,4,4,6,6-pentafluoro-1,3,5,2λ 5 ,4λ 5 ,6λ 5 Preparation of electrolyte for lithium secondary battery containing -triazatriphosphinin-2-yl)oxy)propane)>

[0159] After dissolving LiPF6 to 1.0 M in a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (EC / EMC=25 / 75 volume ratio), 0.5 wt% of 1,3-propene sultone (PRS), 1.0 wt% of fluoroethylene carbonate (FEC), 0.5 wt% of propane sultone (PS), 0.5 wt% of ethylene sulfate (Esa) and 1,3-bis((2,4,4,6,6-pentafluoro-1,3,5,2λ) of the above synthetic example represented by the above chemical formula 1 were added to the mixed solution. 5 ,4λ 5 ,6λ 5 -Triazatriphosphinin-2-yl)oxy)propane(1,3-Bis((2,4,4,6,6-pentafluoro-1,3,5,2λ 5 ,4λ 5 ,6λ 5 An electrolyte for a lithium secondary battery containing a compound of chemical formula 1 was prepared by adding 0.5 wt% of -triazatriphosphinin-2-yl)oxy)propane.

[0160] <1,3-Bis((2,4,4,6,6-pentafluoro-1,3,5,2λ 5 ,4λ 5 ,6λ 5 - Manufacture of a lithium secondary battery comprising an electrolyte for a lithium secondary battery containing triazatiphosphinin-2-yl)oxy)propane (compound of chemical formula 2)>

[0161] Li[Ni x Co y Mnz ]O2(0.5≤x<1, 0≤y≤0.5, 0≤z≤0.5, x+y+z=1), 2 wt% of conductive agent (Super-P), and 2 wt% of binder (PVdF) were added to N-methyl 2-pyrrolidinone (NMP), an organic solvent, to prepare a slurry of positive electrode active material. The slurry of positive electrode active material was applied to an aluminum thin film as a current collector, dried, and then rolled with a roll press to prepare a final positive electrode. In addition, silicon oxide (SiO x (0 <x<2))을 포함하는 흑연계 음극 활물질 96 중량%, 도전재(Super-P) 1중량%, 바인더 SBR 1.5중량%, CMC 1.5중량%를 혼합하여 음극 활물질 슬러리를 제조하였다. 상기 음극 활물질 슬러리를 음극 집전체인 구리 박막에 도포하고 건조하여 음극을 만들었다.

[0162] The positive and negative electrodes manufactured as described above were prepared, and a separator was interposed between them. Then, an electrolyte for a lithium secondary battery containing the compound of chemical formula 1 was injected between the two electrodes on which the separator was placed, thereby manufacturing a lithium secondary battery containing an electrolyte containing the compound of chemical formula 1 in the form of an aluminum pouch (Al-Pouch type).

[0163] [Comparative Example 1]

[0164] <Manufacture of a lithium secondary battery that does not contain a compound of chemical formula 1>

[0165] 1,3-bis((2,4,4,6,6-pentafluoro-1,3,5,2λ) represented by the above chemical formula 1 as an electrolyte 5 ,4λ 5 ,6λ 5A lithium secondary battery including an electrolyte that does not include the compound of formula 1 was manufactured in the same manner as the manufacturing of the lithium secondary battery of the above example, except that an electrolyte for a lithium secondary battery without adding a -triazatriphosphinin-2-yl)oxy)propane compound was used.

[0166] [Comparative Example 2]

[0167] <Manufacture of a lithium secondary battery containing an electrolyte containing lithium difluorophosphate (LiPO2F2) additive>

[0168] 1,3-bis((2,4,4,6,6-pentafluoro-1,3,5,2λ) represented by the above chemical formula 1 as an electrolyte 5 ,4λ 5 ,6λ 5 -A lithium secondary battery was manufactured using the same method as in the above example for manufacturing a lithium secondary battery, except that a lithium secondary battery electrolyte containing lithium difluorophosphate (LiPO2F2) was used without adding a triazatiphosphinin-2-yl)oxy)propane compound, and a lithium secondary battery containing a lithium difluorophosphate (LiPO2F2) electrolyte was manufactured instead of the compound of formula 1.

[0169] The composition of the electrolyte for lithium secondary batteries of the above examples and comparative examples is shown in Table 1 below.

[0170] <Composition of electrolyte for lithium secondary batteries>

[0171] Chemical Formula 11,3-Propene Sultone (PRS) Fluoroethylene Carbonate (FEC) Lithium Difluorophosphate (LiPO2F2) 1,3-Propane Sultone (PS) Ethylene Sulfate (Esa) Example OOOOO Comparative Example 1 OOOOO Comparative Example 2 OOOOO

[0172] [Experimental Example]

[0173] <Experimental Example 1> Measurement of high temperature (45℃) life capacity retention rate

[0174] A pouch-shaped lithium secondary battery manufactured using the electrolyte for lithium secondary batteries of the above examples and comparative examples was charged to 4.2 V at a 1 C rate at a high temperature (45°C), followed by a 10-minute rest period, discharged to 2.7 V at a 1 C rate, and then rested for another 10 minutes. The above process was repeated 500 times, and the discharge capacity (mAh) and life-cycle capacity retention rate (retention, %) of the battery were measured. The measured discharge capacities and life-cycle capacity retention rates of the secondary batteries were compared, and the results are shown in Table 2.

[0175] 1-time discharge capacity (mAh) 500-time discharge capacity (mAh) Life-span capacity retention rate (%) Example 1 131.29 78.58 6.5 Comparative example 1 139.59 10.57 9.9 Comparative example 2 1129.79 29.78 2.3

[0176] As shown in Table 2 above, the results of the life evaluation at high temperatures showed that the lithium secondary battery of the above example had a higher life capacity retention rate at high temperatures than the lithium secondary battery of the above comparative example.

[0177] Therefore, it was confirmed that the lithium secondary battery of the above example had a high life capacity retention rate without deterioration in high-temperature life performance of the secondary battery compared to the lithium secondary battery of the comparative example by including an electrolyte containing the compound represented by the chemical formula 1. In other words, the compound additive of the chemical formula 1 improved the life capacity retention rate at high temperatures without deterioration in performance due to side reactions with other additives.

[0178] <Experimental Example 2> Measurement of high-temperature (60℃) storage characteristics

[0179] The volume change rate, capacity retention rate, and capacity recovery rate of the pouch-type lithium secondary batteries manufactured using the electrolytes for lithium secondary batteries of the above examples and comparative examples were measured after storing them at a high temperature (60°C) for 6 weeks. Table 3 below shows the results of the volume change rate, capacity retention rate, and capacity recovery rate of the secondary batteries after 6 weeks of storage at a high temperature (60°C) compared to week 0.

[0180] Volume increase rate (%) after 6 weeks of storage at 60℃ Capacity retention rate (%) after 6 weeks of storage at 60℃ Capacity recovery rate (%) after 6 weeks of storage at 60℃ Example 2.7581.0983.19 Comparative example 17.8677.5880.78 Comparative example 28.1376.3078.90

[0181] As shown in Table 3, the volume increase rate of the secondary battery of the example was lower than that of the secondary battery of the comparative example. This demonstrates that the additive of the present invention has the effect of suppressing gas generation.

[0182] Additionally, as shown in Table 3, the secondary battery of the example had a higher capacity retention rate and capacity recovery rate than the secondary battery of the comparative example. From this, it can be seen that the additive of the present invention is an additive with excellent capacity retention rate and capacity recovery rate after 6 weeks.

[0183] From the above experimental results, it can be seen that the additive of the present invention is an additive that has excellent high-temperature life characteristics at 45°C, suppresses gas generation, and has excellent age retention and capacity recovery rate.

Claims

1. Additives; Additional additives; lithium salt; and A non-aqueous electrolyte for a lithium secondary battery containing a non-aqueous organic solvent, The above additive is a non-aqueous electrolyte for lithium secondary batteries, which is a phosphorus compound of the fluorinated phosphazene series.

2. In paragraph 1, the additive is a non-aqueous electrolyte for a lithium secondary battery, which is a compound of the following chemical formula 1. [Chemical Formula 1] (n is an integer from 0 to 5) 3. A non-aqueous electrolyte for a lithium secondary battery, wherein the additive is included in an amount of 0.05 wt% to 20 wt% based on the total weight of the non-aqueous electrolyte for a lithium secondary battery in the first or second paragraph.

4. A non-aqueous electrolyte for a lithium secondary battery according to claim 1 or 2, wherein the additional additive is at least one compound selected from the group consisting of a halogen-substituted or unsubstituted carbonate-based compound, a nitrile-based compound, a borate-based compound, a lithium salt-based compound, a phosphate-based compound, a sulfite-based compound, a sulfone-based compound, a sulfate-based compound, and a sultone-based compound.

5. Non-aqueous electrolyte for lithium secondary batteries according to paragraph 1 or 2; anode; cathode; and A lithium secondary battery including a separator.

6. In the fifth paragraph, the positive electrode is lithium cobalt oxide (LCO); lithium manganese oxide (LMO); lithium nickel cobalt manganese oxide (LNCMO) in which nickel (Ni) and manganese (Mn) are combined with lithium cobalt oxide (LCO); lithium nickel cobalt aluminum oxide (LNCAO) in which nickel (Ni) and aluminum (Al) are combined with lithium cobalt oxide (LCO); lithium nickel cobalt manganese aluminum oxide (LNCMAO) in which nickel (Ni), manganese (Mn), and aluminum (Al) are combined with lithium cobalt oxide (LCO); lithium iron phosphate (LiFePO4) composed of lithium (Li), iron (Fe), and phosphoric acid (PO4); and Li[Ni x Co y M z ]A lithium secondary battery comprising a cathode material selected from the group consisting of lithium metal oxides represented by O2(0.5≤x<1, 0≤y≤0.5, 0≤z≤0.5, x+y+z=1, M is Al, Sr, Mg, Mn or La).

7. In the 6th paragraph, the lithium nickel cobalt manganese oxide (LNCMO) is Li[Ni x Co y Mn z ]A lithium secondary battery, which is lithium nickel cobalt manganese oxide (LNCMO) represented by O2(0.5≤x<1, 0≤y≤0.5, 0≤z≤0.5, x+y+z=1).

8. A lithium secondary battery in accordance with paragraph 5, wherein the negative electrode comprises a carbon-based negative electrode active material and a silicon-based negative electrode active material.

9. A lithium secondary battery in accordance with paragraph 8, wherein the carbon-based negative electrode active material and the silicon-based negative electrode active material are included in a weight ratio of 100:0 to 50:

50.

10. A lithium secondary battery in accordance with claim 9, wherein the carbon-based negative electrode active material and the silicon-based negative electrode active material are included in a weight ratio of 97:3 to 50:

50.

11. A lithium secondary battery in claim 9, wherein the carbon-based negative electrode active material and the silicon-based negative electrode active material are included in a weight ratio of 90:10 to 60:40.

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