Non-aqueous electrolyte for lithium secondary batteries and lithium secondary batteries containing the same

Abstract

The present invention relates to a non-aqueous electrolyte for a lithium secondary battery that can form a stable coating on the surface of an electrode, and a lithium secondary battery containing the same. Specifically, the non-aqueous electrolyte for a lithium secondary battery of the present invention may contain a lithium salt, a non-aqueous organic solvent, and a compound represented by Chemical Formula 1.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0142019, filed on October 22, 2021, and all the contents disclosed in the document of the Korean Patent Application are incorporated herein by reference in their entirety.

[0002] The present invention relates to a non-aqueous electrolyte for a lithium secondary battery including an additive capable of forming a stable film on the surfaces of a positive electrode and a negative electrode, and a lithium secondary battery having improved high-temperature storage safety by including the same.

Background Art

[0003] In recent years, with the development of the information society, personal IT devices and computer networks have developed, and accordingly, the overall social dependence on electrical energy has increased. Therefore, the development of battery technologies for efficiently storing and utilizing electrical energy is required.

[0004] In particular, as interest in solving environmental problems and realizing a sustainable recycling society has increased, extensive research has been conducted on lithium-ion batteries, which are in the spotlight as clean energy with low carbon dioxide emissions.

[0005] Lithium-ion batteries can be miniaturized to an extent applicable to personal IT devices, etc., and because of their high energy density and operating voltage, they are adopted not only as power sources for notebook computers, mobile phones, etc., but also as power sources for power storage and electric vehicles.

[0006] The lithium-ion secondary battery comprises a positive electrode mainly composed of a lithium-containing transition metal oxide, a negative electrode using a carbonaceous material such as a lithium alloy or graphite, a separator interposed between the positive and negative electrodes, and a non-aqueous electrolyte that serves as a medium for Li ions to move. In this case, the non-aqueous electrolyte is widely used in which an electrolyte such as lithium hexafluoride phosphate (LiPF6) is dissolved in a high dielectric constant organic solvent such as ethylene carbonate or dimethyl carbonate.

[0007] On the other hand, electrolytes such as lithium hexafluoride phosphate (LiPF6) are sensitive to heat and moisture, and react with moisture present inside the cell or undergo thermal decomposition to generate Lewis acids such as PF5. Such Lewis acids can erode the passive film formed at the electrode-electrolyte interface and may induce the elution of transition metal ions from the positive electrode. These eluted transition metal ions can accelerate gas generation by promoting the decomposition of the electrolyte solvent, or they can be re-deposited onto the positive electrode, increasing its resistance. They can also move to the negative electrode via the electrolyte and be electrodeposited onto the negative electrode, causing self-discharge of the negative electrode, destruction and regeneration of the SEI (solid electrolyte interphase) film, additional lithium ion consumption, and increased resistance.

[0008] Therefore, there is a need for a non-aqueous electrolyte composition that can improve not only safety but also battery performance, such as high-rate charge-discharge characteristics, by removing by-products (such as HF and PF5) generated by the thermal decomposition of lithium salts, forming a stable film on the electrode surface to suppress the elution of transition metals, or preventing the electrodeposition of eluted transition metal ions onto the negative electrode. [Overview of the project] [Problems that the invention aims to solve]

[0009] To solve the above-mentioned problems, the present invention aims to provide a non-aqueous electrolyte for lithium secondary batteries that contains an additive capable of forming a stable ion-conductive film on the surface of the electrode and effectively removing decomposition products of lithium salts.

[0010] Furthermore, the present invention aims to provide a lithium secondary battery with improved high-temperature storage safety by including the aforementioned non-aqueous electrolyte for lithium secondary batteries. [Means for solving the problem]

[0011] According to one embodiment, the present invention is Lithium salts and Non-aqueous organic solvents, The present invention provides a non-aqueous electrolyte for lithium secondary batteries containing a compound represented by the following chemical formula 1.

[0012] [ka]

[0013] In the aforementioned chemical formula 1, R is an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 1 to 6 carbon atoms, or an alkynyl group having 1 to 6 carbon atoms. R1 is an alkylene group having 1 to 3 carbon atoms. X is either O or S.

[0014] Furthermore, one embodiment of the present invention provides a lithium secondary battery comprising a negative electrode, a positive electrode, a separator interposed between the negative electrode and the positive electrode, and a non-aqueous electrolyte for lithium secondary batteries of the present invention. [Effects of the Invention]

[0015] The non-aqueous electrolyte of the present invention, by including a compound containing an isocyanate (-NCO) or isothiocyanate (-NCS) terminal group as an additive, effectively removes Lewis acids generated as decomposition products of the electrolyte salt, forms a stable film on the surfaces of the positive and negative electrodes, and reduces the degradation of the SEI film.

[0016] Therefore, by using the non-aqueous electrolyte of the present invention, it is possible to suppress the elution of transition metals from the positive electrode and realize a lithium secondary battery with improved high-temperature storage safety. [Modes for carrying out the invention]

[0017] The present invention will be described in more detail below.

[0018] The terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors may appropriately define the concepts of terms in order to best describe their invention.

[0019] On the other hand, in this specification, terms such as “includes,” “equip,” or “have” are intended to specify the presence of implemented features, figures, steps, components, or combinations thereof, and should be understood not to preemptively exclude the presence or possibility of adding one or more other features, figures, steps, components, or combinations thereof.

[0020] Furthermore, prior to describing the present invention, in the description of "a to b carbon atoms" in the specification, "a" and "b" refer to the number of carbon atoms contained in a specific functional group. That is, the functional group may contain "a" to "b" carbon atoms. For example, "alkyl group with 1 to 5 carbon atoms" refers to alkyl groups containing 1 to 5 carbon atoms, i.e., -CH3, -CH2CH3, -CH2CH2CH3, -CH2(CH3)CH3, -CH(CH3)CH3, and -CH(CH3)CH2CH3, etc.

[0021] Furthermore, in this specification, unless otherwise defined, "substitution" means that at least one hydrogen atom bonded to a carbon atom is substituted with an element other than hydrogen, for example, with an alkyl group having 1 to 4 carbon atoms or with a fluorine element.

[0022] Furthermore, in this specification, "%" means weight percent unless explicitly indicated otherwise.

[0023] During operation of secondary batteries, repeated charging and discharging can cause structural changes in the positive electrode, leading to the easy leaching of transition metal ions from the positive electrode into the electrolyte. This reduces the amount of available lithium ions in the battery, resulting in battery capacity degradation. In particular, the degradation of passive films such as the SEI (solid electrolyte interphase) due to Lewis acids generated by the thermal decomposition of electrolyte salts exacerbates the leaching of transition metal ions. These leached transition metal ions can either be re-deposited onto the positive electrode, increasing its resistance, or electrodeposited onto the surface of the negative electrode, destroying the SEI film and potentially causing an internal short circuit. This series of reactions accelerates the decomposition of the electrolyte, increasing gas generation, increasing the interfacial resistance and self-discharge of the negative electrode, and causing low-voltage failures.

[0024] An object of the present invention is to provide a non-aqueous electrolyte for a lithium secondary battery that can suppress additional elution and electrodeposition of transition metal ions by removing Lewis acid that causes such deterioration and poor behavior and forming a strong film on the surfaces of the positive and negative electrodes.

[0025] Nonaqueous electrolyte for lithium secondary batteries One embodiment of the present invention provides a non-aqueous electrolyte for a lithium secondary battery.

[0026] The non-aqueous electrolyte for a lithium secondary battery contains a lithium salt, a non-aqueous organic solvent, and a compound represented by the following chemical formula 1.

[0027]

Chemical formula

[0028] In the chemical formula 1, R is an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 1 to 6 carbon atoms, or an alkynyl group having 1 to 6 carbon atoms, R1 is an alkylene group having 1 to 3 carbon atoms, X is O or S.

[0029] (1) Lithium salt The lithium salt can be used without limitation as those commonly used in electrolytes for lithium secondary batteries. For example, as a cation, Li

[0029] , - , - , - , - , - , - , 10 , , - , - , - , - , - , + , - , , 10 is included, and as an anion, F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , B 10 , Cl 10 - , AlCl4 - , AlO4 - , PF6 -CF3SO3 - CH3CO2 - CF3CO2 - AsF6 - SbF6 - CH3SO3 - , (CF3CF2SO2)2N - (CF3SO2)2N - , (FSO2)2N - BF2C2O4 - BC4O8 - PF4C2O4 - PF2C4O8 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - , C4F9SO3 - CF3CF2SO3 - CF3CF2(CF3)2CO - (CF3SO2) 2CH - CF3(CF2)7SO3 - , and SCN - At least one of the following can be selected from the group, and other lithium salts commonly used in the electrolyte of lithium secondary batteries can also be used without restriction.

[0030] Specifically, the lithium salts are LiCl, LiBr, LiI, LiBF4, LiClO4, and LiB 10 Cl 10It may include at least one selected from the group consisting of LiAlCl4, LiAlO4, LiPF6, LiCF3SO3, LiCH3CO2, LiCF3CO2, LiAsF6, LiSbF6, LiCH3SO3, LiN(SO2F)2 (Lithium bis(fluorosulfonyl)imide, LiFSI), LiN(SO2CF2CF3)2 (lithium bis(perfluoroethanesulfonyl)imide, LiBETI), and LiN(SO2CF3)2 (lithium bis(trifluoromethanesulfonyl)imide, LiTFSI), and more specifically, at least one selected from the group consisting of LiBF4, LiClO4, LiPF6, LiN(SO2F)2, LiN(SO2CF2CF3)2, and LiN(SO2CF3)2.

[0031] The lithium salt may be appropriately changed within a range of normal use, but may be included in the electrolyte at a concentration of 0.8 M to 3.0 M, specifically 1.0 M to 3.0 M, in order to obtain the optimal effect of forming a corrosion-preventive film on the electrode surface. When the concentration of the lithium salt satisfies the above range, the viscosity of the non-aqueous electrolyte can be controlled to achieve optimal impregnation, thereby improving the mobility of lithium ions and improving the capacity characteristics and cycle characteristics of the lithium secondary battery.

[0032] (2) Non-aqueous organic solvents The non-aqueous organic solvent of the present invention may include a cyclic carbonate organic solvent, a linear carbonate organic solvent, or a mixture thereof.

[0033] The aforementioned cyclic carbonate-based organic solvent is a highly viscous organic solvent that readily dissociates lithium salts in the electrolyte due to its high dielectric constant. Specific examples of such organic solvents include at least one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate, and among these, ethylene carbonate may be included.

[0034] Furthermore, the linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and as a representative example, at least one organic solvent selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate, and ethyl propyl carbonate may be used, and specifically, dimethyl carbonate (DMC) may be included.

[0035] In the present invention, in order to ensure high ionic conductivity of the non-aqueous electrolyte, the cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent may be mixed and used in a volume ratio of 10:90 to 50:50, specifically 15:85 to 30:70.

[0036] Furthermore, the non-aqueous organic solvent may further contain at least one of the linear ester organic solvents and cyclic ester organic solvents, which have a lower melting point and higher storage safety at high temperatures compared to the cyclic carbonate organic solvent and / or linear carbonate organic solvent, in order to produce an electrolyte with high ionic conductivity.

[0037] Specific examples of such linear ester-based organic solvents include at least one organic solvent selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate.

[0038] Furthermore, the cyclic ester organic solvent may be at least one organic solvent selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0039] The non-aqueous organic solvent may, if necessary, be used with an additional, unrestricted, organic solvent commonly used in electrolytes for lithium secondary batteries. For example, it may further contain at least one organic solvent from among ether-based organic solvents, amide-based organic solvents, and nitrile-based organic solvents.

[0040] (3) Compounds represented by chemical formula 1 The non-aqueous electrolyte for lithium secondary batteries of the present invention may contain, as a first additive, a compound represented by the following chemical formula 1.

[0041] [ka]

[0042] In the aforementioned chemical formula 1, R is an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 1 to 6 carbon atoms, or an alkynyl group having 1 to 6 carbon atoms. R1 is an alkylene group having 1 to 3 carbon atoms. X is either O or S.

[0043] The compound represented by chemical formula 1 contains an isocyanate (-NCO) or isothiocyanate (-NCS) terminal group containing a nitrogen element in its structure. The lone pair of electrons of the nitrogen element reacts with and binds to Lewis acids, such as HF, generated as decomposition products of the electrolyte salt, forming a complex and effectively scavenging the Lewis acids. Furthermore, the compound represented by chemical formula 1 is reduced before non-aqueous organic solvents on the surfaces of the negative and positive electrodes, forming a stable passivation film. This suppresses the elution of transition metals from the positive electrode, inhibits additional electrolyte decomposition reactions, and provides gas reduction during high-temperature storage and improved high-temperature cycle performance.

[0044] Specifically, in the above chemical formula 1, R may be a substituted or unsubstituted C1-C6 alkyl group, or a substituted or unsubstituted C1-C6 alkynyl group.

[0045] Furthermore, in the above chemical formula 1, R may be a substituted or unsubstituted C1-C4 alkyl group, or a substituted or unsubstituted C1-C4 alkynyl group.

[0046] In this case, the substituted substituent may be selected from, as a representative example, alkyl groups having 1 to 4 carbon atoms and at least one fluorine.

[0047] Preferably, the compound represented by chemical formula 1 may be at least one of the compounds represented by the following chemical formulas 1-1 to 1-4.

[0048] [ka]

[0049] [ka]

[0050] [ka]

[0051] [ka]

[0052] The compound represented by chemical formula 1 may be included in an amount of 0.3% to 5% by weight based on the total weight of the non-aqueous electrolyte for lithium secondary batteries.

[0053] When the compound represented by chemical formula 1 is included within the above range, secondary batteries with improved performance can be manufactured. For example, if the content of the compound represented by chemical formula 1 is 0.3% by weight or less, the SEI formation effect is minimal, and the gas reduction effect during high-temperature storage and the improvement effect of high-temperature cycle characteristics may be minimal. Specifically, if the content of the compound represented by chemical formula 1 is 0.3% by weight or more, a stabilization effect and an elution suppression effect can be obtained when the SEI film is formed, and if the content of the compound represented by chemical formula 1 is 5% by weight or less, it is possible to prevent an increase in the viscosity of the electrolyte due to excess compound while minimizing the increase in resistance, and to effectively prevent an increase in battery resistance by suppressing the formation of an excessive film, thereby obtaining the maximum elution suppression effect within the acceptable resistance increase.

[0054] Specifically, the compound represented by chemical formula 1 may be included in an amount of 0.5% to 3% by weight based on the total weight of the non-aqueous electrolyte for lithium secondary batteries.

[0055] (4) Other additives Furthermore, the non-aqueous electrolyte of the present invention may further contain a second additional additive to prevent the non-aqueous electrolyte from decomposing in a high-power environment, thereby preventing the collapse of the negative electrode, or to further improve low-temperature high-rate discharge characteristics, high-temperature stability, overcharge prevention, and the effect of suppressing battery swelling at high temperatures.

[0056] Examples of other additives include at least one selected from the group consisting of cyclic carbonate compounds, halogen-substituted carbonate compounds, sultone compounds, sulfate compounds, phosphate or phosphite compounds, borate compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds.

[0057] Examples of the aforementioned cyclic carbonate compounds include vinylene carbonate (VC) and vinylethylene carbonate (VEC).

[0058] Examples of halogen-substituted carbonate compounds include fluoroethylene carbonate (FEC).

[0059] The sultone compound may be, for example, at least one compound selected from the group consisting of 1,3-propanesultone (PS), 1,4-butanesultone, ethensultone, 1,3-propensultone (PRS), 1,4-butensultone, and 1-methyl-1,3-propensultone.

[0060] The sulfate compound may be, for example, ethylene sulfate (Esa), trimethylene sulfate (TMS), or methyl trimethylene sulfate (MTMS).

[0061] The phosphate or phosphite compound may be, for example, one or more compounds selected from the group consisting of lithium difluoro(bisoxalato) phosphate, lithium difluorophosphate, tris(trimethylsilyl) phosphate, tris(trimethylsilyl) phosphite, tris(2,2,2-trifluoroethyl) phosphate, and tris(trifluoroethyl) phosphite.

[0062] Examples of the borate compounds include tetraphenyl borate, lithium oxalyl difluoroborate (LiODFB) which can form a film on the surface of the negative electrode, and lithium bisoxalate borate (LiB(C2O4)2, LiBOB).

[0063] The benzene compound may be fluorobenzene, the amine compound may be triethanolamine, ethylenediamine, etc., and the silane compound may be tetravinylsilane, etc.

[0064] The lithium salt compound is a compound different from the lithium salt contained in the non-aqueous electrolyte, and examples include LiPO2F2 or LiBF4.

[0065] Among such other additives, at least one selected from the group consisting of vinylene carbonate, vinylethylene carbonate, fluoroethylene carbonate (FEC), propensultone, ethylene sulfate, LiBF4, and lithium oxalyl difluoroborate (LiODFB) may be included in order to form an even stronger SEI film on the surface of the negative electrode during the initial activation process, as it has an excellent film-forming effect on the negative electrode surface.

[0066] The aforementioned other additives may be used in combination of two or more compounds, and may be present in an amount of 0.01 to 20% by weight, specifically 0.01 to 10% by weight, based on the total weight of the non-aqueous electrolyte.

[0067] When the aforementioned other additives are included within the above range, secondary batteries with further improved performance can be manufactured. For example, when the aforementioned other additives are included in an amount of 0.01% by weight or more, the durability of the SEI film is improved, and when they are included in an amount of 20% by weight or less, the increase in resistance is minimized, and the long-term maintenance and upkeep of the SEI film is achieved within an acceptable resistance increase.

[0068] Lithium-ion rechargeable battery In addition, another embodiment of the present invention provides a lithium secondary battery including a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and the non-aqueous electrolyte of the present invention described above.

[0069] The lithium secondary battery of the present invention can be manufactured by forming an electrode assembly in which a separator is sequentially laminated between a positive electrode, a negative electrode, and then housing the electrode assembly in a battery case, and then injecting the non-aqueous electrolyte of the present invention.

[0070] The lithium secondary battery of the present invention can be manufactured by a conventional method known in the art, and the manufacturing method of the lithium secondary battery of the present invention is specifically as described below.

[0071] (1) Positive electrode The positive electrode according to the present invention includes a positive electrode active material layer containing a positive electrode active material, and optionally, the positive electrode active material layer may further contain a conductive material and / or a binder.

[0072] The positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and specifically, may include a lithium composite metal oxide containing one or more metals such as cobalt, manganese, nickel, or aluminum and lithium.

[0073] Specifically, the positive electrode active material is a lithium-cobalt-based oxide (for example, LiCoO2, etc.), a lithium-manganese-based oxide (for example, LiMnO2, LiMn2O4, etc.), a lithium-nickel-based oxide (for example, LiNiO2, etc.), a lithium-nickel-manganese-based oxide (for example, LiNi 1-Y Mn Y O2 (where 0 < Y < 1), LiMn 2-Z Ni Z O4 (where 0 < Z < 2), etc.), a lithium-nickel-cobalt-based oxide (for example, LiNi 1-Y1 Co Y1 O2 (where 0 < Y1 < 1), etc.), a lithium-manganese-cobalt-based oxide (for example, LiCo 1-Y2 MnY2 O2 (where 0 < Y2 < 1), LiMn 2-Z1 Co Z1 O4 (where 0 < Z1 < 2), etc.), lithium-nickel-manganese-cobalt oxide (e.g., Li(Ni p Co q Mn r1 )O2 (where 0 < p < 1, 0 < q < 1, 0 < r1 < 1, p + q + r1 = 1) or Li(Ni p1 Co q1 Mn r2 )O4 (where 0 < p1 < 2, 0 < q1 < 2, 0 < r2 < 2, p1 + q1 + r2 = 2), etc.), lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r3 M s2 )O2 (where M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, Ti, and Mo, and p2, q2, r3, and s2 are the atomic fractions of the respective independent elements, 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1, and p2 + q2 + r3 + s2 = 1), etc. may be included, and any one or two or more of these compounds may be included.

[0074] Among them, from the viewpoint of being able to enhance the capacity characteristics and stability of the battery, the positive electrode active material may include at least one selected from the group consisting of lithium-cobalt oxide, lithium-manganese oxide, lithium-nickel-manganese-cobalt oxide, and lithium-nickel-cobalt-transition metal (M) oxide.

[0075] Specifically, the positive electrode active material may include at least one selected from a lithium-nickel-manganese-cobalt oxide having a nickel content of 55 atm% or more and a lithium-nickel-cobalt-transition metal (M) oxide having a nickel content of 55 atm% or more. Specifically, the positive electrode active material may include a lithium-nickel-manganese-cobalt oxide represented by the following Chemical Formula 2.

[0076] [Chemical Formula 2] Li(Ni) a Co b Mn c M d )O2

[0077] In the aforementioned chemical formula 2, M is W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, or Mo; a, b, c, and d are the atomic fractions of independent elements, 0.55 ≤ a < 1, 0 <b≦0.3、0<c≦0.3、0≦d≦0.1、a+b+c+d=1である。

[0078] Specifically, a, b, c, and d may be 0.60 ≤ a ≤ 0.95, 0.01 ≤ b ≤ 0.20, 0.01 ≤ c ≤ 0.20, and 0 ≤ d ≤ 0.05, respectively.

[0079] Specifically, a typical example of the positive electrode active material is Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni 0.7 Mn 0.15 Co 0.15 )O2, Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, and Li(Ni 0.9 Co 0.06 Mn 0.03 Al 0.01 ) At least one selected from the group consisting of O2.

[0080] The positive electrode active material may be present in an amount of 80% to 99% by weight, specifically 90% to 99% by weight, based on the total weight of solids in the positive electrode slurry. However, if the content of the positive electrode active material is 80% by weight or less, the energy density may decrease, potentially leading to a reduction in capacity.

[0081] The conductive material is not particularly limited as long as it does not cause a chemical change in the battery and is conductive. For example, carbon powders such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; graphite powders such as natural graphite, artificial graphite, or graphite with a well-developed crystalline structure; conductive fibers such as carbon fibers or metal fibers; conductive powders such as fluorinated carbon powder, aluminum powder, or nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives may be used.

[0082] The conductive material is usually added in an amount of 1 to 30% by weight, based on the total weight of the solid content in the positive electrode active material layer.

[0083] The binder is a component that plays a role in improving adhesion between positive electrode active material particles and adhesion between the positive electrode active material and the current collector, and is usually added at a concentration of 1 to 30% by weight based on the total weight of solids in the positive electrode active material layer. Examples of such binders include fluororesin binders containing polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE); rubber binders containing styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, and styrene-isoprene rubber; cellulose binders containing carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, and regenerated cellulose; polyalcohol binders containing polyvinyl alcohol; polyolefin binders containing polyethylene and polypropylene; polyimide binders; polyester binders; and silane binders.

[0084] The positive electrode of the present invention described above can be manufactured by a positive electrode manufacturing method known in the art. For example, the positive electrode can be manufactured by a method in which a positive electrode slurry prepared by dissolving or dispersing a positive electrode active material, a binder, and / or a conductive material in a solvent is applied to a positive electrode current collector, and then dried and rolled to form a positive electrode active material layer, or by a method in which the positive electrode active material layer is cast onto another support, the support is peeled off, and the resulting film is laminated onto the positive electrode current collector.

[0085] The positive electrode current collector is not particularly limited as long as it does not cause a chemical change in the battery and is conductive. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc. may be used.

[0086] The solvent may include organic solvents such as NMP (N-methyl-2-pyrrolidone), and may be used in an amount that results in a suitable viscosity when the positive electrode active material and selectively include binders and conductive materials. For example, the solvent may be included such that the concentration of solids in the active material slurry containing the positive electrode active material and selectively including binders and conductive materials is 10% to 90% by weight, preferably 30% to 80% by weight.

[0087] (2) Negative electrode Next, I will explain the negative electrode.

[0088] The negative electrode according to the present invention comprises a negative electrode active material layer containing a negative electrode active material, the negative electrode active material layer may further contain a conductive material and / or a binder as needed.

[0089] As the anode active material, various anode active materials used in the industry, such as carbon-based anode active materials, silicon-based anode active materials, or mixtures thereof, may be used.

[0090] According to one embodiment, the anode active material may include a carbon-based anode active material, and as the carbon-based anode active material, various carbon-based anode active materials used in the industry can be used, such as graphite-based materials such as natural graphite, artificial graphite, and Kish graphite; high-temperature calcined carbon such as pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and petroleum or coal tar pitch-derived cokes, as well as soft carbon and hard carbon. The shape of the carbon-based anode active material is not particularly limited, and materials of various shapes such as amorphous, plate-like, flaky, spherical, or fibrous may be used.

[0091] Preferably, at least one carbon-based negative electrode active material, such as natural graphite and artificial graphite, can be used as the negative electrode active material. In order to increase adhesion to the current collector and suppress detachment of the active material, both natural graphite and artificial graphite may be used.

[0092] According to other embodiments, the negative electrode active material may include a silicon-based negative electrode active material together with the carbon-based negative electrode active material.

[0093] The silicon-based negative electrode active material is, for example, metallic silicon (Si) or silicon oxide (SiO x, where 0 < x < 2), silicon carbide (SiC), and Si-Y alloy (where Y is an element selected from the group consisting of alkali metals, alkaline earth metals, group 13 elements, group 14 elements, transition metals, rare earth elements, and combinations thereof, and is not Si) may include one or more selected from the group consisting of. The element Y may be selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db (dubnium), 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, and combinations thereof.

[0094] Since the silicon-based negative electrode active material exhibits higher capacity characteristics than the carbon-based negative electrode active material, when the silicon-based negative electrode active material is further included, even more excellent capacity characteristics can be obtained. However, the negative electrode containing the silicon-based negative electrode active material contains more oxygen (O)-rich components in the SEI film than the graphite negative electrode, and the SEI film containing the O-rich component is more likely to be further decomposed when Lewis acids such as HF or PF5 are present in the electrolytic solution. Therefore, in order for the negative electrode containing the silicon-based negative electrode active material to maintain a stable SEI film, it is necessary to suppress the generation of Lewis acids such as HF and PF5 in the electrolytic solution or to remove (or scavenge) the generated Lewis acids. The non-aqueous electrolytic solution according to the present invention forms a stable film on the positive and negative electrodes and contains an electrolytic solution additive excellent in the effect of removing Lewis acids, so that the decomposition of the SEI film can be effectively suppressed when using a negative electrode containing a silicon-based active material.

[0095] On the other hand, the mixing ratio of the carbon-based negative electrode active material and the silicon-based negative electrode active material may be 50:50 to 99:1, preferably 85:15 to 95:5, in terms of weight ratio. When the mixing ratio of the carbon-based negative electrode active material and the silicon-based negative electrode active material satisfies the above range, the capacity characteristics can be improved, the volume expansion of the silicon-based negative electrode active material can be suppressed, and excellent cycle performance can be ensured.

[0096] On the other hand, as needed, instead of the carbon-based negative electrode active material or the silicon-based negative electrode active material, the negative electrode active material may use at least one selected from the group consisting of lithium metal, an alloy of metal and lithium, a metal composite oxide, and a transition metal oxide.

[0097] As the alloy of metal and lithium, a metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn or an alloy of these metals and lithium can be used.

[0098] Examples of the metal composite oxide include PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5, Li x Fe2O3 (0 ≦ x ≦ 1), Li x WO2 (0 ≦ x ≦ 1), and Sn x Me 1-x Me’ y O z (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, elements of Group 1, Group 2, Group 3 of the periodic table, halogen; 0 < x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8) can be selected from the group consisting of.

[0099] Examples of the transition metal oxide include lithium-containing titanium composite oxide (LTO), vanadium oxide, lithium vanadium oxide, and the like.

[0100] The negative electrode active material may be contained at 80% to 99% by weight based on the total weight of the solid content in the negative electrode slurry.

[0101] The conductive material is a component for further improving the conductivity of the negative electrode active material and may be added in an amount of 1 to 20% by weight based on the total weight of the solid content in the negative electrode active material layer. Such a conductive material is not particularly limited as long as it does not cause a chemical change in the battery and is conductive, and may be used, for example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; conductive fibers such as carbon fibers or metal fibers; conductive powders such as carbon fluoride powder, aluminum powder, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive materials such as polyphenylene derivatives.

[0102] The binder is a component that assists in bonding between the conductive material, the active material, and the current collector, and is usually added at a concentration of 1 to 30% by weight based on the total weight of the solids in the negative electrode active material layer. Examples of such binders include fluoropolymer binders containing polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE); rubber binders containing styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, and styrene-isoprene rubber; cellulose binders containing carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, and regenerated cellulose; polyalcohol binders containing polyvinyl alcohol; polyolefin binders containing polyethylene and polypropylene; polyimide binders; polyester binders; and silane binders.

[0103] The anode can be manufactured by a method for manufacturing anodes known in the art. For example, the anode can be manufactured by forming a anode active material layer by applying a slurry of anode active material, prepared by dissolving or dispersing a anode active material, a binder, and a conductive material selectively in a solvent, onto a anode current collector, and then rolling and drying it; or by casting the anode active material layer onto another support, peeling off the support, and then laminating the resulting film onto the anode current collector.

[0104] The negative electrode current collector generally has a thickness of 3 to 500 μm. Such a negative electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel with surface treatment using carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloy may be used. Also, similar to the positive electrode current collector, the bonding force of the negative electrode active material may be strengthened by forming fine irregularities on the surface, and it may be used in various forms such as film, sheet, foil, mesh, porous material, foam, and nonwoven fabric.

[0105] The solvent may include water or an organic solvent such as NMP or alcohol, and may be used in an amount that results in a suitable viscosity when the negative electrode active material and selectively the binder and conductive material are included. For example, the solvent may be included such that the concentration of solids in the active material slurry containing the negative electrode active material and selectively the binder and conductive material is 50% to 75% by weight, preferably 40% to 70% by weight.

[0106] (3) Separator The separator included in the lithium secondary battery of the present invention may be a porous polymer film made from a commonly used, ordinary porous polymer film, such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, or an ethylene / methacrylate copolymer, either alone or in a laminated form. Alternatively, an ordinary porous nonwoven fabric, such as a nonwoven fabric made of high-melting-point glass fibers or polyethylene terephthalate fibers, may be used, but is not limited to these.

[0107] The external shape of the lithium secondary battery of the present invention is not particularly limited, but it may be cylindrical, rectangular, pouch-shaped, or coin-shaped using a can.

[0108] The present invention will be described in detail below with reference to examples. However, the examples of the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the examples detailed below. The examples of the present invention are provided to give a more complete explanation of the present invention to a person of average skill in the art.

[0109] Examples Example 1. (Manufacturing of non-aqueous electrolytes for lithium secondary batteries) A non-aqueous electrolyte was prepared by dissolving LiPF6 in a non-aqueous organic solvent, which was a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 30:70, to a concentration of 1.0 M. Then, 0.3 wt% of the compound represented by chemical formula 1-1, 2.0 wt% of vinylene carbonate (VC), and 1.0 wt% of 1,3-propanesultone (PS) were added to the mixture to prepare a non-aqueous electrolyte (see Table 1 below).

[0110] (Manufacturing of secondary batteries) Cathode active material (Li(Ni) 0.8 Mn 0.1 Co 0.1A positive electrode slurry (solid content: 50% by weight) was prepared by adding a conductive material (carbon black) and a binder (polyvinylidene fluoride) in a weight ratio of 97.5:1:1.5 to the solvent N-methyl-2-pyrrolidone (NMP). The positive electrode slurry was then applied to a 12 μm thick aluminum (Al) thin film, which served as the positive electrode current collector, and dried. Finally, the positive electrode was manufactured by roll pressing.

[0111] A negative electrode slurry (solid content: 60% by weight) was prepared by adding a negative electrode active material (graphite and SiO=90:10 by weight), a binder (SBR-CMC), and a conductive material (carbon black) in a weight ratio of 97.5:1.5:1.0 to water, which was used as a solvent. The negative electrode slurry was then applied to a 6 μm thick copper (Cu) thin film, which served as a negative electrode current collector, and dried. Finally, the negative electrode was manufactured by roll pressing.

[0112] An electrode assembly was manufactured by sequentially stacking the positive electrode, a polyolefin-based porous separator coated with inorganic particles (Al2O3), and a negative electrode. This assembly was then wound into a jelly-roll shape, placed inside a cylindrical battery case, and the non-aqueous electrolyte for lithium secondary batteries was poured in to produce a cylindrical lithium secondary battery with a driving voltage of 4.2V or higher.

[0113] Example 2. A non-aqueous electrolyte for a lithium secondary battery and a cylindrical lithium secondary battery containing the same were manufactured by the same method as in Example 1, except that the compound represented by chemical formula 1-2 was used instead of the compound represented by chemical formula 1-1 to produce the non-aqueous electrolyte for a lithium secondary battery.

[0114] Example 3. A non-aqueous electrolyte for a lithium secondary battery and a cylindrical lithium secondary battery containing the same were manufactured by the same method as in Example 1, except that the compound represented by chemical formula 1-3 was used instead of the compound represented by chemical formula 1-1 to produce the non-aqueous electrolyte for a lithium secondary battery.

[0115] Example 4. A non-aqueous electrolyte for a lithium secondary battery and a cylindrical lithium secondary battery containing the same were manufactured by the same method as in Example 1, except that the compound represented by chemical formula 1-4 was used instead of the compound represented by chemical formula 1-1 to produce the non-aqueous electrolyte for a lithium secondary battery.

[0116] Example 5. A non-aqueous electrolyte for lithium secondary batteries and a cylindrical lithium secondary battery containing the same were manufactured by the same method as in Example 1, except that LiPF6 was dissolved in a non-aqueous organic solvent prepared by mixing ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 30:70 to a concentration of 1.0 M, and then 5.0% by weight of the compound represented by chemical formula 1-1, 2.0% by weight of vinylene carbonate (VC), and 1.0% by weight of 1,3-propanesultone (PS) were added to produce the non-aqueous electrolyte for lithium secondary batteries.

[0117] Example 6. A non-aqueous electrolyte for a lithium secondary battery and a cylindrical lithium secondary battery containing the same were manufactured by the same method as in Example 5, except that the compound represented by chemical formula 1-2 was used instead of the compound represented by chemical formula 1-1 to produce the non-aqueous electrolyte for a lithium secondary battery.

[0118] Example 7. A non-aqueous electrolyte for lithium secondary batteries and a cylindrical lithium secondary battery containing the same were manufactured by the same method as in Example 5, except that the compound represented by chemical formula 1-3 was used instead of the compound represented by chemical formula 1-1 to produce the non-aqueous electrolyte for lithium secondary batteries.

[0119] Example 8. A non-aqueous electrolyte for lithium secondary batteries and a cylindrical lithium secondary battery containing the same were manufactured by the same method as in Example 5, except that the compound represented by chemical formula 1-4 was used instead of the compound represented by chemical formula 1-1 to produce the non-aqueous electrolyte for lithium secondary batteries.

[0120] Comparative Example 1. A non-aqueous electrolyte for lithium secondary batteries and a cylindrical lithium secondary battery containing the same were manufactured by the same method as in Example 1, except that LiPF6 was dissolved in a non-aqueous organic solvent prepared by mixing ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 30:70 to a concentration of 1.0 M, and then 2.0% by weight of vinylene carbonate (VC) and 1.0% by weight of 1,3-propanesultone (PS) were added to produce a non-aqueous electrolyte for lithium secondary batteries.

[0121] Comparative Example 2. A non-aqueous electrolyte for lithium secondary batteries and a cylindrical lithium secondary battery containing the same were manufactured by the same method as in Example 1, except that the compound represented by Chemical Formula 3 below was used instead of the compound represented by Chemical Formula 1-1 to produce the non-aqueous electrolyte for lithium secondary batteries.

[0122] [ka]

[0123] Comparative Example 3. A non-aqueous electrolyte for lithium secondary batteries and a cylindrical lithium secondary battery containing the same were manufactured by the same method as in Example 1, except that the compound represented by Chemical Formula 4 below was used instead of the compound represented by Chemical Formula 1-1 to produce the non-aqueous electrolyte for lithium secondary batteries.

[0124] [ka]

[0125] Comparative Example 4. A non-aqueous electrolyte for a lithium secondary battery and a cylindrical lithium secondary battery containing the same were manufactured by the same method as in Example 5, except that the compound represented by Chemical Formula 4 was used instead of the compound represented by Chemical Formula 1-1 to produce the non-aqueous electrolyte for a lithium secondary battery.

[0126] [Table 1]

[0127] In Table 1 above, the abbreviations for the compounds have the following meanings: EC: Ethylene carbonate DMC: Dimethyl carbonate VC: Vinylen carbonate PS: 1,3-propanethultone

[0128] Experimental example Experimental Example 1. Evaluation of volume retention rate after storage at high temperature (60°C). The lithium secondary batteries manufactured in Examples 1-8 and Comparative Examples 1-4 were charged at 25°C under constant current / constant voltage (CC / CV) conditions of 0.5C / 4.2V, and then discharged under constant current conditions of 0.5C / 2.5V. The measured discharge capacity was defined as the initial discharge capacity.

[0129] Next, each lithium secondary battery was charged to 100% SOC under the same charging conditions as described above, and then stored at a high temperature of 60°C for 30 days.

[0130] Subsequently, the batteries were charged at 25°C under constant current / constant voltage (CC / CV) conditions of 0.5C / 4.2V, and then discharged under constant current conditions of 0.5C / 2.5V. The measured discharge capacity was defined as the discharge capacity after high-temperature storage.

[0131] The initial discharge capacity and the discharge capacity after high-temperature storage were substituted into Equation 1 below to measure the capacity retention rate, and the results are shown in Table 2 below.

[0132] [Formula 1] Capacity retention rate (%) = (Discharge capacity after high-temperature storage / Initial discharge capacity) × 100

[0133] [Table 2]

[0134] Referring to Table 2 above, it can be seen that all of the lithium secondary batteries of Examples 1 to 8 of the present invention exhibit superior capacity retention rates after high-temperature storage compared to the lithium secondary batteries of Comparative Examples 1 to 4.

[0135] In particular, under conditions where the additive content is the same, the lithium secondary batteries of Examples 1 to 4 exhibit superior capacity retention after high-temperature storage compared to the lithium secondary batteries of Comparative Examples 2 and 3, and the secondary batteries of Examples 5 to 8 exhibit superior capacity retention after high-temperature storage compared to the lithium secondary battery of Comparative Example 4.

[0136] Experimental Example 2. Evaluation of the resistance increase rate after storage at high temperature (60°C). The lithium secondary batteries manufactured in Examples 1-8 and Comparative Examples 1-4 were charged at 25°C under constant current / constant voltage (CC / CV) conditions of 0.5C / 4.2V, and discharged under constant current conditions of 0.5C / 2.5V to bring the battery charge state to 50%. Then, the voltage drop observed while a discharge pulse (0.5C) was applied for 10 seconds was measured to obtain the initial resistance value.

[0137] Next, each lithium secondary battery was charged to 100% SOC under the same charging conditions as described above, and then stored at a high temperature of 60°C for 30 days.

[0138] Subsequently, the battery was charged at 25°C under constant current / constant voltage (CC / CV) conditions of 0.5C / 4.2V, and discharged under constant current conditions of 0.5C / 2.5V to bring the battery's state of charge (SOC) to 50%. Then, the voltage drop observed while applying a discharge pulse (0.5C) for 10 seconds was measured to obtain the resistance value after high-temperature storage.

[0139] The initial resistance value and the resistance value after high-temperature storage were substituted into Equation 2 below to calculate the resistance increase rate (capacity retention), and the results are shown in Table 3 below.

[0140] [Formula 2] Resistance increase rate (%) = {(Resistance after high-temperature storage - Initial resistance) / Initial resistance}×100

[0141] [Table 3]

[0142] Referring to Table 3 above, it can be seen that the lithium secondary batteries of Examples 1 to 8 of the present invention show an improved resistance increase rate after high-temperature storage compared to the lithium secondary battery of Comparative Example 1.

[0143] In particular, under conditions where the additive content is the same, the lithium secondary batteries of Examples 1 to 4 show an improved resistance increase rate after high-temperature storage compared to the lithium secondary batteries of Comparative Examples 2 and 3, and the secondary batteries of Examples 5 to 8 show an improved resistance increase rate after high-temperature storage compared to the lithium secondary battery of Comparative Example 4.

[0144] Experimental Example 3. Evaluation of gas generation after high-temperature (60°C) storage. The lithium secondary batteries produced in Examples 1-8 and Comparative Examples 1-4 were charged to 100% State of Charge (SOC) and then stored at a high temperature of 60°C for 30 days.

[0145] Subsequently, the amount of gases such as CO and CO2 generated inside the battery was measured.

[0146] The relative gas generation amounts of each battery were measured based on the gas generation amount measured in Comparative Example 1, and the results are shown in Table 4 below.

[0147] [Table 4]

[0148] Referring to Table 4 above, it can be seen that, under conditions where the additive content is the same, the lithium secondary batteries of Examples 1 to 4 produce less gas after high-temperature storage compared to the lithium secondary batteries of Comparative Examples 2 and 3, and the secondary batteries of Examples 5 to 8 produce less gas after high-temperature storage compared to the lithium secondary battery of Comparative Example 4.

[0149] Experimental Example 4. Evaluation of capacity retention rate after rapid charging and discharging at high temperature (40°C). The lithium secondary batteries manufactured in Examples 1-8 and the lithium secondary batteries manufactured in Comparative Examples 1-4 were subjected to 50 cycles each of constant current / constant voltage (CC / CV) charging at 1.0C / 4.2V and constant current discharge at 1.0C / 2.85V at a high temperature (40°C).

[0150] In this case, the discharge capacity measured during the first test was set as the initial capacity.

[0151] Subsequently, the initial discharge capacity (100%) and the discharge capacity at the 50th discharge were substituted into Equation 1 to measure the capacity retention rate, and the results are shown in Table 5 below.

[0152] [Table 5]

[0153] Referring to Table 5 above, it can be seen that the lithium secondary batteries of Examples 1 to 8 of the present invention have superior capacity retention rates after high-temperature rapid charge and discharge compared to the lithium secondary batteries of Comparative Examples 1 to 4.

Claims

1. Lithium salts and Non-aqueous organic solvents, A non-aqueous electrolyte for lithium secondary batteries containing the compound represented by the following chemical formula 1: 【Chemistry 1】 (In the above chemical formula 1, R is a substituted or unsubstituted alkynyl group having 1 to 6 carbon atoms. R １ This is an alkylene group having 1 to 3 carbon atoms. X is S.

2. The non-aqueous electrolyte for lithium secondary batteries according to claim 1, wherein R in the chemical formula 1 is a substituted or unsubstituted alkynyl group having 1 to 4 carbon atoms.

3. The non-aqueous electrolyte for lithium secondary batteries according to claim 1, wherein the substituted substituent in the chemical formula 1 is at least one selected from the group consisting of alkyl groups having 1 to 4 carbon atoms and at least one fluorine.

4. The non-aqueous electrolyte for lithium secondary batteries according to claim 1, wherein the compound represented by chemical formula 1 is the compound represented by the following chemical formulas 1 and 4. 【Chemistry 2】

5. The non-aqueous electrolyte for lithium secondary batteries according to claim 1, wherein the compound represented by chemical formula 1 is contained in an amount of 0.3% to 5% by weight based on the total weight of the non-aqueous electrolyte for lithium secondary batteries.

6. The non-aqueous electrolyte for lithium secondary batteries according to claim 1, wherein the compound represented by chemical formula 1 is included in an amount of 0.5% to 3% by weight based on the total weight of the non-aqueous electrolyte for lithium secondary batteries.

7. The non-aqueous electrolyte for a lithium secondary battery according to claim 1, further comprising at least one additive selected from the group consisting of cyclic carbonate compounds, halogen-substituted carbonate compounds, sultone compounds, sulfate compounds, phosphate or phosphite compounds, borate compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds.

8. It comprises a negative electrode, a positive electrode, a separator interposed between the negative electrode and the positive electrode, and a non-aqueous electrolyte. A lithium secondary battery comprising the non-aqueous electrolyte described in any one of claims 1 to 7.

9. The lithium secondary battery according to claim 8, wherein the positive electrode comprises a positive electrode active material layer containing a positive electrode active material, and the positive electrode active material comprises at least one selected from the group consisting of lithium-cobalt oxide, lithium-manganese oxide, lithium-nickel-manganese-cobalt oxide, and lithium-nickel-cobalt-transition metal (M) oxide.

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