Positive electrode for lithium secondary battery comprising positive electrode additive

Abstract

A positive electrode of the present invention comprises a positive electrode active material layer, the positive electrode active material layer comprising: a positive electrode active material; a conductive material; a binder; and a positive electrode additive, wherein the positive electrode additive comprises a substituent having a cyclic sulfonic ester (sultone) or cyclic sulfate structure, so that oxygen desorption of the positive electrode active material is suppressed, leading to improved structural stability of the positive electrode active material.

Description

Anode for lithium secondary batteries containing cathode additives

[0001] The present invention relates to an anode comprising a cathode additive.

[0002] Recently, as the application areas of lithium secondary batteries have rapidly expanded to include not only power supply for electronic devices such as electric, electronic, communication, and computer devices, but also power storage for large-area devices such as automobiles and power storage devices, the demand for high-capacity, high-output, and high-stability secondary batteries is increasing.

[0003] Lithium secondary batteries have safety issues, such as the generation of gas and swelling that increases the thickness of the battery when used continuously for a long time or when left at high temperatures. This is recognized as one of the important issues that must be resolved in high-capacity, high-output lithium secondary batteries.

[0004]

[0005] The present invention provides an anode comprising an anode additive capable of forming a strengthened electrolyte-electrode film.

[0006] In addition, the present invention provides a lithium secondary battery that exhibits excellent long-term durability even when driven at high voltage in order to improve the energy density of the lithium secondary battery.

[0007]

[0008] The present invention provides a positive electrode comprising a positive electrode active material layer, wherein the positive electrode active material layer comprises a positive electrode active material, a conductive material, a binder, and a positive electrode additive, and wherein the positive electrode additive comprises at least one of a compound represented by the following chemical formula 1 and a compound represented by the following chemical formula 2.

[0009] [Chemical Formula 1]

[0010]

[0011]

[0012] In the above chemical formula 1, X1 and X2 are each independently *-O-* or *-C(R X1)(R X2 )-*, and the above R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R X1 and R X2 are each independently one selected from H, F, and an alkyl group having 1 to 5 carbon atoms, L is one selected from a direct bond, a divalent organic group represented by the following chemical formula 1-1, and a divalent organic group represented by the following chemical formula 1-2, and m and n are each independently 1 or 2.

[0013] [Chemical Formula 1-1]

[0014]

[0015]

[0016] In the above chemical formula 1-1, the L 11 and L 12 are each independently an alkylene group having 1 to 5 carbon atoms which may be directly bonded or substituted with one or more fluorines, and p is 1 or 2.

[0017] [Chemical Formula 1-2]

[0018]

[0019]

[0020] In the above chemical formula 1-2, the L 21 and L 22 are each independently an alkylene group having 1 to 5 carbon atoms, which may be directly bonded or substituted with one or more fluorines.

[0021] [Chemical Formula 2]

[0022]

[0023]

[0024] In the above chemical formula 2, X3 and X4 are each independently *-O-* or *-C(R X3 )(R X4)-*, and the above R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 , R 28 , R X3 and R X4 are each independently one selected from H, F, and an alkyl group having 1 to 5 carbon atoms.

[0025]

[0026] In addition, the present invention provides a lithium secondary battery including the positive electrode; negative electrode; and electrolyte.

[0027]

[0028] The cathode additive of Chemical Formula 1 or Chemical Formula 2 included in the cathode according to the present invention can form a strong and durable cathode-electrolyte interface on the cathode by including a substituent having a cyclic sulfonic ester (sultone) or cyclic sulfate structure. For example, the compound of Chemical Formula 1 or Chemical Formula 2, which is a cathode additive directly injected into the cathode, reacts with lithium byproducts on the cathode surface, and a ring-opening reaction proceeds in a ring containing sulfur in the additive of Chemical Formula 1 or Chemical Formula 2, thereby forming a film on the cathode surface.

[0029] This suppresses oxygen desorption from the positive electrode active material, thereby improving the structural stability of the positive electrode active material. Therefore, a secondary battery comprising the positive electrode according to the present invention exhibits excellent cycle characteristics. Furthermore, electrolyte side reactions on the positive electrode surface are suppressed, thereby reducing gas generation. Furthermore, lithium byproducts present on the positive electrode active material surface are removed, thereby suppressing side reactions with the electrolyte, thereby reducing gas generation.

[0030] In addition, the cathode additive of Chemical Formula 1 or Chemical Formula 2 included in the cathode according to the present invention includes two or more cyclic sulfonic ester (sultone) or cyclic sulfate structure substituents within its structure. Therefore, the cathode including the cathode additive of the present invention is not lost due to vaporization or other causes during the electrode process.

[0031] Accordingly, when the cathode of the present invention is driven in a completed lithium secondary battery, a sufficiently durable cathode-electrolyte interface can be formed.

[0032] Therefore, the positive electrode according to the present invention can be applied to a lithium secondary battery to improve the overall performance of the lithium secondary battery.

[0033]

[0034] The following drawings attached to this specification illustrate embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0035] Figure 1 shows the structure of a lithium secondary battery according to one embodiment of the present invention.

[0036] FIG. 2 is a drawing for explaining an automobile including a battery pack composed of the lithium secondary battery of FIG. 1.

[0037] In some of the accompanying drawings, corresponding components are designated by the same reference numerals. Those skilled in the art will appreciate that the drawings illustrate elements simply and clearly and are not necessarily drawn to scale. For example, to facilitate understanding of various embodiments, the dimensions of some elements depicted in the drawings may be exaggerated relative to other elements. Furthermore, elements of known technology that are useful or essential in commercially feasible embodiments may often not be depicted so as not to obscure the spirit of various embodiments of the present invention.

[0038]

[0039] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best possible manner.

[0040] It should be understood that the terms “include,” “comprising,” or “having” used in this specification are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0041] In addition, in the description of "carbon atoms a to b" in the present specification, "a" and "b" refer to the number of carbon atoms included in a specific functional group. That is, the functional group may include "a" to "b" carbon atoms. For example, "alkylene group having 1 to 5 carbon atoms" refers to an alkylene group including 1 to 5 carbon atoms, i.e., -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2(CH3)CH-, -CH(CH3)CH2-, or -CH(CH3)CH2CH2-.

[0042] In addition, all alkyl groups in this specification may be substituted or unsubstituted. The term "substituted" as used herein, unless otherwise defined, means that at least one hydrogen bonded to carbon is replaced with an element other than hydrogen, for example, it means that it is replaced with a halogen atom, a nitro group, a nitrile group, etc.

[0043]

[0044] High capacity, high output, and long lifespan are becoming increasingly important characteristics for lithium secondary batteries used in automotive applications. Accordingly, to increase the capacity of secondary batteries, high-nickel-content cathode active materials with high energy density but low stability are used, or secondary batteries can be operated at high voltages.

[0045] However, when operating secondary batteries at high voltages to increase their capacity, the electrolyte within the battery can deteriorate as charging and discharging progress. This deterioration tends to accelerate when the positive electrode potential increases or the battery is exposed to high temperatures.

[0046] In addition, when a lithium secondary battery is used continuously for a long time or is left at a high temperature, gas is generated, causing the thickness of the battery to increase, which is called swelling. The gas generated at this time may be caused by a side reaction of the electrolyte.

[0047] Taking these points into consideration, the present invention provides a lithium secondary battery that exhibits excellent long-term durability even when driven at high voltage.

[0048]

[0049] Hereinafter, the present invention will be described in more detail.

[0050] Referring to FIG. 1, a lithium secondary battery (100) according to one embodiment of the present invention includes an electrode assembly comprising a positive electrode (110), a negative electrode (120) facing the positive electrode (110), a separator (130) interposed between the positive electrode (110) and the negative electrode (120), and a battery case (150) that accommodates a non-aqueous electrolyte (140) and the electrode assembly and the non-aqueous electrolyte (140).

[0051] The positive electrode (110) of the present invention includes a positive electrode current collector; and a positive electrode active material layer formed on the positive electrode current collector, wherein the positive electrode active material layer includes a positive electrode active material, a conductive material, a binder, and a positive electrode additive.

[0052]

[0053] cathode additives

[0054] The positive electrode additive included in the positive electrode active material layer of the present invention includes at least one of the compound of the following chemical formula 1 and the compound of the following chemical formula 2.

[0055]

[0056] The compound of the following chemical formula 1 can form a strong and durable cathode-electrolyte interface at the cathode (110) by including a substituent having a cyclic sulfonic ester (sultone) or cyclic sulfate structure at both terminals.

[0057] For example, the compound of chemical formula 1, which is a cathode additive directly injected into the cathode (110), reacts with lithium byproducts on the surface of the cathode (110), and a ring-opening reaction proceeds in a ring containing sulfur in the additive of chemical formula 1, thereby forming a polymeric film on the surface of the cathode (110).

[0058] Furthermore, since the positive electrode additive of chemical formula 1 included in the positive electrode (110) according to the present invention includes two or more cyclic sulfonic ester (sultone) or cyclic sulfate structure substituents within its structure, the positive electrode (110) including the positive electrode additive of the present invention is not lost due to vaporization or other causes during the electrode process. Accordingly, when the positive electrode (110) of the present invention is operated in a completed lithium secondary battery (100), a sufficiently durable positive electrode-electrolyte interface can be formed.

[0059]

[0060] [Chemical Formula 1]

[0061]

[0062]

[0063] In the above chemical formula 1, X1 and X2 are each independently *-O-* or *-C(R X1 )(R X2 )-*. Here, * is the binding site.

[0064]

[0065] In the above chemical formula 1, the R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R X1 and R X2 are each independently one selected from H, F, an alkyl group having 1 to 5 carbon atoms, or H or F.

[0066]

[0067] In the above chemical formula 1, m and n are each independently 1 or 2, and in terms of suppressing excessive resistance increase due to an increase in the hydrocarbon content among the film components and facilitating the ring-opening reaction to increase the film formation rate, m and n may be 1.

[0068]

[0069] In the above chemical formula 1, L is any one selected from a direct bond, a divalent organic group represented by the following chemical formula 1-1, and a divalent organic group represented by the following chemical formula 1-2.

[0070] When the above L is a divalent organic group represented by Chemical Formula 1-1, the cyclic sulfonic ester (sultone) or cyclic sulfate structures located at both ends are spaced apart at an appropriate distance, so that the sulfur component (S) content of the organic film formed from the additive can be uniform. By the organic film having a uniform S content formed from the positive electrode (110) additive of the present invention, the decomposition of the organic solvent on the positive electrode surface is reduced, and the increase in resistance at high voltage is reduced.

[0071] In addition, by including a sulfonic ester or sulfate structure in the structure of chemical formula 1-1, a film component capable of strong adsorption with the transition metal included in the anode (110) can be formed, thereby having the effect of suppressing an increase in resistance in the long term.

[0072] [Chemical Formula 1-1]

[0073]

[0074]

[0075] In the above chemical formula 1-1, the L 11 and L 12 are each independently a direct bond or an alkylene group having 1 to 5 carbon atoms that can be substituted with one or more fluorines, or an alkylene group having 1 to 3 carbon atoms that can be substituted with one or more fluorines.

[0076] In the above chemical formula 1-1, p is 1 or 2, and when p is 2 in the above chemical formula 1-1, oxidation stability at high voltage is improved, and film ion conductivity can be improved due to the unshared electron pair of oxygen.

[0077] In the above chemical formula 1-1, * represents a binding site.

[0078]

[0079] For example, the above chemical formula 1-1 may be any one selected from the divalent organic groups of the following chemical formulas 1-1a, 1-1b, 1-1c, and 1-1d. Here, * represents a bonding site.

[0080] [Chemical Formula 1-1a]

[0081]

[0082]

[0083] [Chemical Formula 1-1b]

[0084]

[0085]

[0086] [Chemical Formula 1-1c]

[0087]

[0088]

[0089] [Chemical Formula 1-1d]

[0090]

[0091]

[0092] When the above L is a divalent organic group represented by Chemical Formula 1-2, the cyclic sulfonic ester (sultone) or cyclic sulfate structures located at both ends can be spaced apart at an appropriate distance, so that the S content of the organic film formed from the additive can be uniform. By the organic film having a uniform S content formed from the positive electrode additive of the present invention, the decomposition of the organic solvent on the surface of the positive electrode (110) is reduced, and the increase in resistance at high voltage is reduced.

[0093] In addition, a film having a high dielectric constant is formed by the carbonate group in the structure of chemical formula 1-2, so there is an advantage of high lithium ion conductivity.

[0094] [Chemical Formula 1-2]

[0095]

[0096]

[0097] In the above chemical formula 1-2, L 21 and L 22 are each independently a direct bond or an alkylene group having 1 to 5 carbon atoms that can be substituted with one or more fluorines, or an alkylene group having 1 to 3 carbon atoms that can be substituted with one or more fluorines.

[0098] In the above chemical formula 1-2, * represents a binding site.

[0099] For example, the above chemical formula 1-2 may be any one selected from the divalent organic groups of the following chemical formulas 1-2a, 1-2b and 1-2c. Here, * represents a bonding site.

[0100] [Chemical Formula 1-2a]

[0101]

[0102] [Chemical Formula 1-2b]

[0103]

[0104] [Chemical Formula 1-2c]

[0105]

[0106]

[0107] For example, the compound of formula 1 may be any one of the compounds of formulae 1a to 1d below.

[0108] [Chemical Formula 1a]

[0109]

[0110] [Chemical Formula 1b]

[0111]

[0112] [Chemical Formula 1c]

[0113]

[0114] [Chemical Formula 1d]

[0115]

[0116]

[0117] The compound of the following chemical formula 2 has a structure in which two cyclic sulfate rings are connected in a spiro form, and reacts with a lithium byproduct on the surface of the positive electrode (110), and a ring-opening reaction proceeds in a ring containing sulfur within the structure, thereby forming a polymeric film on the surface of the positive electrode (110).

[0118] In addition, since the positive electrode additive of chemical formula 2 included in the positive electrode (110) according to the present invention includes two or more cyclic sulfonic ester (sultone) or cyclic sulfate structure substituents within its structure, the positive electrode (110) including the positive electrode additive of the present invention is not lost due to vaporization or other causes during the electrode process. Accordingly, when the positive electrode (110) of the present invention is operated in a completed lithium secondary battery (100), a sufficiently durable positive electrode-electrolyte interface can be formed.

[0119]

[0120] [Chemical Formula 2]

[0121]

[0122]

[0123] In the above chemical formula 2, X3 and X4 are each independently *-O-* or *-C(R X3 )(R X4 )-*. Here, * is the binding site.

[0124]

[0125] In the above chemical formula 2, the R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 , R 28 , R X3 and R X4 are each independently one selected from H, F, an alkyl group having 1 to 5 carbon atoms, or H or F.

[0126]

[0127] For example, the compound of formula 2 may be any one of the compounds of formulas 2a to 2c below.

[0128] [Chemical Formula 2a]

[0129]

[0130] [Chemical Formula 2b]

[0131]

[0132] [Chemical Formula 2c]

[0133]

[0134]

[0135] In the present invention, the positive electrode additive may be included in an amount of 0.001 wt% to 10 wt%, 0.005 wt% to 5 wt%, or 0.01 wt% to 5 wt% based on the total weight of the positive electrode active material layer. When the content of the positive electrode additive satisfies the above range, the positive electrode additive and the positive electrode active material can be uniformly mixed, while maintaining the battery capacity within an appropriate range.

[0136]

[0137] anode

[0138] The present invention provides a cathode (110) comprising the above cathode additive.

[0139] For example, specifically, the positive electrode (110) includes a positive electrode active material layer, and the positive electrode active material layer includes a positive electrode active material, a conductive material, a binder, and the positive electrode additive described above. The positive electrode (110) may include a positive electrode current collector and a positive electrode active material layer positioned on at least one surface of the positive electrode current collector. Since the positive electrode additive has been described above, only the remaining components will be described below.

[0140]

[0141] The positive electrode current collector may include a highly conductive metal, and is not particularly limited as long as it is easily adhered to by the positive electrode active material layer and does not react within the voltage range of the battery. The positive electrode current collector may be made of, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. In addition, the positive electrode current collector may typically have a thickness of 3 μm to 500 μm, and fine unevenness may be formed on the surface of the current collector to increase the adhesion of the positive electrode active material. For example, the positive electrode current collector may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0142]

[0143] The above-described positive electrode active material layer may include a positive electrode active material, a conductive material optionally as needed, and a binder together with the above-described positive electrode additive.

[0144]

[0145] The cathode active material according to the present invention may include a lithium transition metal oxide having a nickel content of 60 atm% or more among metal elements other than lithium.

[0146] The above-mentioned positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and may include a lithium metal oxide containing lithium and one or more metals such as cobalt, manganese, nickel or aluminum. According to one embodiment, the lithium metal oxide is a lithium-manganese oxide (e.g., LiMnO2, LiMn2O4, etc.), a lithium-cobalt oxide (e.g., LiCoO2, etc.), a lithium-nickel oxide (e.g., LiNiO2, etc.), a lithium-nickel-manganese oxide (e.g., LiNi 1-Y Mn Y O2 (here, 0 <Y<1), LiMn 2-Z Ni Z O4 (where 0<Z<2), etc.), lithium-nickel-cobalt oxides (e.g., LiNi 1-Y1 Co Y1 O2 (here, 0 <Y1<1) 등), 리튬-망간-코발트계 산화물(예를 들면, LiCo 1-Y2 Mn Y2 O2 (here, 0 <Y2<1), LiMn 2-Z1 Co Z1 O4 (wherein, 0<Z1<2) etc.), lithium-nickel-manganese-cobalt oxides (e.g., Li(Ni p Co q Mn r )O2(wherein, 0<p<1, 0<q<1, 0<r<1, p+q+r=1) or Li(Ni p1 Co q1 Mn r1)O4 (wherein, 0<p1<2, 0<q1<2, 0<r1<2, p1+q1+r1=2) etc.), or lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r2 M s2 )O2 (wherein, M is selected from Al, Fe, V, Cr, Ti, Ta, Mg and Mo, and p2, q2, r2 and s2 are atomic fractions of independent elements, respectively, 0<p2<1, 0<q2<1, 0<r2<1, 0<s2<1, p2+q2+r2+s2=1), and one or more compounds of these may be included.

[0147] Among these, the lithium metal oxides are LiCoO2, LiMnO2, LiNiO2, lithium nickel manganese cobalt oxide (e.g., Li(Ni)) in that they can improve the capacity characteristics and stability of the battery. 1 / 3 Mn 1 / 3 Co 1 / 3 )O2, Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni) 0.5 Mn 0.3 Co 0.2 )O2, Li(Ni 0.7 Mn 0.15 Co 0.15 )O2 and Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, etc.), or lithium nickel cobalt aluminum oxide (e.g., Li(Ni 0.8 Co 0.15 Al 0.05 )O2, etc.), and any one of these or a mixture of two or more of them may be used.

[0148] Among these, the lithium transition metal oxide included in the positive electrode active material of the present invention may have a composition represented by the following chemical formula 3.

[0149] [Chemical Formula 3]

[0150] Li a Ni 1-x-y Co x M 1 y M 2 z O2

[0151] In the above chemical formula 3, M 1 It may be at least one selected from Mn and Al, and may be a combination of Mn or Mn and Al.

[0152] In the above chemical formula 3, M 2 may be one or more elements selected from Zr, Ti, Mg, Ta, Nb, W, Mo and Cr.

[0153] The above a represents the molar ratio of lithium in the lithium transition metal oxide, and may be 1.0≤a≤1.3, 1.0≤a≤1.2, or 1.0≤a≤1.1.

[0154] The above 1-xy represents the molar ratio of nickel among the metal elements excluding lithium in the lithium transition metal oxide, and may be 0.6≤1-xy<1.0, 0.70≤1-xy≤0.98, or 0.80≤1-xy≤0.95. When the nickel content satisfies the above range, high-capacity characteristics can be realized.

[0155] The above x represents the molar ratio of cobalt among the metal elements excluding lithium in the lithium transition metal oxide, and is 0. <x<0.4, 0<x≤0.2, 또는 0.01≤x≤0.10일 수 있다.

[0156] The above y is M among the metal elements excluding lithium in the lithium transition metal oxide. 1 It represents the molar ratio of 0 <y<0.4, 0<y≤0.2, 또는 0.01≤y≤0.10일 수 있다.

[0157] The above z is M among the metal elements excluding lithium in the lithium transition metal oxide. 2 It represents the molar ratio, and can be 0≤z≤0.1, or 0≤z≤0.05.

[0158]

[0159] The positive electrode (110) according to the present invention may contain the positive electrode active material in an amount of 80 wt% to 99 wt%, more specifically 85.0 wt% to 98.5 wt%, based on the total weight of the positive electrode active material layer, and may exhibit excellent capacity characteristics when contained within the above content range.

[0160]

[0161] The conductive material is used to provide conductivity to the electrode, and in the battery to be formed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without any special restrictions. For example, graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive tubes such as carbon nanotubes; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, etc., and one of these may be used alone or a mixture of two or more may be used. The conductive material may be included in an amount of 0.1 wt% to 15 wt% based on the total weight of the positive electrode active material layer.

[0162]

[0163] The above binder serves to improve the adhesion between positive electrode active material particles and the adhesion between the positive electrode active material and the current collector. Examples thereof include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylalcohol, polyacrylonitrile, polymethyl methacrylate, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluoroelastomer, polyacrylic acid, and polymers in which hydrogens of these are substituted with Li, Na, or Ca, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof. The above binder may be included in an amount of 0.1 wt% to 15 wt% based on the total weight of the positive electrode active material layer.

[0164]

[0165] lithium secondary battery

[0166] In addition, the present invention provides a lithium secondary battery (100) including the positive electrode (110).

[0167] For example, the lithium secondary battery (100) includes a positive electrode (110), a negative electrode (120), and an electrolyte. Or, according to one embodiment, it includes a positive electrode (110) including a positive electrode active material, a negative electrode (120) including a negative electrode active material, a separator (130) interposed between the positive electrode (110) and the negative electrode (120), and the non-aqueous electrolyte (140) described above.

[0168] At this time, the lithium secondary battery (100) of the present invention can be manufactured according to a conventional method known in the art. For example, an electrode assembly can be formed by sequentially stacking a positive electrode (110), a negative electrode (120), and a separator (130) between the positive electrode (110) and the negative electrode (120), and then inserting the electrode assembly into a battery case (150) and injecting a non-aqueous electrolyte (140) according to the present invention.

[0169] Since the above anode (110) is the same as described above, only the remaining configuration will be described below.

[0170]

[0171] The above negative electrode (120) may include a negative electrode active material.

[0172] The above negative electrode (120) may include a negative electrode current collector and a negative electrode active material layer positioned on at least one surface of the negative electrode current collector. The negative electrode active material layer may include the negative electrode active material. The negative electrode active material layer may further include at least one of a binder and a conductive material together with the negative electrode active material.

[0173] The above-mentioned negative electrode (120) can be manufactured, for example, by coating a negative electrode mixture slurry containing a negative electrode active material, a binder, a conductive material, and a solvent on a negative electrode current collector, or a graphite electrode made of carbon (C) or the metal itself can be used as the negative electrode (120).

[0174] For example, when manufacturing a negative electrode (120) by coating a negative electrode mixture slurry on the negative electrode current collector, the negative electrode current collector generally has a thickness of 3 ㎛ to 500 ㎛. The negative electrode current collector is not particularly limited as long as it has high conductivity without causing a chemical change in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, like the positive electrode current collector, the bonding strength of the negative electrode active material can be strengthened by forming fine unevenness on the surface, and can be used in various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric, etc.

[0175] In addition, the negative electrode active material may include at least one selected from lithium metal, a carbon material capable of reversibly intercalating / deintercalating lithium ions, a metal or an alloy of these metals and lithium, a metal composite oxide, a material capable of doping and dedoping lithium, and a transition metal oxide.

[0176] As the carbon material capable of reversibly intercalating / deintercalating the lithium ions, any carbon-based negative electrode active material commonly used in lithium ion secondary batteries may be used without particular limitation, and examples thereof 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) or hard carbon, mesophase pitch carbide, calcined coke, etc.

[0177] The above metal composite oxides 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, 2, and 3 of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 로부터 선택되는 것이 사용될 수 있다.

[0178] Materials capable of doping and dedoping the above lithium include Si, SiO x (0 <x≤2), 실리콘-탄소 복합체(Si-C composite), Si-Y 합금(예를 들면, 상기 Y는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 전이금속, 희토류 원소 및 이들의 조합으로부터 선택되는 원소이며, Si은 아님), Sn, SnO2, Sn-Y(예를 들면, 상기 Y는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 전이금속, 희토류 원소 및 이들의 조합으로부터 선택되는 원소이며, Sn은 아님) 등을 들 수 있고, 또한 이들 중 적어도 하나와 SiO2를 혼합하여 사용할 수도 있다. 상기 원소 Y로는 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, Ge, P, As, Sb, Bi, S, Se, Te, Po 및 이들의 조합으로부터 선택될 수 있다.

[0179] Examples of the above transition metal oxides include lithium-containing titanium composite oxide (LTO), vanadium oxide, and lithium vanadium oxide.

[0180] Among these, the negative active material is graphite and SiO x (0≤x<2) may include at least one of the following. For example, the negative active material may include graphite and SiOx (0≤x<2). The negative active material may include graphite and SiO x When (0≤x<2) is included, the graphite and SiOx(0≤x<2) may be included in a weight ratio of 99:1 to 70:30 in terms of increasing the capacity of the lithium secondary battery (100).

[0181] The above negative electrode active material may be included in an amount of 60 wt% to 99 wt%, 70 wt% to 99 wt%, or 80 wt% to 98 wt% based on the total weight of the solid content in the negative electrode mixture slurry.

[0182]

[0183] The above binder is a component that assists in bonding between the conductive material, the active material, and the current collector. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and various copolymers thereof. For example, styrene-butadiene rubber (SBR)-carboxymethyl cellulose (CMC) can be used due to its high viscosity.

[0184] Typically, the binder may be included in an amount of 1 wt% to 20 wt%, 1 wt% to 15 wt%, or 1 wt% to 10 wt% based on the total weight of solids excluding the solvent in the negative electrode composite slurry.

[0185]

[0186] The above conductive agent is a component for further improving the conductivity of the negative electrode active material. The conductive agent is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and examples thereof include 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 highly developed crystal structure; conductive fibers such as carbon fibers or metal fibers; fluorinated carbon powder; conductive powders such as aluminum powder and 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.

[0187] The above-mentioned conductive agent may be included in an amount of 1 wt% to 20 wt%, 1 wt% to 15 wt%, or 1 wt% to 10 wt% based on the total weight of solids excluding the solvent in the negative electrode mixture slurry.

[0188]

[0189] The solvent may include water or an organic solvent such as NMP (N-methyl-2-pyrrolidone), and may be used in an amount that provides a desirable viscosity when including the negative electrode active material, and optionally a binder and a conductive material. For example, the concentration of the solid content including the negative electrode active material, and optionally a binder and a conductive material may be 50 wt% to 95 wt%, or 70 wt% to 90 wt%.

[0190]

[0191] When using the metal itself as the above-mentioned cathode (120), it can be manufactured by physically bonding, rolling, or depositing the metal onto the metal thin film itself or the cathode current collector. The deposition method can use an electrical deposition method or a chemical vapor deposition method.

[0192] For example, the metal to be bonded / rolled / deposited on the metal thin film itself or the negative electrode current collector may include one metal selected from lithium (Li), nickel (Ni), tin (Sn), copper (Cu), and indium (In), or an alloy of two metals.

[0193]

[0194] In addition, as the separator (130), a conventional porous polymer film conventionally used as a separator, for example, a porous polymer film made of a polyolefin polymer such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, may be used alone or in a laminated manner, or a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. may be used, but is not limited thereto. In addition, a coated separator containing a ceramic component or a polymer material may be used to secure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

[0195] For example, the separators (130) included in the electrode assembly of the present invention may be SRS (safety reinforced separator) separators formed with a coating layer containing a ceramic component or polymer material to secure heat resistance or mechanical strength.

[0196] Alternatively, the separators (130) included in the electrode assembly of the present invention may include a porous separator substrate and a porous coating layer coated entirely on one or both sides of the separator substrate, and the coating layer may include a mixture of inorganic particles selected from among metal oxides, semi-metal oxides, metal fluorides, metal hydroxides, and combinations thereof, and a binder polymer that connects and fixes the inorganic particles to each other.

[0197]

[0198] The above coating layer may include at least one selected from the group consisting of Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, and MgF as inorganic particles. Here, the inorganic particles can improve the thermal stability of the separator (130). That is, the inorganic particles can prevent the separator from shrinking at high temperatures. In addition, the binder polymer can fix the inorganic particles and also improve the mechanical stability of the separator (130).

[0199]

[0200] In addition, examples of the electrolyte used in the present invention include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of a lithium secondary battery (100).

[0201] Among these, the electrolyte may include a lithium salt, an organic solvent, and an electrolyte additive.

[0202] The lithium salt included in the non-aqueous electrolyte (140) of the present invention is used as an electrolyte salt in a lithium secondary battery (100) and is used as a medium for transferring ions. Typically, the lithium salt is, for example, Li as a cation. + , and the anion is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , B 10 Cl 10 - , AlCl4 - , AlO2 - , 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 selected from may be cited.

[0203] For example, the lithium salts include LiCl, LiBr, LiI, LiBF4, LiClO4, LiB 10 Cl 10 , LiAlCl4, LiAlO2, 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). In addition to these, lithium salts commonly used in the electrolyte of a lithium secondary battery (100) can be used without limitation.

[0204] The lithium salt may be appropriately changed within a generally usable range, but in order to obtain an optimal effect of forming a film for preventing corrosion on the electrode surface, it may be included in the electrolyte at a concentration of 0.5 M to 3 M, a concentration of 0.5 M to 2.5 M, or a concentration of 0.8 M to 2 M. When the concentration of the lithium salt satisfies the above range, the effect of improving the cycle characteristics during high-temperature storage of the lithium secondary battery (100) is sufficient, and the viscosity of the non-aqueous electrolyte (140) is appropriate, so that the electrolyte impregnation property can be improved.

[0205]

[0206] The organic solvent included in the non-aqueous electrolyte (140) of the present invention may include at least one organic solvent selected from a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, a linear ester-based organic solvent, and a cyclic ester-based organic solvent.

[0207] For example, the organic solvent may include a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, or a mixed organic solvent thereof.

[0208] The above cyclic carbonate-based organic solvent is a high-viscosity organic solvent with a high dielectric constant that can easily dissociate lithium salts in the electrolyte, and may include at least one organic solvent selected from 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, may include ethylene carbonate.

[0209] In addition, the linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and representative examples thereof include at least one organic solvent selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate, and ethylpropyl carbonate, and may include ethylmethyl carbonate (EMC).

[0210] In addition, the organic solvent may additionally include at least one carbonate organic solvent selected from the cyclic carbonate organic solvent and the linear carbonate organic solvent, and at least one ester organic solvent selected from the linear ester organic solvent and the cyclic ester organic solvent, in order to produce an electrolyte having high ionic conductivity.

[0211] Such linear ester organic solvents may include at least one organic solvent selected from methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate.

[0212] In addition, the cyclic ester organic solvent may include at least one organic solvent selected from γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0213]

[0214] Meanwhile, the organic solvent may be used without limitation by adding organic solvents commonly used in non-aqueous electrolytes (140) as needed. For example, at least one organic solvent among ether-based organic solvents, glyme-based solvents, and nitrile-based organic solvents may be additionally included.

[0215] As the above ether solvent, any one selected from dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, 1,3-dioxolane (DOL), and 2,2-bis(trifluoromethyl)-1,3-dioxolane (TFDOL) or a mixture of two or more thereof may be used, but is not limited thereto.

[0216] The above glyme-based solvent has a high dielectric constant and low surface tension compared to linear carbonate-based organic solvents, and is a solvent with low reactivity with metals, and may include at least one selected from dimethoxyethane (glyme, DME), diethoxyethane, diglyme, tri-glyme, and tetra-glyme (TEGDME), but is not limited thereto.

[0217] The above nitrile solvent may be at least one selected from acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile, but is not limited thereto.

[0218]

[0219] The non-aqueous electrolyte (140) of the present invention may contain a known electrolyte additive in the non-aqueous electrolyte (140) as needed to prevent or suppress the decomposition of the non-aqueous electrolyte (140) in a high-power environment, thereby causing collapse of the negative electrode (120), or to further improve low-temperature high-rate discharge characteristics, high-temperature stability, overcharge prevention or suppression, and high-temperature battery expansion suppression effects.

[0220] Such electrolyte additives may include at least one SEI film forming additive selected from representative examples thereof, such as cyclic carbonate compounds, sultone compounds, sulfate compounds, phosphate compounds, phosphite compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds.

[0221] The above cyclic carbonate compounds may include vinylene carbonate (VC), vinylethylene carbonate, or fluoroethylene carbonate.

[0222] The above sultone compound may include at least one compound selected from 1,3-propane sultone (PS), 1,4-butane sultone, ethene sultone, 1,3-propene sultone (PRS), 1,4-butene sultone, and 1-methyl-1,3-propene sultone.

[0223] The above sulfate compounds may include ethylene sulfate (Esa), trimethylene sulfate (TMS), or methyl trimethylene sulfate (MTMS).

[0224] The above phosphate compound or phosphite compound may include at least one compound selected from lithium difluoro oxalato phosphate (LiDFOP), lithium difluoro(bisoxalato)phosphate, lithium difluorophosphate, tris(trimethylsilyl) phosphate, tris(trimethylsilyl) phosphite, tris(2,2,2-trifluoroethyl) phosphate, and tris(2,2,2-trifluoroethyl) phosphite.

[0225] The above borate compounds include tetraphenylborate, lithium oxalyldifluoroborate (LiODFB), and lithium bisoxalatoborate (LiB(C2O4)2, LiBOB).

[0226] The above nitrile compound may include at least one compound selected from succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile.

[0227] The benzene compound may include fluorobenzene, the amine compound may include triethanolamine or ethylenediamine, and the silane compound may include tetravinylsilane.

[0228] The above lithium salt compound is a compound different from the lithium salt included in the non-aqueous electrolyte (140), and may include LiPO2F2 or LiBF4.

[0229] Among these other electrolyte additives, when at least one selected from vinylene carbonate (VC), vinyl ethylene carbonate (VEC), fluoro ethylene carbonate (FEC), propane sultone (PS), propene sultone (PRS), ethylene sulfate (Esa), LiBF4, lithium difluoro phosphate (LiDFP), lithium difluoro oxalato borate (LiODFB), lithium bis(oxalato) borate (LiBOB), lithium difluoro oxalato phosphate (LiDFOP), and propargyl-1H-imidazole-1-carboxylate is included, a more robust SEI film can be formed on the surface of the negative electrode (120) during the initial activation process of the secondary battery, and gas generation that may be generated due to decomposition of the electrolyte at high temperatures can be suppressed, thereby improving the high-temperature stability of the secondary battery.

[0230]

[0231] Meanwhile, two or more of the above electrolyte additives may be mixed and used, and may be included in an amount of 0.1 wt% to 10 wt%, 0.2 wt% to 8 wt%, or 0.5 wt% to 8 wt% based on the total weight of the non-aqueous electrolyte (140). When the content of the electrolyte additive satisfies the above range, the effect of improving ionic conductivity and cycle characteristics is more excellent.

[0232]

[0233] There is no particular limitation on the external shape of the lithium secondary battery (100) of the present invention, but it may be a cylindrical shape using a can, a square shape, a pouch shape, or a coin shape.

[0234] The lithium secondary battery (100) according to the present invention can be used not only as a battery cell used as a power source for a small device, but can also be used as a unit battery in a medium- to large-sized battery module including a plurality of battery cells.

[0235] Examples of the above medium and large devices include, but are not limited to, electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and power storage systems.

[0236]

[0237] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0238]

[0239] Example

[0240] Example 1

[0241] LiNi as a cathode active material 0.6 Co 0.1 Mn 0.3A positive electrode slurry was prepared by mixing 0296.6 wt% of a conductive agent, 1.5 wt% of carbon black Super P, 1.5 wt% of polyvinylidene pyrrolidone (PVDF) as a binder, and 0.4 wt% of a compound of the following chemical formula 1a as a positive electrode additive in an NMP solvent (solid content 75 wt%). The positive electrode slurry was applied to one surface of an aluminum current collector, dried in a vacuum at 110°C for 12 hours, and then rolled to prepare a positive electrode.

[0242] [Chemical Formula 1a]

[0243]

[0244] A negative electrode slurry (solid content 60 wt%) was prepared by adding a negative electrode active material (graphite:SiO = 90.0:10.0 weight ratio): conductive material (carbon black): binder (styrene-butadiene rubber (SBR)-carboxymethyl cellulose (CMC)) in a weight ratio of 97.6:0.8:1.6 to a solvent, N-methyl-2-pyrrolidone (NMP). The negative electrode slurry was applied to one surface of a 6 ㎛ thick negative electrode current collector (Cu thin film), and drying and roll pressing were performed to prepare a negative electrode. An electrode assembly was prepared by interposing a polypropylene separator between the positive electrode and the negative electrode.

[0245] An electrode assembly was manufactured by interposing a polyolefin porous separator coated with inorganic particles Al2O3 between the positive and negative electrodes manufactured above in a dry room.

[0246] An electrolyte was prepared by adding ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 2:7:1 to an organic solvent containing 1.2 M concentration of lithium salt LiPF6 and 0.5 wt% concentration of vinylene carbonate (VC), an additive.

[0247] The above electrode assembly was positioned inside the case and the above-mentioned manufactured electrolyte was injected to manufacture a lithium secondary battery.

[0248]

[0249] Example 2

[0250] LiNi as a cathode active material 0.6 Co 0.1 Mn 0.3 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a cathode slurry was manufactured by mixing 0296.6 wt% of O, 1.5 wt% of carbon black Super P as a conductive agent, 1.5 wt% of polyvinylidene pyrrolidone (PVDF) as a binder, and 0.4 wt% of a compound of the following chemical formula 1c as a cathode additive in an NMP solvent (solid content 75 wt%).

[0251] [Chemical Formula 1c]

[0252]

[0253] Example 3

[0254] LiNi as a cathode active material 0.6 Co 0.1 Mn 0.3 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a cathode slurry was manufactured by mixing 0296.6 wt% of O, 1.5 wt% of carbon black Super P as a conductive agent, 1.5 wt% of polyvinylidene pyrrolidone (PVDF) as a binder, and 0.4 wt% of a compound of the following chemical formula 1d as a cathode additive in an NMP solvent (solid content 75 wt%).

[0255] [Chemical Formula 1d]

[0256]

[0257]

[0258] Example 4

[0259] LiNi as a cathode active material 0.6 Co 0.1 Mn 0.3A lithium secondary battery was manufactured in the same manner as in Example 1, except that a positive electrode slurry was manufactured by mixing 0296.6 wt% of O, 1.5 wt% of carbon black Super P as a conductive agent, 1.5 wt% of polyvinylidene pyrrolidone (PVDF) as a binder, and 0.4 wt% of a compound of the following chemical formula 2a as a positive electrode additive in an NMP solvent (solid content 75 wt%).

[0260] [Chemical Formula 2a]

[0261]

[0262]

[0263] Comparative Example 1

[0264] LiNi as a cathode active material 0.6 Co 0.1 Mn 0.3 A secondary battery was manufactured in the same manner as Example 1, except that a cathode slurry was prepared by mixing 297 wt% of O, 1.5 wt% of carbon black Super P as a conductive agent, and 1.5 wt% of polyvinylidene pyrrolidone (PVDF) as a binder (solid content 75 wt%) in an NMP solvent.

[0265]

[0266] Comparative Example 2

[0267] LiNi as a cathode active material 0.6 Co 0.1 Mn 0.3 A positive electrode slurry was prepared by mixing 297 wt% of O, 1.5 wt% of carbon black Super P as a conductive agent, and 1.5 wt% of polyvinylidene pyrrolidone (PVDF) as a binder in an NMP solvent (solid content 75 wt%). The positive electrode slurry was applied to one surface of an aluminum current collector, dried in a vacuum at 110°C for 12 hours, and then rolled to prepare a positive electrode. For example, in the case of Comparative Example 2, the positive electrode slurry was prepared without using a positive electrode additive, as in the case of Comparative Example 1.

[0268] A negative electrode slurry (solid content 60 wt%) was prepared by adding a negative electrode active material (graphite:SiO = 90.0:10.0 weight ratio): conductive material (carbon black): binder (styrene-butadiene rubber (SBR)-carboxymethyl cellulose (CMC)) in a weight ratio of 97.6:0.8:1.6 to a solvent, N-methyl-2-pyrrolidone (NMP). The negative electrode slurry was applied to one surface of a 6 ㎛ thick negative electrode current collector (Cu thin film), and drying and roll pressing were performed to prepare a negative electrode. An electrode assembly was prepared by interposing a polypropylene separator between the positive electrode and the negative electrode.

[0269] An electrode assembly was manufactured by interposing a polyolefin porous separator coated with inorganic particles Al2O3 between the positive and negative electrodes manufactured above in a dry room.

[0270] An electrolyte was prepared by adding ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 2:7:1 to an organic solvent containing 1.2 M concentration of lithium salt LiPF6, 0.5 wt% of vinylene carbonate (VC) as an additive, and 1.0 wt% of a compound of chemical formula 1a.

[0271] The above electrode assembly was positioned inside the case and the above-mentioned manufactured electrolyte was injected to manufacture a lithium secondary battery.

[0272]

[0273] Comparative Example 3

[0274] A lithium secondary battery was manufactured in the same manner as in Comparative Example 2, except that an electrolyte was prepared by adding 1.2 M concentration of lithium salt LiPF6, 0.5 wt% of vinylene carbonate (VC), and 1.0 wt% of the compound of formula 2a to an organic solvent containing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 2:7:1, and adding the additive. For example, in the case of Comparative Example 3, a positive electrode slurry was manufactured without using a positive electrode additive, as in Comparative Examples 1 and 2.

[0275]

[0276] Experimental Example 1 - Evaluation of High-Temperature Cycle Characteristics

[0277] For each of the lithium secondary batteries manufactured in Examples 1 to 4 and Comparative Examples 1 to 3, cycle characteristics were evaluated.

[0278] For example, each of the lithium secondary batteries manufactured in Examples 1 to 4 and Comparative Examples 1 to 3 was charged to 4.2 V at a constant current of 0.33 C at 45°C, and discharged to 2.8 V at a constant current of 0.33 C, which was considered one cycle, and then 300 cycles of charge and discharge were performed. After 300 cycles, the capacity retention rate compared to the initial capacity, the resistance increase rate compared to the initial resistance after 300 cycles, and the amount of gas generated after 300 cycles were measured. At this time, the percentage ratio of the increased resistance to the initial resistance of the lithium secondary battery was calculated to derive the resistance increase rate after 300 cycles.

[0279] The results are shown in Table 1 below.

[0280] Capacity retention rate (%) Resistance increase rate (%) Gas generation amount (uL) Example 195.3 18.72 100 Example 295.0 20.82 300 Example 394.9 21.32 280 Example 493.8 23.83 100 Comparative example 157.8 54.65 800 Comparative example 288.9 38.34 200 Comparative example 386.3 41.85 000

[0281]

[0282] As shown in Table 1, it can be seen that the lithium secondary batteries of Examples 1 to 4 using the positive electrode additive of the present invention have higher capacity retention, lower resistance increase, and lower gas generation compared to the lithium secondary batteries of Comparative Examples 1 to 3 not using the positive electrode additive of the present invention. Therefore, the lithium secondary batteries of Examples 1 to 4 have superior high-temperature cycle characteristics compared to the lithium secondary batteries of Comparative Examples 1 to 3.

[0283] Experimental Example 2 - Evaluation of High-Temperature Storage Characteristics

[0284] For each of the lithium secondary batteries manufactured in Examples 1 to 4 and Comparative Examples 1 to 3, high-temperature storage characteristics were evaluated.

[0285] For example, the lithium secondary batteries of Examples 1 to 4 and Comparative Examples 1 to 3 were each fully charged to 4.2 V and then stored at 60°C for 8 weeks. After 8 weeks, the capacity retention rate compared to the initial capacity, the resistance increase rate compared to the initial resistance, and the amount of gas generated after 8 weeks of storage were measured for the stored secondary batteries.

[0286] The results are shown in Table 2 below.

[0287]

[0288] Capacity retention rate (%) Resistance increase rate (%) Gas generation amount (uL) Example 195.92 1.82 500 Example 293.72 1.92 700 Example 394.32 2.62 800 Example 492.92 5.82 600 Comparative example 163.54 9.27 400 Comparative example 285.93 3.84 300 Comparative example 386.53 5.43 900

[0289]

[0290] As shown in Table 2 above, it can be seen that the lithium secondary batteries of Examples 1 to 4 using the positive electrode additive of the present invention have higher capacity retention, lower resistance increase, and lower gas generation compared to the lithium secondary batteries of Comparative Examples 1 to 3 not using the positive electrode additive of the present invention. Therefore, it was confirmed that the lithium secondary batteries of Examples 1 to 4 have more stable performance at high temperatures compared to the lithium secondary batteries of Comparative Examples 1 to 3.

[0291] FIG. 2 is a drawing for explaining an automobile (300) including a battery pack (200) composed of the lithium secondary battery (100) of FIG. 1.

[0292] Referring to FIG. 2, a vehicle (300) according to one embodiment of the present invention may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle, and includes a battery pack (200) composed of a lithium secondary battery (100) according to one embodiment of the present invention. The vehicle (300) includes a four-wheeled vehicle and a two-wheeled vehicle. The vehicle (300) operates by receiving power from the battery pack (200) according to one embodiment of the present invention.

[0293] Although the present disclosure has been described above with reference to embodiments thereof, it will be understood by those skilled in the art or having ordinary knowledge in the art that various modifications and changes to the various embodiments of the present disclosure may be made without departing from the technical scope of the various embodiments of the present disclosure as set forth in the claims below. Accordingly, the technical scope of the various embodiments of the present disclosure should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

[0294]

[0295] <Explanation of symbols>

[0296] 100: Lithium secondary battery

[0297] 110: Positive

[0298] 120: Cathode

[0299] 130: Membrane

[0300] 140: Non-aqueous electrolyte

[0301] 150: Battery case

[0302] 200: Battery Pack

[0303] 300: Car

Claims

1. Contains a positive electrode active material layer, The above positive electrode active material layer includes a positive electrode active material, a conductive material, a binder, and a positive electrode additive, The positive electrode additive comprises at least one of the compounds of the following chemical formula 1 and the compounds of the following chemical formula 2: [Chemical Formula 1] In the above chemical formula 1, The above X1 and X2 are each independently *-O-* or *-C(R X1 )(R X2 )-* and, The above R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R X1 and R X2 are each independently one selected from H, F, and an alkyl group having 1 to 5 carbon atoms, The above L is one selected from a direct bond, a divalent organic group represented by the following chemical formula 1-1, and a divalent organic group represented by the following chemical formula 1-2, The above m and n are each independently 1 or 2, The above * is a binding site, [Chemical Formula 1-1] In the above chemical formula 1-1, Above L 11 and L 12 are each independently a direct bond or an alkylene group having 1 to 5 carbon atoms that can be substituted with one or more fluorines, The above p is 1 or 2, The above * is a binding site, [Chemical Formula 1-2] In the above chemical formula 1-2, Above L 21 and L 22 are each independently a direct bond or an alkylene group having 1 to 5 carbon atoms that can be substituted with one or more fluorines, The above * is a binding site, [Chemical Formula 2] In the above chemical formula 2, The above X3 and X4 are each independently *-O-* or *-C(R X3 )(R X4 )-* and, The above R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 , R 28 , R X3 and R X4 are each independently one selected from H, F, and an alkyl group having 1 to 5 carbon atoms, The above * indicates a binding site.

2. In paragraph 1, L of the above chemical formula 1 is an anode selected from any one of the divalent organic groups of the following chemical formulas 1-1a, 1-1b, 1-1c, or 1-1d: [Chemical Formula 1-1a] [Chemical Formula 1-1b] [Chemical Formula 1-1c] [Chemical Formula 1-1d] .

3. In paragraph 1, L of the above chemical formula 1 is an anode selected from any one of the divalent organic groups of the following chemical formulas 1-2a, 1-2b, or 1-2c: [Chemical Formula 1-2a] [Chemical Formula 1-2b] [Chemical Formula 1-2c] .

4. In paragraph 1, A positive electrode in which m and n in the above chemical formula 1 are 1.

5. In paragraph 1, The positive electrode in the above chemical formula 1-1 is p = 2.

6. In paragraph 1, X3 and X4 of the above chemical formula 2 are positive electrodes of *-O-*.

7. In paragraph 1, R of the above chemical formula 2 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 , and R 28 is the positive pole of H.

8. In paragraph 1, A positive electrode in which the positive electrode additive is included in an amount of 0.001 wt% to 10 wt% based on the total weight of the positive electrode active material layer.

9. In paragraph 1, The positive electrode active material is a positive electrode including a lithium transition metal oxide represented by the following chemical formula 3: [Chemical Formula 3] Li a Ni 1-x-y Co x M 1 y M 2 z O2 In the above chemical formula 3, M 1 is Al, Mn or a combination thereof, M 2 is one or more elements selected from Zr, Ti, Mg, Ta, Nb, W, Mo and Cr, 1.0≤a≤1.3, 0 <x<0.4, 0<y<0.4, 0≤z≤0.1, 0.6≤1-x-y<1.0이다.

10. The positive pole of paragraph 1; cathode; and A lithium secondary battery containing an electrolyte.

11. In paragraph 10, A lithium secondary battery comprising the electrolyte comprising a lithium salt, an organic solvent and an electrolyte additive.

12. In paragraph 11, A lithium secondary battery, wherein the electrolyte additive is at least one selected from vinylene carbonate (VC), vinyl ethylene carbonate (VEC), fluoro ethylene carbonate (FEC), propane sultone (PS), propene sultone (PRS), ethylene sulfate (Esa), LiBF4, lithium difluoro phosphate (LiDFP), lithium difluoro oxalato borate (LiODFB), lithium bis(oxalato) borate (LiBOB), lithium difluoro oxalato phosphate (LiDFOP), and propargyl-1H-imidazole-1-carboxylate.

13. In paragraph 11, A lithium secondary battery, wherein the organic solvent comprises at least one organic solvent selected from a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, a linear ester-based organic solvent, and a cyclic ester-based organic solvent.

14. In paragraph 10, The above negative electrode includes a negative electrode active material, It includes a negative electrode active material layer formed on a negative electrode current collector, The above negative active material is graphite and SiO x A lithium secondary battery comprising at least one of (0≤x<2).

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