KR-20260066628-A - NON-AQUEOUS ELECTROLYTE AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME

KR20260066628AKR 20260066628 AKR20260066628 AKR 20260066628AKR-20260066628-A

Abstract

The present invention relates to a non-aqueous electrolyte and a lithium secondary battery comprising the same. The non-aqueous electrolyte comprises a lithium salt; an organic solvent; and an additive; wherein the organic solvent comprises a carbonate-based organic solvent and a cyclic lactone compound, and the additive comprises a first additive and a second additive, wherein the first additive is lithium nitrate ( LiNO₃ ) and the second additive may comprise a compound represented by the following chemical formula 1. [Chemical Formula 1] In the above chemical formula 1, R 1 is -O-NO 2 , and L1 is an alkyleneoxy group having 1 to 5 carbon atoms, and M is a metal cation or an organic cation, and a is the valence of M when M is a metal cation, 1 when M is an organic cation, and a=b.

Inventors

정유경
임태영
서수민
오영호
안경호
이철행

Assignees

주식회사 엘지에너지솔루션

Dates

Publication Date: 20260512
Application Date: 20251028
Priority Date: 20241104

Claims (15)

As a non-aqueous electrolyte comprising a lithium salt; an organic solvent; and an additive, The above organic solvent includes a carbonate-based organic solvent and a cyclic lactone compound, and The above additive includes a first additive and a second additive, and The first additive above is lithium nitrate ( LiNO₃ ), and The above second additive is a non-aqueous electrolyte that is a compound represented by the following chemical formula 1: [Chemical Formula 1] In the above chemical formula 1, R 1 is -O-NO 2 , and L1 is an alkyleneoxy group having 1 to 5 carbon atoms, and M is a metal cation or an organic cation, and a is the valence of M when M is a metal cation, 1 when M is an organic cation, and a=b.
In paragraph 1, The above carbonate-based organic solvent is a non-aqueous electrolyte comprising a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent.
In paragraph 1, The above-mentioned cyclic lactone compound is a non-aqueous electrolyte containing gamma-butyrolactone.
In paragraph 1, The above-mentioned first additive is a non-aqueous electrolyte included in an amount of 0.2% to 5% by weight based on the total weight of the electrolyte.
In paragraph 1, In the above chemical formula 1, M is a metal cation, and The above M is a non-aqueous electrolyte selected from the group consisting of Li, K, Ca, Mg and Cs.
In paragraph 1, In the above chemical formula 1, M is an organic cation, and The above M is a non-aqueous electrolyte selected from the group consisting of compounds represented by the following chemical formulas M-1 to M-6: [Chemical Formula M-1] In the above formula M-1, X M1 is -N(R M15 )- or -S-, and R M11 , R M12 , R M13 , R M14 and R M15 are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. [Chemical Formula M-2] In the above formula M-2, X M2 is -N(R M25 )- or -S-, and R M21 , R M22 , R M23 , R M24 and R M25 are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoethyl group having 1 to 12 carbon atoms, an alkoxyalkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. [Chemical Formula M-3] In the above formula M-3, R M31 , R M32 , R M33 , R M34 , R M35 , and R M36 are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoethyl group having 1 to 12 carbon atoms, an alkoxyalkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. [Chemical Formula M-4] In the above chemical formula M-4, R M41 , R M42 , R M43 , and R M44 are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoethyl group having 1 to 12 carbon atoms, an alkoxyalkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and at least two of R M41 , R M42 , R M43 , and R M44 can be bonded to each other to form an aliphatic hydrocarbon ring. [Chemical Formula M-5] In the above chemical formula M-5, R M51 , R M52 , R M53 , and R M54 are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoethyl group having 1 to 12 carbon atoms, an alkoxyalkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and at least two of R M51 , R M52 , R M53 , and R M54 can be bonded to each other to form an aliphatic hydrocarbon ring. [Chemical Formula M-6] In the above chemical formula M-6, R M61 , R M62 , and R M63 are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoethyl group having 1 to 12 carbon atoms, an alkoxyalkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and at least two of R M61 , R M62 , and R M63 can be bonded to each other to form an aliphatic hydrocarbon ring.
In paragraph 1, The compound represented by the above chemical formula 1 is a non-aqueous electrolyte comprising the compound represented by the following chemical formula 1-A: [Chemical Formula 1-A] In the above chemical formula 1-A, each of M, a, b, and R1 is as defined in the above chemical formula 1.
In paragraph 1, The compound represented by the above chemical formula 1 is a non-aqueous electrolyte comprising the compound represented by the following chemical formula 1-A-1: [Chemical Formula 1-A-1] In the above chemical formula 1-A-1, each of M, a, and b is as defined in the above chemical formula 1.
In paragraph 1, The compound represented by the above chemical formula 1 is a non-aqueous electrolyte comprising the compound represented by the following chemical formula 1-a-1: [Chemical Formula 1-a-1] .
In paragraph 1, The compound represented by the above chemical formula 1 is a non-aqueous electrolyte included in an amount of 0.1% to 3% by weight based on the total weight of the non-aqueous electrolyte.
anode; A cathode opposite to the anode above; A separator interposed between the above cathode and the above anode; and A lithium secondary battery comprising a non-aqueous electrolyte according to claim 1.
In Paragraph 11, The above-mentioned positive electrode includes a positive electrode active material, and The above positive active material is a lithium secondary battery comprising lithium iron phosphate.
In Paragraph 12, The above lithium iron phosphate is a lithium secondary battery comprising a compound represented by the following chemical formula P-1: [Chemical Formula P-1] Li 1+e Fe 1-g M 2 g (PO 4-f )X f In the above chemical formula P-1, M 2 is one or more elements selected from Co, Ni, Mn, Al, Mg, Ti and V, X is F, S, or N, and 0≤g≤0.5; -0.5≤e≤+0.5; 0≤f≤0.1.
In Paragraph 13, The above lithium iron phosphate is a lithium secondary battery comprising LiFePO4 , LiMn 0.5 Fe 0.5 PO4 , or LiMn 0.6 Fe 0.4 PO4 .
In Paragraph 11, The above cathode includes a cathode active material, and The above negative electrode active material comprises at least one selected from carbon-based active materials and silicon-based active materials, forming a lithium secondary battery.

Description

Non-aqueous electrolyte and lithium secondary battery comprising the same The present invention relates to a non-aqueous electrolyte and a lithium secondary battery containing the same. Recently, as the application areas of lithium-ion batteries have rapidly expanded to include not only power supply for electronic devices such as electrical, electronic, telecommunications, and computers, but also power storage for large-area devices such as automobiles and power storage systems, there is a growing demand for high-capacity, high-output, and high-stability secondary batteries. The above lithium secondary battery generally consists of a positive electrode containing a positive active material, a negative electrode containing a negative active material, an electrolyte serving as a medium for transmitting lithium ions, and a separator. At this time, carbon-based active materials, silicon-based active materials, lithium transition metal oxides, lithium metal, etc., may be used as the negative active material. In addition, lithium transition metal oxides such as lithium cobalt oxide ( LiCoO2 ), lithium nickel oxide ( LiNiO2 ), lithium nickel-cobalt-manganese composite oxide, and lithium iron phosphate may be used as the positive active material. During the charging of a lithium secondary battery, lithium ions are generated from the positive electrode and can be converted into stacked or alloyed forms for storage on the negative electrode, while discharge proceeds in the opposite direction. Theoretically, the movement of lithium ions to the positive and negative electrodes during charging and discharging should be reversible; however, in reality, the movement of lithium within the battery may be partially irreversible. Specifically, the medium through which lithium ions can move is the electrolyte. During charging, most lithium ions are stacked or alloyed within the negative electrode active material; however, some may be reduced along with the organic and inorganic materials constituting the electrolyte to form nano-sized organic-inorganic composites on the surface of the negative electrode material. This represents an irreversible, permanent loss of lithium ions provided by the positive electrode, and the organic-inorganic film formed in this way is called the solid electrolyte interface layer (SEI layer). On the surface of the positive electrode active material, a solid electrolyte interface layer can be formed through the oxidation reaction of the materials constituting the electrolyte. When the above solid electrolyte interface layer is formed, irreversible loss of lithium ions is reduced, and a wide driving potential of the electrolyte is secured, enabling smooth reversible movement of lithium ions between the anode and the cathode. Since this solid electrolyte interface layer can contribute to lowering the energy barrier required for charge transfer of lithium ions to the cathode or anode depending on its internal components, the proper design of the solid-electrolyte interface layer has been a research task for improving the performance of lithium secondary batteries. Specifically, the lifespan characteristics and durability of lithium secondary batteries can be determined by the stability of the solid-electrolyte interface layer. For example, as charging and discharging progresses, the instability of the initially formed solid-electrolyte interface layer can lead to additional reduction of lithium ions on the surface of the anode material, resulting in the formation of a film thicker than the initially formed interface layer. Due to the additional loss of lithium ions, an additional interface layer thicker than the initially formed one may develop on the surface of the cathode material, or structural degradation of the cathode material may occur. This can be one of the causes of increased resistance in lithium secondary batteries. When lithium secondary batteries are exposed to high temperatures, the materials constituting the electrolyte undergo decomposition; the resulting by-products can degrade the performance of the electrolyte and increase the resistance of the lithium secondary battery. Furthermore, when lithium secondary batteries are exposed to low temperatures, the increasing resistance with repeated charging and discharging can cause the anode and cathode to operate at voltages lower than their initial lifespan. This accelerates oxidation and reduction reactions of the electrolyte at the anode and cathode, which can degrade the performance of the lithium secondary battery. Additionally, instability in the solid-electrolyte interface layer can lead to continuous oxidation and reduction reactions of the electrolyte, resulting in gas generation within the lithium secondary battery. In other words, strengthening the stability of the solid-electrolyte interface layer is a critical task for ensuring stable operation and securing battery performance characteristics such as long lifespan, low-temperatur