KR-20260065424-A - NON-AQUEOUS ELECTROLYTE FOR SECONDARY BATTERY AND SECONDARY BATTERY COMPRISING THE SAME

Abstract

The present invention relates to a non-aqueous electrolyte and a lithium secondary battery comprising the same. The non-aqueous electrolyte of the present invention comprises a lithium salt, a non-aqueous electrolyte, and an additive, wherein the additive may comprise a polymer comprising a repeating unit represented by Chemical Formula 1.

Inventors

• 지수현
• 이철행
• 이정민

Assignees

• 주식회사 엘지에너지솔루션

Dates

Publication Date

20260508

Application Date

20241101

Claims (13)

1. Lithium salt; including non-aqueous organic solvents and additives, The above additive is a non-aqueous electrolyte comprising a polymer having repeating units represented by the following chemical formula 1: [Chemical Formula 1] In the above chemical formula 1, R1 is an alkyl group having 1 to 5 carbon atoms that is substituted or unsubstituted with hydrogen or at least one fluorine.
2. In paragraph 1, A non-aqueous electrolyte in which, in the above chemical formula 1, R1 is a carbon-1 to carbon-3 alkyl group substituted or unsubstituted with hydrogen or at least one fluorine.
3. In paragraph 1, A non-aqueous electrolyte in which the compound represented by the above chemical formula 1 is at least one selected from the group consisting of compounds represented by the following chemical formulas 1A to 1D: [Chemical Formula 1A] [Chemical Formula 1B] [Chemical Formula 1C] [Chemical Formula 1D] .
4. In paragraph 1, A non-aqueous electrolyte in which the repeating unit represented by the above chemical formula 1 is included in the polymer in an amount of 1 to 99 mol%.
5. In paragraph 1, The above polymer is a non-aqueous electrolyte further comprising a repeating unit represented by the following chemical formula 2: [Chemical Formula 2] In the above chemical formula 2, R 2 is *-C(O)-Ra-CN (Ra is an alkylene group having 1 to 10 carbon atoms) or *-C(O)-Rb (Rb is a nitrogen-containing heterocycloalkyl group or a lactam group).
6. In paragraph 5, In the above chemical formula 2, R2 is a non-aqueous electrolyte in which *-C(O)-Ra-CN (Ra is an alkylene group having 1 to 5 carbon atoms) or *-C(O)-Rb (Rb is a nitrogen-containing heterocycloalkyl group or a lactam group).
7. In paragraph 5, In the above chemical formula 2, R₂ is *-C(O) -CH₂ -CN, *-C(O) -CH₂CH₂ - CN, *-C(O) -CH₂CH₂CH₂ - CN or Non-aqueous electrolytes that are.
8. In paragraph 5, A non-aqueous electrolyte comprising a repeating unit represented by the above chemical formula 2 or a repeating unit represented by the following chemical formula 2A or the following chemical formula 2B: [Chemical Formula 2A] [Chemical Formula 2B] .
9. In paragraph 1, The above polymer is a non-aqueous electrolyte further comprising a repeating unit represented by the following chemical formula 3: [Chemical Formula 3] .
10. In paragraph 1, The above polymer is a non-aqueous electrolyte comprising 0.001% to 18.0% by weight based on the total weight of the non-aqueous electrolyte.
11. In paragraph 1, The above polymer is a non-aqueous electrolyte comprising 0.01% to 15.0% by weight based on the total weight of the non-aqueous electrolyte.
12. In Paragraph 1, The above-mentioned non-aqueous electrolyte further comprises at least one other additive selected from the group consisting of cyclic carbonate compounds, halogen-substituted carbonate compounds, sulfone compounds, sulfate compounds, phosphate compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds.
13. 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.

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. As dependence on electrical energy gradually increases in modern society, the development of large-capacity power storage devices capable of stably supplying power while simultaneously increasing production is emerging. Furthermore, the need for high-capacity portable power is growing due to the performance improvements of electronic products, ranging from small devices such as mobile phones to medium-to-large devices such as electric vehicles. Lithium-ion batteries, which possess the highest potential, satisfy high-capacity power storage performance requirements and are therefore utilized in a wide range of applications, from small electronic devices to electric vehicles (EVs) and energy storage systems (ESS). 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 of such lithium secondary batteries 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, but some are reduced together 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 formed organic-inorganic film is called a solid electrolyte interface layer (SEI layer). Meanwhile, a solid electrolyte interface layer can also be formed on the surface of the positive electrode active material through the oxidation reaction of the materials constituting the electrolyte. While such a solid-electrolyte interface layer causes irreversible permanent loss of lithium ions supplied by the anode during formation, once formed, this irreversible loss is reduced, and a wide driving potential of the electrolyte is secured, enabling smooth reversible movement of lithium ions between the anode and cathode. Depending on its internal composition, this solid-electrolyte interface layer can contribute to lowering the energy barrier required for charge transfer of lithium ions to the cathode or anode, or its stability can determine the lifespan characteristics and durability of the lithium secondary battery. Meanwhile, as the charging and discharging of the lithium secondary battery progresses, the deterioration of the initially formed solid-electrolyte interface layer causes the decomposition of the electrolyte, resulting in increased resistance and structural degradation of the cathode material, which leads to the leaching of transition metals from the cathode. The transition metal ions leached out in this way are re-deposited on the cathode, which causes an increase in the resistance of the cathode. Conversely, they move through the electrolyte to the anode and are electrodeposited on the anode, causing self-discharge of the anode. Furthermore, due to the destruction and regeneration of the solid-electrolyte interface layer, additional lithium ions are consumed, causing an increase in resistance and a deterioration of lifespan. Therefore, to improve the performance of lithium secondary batteries, strengthening the stability of the solid-electrolyte interface layer formed on the surfaces of the anode and cathode is emerging as an important challenge. The terms and words used in this specification and claims are used merely to describe exemplary embodiments and should not be interpreted as being limited to their ordinary or dictionary meanings, and should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention. For example, in this specification, terms such as “comprising,” “having,” or “having” are inten