US-12620626-B2 - Lithium secondary battery

US12620626B2US 12620626 B2US12620626 B2US 12620626B2US-12620626-B2

Abstract

The present disclosure relates to a lithium secondary battery comprising a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and a non-aqueous electrolyte. The non-aqueous electrolyte includes an organic solvent, a lithium salt, a coumarin-based compound represented by [Chemical Formula 1], and a halogen-substituted cyclic carbonate, and the positive electrode active material includes a lithium manganese-rich oxide represented by [Chemical Formula 2].

Inventors

Jung Min Lee
Jung Gu HAN
Su Hyeon Ji
Chul Eun Yeom
Chul Haeng Lee
Kyung Mi LEE

Assignees

LG ENERGY SOLUTION, LTD.

Dates

Publication Date: 20260505
Application Date: 20230203
Priority Date: 20220208

Claims (9)

1 . A lithium secondary battery comprising: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and a non-aqueous electrolyte, wherein: the non-aqueous electrolyte includes an organic solvent, a lithium salt, a coumarin-based compound represented by [Chemical Formula 1] below, and a halogen-substituted cyclic carbonate; and the positive electrode active material includes a lithium manganese-rich oxide represented by [Chemical Formula 2] below: Li 1+a [Ni b Co c Mn d M 1 e ]O 2+a [Chemical Formula 2] wherein in Chemical Formula 2 above, 0.05≤a≤1, 0≤b≤0.5, 0≤c≤0.3, 0.5≤d<1.0, and 0≤e≤0.2, and M 1 is at least one selected from the group consisting of metal ions of Al, B, Co, W, Mg, V, Ti, Zn, Ga, In, Ru, Nb, Sn, Sr, and Zr, wherein the coumarin-based compound represented by [Chemical Formula 1] above is included in an amount of 0.5 wt % to 3 wt % based on the total weight of the non-aqueous electrolyte, and the halogen-substituted cyclic carbonate is included in an amount of 0.5 wt % to 10 wt % based on the total weight of the non-aqueous electrolyte.
2 . The lithium secondary battery of claim 1 , wherein the weight ratio of the courmarin-based compound by represented by [Chemical Formula 1]: the halogen-substituted cyclic carbonate is 1:1˜3.
3 . The lithium secondary battery of claim 1 , wherein the halogen-substituted cyclic carbonate is at least one selected from the group consisting of fluorinated ethylene carbonate, trifluoroethoxyethylen carbonate and difluoroethylene carbonate.
4 . The lithium secondary battery of claim 1 , wherein the non-aqueous electrolyte further comprises one or more additive selected from the group consisting of a cyclic carbonate-based compound, a sultone-based compound, a sulfate-based compound, a phosphate-based compound, a borate-based compound, a benzene-based compound, an amine-based compound, a silane-based compound, and a lithium salt-based compound.
5 . The lithium secondary battery of claim 1 , wherein the lithium manganese-rich oxide is represented by [Chemical Formula 2-1] below: X Li 2 MnO 3 ·(1−X)Li[Ni 1-y-z-w Mn y Co z M 1 w ]O 2 [Chemical Formula 2-1] wherein in [Chemical Formula 2-1] above, 0.1≤X≤0.5, 0.5≤y<1, 0≤z≤0.3, and 0≤w≤0.2, and M 1 is at least one selected from the group consisting of metal ions of Al, B, Co, W, Mg, V, Ti, Zn, Ga, In, Ru, Nb, Sn, Sr, and Zr.
6 . The lithium secondary battery of claim 1 , wherein the negative electrode active material comprises a silicon-based negative electrode active material.
7 . The lithium secondary battery of claim 6 , wherein the silicon-based negative active material is selected from the group consisting of Si, SiO m (wherein 0<m≤2), a Si—C composite, an Si-M a alloy (wherein M a is one or more selected from the group consisting of Al, Sn, Mg, Cu, Fe, Pb, Zn, Mn, Cr, Ti, and Ni), and a combination thereof.
8 . The lithium secondary battery of claim 6 , wherein the negative electrode active material further comprises a carbon-based negative electrode active material.
9 . The lithium secondary battery of claim 8 , wherein the negative electrode active material comprises the silicon-based negative electrode active material: the carbon-based negative electrode active material at a weight ratio of 1:99 to 50:50.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of Korean Patent Application No. 10-2022-0016541, filed on Feb. 8, 2022, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. BACKGROUND OF THE INVENTION The present disclosure relates to a lithium secondary battery, and more specifically, to a lithium secondary battery to which a lithium manganese-rich positive electrode active material is applied. In recent years, interest in energy storage technology has been increased, and as the application field of the technology is expanded to mobile phones, camcorders, notebook PCs, and furthermore, to electric vehicles, efforts for research and development of electrochemical devices are gradually becoming actualized. Among electrochemical devices, interest in the development of secondary batteries that are able to be charged and discharged is rising, and particularly, lithium secondary batteries developed in the early 1990s are in the spotlight due to having high operating voltage and a very high energy density. A lithium secondary battery is generally manufactured by interposing a separator between a positive electrode including a positive electrode active material having a transition metal oxide containing lithium, and a negative electrode including a negative electrode active material capable of storing lithium ions, thereby providing an electrode assembly, inserting the electrode assembly into a battery case, injecting thereto a non-aqueous electrolyte, which is a medium for transferring the lithium ions, and then sealing the battery case. The non-aqueous electrolyte generally includes a lithium salt, and an organic solvent capable of dissolving the lithium salt. Recently, as the demand for secondary batteries with high energy density, such as batteries for electric vehicles, has increased, the development of high-voltage secondary batteries driven at high voltages has been actively conducted. However, when a driving voltage is increased, electrolyte decomposition is accelerated due to structural collapse, transition metal elution, gas generation at the like on the surface of a positive electrode, and thus there is a problem in that lifespan properties of a battery are rapidly deteriorated. In addition, in order to reduce the manufacturing cost of batteries for electric vehicles, batteries using a hyper-lithium manganese-rich (Mn-rich) positive electrode active material, which is cheaper than a typical lithium nickel-based positive electrode active material and has excellent stability, are being developed. In the case of a battery to which a hyper-lithium Mn-rich positive electrode active material is applied, it is required to perform an initial activation process at a high voltage of 4.6 V or greater, and in the activation process, active oxygen is generated, resulting in increasing side reactions and resistance with an electrolyte solution, so that there is a problem in that a positive electrode is deteriorated, thereby degrading lifespan properties. Therefore, there is a demand for the development of a battery including a lithium manganese-rich positive electrode active material and capable of suppressing gas generation and positive electrode deterioration. SUMMARY OF THE INVENTION The present disclosure has been made to solve the above problems and is directed to providing a lithium secondary battery which exhibits excellent lifespan properties and swelling properties by including a coumarin-based compound and a halogenated cyclic carbonate in a non-aqueous electrolyte of a battery to which a lithium manganese-rich positive electrode active material is applied, thereby removing active oxygen generated during high-voltage activation. According to an aspect of the present disclosure, there is provided a lithium secondary battery including a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte includes an organic solvent, a lithium salt, a coumarin-based compound represented by [Chemical Formula 1] below, and a halogen-substituted cyclic carbonate, and the positive electrode active material includes a lithium manganese-rich oxide represented by [Chemical Formula 2] below. Li1+a[NibCocMndM1e]O2+a [Chemical Formula 2] In Chemical Formula 2 above, 0.05≤a≤1, 0≤b≤0.5, 0≤c≤0.3, 0.5≤d≤1.0, and 0≤e≤0.2, and M1 is at least one selected from the group consisting of metal ions of Al, B, Co, W, Mg, V, Ti, Zn, Ga, In, Ru, Nb, Sn, Sr, and Zr. In the present disclosure, the coumarin-based compound represented by [Chemical Formula 1] above may be included in an amount of 0.5 wt % to 3 wt % based on the total weight of the non-aqueous electrolyte, and the halogen-substituted cyclic carbonate may be included in an amount of 0.5 wt % to 10 wt % based on the total weight of the non-aqueous