Electrolyte for lithium secondary battery and lithium secondary battery

A lithium secondary battery, electrolyte technology, applied in secondary batteries, secondary battery repair/maintenance, electrolyte battery manufacturing, etc., can solve the problems of inability to reduce lithium metal electrochemical side reactions and limited solubility, etc. Achieve the effect of preventing direct contact, reducing irreversible side reactions, and improving cycle performance

Active Publication Date: 2021-12-03
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For lithium metal anode batteries, a relatively high concentration of lithium salt electrolyte is required to maintain the electrochemical stability of the electrolyte to lithium metal during battery cycling, and LiPF6 in carbonate / ether electrolyte The solubility of lithium metal in the electrolyte is limited, and the electrochemical side reactions of lithium metal in the electrolyte cannot be well reduced.

Method used

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  • Electrolyte for lithium secondary battery and lithium secondary battery
  • Electrolyte for lithium secondary battery and lithium secondary battery
  • Electrolyte for lithium secondary battery and lithium secondary battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment approach

[0020] According to a preferred embodiment of the present invention, the alkali metal ions are selected from cesium or silver, which is more conducive to the shielding effect of alkali metal ions on the tip of lithium dendrites, effectively guiding Li + Deposits away from the Li dendrite tip, guiding the Li + Even deposition.

[0021] Preferably, the alkyl group is selected from at least one of straight-chain alkyl, branched-chain alkyl and heteroatom-containing alkyl, wherein the heteroatom is selected from at least one of F, N, O and S; Further preferably, the alkyl group is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, methoxy, ethoxy, fluoromethoxy, thiomethyl, At least one of methylamine and fluoromethyl. The use of a preferred alkyl group can effectively prevent molecular accumulation of the heterocyclic compound in the solution and improve the solubility of the additive.

[0022] Preferably, the halogen is selected from fluorine, chlorine, brom...

Embodiment 1

[0054] Electrolyte preparation : Add an organic solvent containing ethylene glycol dimethyl ether (DME) and 1,3-dioxolane (DOL) at a volume ratio of 50:50, and 1 mol / L based on the total amount of non-aqueous electrolyte amount of LiTFSI as a lithium salt, and then, based on the total amount of the non-aqueous electrolyte, 0.5% by weight of 1,2,5-thiadiazoline-1,1-dioxide as an electrolyte additive was added Electrolyte S1 is obtained.

[0055] Preparation of lithium secondary battery :

[0056] (1) By adding 98% by weight of Li(Ni) as a positive active material to N-methyl-2-pyrrolidone as a solvent 0.33 co 0.33 mn 0.33 )O 2 , 1% by weight of carbon black as a conductive agent and 1% by weight of polyvinylidene fluoride as a binder to prepare positive electrode slurry. The positive electrode slurry was then coated on an aluminum current collector with a thickness of 50 μm to form a positive electrode film, and dried and then rolled to prepare a positive electrode.

...

Embodiment 2

[0060] Electrolyte preparation : Addition of ethylene glycol dimethyl ether (DME) and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) in a volume ratio of 50:50 An organic solvent, and LiFSI as a lithium salt in an amount of 2 mol / L based on the total amount of the non-aqueous electrolyte, and then, based on the total amount of the non-aqueous electrolyte, 0.5% by weight of 1,2, 5-Thiadiazoline-1,1-dioxo-2,5-dilithium salt Electrolyte S2 is obtained.

[0061] The preparation of the lithium secondary battery was the same as that in Example 1 to obtain the lithium secondary battery SP2.

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Abstract

The invention relates to a lithium ion battery, in particular to an electrolyte for a lithium secondary battery and the lithium secondary battery. The electrolyte contains an additive, the additive is selected from at least one of compounds represented by structural formulas (I)-(IX), and M is selected from hydrogen and C1-C5 alkyl; L is selected from alkali metal and silver; R1 to R16 are respectively and independently selected from hydrogen, halogen and C1-C5 alkyl groups; and n is an integer selected from 1-5. The electrolyte provided by the invention has relatively good positive and negative electrode film-forming performance and high-temperature performance, and the cycle performance of the lithium secondary battery is greatly improved.

Description

technical field [0001] The invention relates to a lithium ion battery, in particular to an electrolyte solution for a lithium secondary battery and a lithium secondary battery. Background technique [0002] Lithium-ion batteries have many advantages such as high energy density, long service life, and environmental friendliness, and are widely used in consumer electronics, electric vehicles, power tools, and medical electronics. However, the limitation of energy density of lithium-ion batteries using graphite anodes makes people have to consider using lithium metal anodes with higher specific capacity. [0003] At present, commercial lithium-ion battery products generally use LiPF 6 as an electrolyte in the electrolyte. However, at higher temperatures (>55°C), LiPF 6 / Carbonate electrolyte is unstable and will undergo decomposition reaction to generate LiF and PF 5 , PF 5 is a strong Lewis acid, in H 2 In the presence of O or small molecule alcohol impurities, a sel...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/0567H01M10/058H01M10/0525H01M10/42
CPCH01M10/0567H01M10/058H01M10/0525H01M10/4235Y02E60/10Y02P70/50
Inventor 陈嵩郭姿珠马永军吴荣方
Owner BYD CO LTD
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