Non-aqueous electrolyte for lithium battery and lithium ion battery

Abstract

The invention discloses a non-aqueous electrolyte for a lithium battery and the lithium ion battery. The non-aqueous electrolyte for the lithium battery comprises an electrolyte salt, a non-aqueous solvent and an additive, and the additive comprises an olefine acid salt additive. According to the non-aqueous electrolyte for the lithium battery, a small amount of the olefine acid salt additive is added, the use amount of DTD can be not used or reduced, the non-aqueous electrolyte has high film-forming sensitivity, the lithium conductivity of the battery is improved, the impedance of the battery is reduced, meanwhile, gas production is reduced, and the high-temperature cycle retention rate and the capacity recovery rate are improved.

Description

technical field [0001] The invention relates to the technical field of electrolytes, in particular to a non-aqueous electrolyte for a lithium battery and a lithium ion battery. Background technique [0002] Due to the advantages of high voltage, high specific energy, no memory effect and long cycle life, lithium-ion batteries are widely used in 3C consumer electronic products such as mobile phones, cameras, and notebook computers. Lithium-ion batteries are mainly composed of positive electrodes, negative electrodes, separators, and electrolytes. [0003] In the electrolyte, the commonly used film-forming additives are mainly vinylene carbonate (VC) and fluorinated ethylene carbonate (FEC). Although such film-forming additives can improve the high-temperature cycle stability of the battery and reduce high-temperature storage gas production, However, thicker film formation also brings greater initial DC resistance and DC resistance (DCR) growth. In the application of ternary...

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Problems solved by technology

[0003] In the electrolyte, the commonly used film-forming additives are mainly vinylene carbonate (VC) and fluorinated ethylene carbonate (FEC). Although such film-forming additives can improve the high-temperature cycle stability of the battery and reduce high-temperature storage gas production, However, thicker film formation also brings greater initial DC resistance and DC resistance (DCR) growth

In the application of ternary batteries and iron-lithium batteries, when the amount of VC added is insufficient, the effect of improving the high-temperature cycle stability is not obvious, and if it exceeds a certain mass percentage, it will bring a large initial DCR and DCR growth; in addition, in storage The price of VC is higher under the background of the growth of energy battery demand

Compared with VC, FEC has a thinner film and lower impedance. The principle of action is that FEC itself slowly removes HF under electrocatalysis to generate VC. It is widely used in silicon-carbon systems, but due to the high price of FEC itself, and electrolytes with high FEC content will appear. Increased acidity and high gas production during high-temperature cycles threaten battery cycle performance and high-temperature stability

[0004] Vinyl sulfate (DTD), 1,3-propane sultone (PS), and 1,3-propene sultone (PST) are commonly used additives in lithium-ion batteries to reduce battery impedance, reduce gas production, and maintain Cycle balance, the function of DTD is to reduce the cycle resistance of the battery, but its formation and gas production are large, which brings difficulties in the process, and requires low-temperature storage, which increases the cost of the electrolyte; at the same time, PS and PST are common high-temperature additives with good It has the effect of reducing gas production, improving high-temperature cycle retention rate and capacity recovery rate, but it has the risk of environmental impact assessment, and it is difficult to export. At the same time, it is sensitive to the amount of addition. A little more will lead to a sharp increase in battery impedance

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