2018年5月2日星期三

EDOT(126213-50-1) as electrolyte additive for lithium ion battery

The safety of lithium ion battery is one obstacle to limit its large-scale application in automobile. Some researches show that decomposition of electrolyte on cathode under high potential is one reason leading to the thermal runaway or even the combustion of electrolyte. In order to solve the above problem, one way is to form a thin film on cathode surface to prevent the decomposition of electrolyte on it. Researchers have found that 3, 4-ethylene dioxythiophene (EDOT) can be used as electrolyte additive to improve the safety of the battery. And the addition of EDOT has no effect on electrochemical performance of lithium ion battery. Some details of the experiment are described as follows.
In the experiment, LiCoO2 was used as cathode and EDOT was added into the standard electrolyte. Oxidation potential of EDOT was measured by cyclic voltammetry which oxidation peak occurred at 3.95V, which is situated at the range of charge voltage of LiCoO2. So EDOT can be oxidized to form polymerization film (PEDOT) on cathode surface in the first charge-discharge cycle. And TEM experiment also verifies this. The polymerization film on cathode surface suppresses the decomposition of electrolyte to improve the lithium ion battery safety.

The thermal stability of LiCoO2 cathode after delithiation in the electrolyte with EDOT or without is detected by DSC. The experiment results show that PEDOT-modified cathode has a 26% exothermic reduction. And this demonstrates the heat generation due to electrolyte decomposition is reduced to a certain extent. The cyclic performance of the full cell shows that the capacity retention is improved for the electrolyte with addition of EDOT.

In a word, EDOT polymer as electrolyte additive can improve the safety of lithium ion battery. And it has no effect on electrochemical performance of lithium ion battery.

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