Studies of Ozone-Sensitized Low- and High-Temperature Oxidations of Diethyl Carbonate

Diethyl carbonate (DEC) oxidation with different levels of O₃ addition was performed in an atmospheric laminar flow reactor from 400 to 850 K. Experimental results showed that, without O₃ addition, the oxidation of DEC began from 650 K with no low-temperature reactivity, while with O₃ addition the low-temperature chemistry of DEC was observed from 450 K. A DEC/O₃ kinetic model was developed, and the model predictions agreed with the experimental data reasonably well with a slight overprediction of DEC oxidation between 550 and 750 K. The low-temperature chemistry of DEC with O₃ addition was described in the reaction pathway of DEC. It was found that O₃ assisted the low-temperature oxidation of DEC mainly through the production of the active O: atom instead of the direct reaction with the fuel molecule. The present work indicated that the Li-ion battery degradation at 400-500 K might result from the low-temperature chemistry of DEC with active oxygen supplies from the cathode metal oxide materials or from singlet O₂ during the battery discharge process. This article used O₃ to mimic the oxidizing environment in the Li-ion battery by providing active atomic oxygen. It provided insights into the chemically sensitized gas-phase low-temperature chemistry of DEC and explained the mechanism of battery degradation involving the low-temperature oxidation at the electrolyte solvent and the cathode interface from 400 to 500 K.