SOLUBILITY OF OXYGEN IN LITHIUM-AIR BATTERY ELECTROLYTES: A MOLECULAR DYNAMICS STUDY

A Deshpande and P Dutta and S Banerjee, ASME INTERNATIONAL MECHANICAL ENGINEERING CONGRESS AND EXPOSITION, 2014, VOL 6A, V06AT07A036 (2015).

Ionic liquids are widely considered as potential electrolytes for lithium batteries due to their tunable electrochemical properties and extremely low vapor pressure, which makes them highly non-inflammable However, the solubility of oxygen in ionic liquid based electrolytes is an important parameter that determines the performance of batteries. In the present study, we have employed molecular dynamics simulations to calculate the Henry's constant and corresponding solubility values of atmospheric oxygen in N-methyl-N-propyl pyrrolidinium bis(trifluoromethanesulfonyl) imide (mppy(+)TFSI(-)) ionic liquids. After qualitatively validating the results at 323 K, we calculated the solubility of oxygen in mppy(+)TFSI(-), as the ratio of the partial pressure of oxygen gas in the atmosphere and the Henry's constant, at a range of temperatures that occur in realistic battery electrolytes. The solubility of oxygen increases with increasing temperature. Comparison of these solubility values with those of commonly used organic electrolytes provides valuable information regarding the feasibility of using ionic liquid electrolytes in lithium-air batteries.

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