Exploring the Faster Reaction Kinetics between LiOH And I2 to Resolve Abnormal High Discharge Potential for Aprotic Li-O2 Battery
作者单位：Shanghai University
会议名称：《中国化学会第二十次全国电化学大会》
会议日期：2019年
学科分类：0808[工学-电气工程] 07[理学] 070304[理学-物理化学(含∶化学物理)] 08[工学] 0703[理学-化学]
关 键 词：LiOH LiI disordering solvent densityfunctionaltheory machinelearning
摘 要：An effective way to thermodynamically resolve the cathode irreversibility of Li-O2 battery is the usage of redox mediators（RM）. However, the sluggish reaction between RM and discharge products is still common, which inhibits the efficiency of RM. Here, with the reaction between LiOH and I2 as a model, we attempt to improve the reaction kinetics by unraveling the elementary reaction steps and the solvent effect via the first principles calculation and machine learning. Also, in terms of the debate on the reversibility of LiOH, we have experimentally clarified the particular experimental conditions to generate O2. The reaction processes were calculated for LiOH with various disordering degree, which is quantitatively defined based on the bond length deviation against the perfect crystalline structure. The solvation effects of 28 solvents on the lithium desorption（the rate determined step） were compared. The detailed theoretical and experimental exploration shows that an appropriate H2O content is the key to yielding O2. The discharge products having the higher disordering extent possesses faster reaction kinetics with RM. The functional group of the solvent molecule is proposed as the key to regulating reaction kinetics, as only the atoms involved in the functional group can predict the solvent effect well using the machine learning method. Moreover, the phosphate-based solvent is predicted to promote the LiOH decomposition kinetics most. These findings indicate that the rational discharge product structure regulation and appropriate solvent selection are prospect strategies for the pursuit of faster reaction kinetics between RM and the discharge products.