일시 : 2017년 3월 22일(수) 오후5시-7시

장소 : 과학관 604호

연사 : 변혜령 교수님(카이스트, 화학과)

The rechargeable lithium-oxygen (Li-O2) battery, providing theoretically high specific-energy-density calculated as ~3 kWh kg-1cell, is a promising future energy storage system. However, the over-potential is considerably severe during charge due to difficulty of Li2O2 decomposition (Li2O2(s)  2Li+ + O2(g) + 2e−, Erev = 2.96 V vs. Li+/Li), which is one of the greatest challenges for implementation of practical battery systems. Much effort has been devoted by incorporation of metal oxide promoters and soluble redox mediator. However, these additive materials give rise to more side reactions and require high cost. Here I present the new strategy of Li2O2 structural engineering to reduce the charge over-potential. The design of electrode surface can enhance adsorption affinity of O2 and LiO2, which determines morphology and structure of Li2O2. We found that the resulting amorphous Li2O2 facilely decomposes in comparison with crystal structure, which is attributed to increased ionic and electronic conductivity of Li2O2.