Inhibiting I–/I3– redox shuttling in Li-O2 batteries by MOF decorated separator

Abstract

Redox mediators (RMs) have been considered by far the most effective strategy to lower the huge charge polarization of Li-O2 batteries, which is caused by the sluggish electrochemical oxidization of discharge products Li2O2. However, the RMs can not only restrict at the cathodic side but also shuttle to the lithium (Li) anode and further react with it, leading to unexpected degradation of both cathodes and anodes, thereby compromising the sustainability of the battery. Herein, we have developed a MOF-decorated glass fibers as separator (HUKST-1/GF) which is capable of suppressing the I–/I3– redox shutting involved in Li-O2 batteries. The interstices of the MOF are compact with optimal pore size, thus acting as an effective sieve to hinder the transference of the I3–. Moreover, the prepared separator possesses high ionic conductivity (1.35×10−3 S cm−1) and Li+ transference number (0.46). As a result, the Li-O2 batteries based on HUKST-1/GF separators exhibit exceptional electrochemical performance compared with those employing traditional separators.