Resolving the cathode passivation of lithium-oxygen batteries with an amination SiO_2/TiO_2 functional separator

摘要

The issue of cathode passivation during cycling resulting in rapid capacity fading and premature battery death is a major challenge that hinders the applications of lithium-oxygen (Li-O-2) batteries. Here, a facile strategy of introducing a functional separator based on flexible amination SiO2/TiO2 inorganic woven film (STON WF) is proposed to suppress the cathode passivation problem. The by-products, i.e. HCOOLi, CH3COOLi and Li2CO3 can be selectively adsorbed on the STON WF separator preferably compared with the cathode and further proved by the density functional theory (DFT) calculations. Thus, benefiting from the separator, the Li-O-2 cells with super P carbon and catalyst-free cathode show enhanced electrochemical performance (5645 mA h g(-1) at a current density of 200 mA g(-1)), good rate capability (discharge voltage of 2.43 V at a current density of 1.5 A g(-1)) and especially superior cycle stability up to 268 cycles. These findings present a promising approach to prevent the premature battery death.