Ru clusters anchored on Magnéli phase Ti4O7 nanofibers enables flexible and highly efficient Li–O2 batteries

Abstract

Lithium–oxygen (Li–O2) batteries have attracted tremendous attention due to their high specific energy density. However, their sluggish conversion kinetics and detrimental parasitic reactions would deteriorate the lifespan of batteries. Herein, a combined density functional theory (DFT) calculation and experimental approach is carried out to design an efficient cathode electrocatalyst for Li–O2 batteries. A self-supporting film of Ru clusters anchored on Magnéli phase Ti4O7 enriched with oxygen vacancy (Ru/Ti4O7) is fabricated upon electrospinning and carbothermal reduction. In such a synergistic configuration of Ru/Ti4O7 hybrid film, the strong metal-support interaction (SMSI) between Ru and Ti4O7 can improve the charge transfer at the interface and enhance the adsorption energy of intermediates, accelerating the reaction kinetics of the formation/decomposition of Li2O2. Benefitting from this SMSI, the electrochemical stability of Ru/Ti4O7 over cycling is also enhanced. As a result, as-prepared Ru/Ti4O7 cathodes could realize excellent electrochemical performance, including high specific capacity (11000 mAh g–1), low discharge/charge polarization (0.36 V), long lifespan (> 100 cycles) and superior rate capability. Furthermore, a flexible Li–O2 pouch cell, constructed with as-fabricated Ru/Ti4O7 film cathode, lithium foil anode and GPE, can exert an impressive areal capacity of 5 mAh cm–2 with a low voltage gap of 0.82 V in ambient air. This work suggests that the activity of catalysts can be significantly enhanced with interfacial modification, offering an efficient approach for rational designing of electrocatalysts for use in Li–air batteries and beyond.