Induced construction of large-area amorphous Li2O2 film via elemental co-doping and spatial confinement to achieve high-performance Li-O2 batteries

Abstract

In aprotic lithium-oxygen batteries (LOBs), it is hard to simultaneously achieve both high specific capacity and good reversibility with the insulating solid Li2O2 formed via traditional surface or solution route. Tuning the structure of Li2O2 to construct a large-area amorphous film on the surfaces of catalysts is expected to break the above performance limitation. In this work, nitrogen and sulfur co-doped carbon nanotube (CNT) arrays grown on the three-dimensional graphene (NS-CNTA/3DG) was developed as the efficient catalysts for LOBs. Large-area thin amorphous Li2O2 film is induced through the synergistic effect between doping engineering and spatial confinement on CNT arrays, confirmed by theoretical calculation and in-situ Raman examination. Consequently, the NS-CNTA/3DG cathode delivers both high specific capacity (23778 mAh g−1 at 200 mA g−1) and a high round-trip coulombic efficiency (∼87.8%) in the first deep discharge-charge process. This work contributes a new approach to optimize the formation of Li2O2 film, which will inspire the design and fabrication of new catalysts for high-performance LOBs.