Self-assembling RuO2 nanogranulates with few carbon layers as an interconnected nanoporous structure for lithium-oxygen batteries

Electrocatalysis for cathodic oxygen is of great significance for achieving high-performance lithium-oxygen batteries. Herein, we report a facile and green method to prepare an interconnected nanopores three-dimensional (3D) architecture, which is composed of RuO2 nanogranulates coated with few layers of carbon (1-2 layers). The as-prepared 3D nanoporous RuO2@C nanostructure can demonstrate a high initial specific discharge capacity of 4000 mAh g-1 with high round-trip efficiency of 95 %. Meanwhile, the nanoporous RuO2@C could achieve stable cycling performance with a fixed capacity of 1500 mAh g-1 over 100 cycles. The terminal discharge and charge potentials of nanoporous RuO2@C are well maintained with minor potential variation of 0.14 and 0.13 V at the 100th cycle, respectively. In addition, the formation of discharge products is monitored by using in-situ high-energy synchrotron X-ray diffraction (XRD).