Synthesis of oxygen vacancies implanted ultrathin WO_3-x nanorods/reduced graphene oxide anode with outstanding Li-ion storage

Transition metal oxides have shown an extraordinary potential for lithium-storage capability to date. However, it remains enormous challenge to gain high capacities, good rate performance and cyclability due to their inferior conductivity. To address this issue, oxygen vacancies (V_Os) implanted ultrathin WO₃ nanorods (the diameter around 5 nm and the length less than 100 nm) composed with reduced graphene oxide (namely WO_3-x/rGO), were synthesized by proposing a logical design. For the sake of better showing the outcome of such configuration, holy nanosheets of pure WO₃ anode were proposed to compare with nanorods WO_3-x/rGO one in terms of electrochemical properties, and they were obtained via annealing H₂WO₄/rGO precursor in air and argon atmosphere with the same annealing ramp, respectively. By contrast, both electron paramagnetic resonance and X-ray photoelectron spectroscopic characterizations demonstrate the existence of V_Os in WO_3-x/rGO composite. The generation of V_Os together with the reserve of rGO, the conductivity of WO_3-x/rGO anode is distinctly enhanced, which is then verified by the compared electrochemical performance in this work. It is clearly shown that the WO_3-x/rGO nanocomposite displays a capacity of 745 mAh g⁻¹ at a current density of 0.1 A g⁻¹ after 200 cycles and excellent cycling stability up to 1000 cycles with capacity of 428 mAh g⁻¹ at 1 A g⁻¹. These findings exhibit that nanorods WO_3-x/rGO nanocomposite is a promising candidate for high-performance Li-ion battery anode.