Binary tungsten-molybdenum oxides nanoneedle arrays as an advanced negative electrode material for high performance asymmetric supercapacitor

Herein, the novel binary tungsten-molybdenum oxides (W 0.4 Mo 0.6 O 3 ) nanoneedle arrays have been prepared by a facile one-step hydrothermal method without adding any surfactant. The as-prepared W 0.4 Mo 0.6 O 3 nanoneedle arrays can provide abundant exposed reaction active sites and utilize expedite transport channel to facilitate the diffusion of electrolyte ion. Thus, as an electrode for supercapacitor , it exhibits a high specific capacity of 115.7 mAh g −1  at the current density of 1 A g −1 and good rate performance. To achieve the high energy density of supercapacitor, an asymmetric supercapacitor is fabricated by using the W 0.4 Mo 0.6 O 3 nanoneedle arrays as the negative electrode and the polygni multiflori caulis-based honeycomb-like carbon (PMCHC) as the positive electrode, which possesses a high output voltage of 1.5 V and an energy density of 20.2 Wh kg −1  at a high power density of 750.6 W kg −1 , as well as good cycling stability. Such facile synthesis strategy and outstanding electrochemical behaviors imply that the binary metal oxides nanoneedle arrays is a promising electrode material for energy-storage system.