Highly porous silver dendrites on carbon nanotube wrapped copper cobaltite nano-flowers for boosting energy density and cycle stability of asymmetric supercapattery

In the present work, we have demonstrated the rapid synthesis of Ag dendrites on carbon nanotubes (CNTs) wrapped CuCo2O4 nanoflowers (CNT-CuCo2O4@Ag) by using a two-step chemical approach. The as-synthesized CNT-CuCo2O4@Ag is used as an electrode for supercapattery application. Individually, CNT-CuCo2O4 @Ag electrode shows the exceptional capacity of 590 mAh g(-1) at a current density of 0.5 A g(-1). This capacity is 1.8 and 1.6 times those of the pure CuCo2O4 and CNT-CuCo2O4 nanoflower-based electrodes, respectively. Furthermore, an all-solid-state asymmetric supercapattery (ASC), CNT-CuCo2O4@Ag//AC, has been fabricated using the CNT-CuCo2O4@Ag nanoflowers as the positive electrode and a thermocol-derived activated carbon (AC) as the negative electrode. Interestingly, the ASC device delivers an ultrahigh energy density of 91 Wh kg(-1) at the power density of 0.42 kW kg(-1); even at the high power density of 18 kW kg(-1), the ASC device still maintains an energy density of 50 Wh kg(-1). The ASC device also exhibits excellent cyclic stability by showing 98% of capacity retention over 20,000 cycles at a high current density of 10 A g(-1). This rapid in situ synthesis strategy for Ag dendrite growth and CNT wrapping is also applicable to other metal oxides and metal sulphides with porous nanostructures containing NH3 molecules.