Facile autoreduction synthesis of core-shell Bi-Bi2O3/CNT with 3-dimensional neural network structure for high-rate performance supercapacitor

Abstract Core-shell Bi-Bi2O3/CNT (carbon nanotube) with 3-dimensional neural network structure where Bi-Bi2O3 nanospheres act as cell bodies supported by a 3-dimensional network of CNTs acting as synapses is designed and prepared by simple solvothermal method and subsequent annealing autoreduction treatment, and this structure facilitates the efficient transport of electrons. It can provide two electron transfer paths due to the double contact of Bi2O3 shell with CNT and metal Bi core which enhances the efficiency of the electrochemical reaction. The Bi-Bi2O3/CNT electrode shows a high gravimetric capacitance of 850 F g−1 (1 A g−1), and the specific capacitance of Bi-Bi2O3/CNT can be still 714 F g−1 at 30 A g−1 indicating excellent rate performance. The asymmetric supercapacitor is assembled with Bi-Bi2O3/CNT as the negative electrode and Ni(OH)2/CNT as the positive electrode, delivering a high energy density of 36.7 Wh kg−1 and a maximum power density of 8000 W kg−1. Therefore, the core-shell Bi-Bi2O3/CNT with 3-dimensional neural network structure as the negative electrode of supercapacitor shows great potential in the field of energy storage in the future.