Asymmetric supercapacitor constructed by self-assembled camellia-like BiOCl and activated carbon microspheres derived from sweet potato starch

In this work, two electrode materials, self-assembled camellia-like bismuth oxychloride (BiOCl) and monodispersed activated carbon microspheres (AC), were fabricated as a new asymmetric supercapacitor (ASC). The AC was synthesized using a renewable carbon source, and it was used as a positive electrode. A specific capacitance of 208 F g−1 at a current density of 1 A g−1 with the capacitance retention of 87.6% after 3000 cycles was obtained. On the other hand, an extremely facile and efficient approach for preparing BiOCl with a controllable morphology is proposed. The camellia-like morphology with a mesoporous structure of as-prepared BiOCl is revealed by SEM, TEM and BET characterization. The chemical composition of BiOCl is analyzed by XRD and XPS method. As a new negative electrode in ASC, the BiOCl electrode delivers a specific capacitance of 1243 F g−1 at 1 A g−1, and 90.3% capacitance retention after 3000 cycles at 5 A g−1. With coupled AC and BiOCl, the full cell of ASC exhibits a maximum capacitance value of 124 F g−1 at 0.5 A g−1 and good cycling stability with 82% of the initial specific capacitance after 3000 cycles at 1 A g−1. [Display omitted] •BiOCl electrode delivers a high specific capacitance of 1243 F g−1 at 1 A g−1.•Monodispersed carbon electrode material was prepared from sweet potato starch.•The assembled BiOCl//AC ASC exhibits high capacitance and cycling stability.