Bismuth oxide nanoflake@carbon film: A free-standing battery-type electrode for aqueous sodium ion hybrid supercapacitors

Abstract

Aqueous hybrid supercapacitors are promising due to their low cost and high safety. Herein, a free-standing battery-type electrode of Bi2O3 nanoflake@C on carbon cloth is designed for aqueous sodium ion hybrid supercapacitors. Due to the integration of nanoarray architecture and the conductive carbon, the Bi2O3@C electrode exhibits a high specific capacity of 207mAh/g at 2A/g (6C), good rate capability and cycling stability (133mAh/g after 1000 cycles). With the activated carbon as the capacitive electrode and neutral sodium salts as the electrolyte, a 1.9V hybrid supercapacitor is assembled, delivering a high energy density of 18.94Wh/kg. The device can still maintain 72.3% of initial capacity after 650 cycles. The present work holds great promise for developing next-generation hybrid supercapacitors.