Kapok-fiber@chitosan derived carbon assisting construction carbon-doped β/α hybrid-crystal Bi2O3 for high specific capacitance supercapacitor

Bismuth trioxide (Bi 2 O 3 ) acts as an ideal material for supercapacitors because of its high theoretical specific capacity, but its crystal form and compact accumulation limit its specific capacitance below its theoretical value of 1370 F g -1 . In this study, a specific kapok fiber@chitosan-derived carbon (KCC) doping inside β/α hybrid-crystal Bi 2 O 3 (KCC-Bi 2 O 3 ) was constructed by KCC assisting to enhance the contact area between Bi-MOF and air during calcination. A specific capacitance of 1135 F g -1 at 1 A g -1 was obtained for KCC-Bi 2 O 3 , which matched 82.3 % of its theoretical value. An asymmetric capacitor, with KCC-Bi 2 O 3 as a negative electrode and NiCo-LDH as a positive electrode, exhibits a potential window of 1.6 V and an energy density of 17.3 Wh kg -1 at 800 W kg -1 . The result demonstrates that incorporating a KCC carbon source can significantly enhance the capacitance of mixed crystal form Bi 2 O 3 , highlighting its potential in supercapacitor applications.