Precisely controllable oxygen vacancy-manufactured Ov-Co3O4@PPy for high energy density supercapacitor

Effective controllable manufacturing oxygen vacancy and polypyrrole coating can optimize the capacitive and cyclic properties of Co3O4. Herein, composition of Ov-Co3O4@PPy with Co3O4 rich in oxygen vacancy defects and polypyrrole was synthesized using NaBH4 reduction and chronoamperometry. Ov-Co3O4 was synthesized while regulating the concentration of the reducing agent NaBH4 solution, and then Ov-Co3O4@PPy was synthesized by electrodeposition of PPy. The specific capacitance of Ov-Co3O4@PPy formed at an optimal NaBH4 concentration and electrodeposition time was about three times that of Co3O4 without reduction treatment and unwrapped PPy. The capacitance retention rate of Ov-Co3O4@PPy was close to 80.5% after 5000 cycles. In addition, Ov-Co3O4@PPy//AC asymmetric supercapacitor was assembled with the as-prepared Ov-Co3O4@PPy as the positive electrode material and activated carbon as the negative electrode, which yielded specific energy density up to 74.55 Wh kg−1 at 850 W kg−1 power density and a capacitance retention rate close to 110% after 10,000 cycles.