Influence of fluorine doping on the structure and electrochemical performance of δ-MnO2 for supercapacitors

Herein, the fluorine-doped δ-MnO2 electrode materials for supercapacitors have been prepared by chemical deposition method, and the effects of doping amount on the morphology, structure and electrochemical performance of δ-MnO2 were explored. The results illustrate that fluorine doping makes the specific surface area of δ-MnO2 increase and the structure more stable, which in turn makes the electrode exhibit greater specific capacitance and cycling stability. Both experimental tests and DFT theoretical calculations show that the electronic conductivity of δ-MnO2 can be increased by fluorine doping. The as-synthesized F0.35 M sample exhibits a maximum capacity of 148.44 F g−1 at 0.5 A g−1. Besides F0.35 M also shows excellent cycling life, retaining 82.80 % of the original capacity after 10000 cycles at 10 A g−1, which is greater than three times that of pure δ-MnO2.