Cooperation of F-doping and oxygen vacancies enhancing the electrochemical performances of NiCo2O4 for supercapacitor application

Designing an inexpensive and durable electrode material toward high electrochemical performance is stilling a challenge for the development of supercapacitors (SCs). In this report, we design new Fluorine (F) doped NiCo 2 O 4 (F- NiCo 2 O 4-x ) algae-like microspheres via an in situ hydrothermal route and chemical reduction etching. The substitution of F element in NiCo 2 O 4 lattice creates abundant oxygen vacancies sites with the help of the chemical etching. The theoretical (DFT) simulation data support the structural and morphological analysis. Such defects act a substantial role in enhancing the electronic conductivity, modulating active surface properties of F-NiCo 2 O 4-x . Benefiting from the above features, the F-NiCo 2 O 4-x electrode material manifests a wonderful specific capacity of 678 C g −1 (1 A g −1 ), good rate performance of 80 % (30 A g −1 ) and super high cycling stability (92.4 % after 25,000 cycles). Interestingly, an asymmetric supercapacitor (ASC) based F-NiCo 2 O 4-x offers a capacitance up to 246F·g −1 (1 A g −1 ) and achieves an impressive energy amount of 77.2 Wh·kg −1 with high power of 750 W kg −1 .Ourstudy not only presents a creative approach to design oxygen vacancies-rich binary metal oxides-based electrode material but also provides insights to design a durable electrode material for industrial-scale production. • Fluorine-doped NiCo 2 O 4-x algae-like microsphere is successfully designed. • The substitution of fluorine in NiCo 2 O 4 creates abundant oxygen vacancies. • The oxygen vacancies enhance the conductivity and accelerate the ionic transport. • As Electrode material, F-NiCo 2 O 4-x delivers good electrochemical performances.