Construction of S-doped ZnCo2O4 microspindles with enhanced electrochemical performance for supercapacitors

Ternary metal oxide, such as ZnCo2O4 has attracted widespread attention as electrode material for super-capacitors owing to its high theoretical activity and rich redox reactions arising from the synergistic effects between two different metal species. However, the compromised electrochemical performance due to low electronic conductivity and deficient active sites of ZnCo2O4 impedes its practical applications. Herein, S-doped ZnCo2O4 microspindles (denoted as S-ZnCo2O4) have been obtained by simple hydrothermal synthesis followed by calcining and sulfurization treatments. It is indicated that the doping of S results in the formation of defects and disorders without altering the crystalline structure of ZnCo2O4, which is beneficial for charge transfer, and exposing more active sites. Taking advantage of the desired structure and composition, the S-ZnCo2O4 displays superior electrochemical properties when acting as an electrode material for supercapacitors. It delivers a high specific capacity of 214.1C g(-1) (522 F/g) at the current density of 0.5 A g(-1), which is almost 8.5 times that of the ZnCo2O4 (25 C g(-1), 61 F/g). Moreover, the S-ZnCo2O4 also shows good rate capability (82% at 10 A g(-1)) and excellent electrochemical stability (78% retention after 5000 cycles). This work demonstrates that anion doping can be an efficacious strategy of boosting electrochemical performance.