Spinel-type FeNi2S4 with rich sulfur vacancies grown on reduced graphene oxide toward enhanced supercapacitive performance

Herein, the reduced graphene oxide (rGO)-based FeNi2S4 electrode material with rich sulfur vacancies (r-FeNi2S4-rGO) was prepared through a facile solvothermal procedure, followed by reduction with NaBH4. During the NaBH4 treatment, some sulfur atoms are removed from the lattice of FeNi2S4 and richer sulfur vacancies are generated, which can facilitate the transfer of electrons and decrease the equilibrium electron cloud density. In addition, the rich sulfur vacancies can enhance the intrinsic conductivity and increase the active sites, and the introduction of rGO can shorten the path of electron transfer, thus effectively boosting the electrochemical properties of the electrode material. Due to the coexistence of rich sulfur vacancies and rGO, the r-FeNi2S4-rGO electrode exhibits an excellent specific capacitance of 746.8 C g(-1) at 1 A g(-1). Moreover, an asymmetric supercapacitor assembled with r-FeNi2S4-rGO and active carbon (r-FeNi2S4-rGO//AC) shows an outstanding energy density of 43.4 W h kg(-1) at 800 W kg(-1) and cycling performance with 87.1% capacity retention at 4 A g(-1) after 1000 cycles, making it an excellent electrode material for supercapacitors. This study offers an effective strategy for the design and optimization of spinel-type sulfide electrode materials.

Automated summary

The FeNi2S4 electrode material with rich sulfur vacancies based on reduced graphene oxide (rGO) was prepared by a solvothermal method and reduced with NaBH4. The material showed enhanced electrochemical properties, with an excellent specific capacitance of 746.8 C g(-1) at 1 A g(-1), making it a promising electrode material for supercapacitors.