An efficient and stable coral-like CoFeS2 for wearable flexible all-solid-state asymmetric supercapacitor applications

Abstract

Exploring efficient and inexpensive materials for supercapacitors has become a research highlight. In this work, coral-like CoFeS₂ nanomaterials were synthesized by an organic solvothermal method and applied to supercapacitors. Due to their large specific surface area and unique coral structure, the CoFeS₂ electrode materials exhibited high specific capacity (1457.1 F g⁻¹ at 2 A g⁻¹) and rate performance in a 2M KOH aqueous electrolyte. An asymmetric CoFeS₂‖AC supercapacitor delivers a high energy density of 66.4 W h kg⁻¹ at a power density of 790 W kg⁻¹, and the retention rate of specific capacitance is 97.6% after 10 000 cycles at a current density of 10 A g⁻¹, showing good cycling stability. The electrode material of CoFeS₂ was assembled into a button battery that can light up an LED or turn on a motor fan. In order to evaluate the feasibility of wearable flexible asymmetric energy storage devices, flexible all-solid-state asymmetric supercapacitors were investigated, which showed a high energy density of 47.2 W h kg⁻¹ at a power density of 525 W kg⁻¹, and the retention rate of specific capacitance was 87.8% after 8000 cycles at a current density of 5 A g⁻¹. This study provides the possibility of applying them in future practical applications, and the synthesis strategy can be extended to synthesize other transition metal sulfide materials with excellent supercapacitor performance.