Core–shell mesoporous carbon@FeS2 nanocubes for advanced quasi-solid-state symmetric and asymmetric configurations

Abstract

Mesoporous carbon (MC) is highly regarded for energy storage applications due to its large surface area and well-defined pore structure. However, its low electrical conductivity and limited mechanical flexibility restrict its utility in flexible devices. This study introduces a novel FeS₂@MC composite architecture to address these challenges. FeS₂ acts as a mechanically robust and electrically conductive substrate, significantly enhancing the performance of MC coatings. The FeS₂@MC composite exhibits excellent electrical conductivity and mechanical flexibility, overcoming the limitations of pristine MC. Electrochemical testing reveals that in a quasi-solid-state symmetric supercapacitor (QSSS), the FeS₂@MC delivers a specific capacitance significantly higher than FeS₂ alone. It achieves an energy density of 43.6 Wh kg⁻¹ at a power density of 699 W kg⁻¹ and a current density of 1 A g⁻¹, with a cycling stability of over 81% retention after 5000 cycles. Furthermore, a quasi-solid-state asymmetric supercapacitor (QSSA) is constructed using FeS₂@MC as the positive electrode and activated carbon (AC) as the negative electrode. This device exhibits an impressive energy density of 68.3 Wh kg⁻¹ at a power density of 753 W kg⁻¹. This study demonstrates the potential of FeS₂@MC composites to advance flexible energy storage systems by leveraging the complementary properties of FeS₂ and MC. The innovative design delivers superior electrochemical performance, enhanced flexibility, and long-term stability, paving the way for efficient and reliable flexible supercapacitors.