Fabrication of N-doped carbon coated CoFeS2 anchored rGO nanosheet composites: a twin carbon design for Li-ion storage and high energy density supercapacitor applications

Abstract

The twin-carbon design represents an innovative strategy to tackle challenges such as insufficient electron/ion transport efficiency, significant volume changes, and various side reactions in various energy-related applications. The present work illustrates the fabrication of N-doped carbon-coated CoFeS₂ anchored rGO nanosheet composites for lithium-ion battery and supercapacitor applications. Due to the twin-carbon design, CoFeS₂@rGO/N–C achieves an impressive first charge/discharge capacity of 688.61/838.07 mA h g⁻¹ at 100 mA g⁻¹, with 82.16% coulombic efficiency. It preserves 82.54% of its initial capacity after 1000 cycles, outperforming both the CoFeS₂ and CoFeS₂@rGO materials. In supercapacitor tests, CoFeS₂@rGO/N–C demonstrates a specific capacity of 322 mA h g⁻¹ (1933 F g⁻¹) at 1 A g⁻¹, with a rate capability of 49% at 30 A g⁻¹. The CoFeS₂@rGO/N–C//activated carbon asymmetric device provides a specific capacity of 176.3 mA h g⁻¹ (352.7 F g⁻¹) at 1 A g⁻¹, along with 79.4 W h kg⁻¹ and 16.9 kW kg⁻¹ energy and power density values respectively. The asymmetric device shows only a 12% decline in initial capacity and maintains 88% cycling stability, with 97% coulombic efficiency after 10 000 continuous cycles at 10 A g⁻¹. Post-study analyses further confirm the high stability of the twin-carbon approach for the CoFeS₂@rGO/N–C composite. This research underscores a comprehensive understanding of the twin-carbon strategic design for developing superior electrodes in sustainable energy storage applications.