Rational design and in-situ construction of nanostructured Ni-Co compounds plasma-assisted on interconnected CNFs-rGO for an ultra-long cycle stability

Combining carbon materials with transition metal compounds is an effective strategy for preparing high-performance electrode materials. However, most currently used synthesis methods suffer from several drawbacks, such as the requirement of high temperatures and pressures, long synthesis times, and complex preparation steps. In this work, a simple and efficient assisted liquid-phase plasma electrolysis technique was employed to successfully fabricate a Ni-Co compounds with carbon nanofibers and reduced graphene oxide (NiCo/CNFs-rGO) composite, and the possible formation mechanism is also discussed. The NiCo/CNFs-rGO composite utilizes a hybrid three-dimensional carbon framework as a matrix, in which carbon nanofibers (CNFs) serve as the supporting skeleton to suppress the excessive restacking of reduced graphene oxide (rGO), while the rGO wrapping around the CNFs further enhances the structural stability, forming an interconnected and stable conductive framework. This framework provides continuous electron transport channels and good dispersion for the Ni-Co compounds, while the synergistic effect between NiCo-LDH and NiCo₂O₄ further improves the electrochemical performance. Specifically, the NiCo0.5/CNFs-rGO composite achieved a high specific capacitance of 2122.5 F/g at 1.0 A/g and retained 98.3% of its initial capacitance after 10,000 cycles. Additionally, the constructed asymmetric supercapacitor (ASC) maintained a capacitance retention rate of 95.2% even up to 40,000 cycles.