Phase Modulation and Electrochemical Behavior of Fe<sub>3</sub>Mo<sub>3</sub>C/Mo<sub>2</sub>C Composite Nanofibers as Supercapacitor Negative Electrodes
Shibo Wu, Ruiyang Hu, Yang Zhou, Jiahao He, Jingrui Cao, Müslüm Demir, Pianpian Ma
Abstract
The advancement of negative electrode materials is essential for enhancing the performance of supercapacitors. Fe–Mo-based bimetallic carbide presents significant potential as a supercapacitor negative electrode material. In this study, Fe 3 Mo 3 C/Mo 2 C composite nanofiber was synthesized using the electrospinning method followed by high-temperature carbonization. As-prepared composite nanofibers consist of two phases: Mo 2 C nanoparticles embedded within the nanofiber and a block-like dispersion of the Fe 3 Mo 3 C phase. The Mo 2 C-dominated Mo 2 C/Fe 3 Mo 3 C-900 electrode shows an optimal specific capacitance of 354.9 F g –1 at 1 A g –1, notably exceeding that of the Fe 3 Mo 3 C-dominated Fe 3 Mo 3 C/Mo 2 C-900 electrode (253.2 F g –1 ). This advancement can be ascribed to the enhanced textural characteristics and lower resistance. The assembled NiCo 2 O 4 //Mo 2 C/Fe 3 Mo 3 C-900 device yields an energy density of 54.6 Wh kg –1 when the power density is 850 W kg –1 . On the other hand, the NiCo 2 O 4 //Mo 2 C/Fe 3 Mo 3 C-900 ASC device retained 67% of its capacitance after 5000 charge–discharge cycles, underperforming that of the NiCo 2 O 4 //Fe 3 Mo 3 C/Mo 2 C-900 (78%). This suggests that composite nanofiber with Mo 2 C as the main phase exhibits superior specific capacitance, while the bimetallic carbide Fe 3 Mo 3 C presents higher conductivity, which further improves its electrochemical stability. In short, the as-designed Fe 3 Mo 3 C/Mo 2 C composite nanofibers present promising negative electrode features for energy storage applications.