Sulfidation-induced ZIF-67 melting and remodeling to enhance its interfacial bonding with hollow carbon microtubes for improving capacitive performance

Abstract

A robust interfacial bonding between CoS₂ and porous carbon with hierarchical ion fast channels is crucial for fabricating capacitive materials with high stability and rate performance. Herein, a method for high-temperature sulfidation-induced ZIF-67 melting and remodeling at the surface of cotton-derived hollow tubular carbon fiber is employed to achieve the interfacial welding of porous carbon/CoS₂ with carbon fiber, thereby constructing a vascular-like scar-shaped CoS₂-C_C-C_KF. Through the in-situ reconfiguration of ZIF-67-derived carbon framework mediated by Co²⁺/2-MIM molar ratio, CoS₂-C_C-C_KF achieves the multiscale collaboration among the conductive network (cotton fiber-derived carbon, C_KF), the interface bridging layer (ZIF-67-derived carbon, C_C), and the active pseudocapacitive CoS₂ nanoparticles, forming an integrated ionic-electronic conductor hierarchical architecture. CoS₂-C_C-C_KF exhibits a low electron transfer impedance of 0.15 and a high ionic diffusion coefficient of 4.7 × 10⁻⁵ cm² s⁻¹ after calculation. CoS₂-C_C-C_KF exhibits a specific capacitance of 997.4 F g⁻¹ at a current density of 1 A g⁻¹, and it still maintains 81 % of its specific capacitance at 10 A g⁻¹, which is higher than that of CoS₂-C_A-C_KF (375.0 F g⁻¹, 69 %) and CoS₂-C_B-C_KF (638.0 F g⁻¹, 75 %). The assembled asymmetric supercapacitor achieves a high energy density of 47.4 Wh kg⁻¹ at 375.0 W kg⁻¹ and exhibits excellent cycle stability (maintaining 81 % capacity after 10,000 cycles). These results demonstrate that the melting reconstruction strategy of ZIF-67 on carbon substrate can enhance the interfacial bonding strength of porous carbon/ CoS₂, thereby improving their cycling stability in supercapacitors.