Hard/Soft Carbon with Tuned Porosity and Defect Via Coating ZIF-8 by Coal Tar Pitch for High-Performance Supercapacitor

Metal–organic framework (MOF)-derived porous carbon has attracted particular attention in the electrochemical energy storage field, of which the key is the design and preparation of electrode materials with adjustable porosity and defects for supercapacitors. Here, a novel strategy of coating ZIF-8 with coal tar pitch (CTP) is presented to tailor the porosity and defects of derived porous carbon, by which the inward contraction of ZIF-8 is prevented to enlarge the ultra-micropores, and the defects of ZIF-8-derived carbon are repaired to form a continuous conjugated network. The tradeoff between porosity and electrical conductivity endows this novel hard/soft carbon electrode with fast ion/electron diffusion, achieving high yet balanced capacitance and rate performance of a top-level specific area-normalized capacitance (40 μF cm⁻²) and a capacitance retention of 52.1% at a 1000-fold increased current density. Meanwhile, the novel electrode realizes a high capacitance of 704 F g⁻¹ at 1 A g⁻¹ and capacitance retention of 91.9% after 50000 cycles in KOH + PPD electrolyte. This study provides an effective approach to designing novel hard/soft carbon with tuned porosity and carbon defects from MOFs and CTP for supercapacitors and other metal-ion batteries.