MOF-derived anion exchange induced 2D/2D CF@CoS2/Co3O4/CNFs for ultra-long stable asymmetric supercapacitors

Co3O4 has received considerable attention as a supercapacitor electrode material with high Faraday activity and high theoretical capacity, but the low electrical conductivity and short cycle life have hampered their development. Herein, we designed a strategy to construct Co3O4 crystals with multidimensional hierarchical structure by anion-exchange method based on metal-organic framework (MOF). The MOF-derived carbon and nitrogen framework (CNF) can withstand the volume expansion during charging and discharging for its excellent structural stability. The introduction of sulfur ions modulates the electronic structure to achieve reversible Faraday reactions. The two-dimensional (2D) nanosheet arrays CF@CoS2/Co3O4/CNFs exhibit a significantly higher specific capacitance of 1380 F g(-1) at 1 A g(-1), which is more than a six-fold increase over pristine Co3O4 (215 F g(-1)). The capacity retention was 78.7% from 1 A g(-1) to 20 A g(-1), and the capacitive control contribution improves from 70% to 87% at 2 mV s(-1) to 20 mV s(-1). The asymmetric supercapacitor (ASC, CF@CoS2/Co3O4/CNFs//activated carbon (AC)) delivers an energy density of up to 38.4 Wh kg(-1) at 800 W kg(-1). ASC exhibits a capacity retention of 100.93% over 20,000 charge/discharge cycles.