Carbon hollow fibers with tunable hierarchical structure as self-standing supercapacitor electrode

Hollow porous carbon fibers (HPCF) have shown great promise as electrode materials for high-performance supercapacitor due to its light weight and short ion diffusion pathway. However, it remains a challenge to prepare self-standing HPCF with abundant active sites and robust secondary structure via facile processing methods. We have fabricated a HPCF with hierarchical pores by a wet-spinning integrated with chemical foaming strategy and subsequent carbonization-activation. The unique cellular structure combined with hierarchical meso-/micro-pores in HPCF allows exposure of abundant active sites. Especially, interconnected macro-pores facilitates the permeability of liquid electrolyte and mesopores promotes the rate of ions transport. The effect of blowing agents (isocyanate) content on the microstructures and electrochemical properties of HPCF were investigated. The HPCF-10 as self-standing electrode delivered a large specific capacitance as high as 283F/g at 1 A/g and long-term cycle stability (100% capacitance retention after 10,000 cycles). The Mn3O4 doped electrode had a pseudocapacitive behavior and showed an improved specific capacitance of 353F/g at 1A/g. The assembled asymmetric supercapacitor displayed an energy density of 17.8 Wh/kg and power density of 2.5 kW/kg. In addition, it displayed an excellent retention of 90.5% after 10,000 cycles. HPCF-based supercapacitors allow great promises for energy storage devices.