Regulating the Pore Structure and Heteroatom Doping of Hollow Carbon Fiber Based on a Trifunctional Template Method for High-Performance Lithium-Ion Capacitors

Poultry feather is an ideal carbon precursor for energy storage with natural fiber structure and abundant element doping. However, the collapse of the feather's natural structure and the loss of doped elements during high-temperature treatment limit the application of feather-based active carbon. Herein, Mg(NO3)2 is introduced as a trifunctional template for morphology supporting, pore creating, and element doping of duck feathers. MgO decomposed from Mg(NO3)2 can prevent the fiber from melting during carbonization, so as to form a hollow structure and etch mesopores on the surface, while NOx decomposed from Mg(NO3)2 will in situ dope the precursor. Benefitting from the hollow fiber structure and rich nitrogen and oxygen doping, feather-derived hierarchical porous carbon shows high specific capacity, excellent rate, and cycling performance as both cathode and anode. The fully assembled lithium-ion capacitor (LIC) can deliver integrated high energy density (160.6 W h kg–1 at 223.8 W kg–1) and high power density (39.7 kW kg–1 at 37.0 W h kg–1), as well as a superior lifespan of 8000 cycles at 2 A g–1. Our work provides an effective synthetic route of biomass-derived carbon materials for advanced LICs.