Thiourea-Induced N/S Dual-Doped Hierarchical Porous Carbon Nanofibers for High-Performance Lithium-Ion Capacitors

Developing advanced carbon nanomaterials with reasonable pore distribution and interconnection and matching the charge-storage capacities and electrode kinetics between the capacitive electrode and the battery-type electrode are two of the biggest challenges in lithium-ion capacitors (LICs). In this work, a sustainable strategy to fabricate N/S dual-doped hierarchical porous carbon nanofibers (N/S-CNF) is developed via electrospinning and thiourea treatment, and the N/S-CNF is employed as both the capacitor-type cathode and the battery-type anode for LICs. With rational design, N/S-CNF can not only offer a large specific surface area with a hierarchical pore structure but also be uniformly doped with heteroatoms, which is desirable for improving the electrochemical performance of both the cathode and the anode for LICs and alleviating the mismatch between the two electrodes. LICs assembled with the designed N/S-CNF electrodes can deliver a high energy density of 154 Wh kg–1 with a stable capacitance retention of 92% after 6000 cycles. Our work is expected to open up new avenues for developing heteroatom-doped porous carbon nanomaterials applied in other energy conversion and storage devices.