Enhanced Electrode Matching Assisted by In Situ Etching and Co-Doping toward High-Rate Dual-Carbon Lithium-Ion Capacitors

Lithium-ion capacitors (LICs) have emerged as prospective energy storage devices, which combine the high energy density of lithium-ion batteries and high power density, as well as the long lifespan of supercapacitors. However, the mismatch between the battery-type anode and the capacitive cathode of LICs hinders the joint enhancement of energy density and power density. In this work, self-standing N, P co-doped carbon nanofiber (NPCNF) membranes synthesized through a sustainable strategy are adopted as both anode and cathode materials for dual-carbon LICs. With a rational design, NPCNF membranes simultaneously possess an interconnected network with hierarchical pores, high level of N and P co-doping (7.53 and 4.41 at. %), and expanded interlayer spacing. These advantageous features have afforded NPCNF electrodes enormous electroactive sites, enhanced electronic conductivity, and improved electrode kinetics, effectively alleviating the imbalance between the anode and the cathode. Dual-carbon LICs based on NPCNF electrodes deliver a high energy density of 143 Wh kg–1 and a high power density of 45 kW kg–1 (at 52 Wh kg–1) with capacitance retention of up to 83.1% after 10 000 cycles. This work illustrates the simultaneous manipulation of porosity and heteroatoms to boost the electrochemical performances of carbon-based electrodes and opens a new avenue to develop advanced carbon nanomaterials for energy storage and conversion applications.