Tailoring 3D Carbon Nanofiber Architectures for Enhanced Li+/PF6− Storage in Dual-Carbon Electrodes of High-Performance Lithium-Ion Capacitors

Lithium-ion capacitors (LICs) are promising energy storage devices that combine the high energy density of lithium-ion batteries and the outstanding power density of supercapacitors. In this study, a dual-carbon LIC utilizing etched vertical graphene-grown carbon nanofibers (eVG@CNFs) as anode and etched hollow carbon nanofibers (ehCNFs) as cathode was presented. The eVG@CNFs feature mesoporous surfaces integrated with vertically aligned graphene sheets, enabling efficient Li + insertion, diffusion, and adsorption for excellent capacity and rate performance. The ehCNFs, derived by carbonization of polymeric core–shell nanofibers, possess hollow nanochannels and an ultrahigh specific surface area of 2884.4 m 2 g −1 with favorable porosity for PF 6 ⁻ adsorption. The eVG@CNF//ehCNF LIC operates over a wide operating voltage of 0.8–4.0 V and delivers a specific cell capacity of 47.9 mAh g −1 at 30 A g −1 . The hybrid dual-carbon LIC achieves a maximum energy density of 268.5 Wh kg −1 and maintains 115.0 Wh kg −1 even at an ultrahigh power density of 72 kW kg −1 . Moreover, it shows great cycling stability, retaining over 84.4% capacitance after 12000 charge–discharge cycles. This work highlights the potential of tailored CNF architectures for high-performance energy storage applications.