High performance Li-ion capacitor achieved by rational design of carbon cloth based intercalated anode and porous cathode

Developing energy storage devices with high energy and power density requires rigorously optimizing both the anode and cathode materials. This work presents a novel approach utilizing commercially available carbon cloth, composed of carbon fibers with a graphitic shell and an amorphous carbon core, as a free-standing electrode for lithium-ion capacitors (LICs). The aligned graphitic layers in the carbon fibers, combined with the three-dimensional structure of the free-standing electrode, reduce tortuosity and enhance power density. To further improve the ion transport kinetics, we employed a FeCl₃ pre-insertion strategy, expanding the graphite lattice in the outer shell of the carbon fibers and significantly improving the Li⁺ ion diffusion rate, leading to enhanced rate capability. The LICs were fabricated using FeCl₃ pre-inserted carbon cloth as a free-standing anode and a porous carbon cloth cathode derived from high-temperature activation. The device achieved an energy density of 5.2 mWh/cm³ (37.7 Wh/kg), surpassing that of commercial 3.6 V lithium-ion batteries (3.2 mWh/cm³), with a 6 mW/cm³ power density. Additionally, the LIC exhibited excellent cycling stability, retaining 86% of its initial capacitance after 10,000 charge-discharge cycles. This study demonstrates a promising strategy for fabricating high-performance, scalable energy storage devices by integrating material design with advanced electrode engineering.