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

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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 an 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 power density of 6 mW/cm3. 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 and scalable energy storage devices by integrating material design with advanced electrode engineering.