Kinetically accelerated and high-mass loaded lithium storage enabled by atomic iron embedded carbon nanofibers

Carbonaceous materials represent the dominant choice of materials for anodic lithium storage in many energy storage devices. Nevertheless, the nonpolar carbonaceous materials offer weak adsorption toward Li⁺ that largely denies the high-rate Li⁺ storage. Herein, the atomic Fe sites decorated carbon nanofibers (AICNFs) facilely produced by electrospinning are reported for kinetically accelerated Li⁺ storage. Theoretical calculation reveals that the atomic Fe sites possess coordination unsaturated electronic configuration, enabling suitable bonding energy and facilitated diffusion path of Li⁺. As a result, the optimal structure displays a high capacitive contribution up to 95.9% at a scan rate of 2.0 mV·s⁻¹. In addition, ultrahigh capacity retention of 97% is afforded after 5,000 cycles at a current density of 3 A·g⁻¹. Moreover, the interlaced fiber structure enabled by electrospinning benefits structural stability and improved conductivity even at thick electrodes, thus allowing a high areal capacity of 1.76 mAh·cm⁻² at a loading of 8 mg·cm⁻². Because of these structure and performance merits, the lithium-ion capacitor containing the AICNF-based anode delivers a high energy density and large power density.