Engineering FeSe2 encapsulated within carboxymethylcellulose-derived porous carbon for enhanced surface reaction kinetics in Li-ion half/full battery anodes

Abstract

Encapsulation of transitional metal selenides within the porous nanocarbon network has been regarded as a highly advantageous strategy for improving anode performance in terms of capacity, cycle-to-cycle stability, and operational durability for Li+ storage. Herein, a mildly sol-gel process and in-situ self-transformation strategy were employed to fabricate FeSe2 encapsulated within eco-friendly carboxymethylcellulose (CMC)-derived porous carbon, achieving a feasible capacity and relatively durable structure. The FeSe2@PC anode with square-built Li+/e− diffusion pathway exhibits a comparatively high reversible capacity of up to 758 mAh g−1 at 0.1 A g−1 and relatively good cycling stability, with a capacity retention of 83% after 500 cycles at 1 A g−1 in half cells. Furthermore, FeSe2@PC//LiMn2O4 full cells also demonstrate relatively outstanding electrochemical performance when paired with a LiMn2O4 cathode. The nanoconfinement electrode configuration, featuring interconnected external/internal carbon shell/FeSe2 nanoparticles, not only provides good electrical conductivity and buffering capacity for volume changes but also facilitates electrolyte infiltration and surface/near-surface interactions between electroactive FeSe2 and Li+. Kinetic analysis through cyclic voltammetry, galvanostatic intermittent titration technique, and electrochemical impedance spectroscopy indicates exceptional Li+/e− transport kinetics. Employing green and eco-friendly materials in energy storage is crucial for advancing sustainable energy technologies, and the engineered FeSe2@PC nanocomposite demonstrated in this study offers promising potential towards this objective.