Oxygen-deficient cobalt vanadium oxide nano-planted mesoporous carbon nanofibers for ultrafast lithium-ion capacitors

Lithium-ion capacitors (LICs) are promising energy storage devices that combine the advantages of their constituent electrodes (battery-type anode + capacitor-type cathode) but require performance optimization (e.g., enhancement of rate capability and energy density retention upon high-rate charge/discharge) to satisfy the demands of commercial applications. Herein, one-pot-induced defective structures are introduced on oxygendeficient cobalt vanadium (CVO) nano-planted mesoporous carbon nanofibers (CVO-PCNFs) as the batterytype anodes of LICs. The CVO nano-planted CNF construction involves CVO nanoparticles-embedded CNF framework with robust chemical linkages, which promote enhanced Li-ion storage and electrochemically reversible Li-ion transport. The defective structures include the simultaneous generation of oxygen vacancies in the CVO crystals and mesopores in the CNFs, which accelerate both Li-ion and electron transport kinetics at ultrafast-rate charge/discharge conditions. As a consequence of the synergistic effects, the battery-type anode fabricated using CVO-PCNFs as the active material exhibited a notable enhancement in discharge capacity (636.6 mAh/g), cyclic stability (capacity retention of 97.9 % after 100 cycles at 100 mA/g), and ultrafast rate capability (capacity retention of 89.5 % after 500 cycles at 2000 mA/g). Furthermore, the LIC full cell fabricated with a CVO-PCNF anode and an activated carbon cathode demonstrated a noteworthy ultrafast rate capability of 9.03 Wh/kg at a power density of 7927.3 W/kg.