Biomass‐Derived, Nitrogen‐Rich Carbon Tubes as Anodes for Sodium‐Ion Hybrid Capacitors

Sodium-ion hybrid capacitors (SIHCs) are considered a prospective alternative to lithium-ion batteries (LIBs) since there are rich and available sodium reserves. Here, nitrogen-doped carbon tubes (N-MJ) derived from metaplexis japonica fluff are prepared by using a facile method of etching and peeling the fluff with urea to prepare a Na+ storage anode. With prominent traits in terms of structure and a high nitrogen content (11.08 %), N-MJ exhibits exceptional Na+ storage performance with a high reversible capacity (390.9 mAh g−1 at 50 mA g−1) and excellent long-term circulation (208.1 mAh g−1 after 2650 cycles at 1 A g−1). Systemic kinetic analysis manifests that the extraordinary performance is responsible for the large-scale capacitance control. Furthermore, the SIHCs assembled by using N-MJ and activated carbon (AC) presents a maximum energy density of 111.4 Wh kg−1 (at 445.8 W kg−1) and power density of 2455.2 W kg−1 (at 34.1 Wh kg−1). Notably, the developed SIHCs maintain a 100 % capacity retention rate at 1 A g−1 after 5000 cycles. Overall, our work not only provides a good choice for storage Na+ anode materials, but also supplies a feasible method for the recycling of waste biomass.