posted on 2024-01-16, 20:02authored byYing Wang, Hongguan Li, Boyin Zhai, Xinglong Li, Ping Niu, Jérémy Odent, Shulan Wang, Li Li
Carbon nitrides with layered structures and scalable
syntheses
have emerged as potential anode choices for the commercialization
of sodium-ion batteries. However, the low crystallinity of materials
synthesized through traditional thermal condensation leads to insufficient
conductivity and poor cycling stability, which significantly hamper
their practical applications. Herein, a facile salt-covering method
was proposed for the synthesis of highly ordered crystalline C3N4-based all-carbon nanocomposites. The sealing
environment created by this strategy leads to the formation of poly(heptazine
imide) (PHI), the crystalline phase of C3N4,
with extended π-conjugation and a fully condensed nanosheet
structure. Meanwhile, theoretical calculations reveal the high crystallinity
of C3N4 significantly reduces the energy barrier
for electron transition and enables the generation of efficient charge
transfer channels at the heterogeneous interface between carbon and
C3N4. Accordingly, such nanocomposites present
ultrastable cycling performances over 5000 cycles, with a high reversible
capacity of 245.1 mAh g–1 at 2 A g–1 delivered. More importantly, they also exhibit an outstanding low-temperature
capacity of 196.6 mAh g–1 at −20 °C.
This work offers opportunities for the energy storage use of C3N4 and provides some clues for developing long-life
and high-capacity anodes operated under extreme conditions.