Recently, carbon nitrides and their carbon-based derivatives
have
been widely studied as anode materials of lithium-ion batteries due
to their graphite-like structure and abundant nitrogen active sites.
In this paper, a layered carbon nitride material C3N3 consisting of triazine rings with an ultrahigh theoretical
specific capacity was designed and synthesized by an innovative method
based on Fe powder-catalyzed carbon–carbon coupling polymerization
of cyanuric chloride at 260 °C, with reference to the Ullmann
reaction. The structural characterizations indicated that the as-synthesized
material had a C/N ratio close to 1:1 and a layered structure and
only contained one type of nitrogen, suggesting the successful synthesis
of C3N3. When used as a lithium-ion battery
anode, the C3N3 material showed a high reversible
specific capacity up to 842.39 mAh g–1 at 0.1 A
g–1, good rate capability, and excellent cycling
stability attributed to abundant pyridine nitrogen active sites, large
specific surface area, and good structure stability. Ex situ XPS results
indicated that Li+ storage relies on the reversible transformation
of −C=N– and −C–N– groups as well
as the formation of bridge-connected −C=C– bonds. To
further optimize the performance, the reaction temperature was further
increased to synthesize a series of C3N3 derivatives
for the enhanced specific surface area and conductivity. The resulting
derivative prepared at 550 °C showed the best electrochemical
performance, with an initial specific capacity close to 900 mAh g–1 at 0.1 A g–1 and good cycling stability
(94.3% capacity retention after 500 cycles at 1 A g–1). This work will undoubtedly inspire the further study of high-capacity
carbon nitride-based electrode materials for energy storage.