N, S co-doped branched carbon nanotubes with hierarchical porous structure and electron/ion transfer pathways for supercapacitors and lithium-ion batteries

Abstract

Rational design of the pore structure and surface heteroatoms modification of the carbonaceous-based electrodes is essential for high performance energy storage. Herein, a N, S co-doped porous carbon nanotubes with hierarchically hollowed and trunk-branched nanotube structure based on polypyrrole was fabricated via simple soft template polymerization and activation. The 3D interconnected structure with uniformly distributed active sites can form intimate contact interface and interconnected channels, thus facilitate the electron transfer and electrolyte infiltration. Therefore, the N, S co-doped branched carbon reveals a large specific capacitance (420.6 F g−1 at 0.5 A g−1), good rate capability (287.2 F g−1 at 30 A g−1) and superior cyclic stability (99.32% capacitance retained after 12000 cycles) in supercapacitor. Moreover, this N, S co-doped branched carbon nanotubes also exhibits a high specific capacity (905 mAh g−1 at 0.1 A g−1) and rate capability (461 mAh g−1 at 12.8 A g−1) as LIBs anode. Additionally, full LIBs battery configured by aNSC-2.5//LiFePO4 can achieve an energy density of 2112 W h kg−1anode (424 W h kg−1cathode). This simple, well-controlled and easy-scalable porous carbon fabrication strategy can be applied in the many practical fields.