High-Level Pyrrolic/Pyridinic N-Doped Carbon Nanoflakes from π-Fused Polyimide for Anodic Lithium Storage

Highly N-doped carbon materials occupy an important position as anodes in high-performance Li-ion batteries (LIBs). In this contribution, pyrolysed carbon flowers covered by nanoflakes with highly pyrrolic/pyridinic N-doping content (4.5/4.2 at.%) were prepared through the Ar-protected pyrolyzation of large π-fused polyimide (the as-formed carbon named as π-polyimide-based carbon, π-PC) or conjugation-interrupted polyimide (the as-resulted carbon named as polyimide-based carbon, PC). π-PC possesses total 14.6 wt.% N-doping while PC only has 4.9 wt.% N-doping. π-PC and PC have been characterized as anodic materials in Li⁺ions batteries. At 100 mA g^–1, the capacity of π-PC electrode kept at 796.9 mAh g^–1by the initial repeatable cycle and maintained 692.2 mAh g^–1by the 11^thcycle, which were ∼1.5 times higher than the corresponding capacity value of 533.5 mAh g^–1and 447.8 mAh g^–1for PC. The capacity of π-PC electrode kept 712.7 mAh g^–1after 188 cycles at 200 mA g^–1. At 1.6 A g^–1, the capacity of π-PC was 352.6 mAh g^–1, which is 1.79 times larger than 196.4 mAh g^–1of PC. This work highlights that the π-fused polyimide could be an useful carbon source for high-level N-doped carbonaceous materials for energy-related applications.