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 pi-fused polyimide (the as-formed carbon named as pi-polyimide-based carbon, pi-PC) or conjugation-interrupted polyimide (the as-resulted carbon named as polyimide-based carbon, PC). pi-PC possesses total 14.6wt.% N-doping while PC only has 4.9wt.% N-doping. pi-PC and PC have been characterized as anodic materials in Li+ ions batteries. At 100mA g(-1), the capacity of pi-PC electrode kept at 796.9 mAh g(-1) by the initial repeatable cycle and maintained 692.2 mAh g(-1) by the 11(th) cycle, which were approximate to 1.5 times higher than the corresponding capacity value of 533.5 mAh g(-1) and 447.8 mAh g(-1) for PC. The capacity of pi-PC electrode kept 712.7 mAh g(-1) after 188 cycles at 200mA g(-1). At 1.6A g(-1), the capacity of pi-PC was 352.6 mAh g(-1), which is 1.79 times larger than 196.4 mAh g(-1) of PC. This work highlights that the pi-fused polyimide could be an useful carbon source for high-level N-doped carbonaceous materials for energy-related applications.