Nitrogen-doped porous carbon with complicated architecture and superior K+ storage performance

Potassium-ion batteries are potential alternatives to lithium-ion batteries for large-scale energy storage attributed to the low cost and high abundance of potassium. However, the limited potassium-ion intercalation capacity of graphite represents the biggest challenge for PIBs. In this regard, nitrogen doped carbon hollow turbostratic tubes (CHTT-N) are synthesized via the amidation reaction and heat treatment process. Benefiting from their open framework, nitrogen doping, large surface area (efficient ion/electron diffusion), and enlarged interlayer spacing (stable ion insertion), the obtained CHTT-N exhibited an unprecedented long cycle life with high reversible capacity (397 mA h g−1 at 0.1 A g−1) as well as outstanding rate capability (212 mA h g−1 at 2 A g−1). The assembled CHTT-N//CHTT-N potassium-ion hybrid supercapacitor delivered a high energy density of 106 W h kg−1 at a power density of 284 W kg−1.