N-Doped Carbon Nanonecklaces as a Potassium-Ion Battery Anode

Potassium-ion batteries (PIBs) have gained tremendous attention to compete with lithium-ion batteries (LIBs), especially for storing energy on a large scale, due to their dominance in the geographical distribution of K resources and similar energy storage mechanisms. Herein, using an electrospinning method, we synthesized a unique material of carbon nanonecklaces with a high content of N-doping (N-CNN). The N-CNN-700 anode (N-CNN annealed at 700 °C) shows outstanding durability in PIBs, delivering 173 mAh g–1 after 1000 cycles at 1 A g–1. The unique characteristics of ultrahigh pyrrolic/pyridinic-N doping and hollow necklace-like structures account for excellent performance, which can enable fast electrolyte diffusion, increase active sites for K+ insertion, and enhance K+ adsorption ability. This object demonstrates a clever strategy to design a structure for improved energy storage technologies.