Superior potassium storage in chitin-derived natural nitrogen-doped carbon nanofibers

Potassium ion batteries (KIBs) are drawing intensive attention as the next-generation energy storage technology, owning to their similar electrochemical properties to lithium system and rich abundance of potassium resources. The carbonaceous materials with low cost, nontoxicity and high safety have been considered as promising candidates for KIBs anodes. However, they still suffer from several problems, such as poor cycling and rate capability, complex activation process steps and multiple procedures to import heteroatoms doping. Herein, the N-doped carbon nanofibers (NCFs) are fabricated by direct pyrolysis of bio-waste chitin, which is the second most abundant biopolymer throughout nature. The as-prepared NCFs used as KIBs anodes, without any additional activation steps, are systematically investigated for the first time. They deliver high capacity, excellent rate capability and long-term cycling stability, which benefit from the multiple synergistic effects of suitable interlayer spacing, heteroatom doping and unique one dimensional mesoporous structure. With the spotlight of environmental friendliness, low cost and high energy density in energy storage field, the chitin-based NCFs demonstrate great potential for future low-cost energy storage applications.