Nitrogen/sulphur dual-doped hierarchical carbonaceous fibers boosting potassium-ion storage

The carbon materials as anode electrodes have been widely studied for potassium ion batteries (PIBs). However, the large size of potassium ions prevents their intercalation/deintercalation, resulting in poor storage behaviors. Herein, a novel design of N/S codoped hierarchical carbonaceous fibers (NSHCF) formed from nanosheets self-assembled by catalyzing Aspergillus niger with Sn is reported. The asprepared NSHCF at 600 degrees C (NSHCF-600) exhibits a high reversible capacity of 345.4 mAh g(-1) at 0.1 A g(-1) after 100 cycles and an excellent rate performance of 124.5 mAh g(-1) at 2 A g(-1). The excellent potassium storage performance can be ascribed to the N/S dual-doping, which enlarges interlayer spacing (0.404 nm) and introduces more defects. The larger interlayer spacing and higher pyridinic N active sites can promote K ions diffusion and storage. In addition, the ex situ transmission electron microscopy reveals the high reversibility of potassiation/depotassiation process and structural stability. (C) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.