Preparation of coal-based porous carbon nanosheets by molten salt strategy as anodes for sodium-ion batteries

The development of low-cost anodes with high charge-storage performance for sodium-ion batteries is the key to its commercialization. Herein, two-dimensional porous carbon nanosheets (CTx) were controllably prepared using coal liquefaction residue with rich aromatic frameworks as carbon precursors by taking advantage of KCl/CaCl2 molten salt, and their electrochemical performance as the anodes for sodium-ion batteries was further explored. It was found that the microstructure of coal-based CTx could be optimized by regulating the carbonization temperature, and the as-obtained sample at 1000°C (CT1000) exhibits a high specific surface area and abundant defect structure. Therefore, a high reversible specific capacity of 221.4 mAh·g−1 was achieved at a current density of 0.1 A·g−1 as the anodes for sodium-ion batteries, and the specific capacity could be maintained at 124.4 mAh·g−1 when the current density was increased to 10 A·g−1, demonstrating excellent rate performance. Furthermore, the CT1000 electrode delivers good cycling stability with a specific capacity retention of 94.2% after 2000 cycles at a current density of 1 A·g−1. © 2022 Chemical Industry Press. All rights reserved.