熔融盐法制备煤基多孔碳纳米片用于钠离子电池负极

低成本、高性能钠离子电池负极材料的开发是其走向商业化应用的关键。以富含芳香结构单元的煤液化固体残渣为碳源，结合KCl/CaCl₂熔融盐的结构导向作用，可控制备了二维多孔碳纳米片（carbon nanosheets， CTx），并探究其用于钠离子电池负极材料的电化学性能。研究发现，通过调控碳化温度可对煤基多孔碳纳米片的微观结构进行优化，在1000℃下制备的二维碳纳米片样品（CT1000）具有相对高的比表面积和丰富的缺陷结构。作为钠离子电池的负极材料，在0.1 A·g^-1 的电流密度下，其可逆比容量为221.4 mAh·g^-1，当电流密度增加至10 A·g^-1时，比容量可以保持在124.4 mAh·g^-1，倍率性能优异。此外，在1 A·g^-1 的电流密度下经2000次循环后，比容量保持率高达94.2%，展现出较大的应用潜力。

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℃ (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.