ZnCl2 regulated flax-based porous carbon fibers for supercapacitors with good cycling stability

Abstract

Flax fibers, with abundant resources and a low cost, are an excellent precursor of carbon fibers for supercapacitors. At present, they are very attractive for designing electrodes with high electrochemical performance via a simple and green way. Hence, we systemically control the specific surface area and pore structure of flax-based carbon fibers by impregnating them with zinc chloride (ZnCl₂) solution. The results show that the dehydration and expansion effects of ZnCl₂ affect the microstructure, which is directly related to the specific capacitance. After activation, the optimized electrode exhibited the highest specific capacitance of 105 F g⁻¹ at a current density of 1 A g⁻¹, which has been improved by more than 10 times compared to that of pure-flax based carbon fibers. Moreover, they also show an excellent cycling stability of 98.7% after 10 000 cycles, even at a high current density of 10 A g⁻¹. These results further demonstrate that flax-based electrodes have potential to be applied to some relevant energy storage applications in the future.