Vinasse-based hard carbon: Preparation and study on its compatibility with ester/ether-based electrolyte for sodium ion storage

Abstract

In this work, a simple method was used to prepare vinasse based hard carbon (HC) for sodium ion storage. The interlayer spacing and closed pore structure of the materials were regulated by different pyrolysis temperature, and the electrochemical evaluations were conducted in ether-based and ester-based electrolytes, respectively. The initial coulombic efficiency (ICE) of 91.1 %, capacity retention rate of 63.1 % at high rate of 10 A g-1 (platform capacity of 121.7mAh g-1), and ultra-long cycle stability of 93.7 % after 8000 cycles at 5 A g-1 fully shows better compatibility in the ether-based electrolyte. The coordination number, de-solvation energy, and diffusion rate of Na+ in the two electrolytes were simulated and calculated by molecular dynamics (MD) combined with density functional theory (DFT). It was elucidated that Na+ partially co-embeds in ether-based electrolytes, avoiding slow de-solvation processes, in addition, when Na+ is embedded alone, it has a lower de-solvation free energy than that in ester-based electrolytes, therefore, the ion diffusion coefficient obtained in ether-based electrolytes is above three times than that in ester-based electrolytes. The ultrafast dynamics achievements excellent rate performance and cycling stability for the sample of optimal structure. This research has a promoting effect on the commercial application of biomass-based hard carbon for sodium ions storage.