The construction of a new deep eutectic solvents system based on choline chloride and butanediol: The influence of the hydroxyl position of butanediol on the structure of deep eutectic solvent and supercapacitor performance

Abstract

The precise regulation of the deep eutectic solvents (DESs) system has an important influence on its structure, performance and application. In this work, choline chloride (ChCl) and three kinds of butanediols are used as hydrogen bond acceptors and donors, respectively. The research focuses on the influence of two hydroxyl positions in butanediols on the structure and properties of DES systems with various characterization techniques. The results show that the DES system composed of 1, 2-butanediol and ChCl (the distance of two hydroxyl group is closest) possesses the largest conductivity (1.26 mS cm−1) and the lowest viscosity (56.99 cP). Moreover, using ChCl and 1, 2-butanediol as the electrolyte, the corresponding voltage of activated carbon (AC) based supercapacitor can reach 2 V, the specific capacitance can reach 116 F g−1 and the highest energy density is 16.14 Wh kg−1. More importantly, this work uses the DFT model to design and verify the DES systems in detail, and then explain the mechanism of the influence of the hydroxyl position on the structure and electrochemical performance of the DES system from a theoretical perspective. Obviously, the DES systems having difference structures and DFT calculation proposed in this article provide a significant way and reference for in-depth understanding of DES electrolytes and applications.