Implementation of a choline bis(trifluoromethylsulfonyl)imide aqueous electrolyte for low temperature EDLCs enabled by a cosolvent  

作　　者：Zhuanpei Wang Francois Béguin 

机构地区：[1]Institute of Chemistry and Technical Electrochemistry,Poznan University of Technology,Berdychowo 4,60-965 Poznan,Poland

出　　处：《Journal of Energy Chemistry》2022年第7期84-94,I0004,共12页能源化学（英文版）

基　　金：financially supported by the National Science Centre(MAESTRO project UMO-2016/22/A/ST4/00092)。

摘　　要：We report a carbon/carbon capacitor based on micro/mesoporous carbon electrodes with cost-effective and eco-friendly aqueous choline bis(trifluoromethylsulfonyl)imide(Ch TFSI)electrolyte with a cosolvent enabling low-temperature operation down to-30℃.For this purpose,a Mg O-templated hierarchical carbon(MP98B)with an average mesopore diameter of 3.5 nm was prepared by pyrolysis of magnesium citrate hydrate at 900℃.To reach lower temperatures,the melting point and viscosity of the aqueous electrolyte were reduced by mixing water(W)with an organic solvent(methanol,M,or isopropanol,I)of high dielectric constant and low viscosity.5 mol kg^(-1)(5 m)Ch TFSI in an optimized volume fraction of cosolvent,M_(0.75)W_(0.25),and I_(0.75)W_(0.25),showed the highest conductivity;the higher conductivity in M_(0.75)W_(0.25)(22.8 and 3.1 m S cm^(-1) at 20 and-30℃,respectively)than in I_(0.75)W_(0.25)(8.5 and0.5 m S cm^(-1)at 20 and-30℃,respectively)is attributed to the lower viscosity of the M_(0.75)W_(0.25)solution.The electrochemical stability window(ESW)of 5 m Ch TFSI in M_(0.75)W_(0.25)and I_(0.75)W_(0.25)(1.6 V)on an MP98B electrode was determined by applying the S-method.Meanwhile,by adjusting the mass ratio of the two electrodes,a MP98B/MP98B capacitor using the 5 m electrolyte in M_(0.75)W_(0.25)could operate with a good life span up to 1.6 V while exhibiting a better charge propagation,greater specific capacitance,and higher specific energy than in I_(0.75)W_(0.25).

关 键 词：Carbon/carbon capacitor Choline bis(trifluoromethylsulfonyl)imide Low-temperature Aqueous electrolyte Cosolvent electrolyte Methanol ISOPROPANOL 

分 类 号：O646.1[理学—物理化学] TM53[理学—化学]