与传统的可充电化学电池相比,超级电容器(Supercapacitors)具有更高的比功率和更长的循环寿命,近年来在电动汽车和其它大功率设备应用方面得到广泛应用.对于应用非水有机电解液的超级电容器,虽可获得更高的比能量,但由于电解液中有机溶剂在高温下易挥发或降解,过充时易燃易爆,
Electrochemical double layer capacitors(EDLCs) composed of various carbon electrodes with different pore sizes and surface areas[carbon nanotubes,mesoporous activated carbons(MEACs) and microporous activated carbons] and ionic liquids based on lithium bis(trifluoromethane sulfone)imide(LiTFSI) with 2-oxazolidinone(OZO) as the electrolyte were studied.Electrochemical performances were evaluated with quantum chemistry calculations,cyclic voltammetry and galvanostatic charge-discharge tests.The LiTFSI-OZO system exhibits superior physicochemical properties,such as a wide liquid-phase range and high ionic conductivity.The configurations of ions("free" ions,contact ion pairs and aggregates) in the electrolyte and their interactions have an important influence on the electrochemical performance of the LiTFSI-OZO system.The EDLCs containing MEACs,which have the largest surface area and most compatible pore size of the carbon materials,possesses the highest specific capacitance of 184.6 F/g.This work shows that it is necessary to closely match the pore sizes of electrode materials with the ion sizes of the electrolyte system to optimize the performance of novel room temperature ionic liquids.