Based on the advantages of rapid charge-discharge, good cycle stability and wide operating voltage window, the electric double layer capacitor based on porous activated carbon material and ionic liquid electrolyte is a promising electrochemical energy storage device.Studies on the application of EDLC in ionic liquids The mechanism of energy storage, especially the mechanism of the influence of the intrinsic structure of anion and cation on the capacitance of porous activated carbon, reveals the mechanism of energy storage from the microscopic level, which has important guiding significance for the proper choice of ionic liquid and reasonable construction of high performance EDLC .
Recently, Yan Xingbin, a researcher at the Clean Energy Chemistry and Materials Laboratory of Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, made important progress in researching EDLC energy storage mechanism in ionic liquids. The researchers prepared four kinds of ionic liquids grafted with nano-silica, The purpose of analyzing the anions and cations is achieved by using only one ion of ionic liquid to freely enter and exit the pores of the activated carbon during charging and discharging.The results can provide a new strategy for studying the energy storage behavior of anion and cation in ionic liquids in EDLC .
Silica grafted ionic liquids are structurally characterized by the fact that one of the ions (cationic BMIMM ++, NBu4 + or anionic NTf2-, PF6-) is free; whereas the counterion with a counter-charged charge is trifluoromethanesulfonimide Anions (NTf-) and methylimidazolium cation (MIM +) were covalently attached to silica nanoparticles with a size of 7 nm.The pore diameter of most of the pores of the selected active carbon material for this study was less than 4 nm, The ions to the silica are trapped outside the pores of the activated charcoal and the free ions to be measured (cations BMIM +, NBu4 + or anions NTf2-, PF6-) can pass through the pores. On this basis, a simple electrochemical test Quantitative analysis of ions entering the channel, ie, the size of the cyclic voltammetry current, directly reflects the capacity of the ion contribution.
Based on the above method, the research team found that the commercially available activated carbon YP-50F can be used as the electrode to characterize the respective contribution of cation BMIM +, NBu4 +, and anion NTf2-, PF6- and the specific voltage window for each ion contribution capacity.Using quartz crystal microbalance (EQCM), the researchers further characterize the energy storage mechanism of activated carbon YP-50F in ionic liquid (BMIM-NTf2) and explain the energy storage mechanism in more depth by combining the electrochemical properties of BMIM + and NTf2-.
Relevant research results published in "Nature - Communications." This research has been funded by the National Natural Science Foundation of China and the Lanzhou Institute of Chemistry 's "Thirteen Five" key cultivation project.
