Electric double-layer capacitors (EDLCs) based on porous activated carbon and ionic liquid electrolytes are highly promising for electrochemical energy storage due to their fast charge/discharge rates, excellent cycle stability, and wide voltage window. Understanding the energy storage mechanism in EDLCs, especially how the intrinsic structure of ionic liquids affects the capacitance of activated carbon, is essential for optimizing performance. By revealing these microscopic mechanisms, researchers can better select ionic liquids and design high-performance EDLCs.
Recently, a research team from the Clean Energy Chemistry and Materials Laboratory at the Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, made significant progress in studying the energy storage behavior of ionic liquids in EDLCs. They developed four types of nano-silica-grafted ionic liquids, enabling selective analysis of anions and cations during charge-discharge cycles. This approach allows for a more precise understanding of how each ion contributes to the overall capacitance.
The key feature of these silica-grafted ionic liquids is that one type of ion (either a cation like BMIM+ or NBu4+, or an anion like NTf2– or PF6–) is covalently bonded to silica nanoparticles, while the counter-ion remains free. The silica particles are about 7 nm in size, and since most pores in the activated carbon used are smaller than 4 nm, the grafted ions are blocked from entering. Only the free ions—such as BMIM+, NBu4+, NTf2–, or PF6–—can pass through the pores. This setup enables quantitative analysis of ion transport using simple electrochemical tests, such as cyclic voltammetry, where the current directly reflects the contribution of each ion to the capacitor’s capacity.
Using commercial activated carbon YP-50F as the electrode, the team characterized the contributions of different ions and their respective voltage windows. They also employed quartz crystal microbalance (EQCM) to further investigate the energy storage mechanism of YP-50F in BMIM-NTf2 ionic liquid. By analyzing the electrochemical behavior of both BMIM+ and NTf2–, they provided a deeper, hierarchical explanation of the energy storage process.
These findings were published in *Nature Communications* and supported by the National Natural Science Foundation of China and the Lanzhou Institute of Chemical Industry under its "1-3" key projects. The study opens new avenues for designing advanced EDLCs with improved performance and efficiency.
Air Pumps,Industry Air Pump,Fish Farming Air Pump,Large Output Air Pump
Sensen Group Co., Ltd.  , https://www.sunsunglobal.com