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Probing Charge Injection-Induced Structural Transition in Ionic Liquids Confined at the MoS2 Surface

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journal contribution
posted on 21.05.2021, 19:04 authored by Wei Chen, Yumiao Lu, Yanlei Wang, Feng Huo, Wei-Lu Ding, Li Wei, Hongyan He
The ability to tune structures and properties of interfacial ionic liquids (ILs) using electric fields lies at the heart of modern energy storage technologies, particularly for supercapacitors with ILs as electrolytes. Direct observation of the underlying structural change caused by charge injection is vitally important, but the data are extremely scarce. Here, we propose a general protocol to explore the dynamic structural response of interfacial ILs subjected to charge injection. The experimental results have revealed asymmetric structural evolution of interfacial ILs with a common feature of enhanced mobility during charge injection. Consequently, the surface ILs diffuse and agglomerate into various patterns, which depend critically on both the charge injection mode and initial structural feature. Slow and mild charge injection is advantageous in maintaining structural stability as well as regulating dielectric constants of interfacial ILs. Finally, we unveil the underlying energy conversion from electric energy to thermal energy that governs the structural evolution trend. Our current findings manifest a universal strategy for structural regulation of interfacial ILs via electric fields and open up opportunities for greatly accelerating charging efficiency of supercapacitors for energy storage and harvesting.