(Digital Presentation) Self-Discharge Study of Carbon-Based Supercapacitors with Tunable Pore Size

Abstract

Electrochemical double-layer capacitors (EDLCs), as a major type of energy storage devices besides rechargeable batteries such as lithium-ion batteries, holds excellent properties such as high power density and ultra-long cycling stability[1-3]; however, its fast self-discharge process has become the major issue that impedes its development and application. Even though research on EDLCs’ self-discharge has demonstrated that the fast self-discharge rate can be tuned even repressed through modifying certain structural properties of electrodes or electrolytes[4-9], to the end of realizing full control over the self-discharge process requires unveiling the fundamental relation between structural parameters (i.e., the pore structure, the surface functionalities, the electrolytic ion size and shape, and etc.) and the self-discharge performance.Carbon, due to its superior chemical stability, high surface area, natural abundance, etc.[4,10], has become one of the main types of electrode materials under extensive research interest for developing advanced EDLCs. Herein, we focus on tuning the pore size, one of the major structural properties of carbon materials relating to its electrochemical performance, to study its effects on self-discharge process and to learn how to construct the optimal pore structure with respect to certain application requirements.In this work, porous carbon materials with designed pore structure are prepared via soft-template method to analyse the self-discharge performance. Through investigating the effects of pore size, as the single variable, on the self-discharge process, as well as on the micro-electrochemical process on the electrode/electrolyte interface, underlying mechanism between pore size and the self-discharge performance has been constructed. These findings should provide guidance on how to locate the optimal pore size for a chosen electrolyte and to realize control over self-discharge, which will serve as solid references for designing the next-generation EDLCs with high performance and controllable self-discharge rates. Reference [1] X. Chen, R. Paul, L. Dai, Natl. Sci. Rev., 2017, 4(3), 453-489.[2] G. Wang, L. Zhang, J. Zhang, Chem. Soc. Rev ., 2012, 41, 797-828.[3] Y. Liu, Y. Shen, L. Sun, J. Li, C. Liu, W. Ren, F. Li, L. Gao, J. Chen, F. Liu, Y. Sun, N. Tang, H. Cheng, Y. Du, Nat. Commun., 2016, 7, 10921.[4] Q. Zhang, C. Cai, J.W. Qin, B.Q. Wei, Nano Energy., 2014, 4, 14-22.[5] T. Tevi, H. Yaghoubi, J. Wang, A. Takshi, J. Power Sources., 2013, 241, 589-596.[6] L. Chen, H. Bai, Z. Huang, L. Li, Energy Environ. Sci., 2014, 7, 1750-1759.[7] G. Shul, D. Bélanger, Phys. Chem. Chem. Phys., 2016, 18, 19137-19145.[8] M. Xia, J. Nie, Z. Zhang, X. Lu, Z.L. Wang, Nano Energy., 2018, 47, 43-50.[9] J. Menzel, E. Frackowiak, K. Fic, Electrochimica Acta, 2020, 332, 135435.[10] D.P. Dubal, O. Ayyad, V. Ruiz, P. Gomez-Romero, Chem. Soc. Rev., 2015, 44, 1777–1790. Figure 1