Mediating Gel Formation from Structurally Controlled Poly(ionic liquids): Towards Ionic Gel Electrolytes for Energy Storage

Abstract

Most sustainable energy sources (solar, hydropowered, geopowered, windpowered) rely on the production of electrical energy. In the last decade, Lithium ion based batteries have emerged as interesting candidates as high-density energy storage devices, enabling the developments of electrical vehicles of constantly growing autonomies. The synthesis of polymer electrolytes and the study of their electrochemical properties is currently a very active topic. Poly(ionic liquids) (PILs), in particular, constitute an increasingly sought-after category of materials, as they are expected to replace flammable, leakage-prone organic solvent electrolytes in future energy storage devices.[1,2] In this communication, we will present a novel synthetic methodology, which provides an easy access to a broad range of PILs from a common monomeric precursor (figure 1). Owing to this straightforward conceptual approach, it is possible to precisely control the structure of the polymeric materials. We will show how the introduction of an anionic functional group on the ATRP initiator is enough to mediate gel formation at low concentrations through electrostatic interactions (Figure 2).[3,4] We will then demonstrate that the incorporation of different additives along the polymer backbone helps optimizing ionogel properties in different electrolytic solvents to form gel electrolyte. Finally, we will illustrate the potential of the resulting gels as quasi-solid materials for energy storage applications through the study of different parameters: its rheological behaviour, electrochemical stability, diffusion and ionic conductivity properties. [1] Yoshizawa, M.; Ogihara, W.; Ohno, H. Polym. Adv. Technol. 2002, 13, 589-594. [2] Wang, P.; Zakeeruddin, S. M.; Moser, J. E.; Nazeeruddin, M. K.; Sekiguchi, T.; Gratzel, M. Nat Mater 2003, 2, 402-407. [3] Appukuttan, V. K.; Dupont, A.; Denis-Quanquin, S.; Andraud, C.; Monnereau, C. Polym. Chem. 2012, 3, 2723-2726. [4] Srour, H.; Ratel, O.; Leocmach, M.; Adams, E. A.; Denis-Quanquin, S.; Appukuttan, V.; Taberlet, N.; Manneville, S.; Majesté, J.-C.; Carrot, C.; Andraud, C.; Monnereau, C. Macromol. Rapid Commun. 2014, DOI: 10.1002/marc.201400478. Figure 1