The incorporation of KF-6017 and LiTFSI benefiting for constructing a transparent, highly conductive polydimethylsiloxane-based ionogel with high-ionic liquid content

The presence of well-conductive polydimethylsiloxane (PDMS)-based ionogel has changed the stereotype of PDMS of being an insulator, owing to continuous ionic liquid (IL) phase with superior ionic conductivity. However, the sacrifice on the transparency of ionogel often occurs if increasing IL content, and to overcome the immiscibility between nonpolar PDMS and polar IL is still regarded as a considerable challenge today. Herein a new strategy to prepare a transparent, highly conductive PDMS-based ionogel with high IL content is proposed, using a “composite” surfactant of KF-6017 and LiTFSI. Benefited from unique microphase separation during gel formation, the optimal ionogel of IG_{70%–1%–1%} can possess excellent transparency (>95%, ~200 μm) with IL content of 70%, while owning ionic conductivity of 3.28 mS/cm and tensile property of 100 kPa. A new mechanism on the conductivity of ionogel is proposed by the molecular simulation. The ionogel can be suitable for applying as electrolyte (B) and a polymer binder for active carbon powders (as electrode A). As a result, the assembled electrochemical double-layer capacitor (A/B/A) can be flexible accompanied with excellent electrochemical performance, which exhibits a promising future for flexible electronics and wearable devices.