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Ionic liquids (ILs) or solidified ionic liquids, known as ionogels, have been actively employed in supercapacitors (SCs) owing to their superior electrochemical stabilities to aqueous and organic electrolytes. However, initial efforts of using ILs and ionogels in SCs were not successful because bulky and sluggish ions cannot effectively access tiny pores of conventional microporous carbons. To address this, a strategy is developed to optimize the electrochemically active surfaces of carbonaceous electrodes and thus to improve the energy storage performance by incorporating 3D ordered/interconnected large mesoporous carbons with ionogel electrolytes. Precisely designed large mesopores interconnected via windows promote mass transport of the electrolyte ions within the solid ionogel electrolytes and effectively utilize the surface of the carbon electrodes for capacitive energy storage, giving rise to record‐high energy storage performance that surpasses the upper bound of the Ragone plots of the current state‐of‐the‐art SCs. In addition, all‐solid‐state SCs with outstanding bending/folding durability are successfully demonstrated. Overall, these results provide critical insight into surface utilization of carbon electrodes as well as capacitive energy storage, when viscous and bulky ILs or ionogels are used as electrolytes. [ABSTRACT FROM AUTHOR]

Abstract Ionic liquid-based polymer electrolyte composites (PECs) with high mechanical strength and ionic conductivity were fabricated by using a semicrystalline homopolymer network. Morphological, mechanical, and electrical properties of semicrystalline homopolymer-based PECs were investigated over the composition range of 10–50 polymer wt%. The PECs consisted of poly(vinylidene fluoride) (PVDF) and a room-temperature ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]). The amorphous PVDF chains were solvated by the liquid electrolyte and interconnected the phase-separated PVDF crystalline-domains, acting as physical crosslinks. The ionic conductivity and specific capacitance of the homopolymer PECs were found to be very high, ranging from 0.4 to 4.9 mS/cm and from 2.6 to 9.1 μF/cm2, respectively. The elastic moduli of the PECs that range from 4 to 38 MPa were also greater than those of PECs prepared by using other polymeric networks. These PECs were successfully applied as electrolyte membranes in electrical double layer supercapacitors and as high-capacitance gate insulators in electrochemical thin-film transistors. These results provide detailed systematic data for fabricating high-performance solid polymer electrolytes for electrochemical thin-film devices. Graphical abstract Image 1 Highlights • Polymer electrolyte composites with both high mechanical strength and ionic conductivity. • Polymer electrolytes as a high-capacitance gate insulator in thin-film transistors. • Low voltage operation (<1 V) of P3HT transistors at high polymer fraction. • Polymer electrolytes as an electrolyte membrane in electric double layer supercapacitors. [ABSTRACT FROM AUTHOR]

Polymer electrolyte composites (PECs) with ionic liquids (ILs), which are also known as ion gels, are fabricated using random copolymers with crystallizable side chain architecture, and the effects of the side chain interactions that establish the physically crosslinked network structure in the PECs are studied. The free radical copolymerization of docosyl acrylates (A22) and tert -butyl acrylates (t BA) leads to the synthesis of poly(tert -butyl acrylate- r -docosyl acrylate) [poly(t BA- r -A22)] copolymers with a random sequence distribution. The previous studies on semicrystalline copolymer/IL composites have mostly focused on a limited composition range. The poly(t BA- r -A22) random copolymers over a wider range of compositions readily form mechanically tough and ionically conductive PECs upon incorporation of small amounts of IL (approximately 20 wt%). Thin-film transistors with these PECs as an electrolyte gate dielectric exhibit comparable performance to previously reported transistors using PECs with high IL loading. The composition dependence of the side chain crystallization behavior of the random copolymers and the PECs, markedly distinct from that of main chain crystallization, provides a simple and versatile means to design and tune the electrolyte properties for various device applications. Image 1 • Polymer electrolyte composite comprising semicrystalline copolymers and ionic liquids. • Network formation by random copolymers with crystallizable side chain architecture. • Mechanically tough and ionically conductive electrolyte composite. • Mechanical and electrical properties adjusted by crystallization behavior. • Thin film transistors with polymer electrolyte composites as gate dielectrics. [ABSTRACT FROM AUTHOR]