Aligned Ionogel Electrolytes for High‐Temperature Supercapacitors

Liu, Xinhua; Taiwo, Oluwadamilola O.; Yin, Chengyao; Ouyang, Mengzheng; Chowdhury, Ridwanur; Wang, Baofeng; Wang, Huizhi; Wu, Billy; Brandon, Nigel P.; Wang, Qigang; Cooper, Samuel J.

doi:10.1002/advs.201801337

Cited by 52 publications

(53 citation statements)

References 47 publications

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“…However, in addition to a reduction in the high frequency real axis intercept (typically associated with the ionic transport between the two electrodes), there is also a reduction in the width of a semicircle feature at intermediate frequencies. These semicircle features are often attributed to a variety of pseudo-capacitive processes taking place in the supercapacitor, which is in line with previous reports 37 but can also be more simply explained by considering a spatially distributed nature of capacitive surface in porous electrodes as reported by Eloot et al 38…”

Section: 15supporting

confidence: 87%

“All-in-Gel” design for supercapacitors towards solid-state energy devices with thermal and mechanical compliance

et al. 2019

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Section: 15supporting

confidence: 87%

“All-in-Gel” design for supercapacitors towards solid-state energy devices with thermal and mechanical compliance

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“…However, as shown in Figure e, the lowest ionic conductivity 0.1 S m −1 of A 15 D 0 –NaAc 1.6 is still higher than that of most nonliquid electrolytes . The hydration layer around NaAc crystals due to precipitation–dissolution equilibrium in Figure S9 in the Supporting Information provides an aligned ion migration channel along the needle‐like crystals, similar to the aligned pores structure within hydrogel electrolyte . The molecular structure of NaAc·3H 2 O comprises 3 moles of crystal water, which means plenty of free water will transform into crystal water during crystallization.…”

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confidence: 83%

Dissolution–Crystallization Transition within a Polymer Hydrogel for a Processable Ultratough Electrolyte

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to be faced. Therefore, it's necessary to develop a new nonliquid electrolyte with comprehensive performance for fulfilling various energy devices.Hydrogel electrolyte with hydrated salt crystal may be a new candidate to solve the above requirements by the introduction of new phase. The hydrated salt crystals, as one kind of industrial liquid-solid phase change materials, can be immobilized into hydrogel by the facile dissolution-crystallization transition. The demonstrated polymer gel electrolyte with NaAc·3H 2 O crystal as aligned porous template was designed by the in situ supersaturated crystallization of NaAc. [16,17] The introduction of inorganic crystal into polymer hydrogel can form the inorganic-organic composite with enhanced mechanical strength due to hydrogen bond or other synergistic effects. [18,19] The bound hydrated salt can suppress the electrochemical activity of water and broaden operating voltage of aqueous electrolyte [20] due to the strong interaction with water molecules, similar to the solvation sheath in "waterin-salt" electrolyte. [21][22][23] The high-concentrated salts within crystal-type gel can also efficiently reduce the freezing point and increase the boiling point of aqueous solutions. [24] At last, the hydrated salt crystal can endow gel electrolytes with thermalresistant performance through liquid-solid phase transition accompanied by endothermic and exothermic phenomena. [25,26] All in all, the crystal-type composite gel electrolyte can realize the comprehensive performance, including ultrahigh toughness, high operating voltage, extreme temperature tolerance, and good interfacial compatibility by a facile dissolution-crystallization transition approach.In this work, the pioneering crystal-type composite gel with excellent performance was prepared using a facile method that employed the crystallization of NaAc. There are only three main components in the precursor solution (Figure 1a,b): distilled water, abundant soluble salt, and a certain amount of monomer (or macromolecule). First, a high concentration of the salt solution was prepared by dissolving excessive soluble salt in the distilled water at high temperature. Then, the hydrogel was formed by UV irradiation for monomer solution (Figure 1c). Finally, the supersaturated salt within hydrogel was initiated to crystallize by placing a small crystal particle as seed on the surface of the hydrogel, and soon the crystal-type composite gel with extensive soluble salt crystals was obtained (Figure 1d). Typically, the crystal-type composite gel containing 15 wt% acrylamide (AAm) monomer and a certain quality of

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“…With the same electrodes covering both sides of the gel electrolyte, the device with anisotropic structure presented improved ionic conductivity and enhanced specific capacitance at high current in comparison to the isotropic, nonaligned gel. With aligned architecture, the supercapacitor energy loss was significantly reduced . Notably, the electrochemical performance with aligned structure was comparable to that of a pure electrolyte device.…”

Section: Introductionmentioning

confidence: 86%

“…Currently, anisotropic hydrogels are mainly synthesized through directional stimuli, including mechanical forces, magnetic field, electric fields, directional freezing, and directional ion diffusion . Particularly, the directional‐freezing, or ice‐templating, is a promising and versatile approach to create well‐defined aligned porous channels along the freezing direction . In this process, the hydrogel precursor solution is frozen along a directional temperature gradient .…”

Section: Introductionmentioning

confidence: 99%

“…Considerable fundamental studies have investigated anisotropic hydrogel structures serving for supercapacitor electrolytes. The Wang group fabricated aligned poly(ethylene glycol) monomethacrylate ionogel, poly( N , N ‐dimethylacrylamide) (PDMAA) ionogel, and polyacrylamide (PAAm) gel as gel electrolytes through directional freezing. With the same electrodes covering both sides of the gel electrolyte, the device with anisotropic structure presented improved ionic conductivity and enhanced specific capacitance at high current in comparison to the isotropic, nonaligned gel.…”

Section: Introductionmentioning

confidence: 99%

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Wood‐Inspired Morphologically Tunable Aligned Hydrogel for High‐Performance Flexible All‐Solid‐State Supercapacitors

Zhao

Alsaid

Yao

et al. 2020

Adv Funct Materials

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Oriented microstructures are widely found in various biological systems for multiple functions. Such anisotropic structures provide low tortuosity and sufficient surface area, desirable for the design of high‐performance energy storage devices. Despite significant efforts to develop supercapacitors with aligned morphology, challenges remain due to the predefined pore sizes, limited mechanical flexibility, and low mass loading. Herein, a wood‐inspired flexible all‐solid‐state hydrogel supercapacitor is demonstrated by morphologically tuning the aligned hydrogel matrix toward high electrode‐materials loading and high areal capacitance. The highly aligned matrix exhibits broad morphological tunability (47–12 µm), mechanical flexibility (0°–180° bending), and uniform polypyrrole loading up to 7 mm thick matrix. After being assembled into a solid‐state supercapacitor, the areal capacitance reaches 831 mF cm−2 for the 12 µm matrix, which is 259% times of the 47 µm matrix and 403% times of nonaligned matrix. The supercapacitor also exhibits a high energy density of 73.8 µWh cm−2, power density of 4960 µW cm−2, capacitance retention of 86.5% after 1000 cycles, and bending stability of 95% after 5000 cycles. The principle to structurally design the oriented matrices for high electrode material loading opens up the possibility for advanced energy storage applications.

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Aligned Ionogel Electrolytes for High‐Temperature Supercapacitors

Cited by 52 publications

References 47 publications

“All-in-Gel” design for supercapacitors towards solid-state energy devices with thermal and mechanical compliance

“All-in-Gel” design for supercapacitors towards solid-state energy devices with thermal and mechanical compliance

Dissolution–Crystallization Transition within a Polymer Hydrogel for a Processable Ultratough Electrolyte

Wood‐Inspired Morphologically Tunable Aligned Hydrogel for High‐Performance Flexible All‐Solid‐State Supercapacitors

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