With the growing demand for high energy and high power density rechargeable lithium-ion batteries, increasing research is focused on improving the output voltage of these batteries. Herein, a series ...of pyrrolidinium and piperidinium cations with various N-substituents (including cyanomethyl, benzyl, butyl, hexyl, and octyl groups) were synthesized and investigated with respect to their electrochemical stability under high voltages. The influence of substitutions at the N-position of pyrrolidinium and piperidinium cations on their high-voltage resistance was studied by both theoretical and experimental approaches. The voltage resistance was enhanced as the electron-donating ability of the substitutes increased. Furthermore, 1-hexyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide (C6PyTFSI) exhibited the highest decomposition voltage at approximately 5.12 V and showed promising potential in a lithium-ion battery.
Gels that are freeze-resistant and heat-resistant and have high ultimate tensile strength are desirable in practical applications owing to their potential in designing flexible energy storage ...devices, actuators, and sensors. Here, a simple method for fabricating ionic liquid (IL)-based click-ionogels using thiol-ene click chemistry under mild condition is reported. These click-ionogels continue to exhibit excellent mechanical properties and resilience after 10,000 fatigue cycles. Moreover, due to several unique properties of ILs, these click-ionogels exhibit high ionic conductivity, transparency, and nonflammability performance over a wide temperature range (-75° to 340°C). Click-ionogel-based triboelectric nanogenerators exhibit excellent mechanical, freeze-thaw, and heat stability. These promising features of click-ionogels will promote innovative applications in flexible and safe device design.
Light-emitting diode based electronic screens emit near-ultraviolet radiation, which causes harm to the human eye after prolonged exposure. Thus, it is of paramount importance to prepare a sensitive ...and adjustable visible near-ultraviolet sensor for retinal warning. Herein, a series of bipyridine derivatives were synthesized to investigate effects of substituent groups and anions on photochromic properties via both experimental and theoretical studies. The introduction of dual hydrogen bonding urea onto substituted groups significantly accelerated the photochromic rate due to strong intermolecular interactions, which reduces molecular spacing and promotes the electron-transfer effect. Moreover, the photochromic rate was tuned by changing the size of the anion. Larger anions widen the molecular spacing and weaken the electron transfer and eventually lead to a decrease in the photochromic rate. Finally, bipyridine derivatives were printed on a polyethylene terephthalate film or paper as a sensitive, adjustable, and visible sensor to monitor near-ultraviolet radiation emitted by an light-emitting diode screen.
Electronic skin can detect minute electrical potential changes in the human skin and represent the body's state, which is critical for medical diagnostics and human–computer interface development. On ...the other hand, sweat has a significant effect on the signal stability, comfort, and safety of electronic skin in a real‐world application. In this study, by modifying the cation and anion of a poly(ionic liquid) (PIL) and employing a spinning process, a PIL‐based multilayer nanofiber membrane (PIL membrane) electronic skin with a dual gradient is created. The PIL electronic skin is moisture‐wicking and breathable due to the hydrophilicity and pore size‐gradients. The intrinsically antimicrobial activities of PILs allow the safe collection of bioelectrical signals from the human body, such as electrocardiography (ECG) and electromyography (EMG). In addition, a robotic hand may be operated in real‐time, and a preliminary human–computer interface can be accomplished by simple processing of the collected EMG signal. This study establishes a novel practical approach for monitoring and using bioelectrical signals in real‐world circumstances via the multifunctional electronic skin.
A dual‐gradient poly(ionic liquid) electronic skin with moisture‐wicking, breathable, and antibacterial properties is prepared. Sweat can be delivered to the outside, away from the skin, keeping the electrode‐skin interface dry, ensuring stable and safe collection of bioelectric signals, further enabling real‐time control of a robotic hand. This work provides an unprecedented practical strategy for monitoring and utilization of bioelectrical signals under real conditions.
Human fingers exhibit both high sensitivity and wide tactile range. The finger skin structures are designed to display gradient microstructures and compressibility. Inspired by the gradient ...mechanical Young's modulus distribution, an electric‐field‐induced cationic crosslinker migration strategy is demonstrated to prepare gradient ionogels. Due to the gradient of the crosslinkers, the ionogels exhibit more than four orders of magnitude difference between the anode and the cathode side, enabling gradient ionogel‐based flexible iontronic sensors having high‐sensitivity and broader‐range detection (from 3 × 102 to 2.5 × 106 Pa) simultaneously. Moreover, owing to the remarkable properties of the gradient ionogels, the flexible iontronic sensors also show good long‐time stability (even after 10 000 cycles loadings) and excellent performance over a wide temperature range (from −108 to 300 °C). The flexible iontronic sensors are further integrated on soft grips, exhibiting remarkable performance under various conditions. These attractive features demonstrate that gradient ionogels will be promising candidates for smart sensor applications in complex and extreme conditions.
Inspired by gradient modulus distribution of human fingers, gradient ionogels are prepared by an electric‐field‐induced cationic crosslinkers migration strategy. The gradient of the modulus distribution enables the gradient‐ionogel‐based flexible sensors to demonstrate high sensitivity and broader‐range detection simultaneously. Moreover, the flexible iontronic sensors also show good longtime stability and excellent performance over a wide temperature range.
Slippery liquid‐infused porous surface (SLIPS) has received widespread attention in the antifouling field, while its controllability of surface lubricity and durability of lubricant are relatively ...insufficient. In this study, inspired by the hagfish's defensive behavior of secreting mucus to escape from predators, a smart SLIPS marine antifouling coating is prepared, which possesses responsively switching lubrication modes and self‐healing property. The responsive supramolecular interaction between azobenzene (Azo) and α‐cyclodextrin (α‐CD) is introduced to regulate the lubricity of SLIPS. cis‐Azo is converted to trans and combined with α‐CD by supramolecular interaction under visible light or heating, driving the shrinkage of polymer chains to squeeze the stored lubricant to the surface. The responsive self‐replenishment of lubricant can adjust the surface lubricity to switch antifouling modes between “enhancive” and “normal” smartly, which adapts to different occasions. Moreover, disulfide and hydrogen bonds are introduced to enhance self‐healing performance (91.73%). In summary, it has efficient self‐cleaning, anti‐protein, antibacterial, anti‐algae properties, and 180‐day real marine field antifouling performance during boom season (the longest antifouling period in real marine field test of reported SLIPS materials), which demonstrates the promising application in neritic sea equipment and other antifouling fields.
Inspired by the hagfish's defensive behavior of secreting mucus, a smart SLIPS marine antifouling coating is prepared, which possesses responsively switching lubrication modes and self‐healing properties. The responsive supramolecular interaction between azobenzene and α‐cyclodextrin is introduced to regulate surface lubricity. It has efficient 180‐day real marine field antifouling performance during boom season, which demonstrates its promising application in neritic sea equipment.
The development of hydrogels and ionic gels for applications in fields such as soft electronics and wearable sensors is limited by liquid evaporation or leakage. Ionic conductors without volatile ...liquids are better choices for flexible and transparent devices. Here, a liquid polymer electrolyte (LPE) is prepared from a mixture of lithium bis(trifluoromethane)sulfonimide and polyethylene glycol (PEG) above the melting point of PEG. A three-dimensional (3D) printable solvent-free ionic elastomer (IE) is introduced by photopolymerization of ethyl acrylate and hydroxyethyl acrylate in the prepared LPE. The conductivity is significantly improved by the presence of a high content of the lithium salt. Dynamic cross-linking networks improve the stretchability and resilience of the elastomer. The pattern design capability of the IE is provided by light-curing 3D printing. These features demonstrate that the IE has broad application prospects in flexible sensors, ion skins, and soft robots.
In this study, we developed a superstrong and reversible adhesive, which can possess a high bonding strength in the “adhesive” state and detach with the application of heating. An ionic crystal (IC) ...gel, in which an IC was immobilized within a soft‐polymer matrix, were synthesized via in situ photo‐crosslinking of a precursor solution composed of N, N‐dimethyl acrylamide (DMAA) and a melted IC. The obtained IC gel is homogenous and transparent at melt point. When cooled to the phase transition temperature of the IC, the gel turns into the adhesive with the adhesion strength of 5.82 MPa (on glasses), due to the excellent wetting of melted gel and a thin layer of crystalline IC with high cohesive strength formed on the substrates. The synergistic effects between IC, polymer networks and substrates were investigated by solid state 1H NMR and molecular dynamics simulation. Such an adhesive layer is reversable and can be detached by heating and subsequent re‐adhesion via cooling. This study proposed the new design of removable adhesives, which can be used in dynamic and complex environments.
Inspired by reversible ice adhesion, a reversible ionic crystal (IC) based gel adhesive was prepared, which showed superstrong and reversible adhesion due to the phase transition of ICs. In addition, the reversible adhesion can be adjusted by heating and light, and be effectively monitored by resistance and capacitance.
Many creatures have excellent control over their form, color, and morphology, allowing them to respond to the interaction of environmental stimuli better. Here, the bioinspired synergistic ...shape–color-switchable actuators based on thermally induced shape-memory triethanolamine cross-linked polyurethane (TEAPU) and thermochromic ionic liquids (ILs) were prepared. The thermochromic ILs with various metalized anions, including bis(1-butyl-3-methylimidazolium) tetrachloro nickelate (Bmim2NiCl4) and bis(1-butyl-3-methylimidazolium) tetrachloride cobalt (Bmim2CoCl4), are investigated. The actuators exhibit thermochromic response, as evidenced by a shift in the color of the composites, which is due to the formation of the tetrahedral complex MCl4 2– (M = Ni and Co) after dehydration. The shape–color-switchable thermochromic actuators have strong molecular interaction between TEAPU and ILs and can mimic natural flowers and change the color and shape quickly in a narrow temperature range (30–70 °C). In addition, these thermochromic actuators can lift more than 50 times their weight and withstand strains of more than 1100%. The results represent the potential application in artificial muscle actuators and intelligent camouflages.
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