Ionic conductive gels are widely sought after for applications that require reliable ionic conduction and mechanical performance under extreme conditions, which remains a grand challenge. To address this limitation, water‐induced hydration interactions are deliberately controlled within the ionic liquid (IL)‐based conductive gels (ionogels) to achieve all‐round performance. Specifically, the competitive interactions between IL, water and cellulose nanofibrils (CNF) are balanced to preserve the nanoscale morphology of CNF while avoiding its dissolution. As a result, both mechanical performance and ionic conductivity of the resultant ionogel are synergistically enhanced. For instance, an ultra stretchable ionogel (up to 10250 ± 412% stretchability) with both high toughness (21.8 ± 0.9 MJ m−3) and ionic conductivity (0.70 ± 0.06 S m−1) is achieved. Furthermore, multimodal sensing functions (strain, compression, temperature, and humidity) are realized by assembling the ionogel as a skin‐like membrane. Due to the low volatility of IL and its strong interaction with water, the ionogel maintains an excellent performance at either ultra‐low temperature (−45 °C), high temperature (75 °C) or low humidity environment (RH < 15%), demonstrating superb anti‐freezing and anti‐drying performance. Overall, a simple yet versatile strategy is introduced that leads to environmentally resilient ionogels to meet the requirements of next‐generation electroactive devices.
Ion conductors (ICs) have gained extensive research interest in various advanced application scenarios including sensors, batteries, and supercapacitors. However, stretchable, tough, and long-term stable ICs are still hard to achieve yet highly demanded. In this study, the authors propose a one-pot green and sustainable fabrication of cellulose based ICs through polymerizable deep eutectic solvents treated cellulose followed by an in situ photo-polymerization. The obtained ICs exhibit extremely high stretchability (3210 ± 302%), high toughness (13.17 ± 2.32 MJ m −3 ), high transparency, and self-healing ability. Notably, the introduction of cellulose fibers greatly enhances the mechanical properties of ICs while eliminating the environmental concerns of traditional nanocellulose fabrication process. More importantly, the ICs possess good long-term performance stability after 1 month storage. Due to these outstanding properties, the feasibility of applying ICs in human motion sensing and physiological signal detecting is demonstrated. This simple and green method will contribute to the development of tough, self-healing, transparent, and long-term stable ICs.
The widespread utilization of cellulose nanofibril (CNF) has been significantly hindered by its inherent flammability. To explore the potential of using CNF aerogel as sustainable material with good fire‐retardant and thermal‐insulating properties, CNF aerogel is modified by in situ supramolecular assembly of melamine (MEL) and phytic acid (PA). This strategy addresses CNF's flammability and avoids the environment issues associated with the incorporation of traditional fire‐retardant. The modified aerogel exhibits highly porous honeycomb structure with low density and good mechanical properties. After modification with MEL–PA, the aerogel exhibits highly improved shape integrity during burning, higher thermal stability, and favorable combustion behavior for fire retardancy. The heat transfer of the modified aerogel is well hindered, which demonstrated effective thermal insulation performance. In view of the excellent thermal and fire‐retardant properties, the MEL–PA/CNF composite aerogel can be a potential fire‐retardant and thermal‐insulating material for applications such as clothing, building, and electronic devices.
Ionic conductors (ICs) find widespread applications across
different
fields, such as smart electronic, ionotronic, sensor, biomedical,
and energy harvesting/storage devices, and largely determine the function
and performance of these devices. In the pursuit of developing ICs
required for better performing and sustainable devices, cellulose
appears as an attractive and promising building block due to its high
abundance, renewability, striking mechanical strength, and other functional
features. In this review, we provide a comprehensive summary regarding
ICs fabricated from cellulose and cellulose-derived materials in terms
of fundamental structural features of cellulose, the materials design
and fabrication techniques for engineering, main properties and characterization,
and diverse applications. Next, the potential of cellulose-based ICs
to relieve the increasing concern about electronic waste within the
frame of circularity and environmental sustainability and the future
directions to be explored for advancing this field are discussed.
Overall, we hope this review can provide a comprehensive summary and
unique perspectives on the design and application of advanced cellulose-based
ICs and thereby encourage the utilization of cellulosic materials
toward sustainable devices.
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