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In order to resolve the global crisis of fossil energy shortage and climate warming, the development of efficient energy storage devices is a significant topic at present. Supercapacitors as the novel type of energy storage devices have the unique advantages, including the fast charging/discharging behaviors, high-energy/power density, and stable cycling performance. Compared with traditional supercapacitors, flexible supercapacitors are environmentally friendly, light weight, small size and high safety. Therefore, flexible supercapacitors have a wide application prospect in emerging electronic devices. Due to its flexibility, biocompatibility, and structure designability, cellulose and its gel materials are gradually used as electrodes, separators and electrolytes in flexible supercapacitors. Several construction processes at molecular scale for high-performance cellulose gels are summarized. Meanwhile, this review covers the recent progress of developing the flexible supercapacitors and all-in-one supercapacitors based on cellulose functional gels. We finally discussed the potential challenges and opportunities for cellulose and its derived materials in new-style flexible supercapacitors and other electronic devices.

The conductive polymer poly-3,4-ethylenedioxythiophene (PEDOT), recognized for its superior electrical conductivity and biocompatibility, has become an attractive material for developing wearable technologies and bioelectronics. Nevertheless, the complexities associated with PEDOT’s patterning synthesis on diverse substrates persist despite recent technological progress. In this study, we introduce a novel deep eutectic solvent (DES)-induced vapor phase polymerization technique, facilitating nonrestrictive patterning polymerization of PEDOT across diverse substrates. By controlling the quantity of DES adsorbed per unit area on the substrates, PEDOT can be effectively patternized on cellulose, wood, plastic, glass, and even hydrogels. The resultant patterned PEDOT exhibits numerous benefits, such as an impressive electronic conductivity of 282 S·m−1, a high specific surface area of 5.29 m2·g−1, and an extensive electrochemical stability range from −1.4 to 2.4 V in a phosphate-buffered saline. To underscore the practicality and diverse applications of this DES-induced approach, we present multiple examples emphasizing its integration into self-supporting flexible electrodes, neuroelectrode interfaces, and precision circuit repair methodologies.

Abstract Structure design provides an effective solution to develop advanced soft materials with desirable mechanical properties. However, creating multiscale structures in ionogels to obtain strong mechanical properties is challenging. Here, an in situ integration strategy for producing a multiscale‐structured ionogel (M‐gel) via ionothermal‐stimulated silk fiber splitting and moderate molecularization in the cellulose‐ions matrix is reported. The produced M‐gel shows a multiscale structural superiority comprised of microfibers, nanofibrils, and supramolecular networks. When this strategy is used to construct a hexactinellid inspired M‐gel, the resultant biomimetic M‐gel shows excellent mechanical properties including elastic modulus of 31.5 MPa, fracture strength of 6.52 MPa, toughness reaching 1540 kJ m−3, and instantaneous impact resistance of 3.07 kJ m−1, which are comparable to those of most previously reported polymeric gels and even hardwood. This strategy is generalizable to other biopolymers, offering a promising in situ design method for biological ionogels that can be expanded to more demanding load‐bearing materials requiring greater impact resistance.

Protolignin extraction can facilitate structure elucidation and valorization of lignin in biorefinery, but is rather challenging due to the complex chemical bonds present. Here, we developed the in situ generated NH3-reline (IGNR) system to realize one-pot protolignin extraction from lignocellulose. In the IGNR system, reline consisting of choline chloride and urea acted as both a solvent and a nucleophile generator, and the nucleophilic addition–elimination mechanism was verified by model compound studies. The in situ generated NH3 could precisely cleave the lignin–carbohydrate esters in lignocellulose with a near-quantitative retention of carbohydrates. The extracted IGNR–Protolignin exhibited native lignin substructure with high molecular weight and high β-O-4′ content (41.5 per 100 aromatic units). In addition, the up-scaled kilogram reaction demonstrated the feasibility of the IGNR system for potential industrial application in a green and sustainable pathway. This work represents a breakthrough toward protolignin extraction in practice with the future goal of achieving total biorefinery.

Abstract An in‐depth understanding of the electronic structures of catalytically active centers and their surrounding vicinity is key to clarifying the structure–activity relationship, and thus enabling the design and development of novel metal‐free carbon‐based materials with desired catalytic performance. In this study, boron atoms are introduced into phosphorus‐doped nanoporous carbon via an efficient strategy, so that the resulting material delivers better catalytic performance. The doped B atoms alter the electronic structures of active sites and cause the adjacent C atoms to act as additional active sites that catalyze the reaction. The B/P co‐doped nanoporous carbon shows remarkable catalytic performance for benzyl alcohol oxidation, achieving high yield (over 91% within 2 h) and selectivity (95%), as well as low activation energy (32.2 kJ mol−1). Moreover, both the conversion and selectivity remain above 90% after five reaction cycles. Density functional theory calculations indicate that the introduction of B to P‐doped nanoporous carbon significantly increases the electron density at the Fermi level and that the oxidation of benzyl alcohol occurs via a different reaction pathway with a very low energy barrier. These findings provide important insights into the relationship between catalytic performance and electronic structure for the design of dual‐doped metal‐free carbon catalysts.

Abstract The separator is of great importance for regulating ion transmission, maintaining electrode stability, and device safety in lithium‐ion batteries. Despite their many advantages, glass microfiber separators have shortcomings that often give rise to poor cycle performance and fatal short‐circuit risk when used in flexible batteries. Here, we propose the use of a scalable non‐Newtonian fluidic cellulose permeation‐diffusion strategy to develop a cellulose/glass microfiber composite film with an hourglass‐gradient structure. Due to the unique gradient morphology resulting from the presence of cellulose macromolecules, the as‐prepared composite film showed an improved surface mass density, adjustable pore structure, controllable ion transport, ideal mechanical flexibility, and robustness. When used as the separator in an assembled lithium‐ion battery, the composite film exhibited rapid ion diffusion and Li dendrite inhibition, which endowed the battery with excellent cycle stability (specific capacity of 108.5 mAh g−1 after 1000 cycles) and good rate performance. This composite film shows great potential application in flexible lithium‐ion batteries including but not limited to pouch cells.