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The aqueous zinc‐ion battery is promising as grid scale energy storage device, but hindered by the instable electrode/electrolyte interface. Herein, we report the lean‐water ionic liquid electrolyte for aqueous zinc metal batteries. The lean‐water ionic liquid electrolyte creates the hydrophobic tri‐layer interface assembled by first two layers of hydrophobic OTF− and EMIM+ and third layer of loosely attached water, beyond the classical Gouy–Chapman–Stern theory based electrochemical double layer. By taking advantage of the hydrophobic tri‐layer interface, the lean‐water ionic liquid electrolyte enables a wide electrochemical working window (2.93 V) with relatively high zinc ion conductivity (17.3 mS/cm). Furthermore, the anion crowding interface facilitates the OTF− decomposition chemistry to create the mechanically graded solid electrolyte interface layer to simultaneously suppress the dendrite formation and maintain the mechanical stability. In this way, the lean‐water based ionic liquid electrolyte realizes the ultralong cyclability of over 10000 cycles at 20 A/g and at practical condition of N/P ratio of 1.5, the cumulated areal capacity reach 1.8 Ah/cm2, which outperforms the state‐of‐the‐art zinc metal battery performance. Our work highlights the importance of the stable electrode/electrolyte interface stability, which would be practical for building high energy grid scale zinc‐ion battery. [ABSTRACT FROM AUTHOR]

3D-printed MXene electrodes hold great promise for the development of next-generation electrochemical devices, offering improved performance, customization, and design flexibility. To this end, it is crucial to improve the 3D printability of MXene ink and address the restacking phenomenon of MXene nanosheets. Herein, a hybrid ink consisting of MXene, cellulose nanofibers (CNFs), and multiwalled carbon nanotubes (MWCNTs) is developed and then printed into high-fidelity, customized, freestanding electrodes using a controlled direct-ink-writing technology. The incorporation of hydrophilic CNFs and highly conductive MWCNTs not only effectively enhances the rheology properties of MXene ink, but also bridges the horizontally aligned MXene nanosheets, resulting in a more integral internal structure and increased interlayer spacing of MXene. Consequently, the 3D-printed flexible electrode exhibits stable conductivity, enhanced surface area accessibility, improved wettability, and excellent electrochemical performance. Furthermore, a cellulose nanofiber/polyacrylamide (CNF/PAM) hydrogel electrolyte is fabricated by in situ radical polymerization. By covering the CNF/PAM hydrogel electrolyte on two 3D printed interdigitated electrodes, we successfully fabricate a flexible interdigitated supercapacitor, which delivers a high energy density of 21.7 μW h cm−2 at 0.3 mW cm−2. The findings of this work provide valuable insights into formulating MXene-based inks for 3D printing of next-generation flexible supercapacitors. [ABSTRACT FROM AUTHOR]

High iodine loading and high‐temperature adaptability of the iodine cathode are prerequisites to achieving high energy density at full battery level and promoting the practical application for the zinc‐iodine (Zn‐I2) battery. However, it would aggravate the polyiodide shuttle effect when employing high iodine loading and working temperature. Here, a sustainable cationic cellulose nanofiber (cCNF) was employed to confine the active iodine species through strong physiochemical adsorption to enlarge the iodine loading and stabilize it even at high temperatures. The cCNF could accommodate dual‐functionality by enlarging the iodine loading and suppressing the polyiodide shuttle effect, owing to the unique framework structure with abundant surface positive charges. As a result, the iodine cathode based on the cCNF could deliver high iodine mass loading of 14.1 mg cm−2 with a specific capacity of 182.7 mAh g−1, high areal capacity of 2.6 mAh cm−2, and stable cycling over 3000 cycles at 2 A g−1, thus enabling a high energy density of 34.8 Wh kg−1 and the maximum power density of 521.2 W kg−1 at a full Zn‐I2 battery level. In addition, even at a high temperature of 60 °C, the Zn‐I2 battery could still deliver a stable cycling. [ABSTRACT FROM AUTHOR]

The titanium carbide nanosheets (MXene) hold great potential for fabricating high‐performance electronics due to their two‐dimensional layered structure, high electrical conductivity, and versatile surface chemistry. However, assembling the small MXene nanosheets into flexible macroscopic films for wearable electronics still remains a challenge. Herein, we report the hierarchical assembling of MXene nanosheets and cellulose nanofibers into high‐performance composite films via an electrostatic self‐assembly strategy induced by polyethyleneimine. Benefited from the nacre‐like microstructure of MXene "bricks" and cellulose nanofibers "mortars" interlocked by polyethyleneimine via hydrogen bonding and electrostatic interaction, composite films possess integrated superior flexibility, high tensile strength, and stable electrical conductivity, which are advantageous for wearable electronic applications. To provide a proof‐of‐concept design, a symmetric quasi‐solid‐state supercapacitor with the as‐prepared composite film as electrode is fabricated, which exhibits a specific capacitance of 93.9 mF cm−2 at a current density of 0.1 mA cm−2 and almost constant capacitive behavior under different bending states. In addition, the composite film possesses capacities of electrothermal conversion and complete degradation in a hydrogen peroxide solution. These results demonstrate that the electrostatically self‐assembled composite films hold great promise in the development of highly flexible, mechanically robust, and environmentally friendly energy storage and conversion devices. [ABSTRACT FROM AUTHOR]

Multifunctional biofilms with early fire-warning capabilities are highly necessary for various indoor and outdoor applications, but a rational design of intelligent fire alarm films with strong weather resistance remains a major challenge. Herein, a multiscale hierarchical biofilm based on lignocellulose nanofibrils (LCNFs), carbon nanotubes (CNTs) and TiO2 was developed through a vacuum-assisted alternate self-assembly and dipping method. Then, an early fire-warning system that changes from an insulating state to a conductive one was designed, relying on the rapid carbonization of LCNFs together with the unique electronic excitation characteristics of TiO2. Typically, the L-CNT-TiO2 film exhibited an ultrasensitive fire-response signal of ~0.30 s and a long-term warning time of ~1238 s when a fire disaster was about to occur, demonstrating a reliable fire-alarm performance and promising flame-resistance ability. More importantly, the L-CNT-TiO2 biofilm also possessed a water contact angle (WCA) of 166 ± 1° and an ultraviolet protection factor (UPF) as high as 2000, resulting in excellent superhydrophobicity, antifouling, self-cleaning as well as incredible anti-ultraviolet (UV) capabilities. This work offers an innovative strategy for developing advanced intelligent films for fire safety and prevention applications, which holds great promise for the field of building materials. [ABSTRACT FROM AUTHOR]