Gel polymer electrolytes for rechargeable batteries toward wide-temperature applications.

Rechargeable batteries, typically represented by lithium-ion batteries, have taken a huge leap in energy density over the last two decades. However, they still face material/chemical challenges in ensuring safety and long service life at temperatures beyond the optimum range, primarily due to the chemical/electrochemical instabilities of conventional liquid electrolytes against aggressive electrode reactions and temperature variation. In this regard, a gel polymer electrolyte (GPE) with its liquid components immobilized and stabilized by a solid matrix, capable of retaining almost all the advantageous natures of the liquid electrolytes and circumventing the interfacial issues that exist in the all-solid-state electrolytes, is of great significance to realize rechargeable batteries with extended working temperature range. We begin this review with the main challenges faced in the development of GPEs, based on extensive literature research and our practical experience. Then, a significant section is dedicated to the requirements and design principles of GPEs for wide-temperature applications, with special attention paid to the feasibility, cost, and environmental impact. Next, the research progress of GPEs is thoroughly reviewed according to the strategies applied. In the end, we outline some prospects of GPEs related to innovations in material sciences, advanced characterizations, artificial intelligence, and environmental impact analysis, hoping to spark new research activities that ultimately bring us a step closer to realizing wide-temperature rechargeable batteries.

Photothermal Fibrous Chitosan/Polydopamine Sponge for Intraoperative Hemostasis and Prevention of Tumor Recurrence in Hepatocellular Carcinoma Resection.

Hepatectomy, a surgical procedure for liver cancer, is often plagued by high recurrence rates worldwide. The recurrence of liver cancer is primarily attributed to microlesions in the liver, changes in the immune microenvironment, and circulating tumor cells in the bloodstream. To address this issue, a novel intervention method that combines intraoperative hemostasis with mild photothermal therapy is proposed, which has the potential to ablate microlesions and improve the immune microenvironment simultaneously. Specifically, the integrated strategy is realized based on the fibrous chitosan/polydopamine sponge (CPDS), which is constructed from shearing-flow-induced oriented hybrid chitosan fibers and subsequent self-assembly of polydopamine. The CPDS demonstrates high elasticity, excellent water absorption, and photothermal conversion performance. The results confirm the efficient hemostatic properties of the fibrous CPDS in various bleeding models. Notably, in subcutaneous and orthotopic postoperative recurrence and metastasis models of hepatocellular carcinoma, the fibrous CPDS significantly inhibits local tumor recurrence and distant metastasis. Moreover, the combination with lenvatinib can substantially enhance the antitumor effect. This comprehensive treatment strategy offers new insights into hepatectomy of liver cancer, representing a promising approach for clinical management.

Biological MWCNT/chitosan composite coating with outstanding anti-corrosion property for implants.

Biocompatible coatings that can protect metal implants have great potential in tissue engineering. In this work, MWCNT/chitosan composite coatings with hydrophobic-hydrophilic asymmetric wettability were facilely prepared by one-step in situ electrodeposition. The resultant composite coating exhibits excellent thermal stability and mechanical strength (0.76 MPa), benefiting from the compact internal structure. The thickness of the coating can be controlled precisely by the amounts of transferred charges. The MWCNT/chitosan composite coating demonstrates a lower corrosion rate due to its hydrophobicity and compact internal structure. Compared with exposed 316 L stainless steel, its corrosion rate is reduced by two orders of magnitude from 3.004 × 10-1 mm/yr to 5.361 × 10-3 mm/yr. The content of iron released from 316 L stainless steel into the simulated body fluid drops to 0.1 mg/L under the protection of the composite coating. In addition, the composite coating enables efficient calcium enrichment from simulated body fluids and promotes the formation of bioapatite layers on the coating surface. This study contributes to furthering the practical application of chitosan-based coatings in implant anticorrosion.

Bioinspired Multiscale Micro-/Nanofiber Network Design Enabling Extremely Compressible, Fatigue-Resistant, and Rapidly Shape-Recoverable Cryogels.

Cryogels with extreme mechanical properties such as ultrahigh compressibility, fatigue resistance, and rapid recovery are attractive in biomedical, environmental remediation, and energy storage applications, which, however, are difficult to achieve in man-made materials. Here, inspired by the multiscale macro-/microfiber network structure of spider web, we construct an ultraelastic chitosan cryogel with interconnected hybrid micro-/nanofibers (CMNF cryogels) via freeze-induced physicochemical cross-linking. Chitosan chains are directionally assembled into high-aspect-ratio microfibers and nanofibers under shear-flow induction, which are further assembled into an interconnected three-dimensional (3D) network structure with staggered microfibers and nanofibers. In this multiscale network, nanofibers connecting the microfibers improve the stability, while microfibers improve the elasticity of the CMNF cryogels through long-range interaction. The synergy of the two-scale fibers endows the CMNF cryogel with extraordinary mechanical properties in comparison to those assembled with single-scale fibers, including its ultrahigh ultimate strain (97% strain with 50 cycles), excellent fatigue resistance (3200 compressing-releasing cycles at 60% compression strain), and rapid water-triggered shape recovery (recovering in ∼1 s). Moreover, the fibrous CMNF cryogel shows excellent functionalization capability via the rapid assembly of nanoscale building blocks for flexible electronics and environmental remediation. Our work thereby demonstrates the potential of this bioinspired strategy for designing gel materials with extreme mechanical properties.

Ionic Liquid "Water Pocket" for Stable and Environment-Adaptable Aqueous Zinc Metal Batteries.

The strong reactivity of water in aqueous electrolytes toward metallic zinc (Zn), especially at aggressive operating conditions, remains the fundamental obstacle to the commercialization of aqueous zinc metal batteries (AZMBs). Here, a water-immiscible ionic liquid diluent 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)amide (EmimFSI) is reported that can substantially suppress the water activity of aqueous electrolyte by serving as a "water pocket", enveloping the highly active H2 O-dominated Zn2+ solvates and protecting them from parasitic reactions. During Zn deposition, the cation Emim+ and anion FSI- function respectively in mitigating the tip effect and regulating the solid electrolyte interphase (SEI), thereby favoring a smooth Zn deposition layer protected by inorganic species-enriched SEI featuring high uniformity and stability. Combined with the boosted chemical/electrochemical stability endowed by the intrinsic merits of ionic liquid, this ionic liquid-incorporated aqueous electrolyte (IL-AE) enables the stable operation of Zn||Zn0.25 V2 O5 ·nH2 O cells even at a challenging temperature of 60 °C (>85% capacity retention over 400 cycles). Finally, as an incidental but practically valuable benefit, the near-zero vapor pressure nature of ionic liquid allows the efficient separation and recovery of high-value components from the spent electrolyte via a mild and green approach, promising the sustainable future of IL-AE in realizing practical AZMBs.

Scalable Production of Biodegradable, Recyclable, Sustainable Cellulose-Mineral Foams via Coordination Interaction Assisted Ambient Drying.

Heavy reliance on petrochemical-based plastic foams in both industry and society has led to severe plastic pollution (the so-called "white pollution"). In this work, we develop a biodegradable, recyclable, and sustainable cellulose/bentonite (Cel/BT) foam material directly from resource-abundant natural materials (i.e., lignocellulosic biomass and minerals) via ambient drying. The strong resistance to the capillary force-driven structural collapse of the preformed three-dimensional (3D) network during the ambient drying process can be ascribed to the purpose-designed cellulose-bentonite coordination interaction, which provides a practical way for the locally scalable production of foam materials with designed shapes without complex processing and intensive energy consumption. Benefiting from the strong cellulose-bentonite coordination interaction, the Cel/BT foam material demonstrates high mechanical strength and outstanding thermal stability, outperforming commercial plastic polystyrene foam. Furthermore, the Cel/BT foam presents environmental impacts much lower than those of petrochemical-based plastic foams as it can be 100% recycled in a closed-loop recycling process and easily biodegraded in the environment (natural cellulose goes back to the carbon cycle, and bentonite minerals return to the geological cycle). This study demonstrates an energy-efficient ambient drying approach for the local and scalable production of an all-natural cellulose/bentonite foam for sustainable packaging, buildings, and beyond, presenting great potential in response to "white pollution" and resource shortage.

Electrical signals regulate the release of insulin from electrodeposited chitosan composite hydrogel: An in vitro and in vivo study.

Electrical signal controlled drug release from polymeric drug delivery system provides an efficient way for accurate and demandable drug release. In this work, insulin was loaded on inorganic nanoplates (layered double hydroxides, LDHs) and coated on a copper wire by co-electrodeposition with chitosan. The formed structure in chitosan composite hydrogel entrapped insulin efficiently, which were proved by various techniques. In addition, the drug loaded chitosan composite hydrogel demonstrated good biocompatibility as suggested by cell attachment. In vitro drug release experiment showed fast responsive pulsed release of insulin by biasing electrical signals. The in vivo experiment in diabetic rats revealed controllable insulin release in plasma and stable decrease of blood glucose can be achieved by using appropriate electrical signal. In addition, HE staining suggested negligible effect to the tissue by electrical signals. This work suggests that the electrical signal controlled insulin release from chitosan composited hydrogel may be a promising administration route for insulin.

Tubular chitosan hydrogels with a tuneable lamellar structure programmed by electrical signals.

The discovery of facile methods to create complex lamellar structures in hydrogels, which mimic the exquisite structures in nature, remains a great challenge. In this work, an ordered lamellar structured hydrogel from the stimuli-responsive amino-polysaccharide chitosan is fabricated by an electro-assembly process, during which the diffusion of OH- and the electrophoresis of the chitosan chains play important roles. Importantly, a complex ordered/disordered structure of chitosan hydrogel can be regulated with high fidelity by programming the input electrical signals.

Electrical Writing Induced Covalent Cross-Linking on Hydrogel for Multidimensional Structural Information Storage.

The storage of dynamic information in hydrogel is extremely interesting due to the reprogrammable and responsive features of hydrogel. Here, we report that structural information can be stored in polysaccharide hydrogel by electrically induced covalent cross-linking, and the imbedded information can be retrieved by different means (dye adsorption, protonation of chitosan, and acid dissolution). Taking the advantage of diffusible feature of hydrogel, OH- was generated from the contacting area of the electrode and controllably diffused by electrical writing, thus the high pH domain (pH ∼ 10) triggered covalent cross-linking of the hydrogel. The written area exhibits different micromorphology, chemical properties, and pH sensitivity, allowing dynamic 2D and 3D information to be stored and read when necessary. This work demonstrates the use of stable electrical inputs to store dynamic structural information in a biopolymer-based hydrogel and how the chemical and physical varies allow eye recognition to the embedded information.