A Star-Structured Polymer Electrolyte for Low-Temperature Solid-State Lithium Batteries.

Solid-state polymer lithium metal batteries (SSLMBs) have attracted considerable attention because of their excellent safety and high energy density. However, the application of SSLMBs is significantly impeded by uneven Li deposition at the interface between solid-state electrolytes and lithium metal anode, especially at a low temperature. Herein, this issue is addressed by designing an agarose-based solid polymer electrolyte containing branched structure. The star-structured polymer is synthesized by grafting poly (ethylene glycol) monomethyl-ether methacrylate and lithium 2-acrylamido-2-methylpropanesulfonate onto tannic acid. The star structure regulates Li-ion flux in the bulk of the electrolyte and at the electrolyte/electrode interfaces. This unique omnidirectional Li-ion transportation effectively improves ionic conductivity, facilitates a uniform Li-ion flux, inhibits Li dendrite growth, and alleviates polarization. As a result, a solid-state LiFePO4||Li battery with the electrolyte exhibits outstanding cyclability with a specific capacity of 134 mAh g-1 at 0.5C after 800 cycles. The battery shows a high discharge capacity of 145 mAh g-1 at 0.1 C after 200 cycles, even at 0 °C. The study offers a promising strategy to address the uneven Li deposition at the solid-state electrolyte/electrode interface, which has potential applications in long-life solid-state lithium metal batteries at a low temperature.

Interfacial Compatibility of Core-Shell Cellulose Nanocrystals for Improving Dynamic Covalent Adaptable Networks' Fracture Resistance in Nanohybrid Vitrimer Composites.

The development of polymeric nanocomposites with dynamic covalent adaptable networks and biobased nanomaterials has been a promising approach toward sustainable advanced materials, enabling reprogramming and recycling capabilities. Herein, a core-shell nanohybrid of functionalized cellulose nanocrystals (CNCs) is explored to provide crucial interfacial compatibility for improving the covalent adaptable networks of epoxy-thiol vitrimers in fracture resistance. The poly(ε-caprolactone) (PCL) shells grafted from CNC surfaces can be cross-linked with the covalent adaptable networks via a hot-pressing transesterification process. According to the additive concentration and annealing temperature, the stress relaxation behavior of nanohybrid vitrimer composites can be effectively regulated by the core-shell PCL-grafted CNC (CNC-PCL) nanohybrids from a dispersed to cross-linked interaction. The addition of 15 wt % of the core-shell CNC-PCLs exhibits the reinforced improvement of nanohybrid vitrimer composites in the average Young's modulus of 2.5×, fracture stress of 5.4×, and fracture strain of 2.0×. The research findings might have profound implications for developing synergistic interfacial compatibility between dynamic vitrimer networks and functional nanoparticles for advanced polymeric nanocomposites.

Preparation and characterization of attapulgite-supported phase change energy storage materials.

Phase change materials (PCMs) for the charge and discharge of thermal energy at a nearly constant temperature are of interest for thermal energy storage and management, and porous materials are usually used to support PCMs for preventing the liquid leakage and shape instability during the phase change process. Compared with commonly used polymer matrices and porous carbons, mineral materials with naturally occurring porous structures have obvious advantages such as cost-saving and abundant resources. Attapulgite (ATP) is a clay mineral with natural porous structures, which can be used to contain PCMs for thermal energy storage. However, the poor compatibility between ATP and PCMs is a significant defect that has rarely been studied. Herein, a facile one-step organic modification method of ATP was developed and the chlorosilane-modified ATP (Si-ATP) possesses great hydrophobic and lipophilic properties. Three types of ATP with different compatibility and pore volumes were used as the supports and paraffin as the energy storage units to fabricate a series of form-stable PCMs (FSPCMs). The results showed that the shape-stabilized ability of Si-ATP for paraffin was significantly enhanced, and the Si-ATP supported FSPCM yielded an optimal latent heat of 83.7 J g-1, which was 64.4% higher than that of the pristine ATP based composite. Meanwhile, the thermal energy storage densities of the resulting FSPCMs were gradually increased with an increase in the pore volumes of the three supporting materials. These results may provide a strategy for preparing porous materials as containers to realize the shape stabilization of PCMs and improve the thermal energy storage densities of the resulting FSPCMs.

Ultrahigh Elastic Polymer Electrolytes for Solid-State Lithium Batteries with Robust Interfaces.

Solid polymer electrolytes (SPEs) are promising for solid-state lithium batteries, but their practical application is significantly impeded by their low ionic conductivity and poor compatibility. Here, we report an ultrahigh elastic SPE based on cross-linked polyurethane (PU), succinonitrile (SN), and lithium bistrifluoromethanesulfonimide (LiTFSI). The resulting electrolyte (PU-SN-LiTFSI) exhibits an ionic conductivity of 2.86 × 10-4 S cm-1, a tensile strength of 3.8 MPa, and a breaking elongation exceeding 3000% at room temperature. A solid-state lithium battery using the electrolyte exhibits a high specific capacity of 150 mAh g-1 at 0.2C and a long cycling life of up to 700 cycles at 0.5C at room temperature, showing one of the best performances among its counterparts. The excellent performances are attributed to the fact that its ultrahigh elasticity, good ionic conductivity, tensile strength, and electrochemical stability contribute to robust electrode/electrolyte interfaces, thus greatly decreasing the charge-transfer resistance in charge/discharge processes. Our investigations provide a novel strategy to address the intrinsic interfacial issue of solid-state batteries.

Stabilizing Lithium Metal Anodes by a Self-Healable and Li-Regulating Interlayer.

Lithium (Li) metal is a promising anode for high-energy-density batteries, but its practical applications are severely hindered by side reactions and dendrite growth at the electrode/electrolyte interfaces. Herein, we propose that the problems can be effectively solved by introducing an interlayer. The interlayer is composed of a trifluorophenyl-modified poly(ethylene imine) network cross-linked by dynamic imine bonding (PEI-3F). The trifluorophenyl moieties of the interlayer can coordinate with Li+, which enables the interlayer to adjust the distribution of Li+ at the electrode/electrolyte interface, while the imine bonding endows the interlayer with self-healing capability. The resulting Li anodes exhibit excellent cycling stability (250 cycles in asymmetric Li||Cu cells) and dendrite-free morphologies. A lithium sulfur (Li-S) cell that uses anodes shows a retention rate of 91% after 100 cycles with a high sulfur loading (5 mg cm-2). This study provides a novel strategy to concern the intrinsic drawbacks of a lithium metal anode, which can be extended to other light-metal electrodes aiming for high energy-density batteries.

Synthesis of Shape-Controllable Anisotropic Microparticles and "Walnut-like" Microparticles via Emulsion Interfacial Polymerization.

Anisotropic microparticles have plenty of applications for their asymmetric structure and precisely modified surface. In our research, the uniform anisotropic microparticles with benzyl chloride group were synthesized successfully via emulsion interfacial polymerization. By varying the degree of cross-linking and the concentration of slightly hydrophilic monomer 4-vinyl benzyl chloride (VBC), several types of microparticles with different concavities and different shapes of microparticles (hemisphere, bowl-like, egg-like, etc.) were obtained. Nanoporous microparticles with a walnut-like heterostructure were achieved with modified hydrophilic seeds with the same strategy. The potential applications of shape-controllable fluorescent microparticles and surface modification of microparticles by thiol-click reaction were explored. The modified microparticles achieved in this study are very useful in labeling, tracing, protein separation, and other biomedical fields.

Self-Healable Hydrogel Electrolyte toward High-Performance and Reliable Quasi-Solid-State Zn-MnO2 Batteries.

Zinc-ion batteries are promising power sources, but their practical application is impeded by the Zn dendrite growth and side reactions at the electrode/electrolyte interface. Here, we report that such issues can be effectively addressed by a self-healable hydrogel electrolyte. The electrolyte is comprised of carboxyl-modified poly(vinyl alcohol) cross-linked by COO-Fe bonding in the presence of Zn(NO3)2 and MnSO4. A quasi-solid-state Zn-MnO2 battery using the electrolyte delivers a specific capacity up to 177 mAh g-1 after 1000 cycles with a retention rate of 83%, which is much better than its equivalent using an aqueous electrolyte. The improvement is attributed to efficient suppression of the dendrite growth and side reactions at the electrode/electrolyte by the hydrogel electrolyte. More importantly, the battery autonomously recovery its energy-storage functions even after multiple physical damages, showing excellent robustness and reliability. The present investigation provides an effective strategy to address the energy-storage performance and reliability of a light-metal battery system.

Fast Healable Superhydrophobic Material.

Self-healability is a crucial feature for developing artificial superhydrophobic surfaces. Although self-healing of microscopic defects has been reported, the restoration of severely damaged superhydrophobic surfaces remains a technological challenge. Here, we report a robust superhydrophobic surface possessing ultrafast recoverability after catastrophic damage. The surface is fabricated via integrating its hierarchical texture comprised of Super P (a conductive carbon black) and TiO2 nanoparticles into a poly(dimethylsiloxane) network cross-linked by dynamic pyrogallol-Fe coordination. In the presence of an electrical trigger, the surface restores its macroscopic configuration, hierarchical texture, mechanical properties, and wettability within 1 min after being cut or plasma etching. The restoration is attributed to the reconstruction of the multiscale structures through dynamic coordination. Application of the self-healable surface is demonstrated by a fast de-icing process. The present investigation offers a novel insight into the durability and reliability of artificial superhydrophobic surfaces against catastrophic damage, which has potential application in the fields including self-cleaning, anti-icing, advanced electronics, and so on.

Surface-engineered vanadium nitride nanosheets for an imaging-guided photothermal/photodynamic platform of cancer treatment.

Of the many strategies for precise tumor treatment, near-infrared (NIR) light-activated "one-for-all" theranostic modality with real-time diagnosis and therapy has attracted extensive attention from researchers. Herein, a brand-new theranostic nanoplatform was established on versatile vanadium nitride (VN) nanosheets, which show significant NIR optical absorption, and resultant photothermal effect and reactive oxygen species activity under NIR excitation, thereby realizing the synergistic action of photothermal/photodynamic co-therapy. As expected, systematic in vitro and in vivo antitumor evaluations demonstrated efficient cancer cell killing and solid tumor removal without recurrence. Meanwhile, the surface modification of VN nanosheets with poly(allylamine hydrochloride) and bovine serum albumin enhanced the biocompatibility of VN and made it more suitable for in vivo delivery. Moreover, VN has been ascertained as a potential photoacoustic imaging contrast for in vivo tumor depiction. Thus, this work highlights the potential of VN nanosheets as a single-component theranostic nanoplatform.

Sodium Hyaluronate: A Versatile Polysaccharide toward Intrinsically Self-Healable Energy-Storage Devices.

Self-healability is an attractive feature for next-generation energy-storage devices aiming at flexible/wearable electronics. However, realizing self-healability usually involves complicated molecular design and synthetic processes. Here, we demonstrate that sodium hyaluronate (SH), a kind of natural polysaccharide, can be used as a versatile polymer to facile fabricate intrinsically self-healable energy-storage devices. Self-healable sodium ion batteries and asymmetric capacitors are fabricated by integrating their electroactive components into dynamic SH networks cross-linked via borate ester bonding. The devices autonomously recover their configuration integrity, microstructure, and mechanical and electrochemical properties even after nine cycles of breaking/healing, exhibiting excellent reliability, easy maintenance, and superior safety. The electrochemical performances and self-healability are estimated to be the best among those of the existing self-healable energy-storage devices. This facile and versatile strategy might greatly accelerate the design and fabrication of smart and robust energy-storage devices applicable for advanced flexible electronics or soft robot, and so on.

Controlled Movement of a Smart Miniature Submarine at Various Interfaces.

Smart miniaturized aquatic devices have many important applications, but their locomotion at different interfaces remains a challenge. Here, we report a smart miniaturized submarine moving at various air/liquid or oil/water interfaces. The microsubmarine is fabricated by a CO2-responsive superhydrophobic copper mesh and is driven by the Marangoni effect. The microsubmarine can not only transfer among different interfaces reversibly but also move horizontally at the interfaces freely. The unique locomotion of the device is attributed to a CO2-triggered switch between superhydrophobicity and underwater superoleophobicity. Moreover, the microsubmarine exhibits good stability and excellent oil repellence at the oil/water interface. Our study provides a strategy for fabricating smart aquatic devices that have potential applications in environment monitoring, water purification, channel-free microfluidics, and so on.

Rationally Designed Self-Healing Hydrogel Electrolyte toward a Smart and Sustainable Supercapacitor.

Excellent self-healability and renewability are crucial for the development of wearable/flexible energy-storage devices aiming for advanced personalized electronics. However, realizing low-temperature self-healing and harmless regeneration remains a big challenge for existing wearable/flexible energy-storage devices, which is fundamentally limited by conventional polymeric electrolytes that are intrinsically neither cryo-healable nor renewable. Here, we rationally design a multifunctional polymer electrolyte on the basis of the copolymer of vinylimidazole and hydroxypropyl acrylate, which exhibits all features solving the above-mentioned limitations. A supercapacitor comprising the electrolyte autonomously restores its electrochemical behaviors at temperatures ranging from 25 to -15 °C after multiple mechanical breakings. Interestingly, it is even able to regenerate for 5 cycles through a simple wetting process in the case of malfunction, while maintaining its capacitive properties and excellent self-healability. Our investigation provides a novel insight into designing smart and sustainable energy-storage devices that might be applied to intelligent apparel, electronic skin or flexible robot, and so on.

Pd(II)/Bipyridine-Catalyzed Conjugate Addition of Arylboronic Acids to α,ß-Unsaturated Carboxylic Acids. Synthesis of ß-Quaternary Carbons Substituted Carboxylic Acids.

Pd(II)/bipyridine-catalyzed conjugate addition of arylboronic acids to α,ß-unsaturated carboxylic acids (including ß,ß-disubstituted acrylic acids) was developed and optimized, which provided a mild and convenient method for the highly challenging synthesis of ß-quaternary carbons substituted carboxylic acids.

Self-Healable and Cold-Resistant Supercapacitor Based on a Multifunctional Hydrogel Electrolyte.

Excellent self-healability and cold resistance are attractive properties for a portable/wearable energy-storage device. However, achieving the features is fundamentally dependent on an intrinsically self-healable electrolyte with high ionic conduction at low temperature. Here we report such a hydrogel electrolyte comprising sodium alginate cross-linked by dynamic catechol-borate ester bonding. Since its dynamically cross-linked alginate network can tolerate high-content inorganic salts, the electrolyte possesses excellent healing efficiency/cyclability but also high ionic conduction at both room temperature and low temperature. A supercapacitor with the multifunctional hydrogel electrolyte completely restores its capacitive properties even after breaking/healing for 10 cycles without external stimulus. At a low temperature of -10 °C, the capacitor is even able to maintain at least 80% of its room-temperature capacitance. Our investigations offer a strategy to assemble self-healable and cold-resistant energy storage devices by using a multifunctional hydrogel electrolyte with rationally designed polymeric networks, which has potential application in portable/wearable electronics, intelligent apparel or flexible robot, and so on.

Remote Manipulation of a Microdroplet in Water by Near-Infrared Laser.

Facile manipulation of a tiny liquid droplet is an important but challenging issue for many miniaturized chemical and biological systems. Here we report that a microdroplet can be readily and remotely manipulated in aqueous environments under ambient conditions. The droplet is encapsulated with photothermal nanoparticles to form a liquid marble, and subsequently irradiated with a near-infrared (NIR) laser. The marble is able to ascend, shuttle, horizontally move, and even suspend in water by simply controlling the laser irradiation. Moreover, filling and draining of the marble can also be conducted on the water surface for the first time. This facile manipulation strategy does not use complicated nanostructures or sophisticated equipment, so it has potential applications for channel-free microfluidics, smart microreators, microengines, microrobots, and so on.

3D Graphene Functionalized by Covalent Organic Framework Thin Film as Capacitive Electrode in Alkaline Media.

To harness the electroactivity of anthraquinone as an electrode material, a great recent effort have been invested to composite anthraquinone with carbon materials to improve the conductivity. Here we report on a noncovalent way to modify three-dimensional graphene with anthraquinone moieties through on-surface synthesis of two-dimensional covalent organic frameworks. We incorporate 2,6-diamino-anthraquinone moieties into COF through Schiff-base reaction with benzene-1,3,5-tricarbaldehyde. The synthesized COF -graphene composite exhibits large specific capacitance of 31.7 mF/cm(2). Long-term galvanostatic charge/discharge cycling experiments revealed a decrease of capacitance, which was attributed to the loss of COF materials and electrostatic repulsion accumulated during charge-discharge circles which result in the poor electrical conductivity between 2D COF layers.

A smart "strider" can float on both water and oils.

Aquatic devices that can work on both water and oils have great scientific and practical significance, but the challenge remains in developing novel materials with excellent repellence to both water and oils. Here, we report that an artificial "strider" can float on both water and oils by using supporting legs with ultraviolet (UV) switchable wettability. The legs were fabricated by immobilizing TiO2 nanoparticles and n-dodecanethiol onto copper foams via a simple mussel-inspired process. At ambient conditions, the strider floated freely on a water surface, but it dived in water and then stood stably at the interface of water/CHCl3 after UV illumination for 2 h. The reason for this unique behavior is that the legs changed their wettability from superhydrophobicity to underwater superoleophobicity after the illumination. It was revealed that the micro/nanohierarchical structures and photosensitivity of the immobilized TiO2 nanoparticles accounted for the switchable wettability and large supporting force of the legs. The findings of this study offer an alternative strategy for fabricating smart aquatic devices that might be used for water environment protection, water resource surveillance, oil spill cleanup, and so on.

Bubble-induced transport of oil droplets in water.

An oil droplet wrapped with poly(N-isopropylacrylamide) grafted nanoparticles can ascend or descend in water repeatedly by simply tuning the temperature of water above or below 33 °C, while avoiding the use of sophisticated equipment and complex nanostructures.

Cobalt-catalyzed cyclization of carbon monoxide, imine, and epoxide.

Cobalt-catalyzed cyclization of CO, imine, and epoxide has been developed. A convenient catalyst system composed of Co2(CO)8 and LiCl is identified, and the substrate scope has been explored. The reaction provides an efficient method for the synthesis of substituted 1,3-oxazinan-4-ones.

Constructing robust liquid marbles for miniaturized synthesis of graphene/Ag nanocomposite.

Miniaturized synthesis is attracting much attention due to many potential applications; a challenge remains in exploring versatile microreactors capable of producing pure products. In this study, we reported a kind of thermally robust liquid marbles and their application for miniaturized synthesis of graphene/Ag nanocomposite. The liquid marbles were constructed by using superhydrophobic Fe3O4/C microsheets as encapsulating agents. Results revealed that the morphology of the encapsulating agent as well as the humidity of atmosphere strongly affected the robustness of liquid marbles at elevated temperature. The resulting graphene/Ag nanocomposite showed one of the best catalytic characteristics for 4-nitroaniline reduction among the reported catalysts. The findings of this study not only offer an alternative insight into the stability of liquid marbles at elevated temperature but also provide a facile strategy for miniaturized synthesis.