Dual-Carbon Phase-Encapsulated Prelithiated SiOx Microrod Anode for Lithium-Ion Batteries.

Among silicon-based anode family for Li-ion battery technology, SiOx, a nonstoichiometric silicon suboxide holds the potential for significant near-term commercial impact. In this context, this study mainly focuses on demonstrating an innovative SiOx@C anode design that adopts a pre-lithiation strategy based on in situ pyrolysis of Li-salt of silsesquioxane trisilanolate without the need for lithium metal or active lithium compounds and creates dual carbon encapsulation of SiOC nanodomains by simply one-step thermal treatment. This ingenious design ensures the pre-lithiation process and pre-lithiation material with high-environmental stability. Moreover, phenyl-rich organosiloxane clusters and polyacrylonitrile polymers are expected to serve as internal and external carbon source, respectively. The formation of an interpenetrating and continuous carbon matrix network would not only synergistically offer an improved electrochemical accessibility of active sites but also alleviate the volume expansion effect during cycling. As a result, this new type of anode delivered a high reversible capacity, remarkable cycle stability as well as excellent high-rate capability. In particular, the L2-SiOx@C material has a high initial coulomb efficienc of 80.4% and, after 500 cycles, a capacity retention as high as 97.5% at 0.5 A g-1 with a reversible specific capacity of 654.5 mA h g-1.

Terraced and 3D Pyramid-Shaped Polymer Single Crystal via Low Temperature-Assisted Microfluidic Technology.

3D pyramidal polymer single crystals provide spatial gradient variations within the crystal molecules, and these variations facilitate the study of the relationship between structure and properties within the molecules of various complexes with anisotropic structures. As described herein, a low-temperature-assisted microfluidic pore channeling approach is proposed to prepare structurally ordered polymer single crystals. A mixture of dichloromethane and dimethyl sulfoxide is used as a prepolymer, and a liquid microfluidic technique is employed to grow the end-functionalized polymers into 3D polymer single crystals. Through the ordered growth of single crystals, a personalized pyramidal pattern with a homogeneous structure is formed. To evaluate the mesh node density, low-temperature growth time and substrate type are also investigated. Rectangular, pyramidal, and dendritic patterns are synthesized via low-temperature single crystal growth. This work shows that low temperature-assisted microfluidics provides a novel means to tune the 3D structure of polymer single crystals.

A soluble star-shaped silsesquioxane-cored polymer-towards novel stabilization of pH-dependent high internal phase emulsions.

A well-defined pH-responsive star-shaped polymer containing poly(N,N-dimethylaminoethyl methacrylate) (PDMA) arms and a cage-like methacryloxypropyl silsesquioxane (CMSQ-T10) core was used as an interfacial stabilizer for emulsions consisting of m-xylene and water. We explored the properties of the CMSQ/PDMA star-shaped polymer using the characteristic results of nuclear magnetic resonance (NMR) spectroscopy, size exclusion chromatography (SEC), dynamic light scattering (DLS), and zeta potential and conductivity measurements. The interfacial tension results showed that the CMSQ/PDMA star-shaped polymer reduced the interfacial tension between water and oil in a pH-dependent manner. Gelled high internal phase emulsions (HIPEs) including o/w and w/o types were formed in the pH ranges of 1.2-5.8 and 9.1-12.3 with the CMSQ/PDMA star-shaped polymer as a stabilizer, when the oil fractions were 80-90 vol% and 10-20 vol%, respectively. The soluble star-shaped polymer aggregated spontaneously to form a microgel that adsorbed to the two immiscible phases. Images of the fluorescently labeled polymers demonstrated that there was a star-shaped polymer in the continuous phase, and the non-Pickering stabilization based on the percolating network of the star-shaped polymer also contributed to the stabilization of the HIPE. This pH-dependent HIPE was prepared with a novel stabilization mechanism consisting of microgel adsorption and non-Pickering stabilization. Moreover, the preparation of HIPEs provided the possibility of their application in porous materials and responsive materials.

Polymerizable Molecular Silsesquioxane Cage Armored Hybrid Microcapsules with In Situ Shell Functionalization.

We prepared core-shell polymer-silsesquioxane hybrid microcapsules from cage-like methacryloxypropyl silsesquioxanes (CMSQs) and styrene (St). The presence of CMSQ can moderately reduce the interfacial tension between St and water and help to emulsify the monomer prior to polymerization. Dynamic light scattering (DLS) and TEM analysis demonstrated that uniform core-shell latex particles were achieved. The polymer latex particles were subsequently transformed into well-defined hollow nanospheres by removing the polystyrene (PS) core with 1:1 ethanol/cyclohexane. High-resolution TEM and nitrogen adsorption-desorption analysis showed that the final nanospheres possessed hollow cavities and had porous shells; the pore size was approximately 2-3 nm. The nanospheres exhibited large surface areas (up to 486 m2 g-1 ) and preferential adsorption, and they demonstrated the highest reported methylene blue adsorption capacity (95.1 mg g-1 ). Moreover, the uniform distribution of the methacryloyl moiety on the hollow nanospheres endowed them with more potential properties. These results could provide a new benchmark for preparing hollow microspheres by a facile one-step template-free method for various applications.

Towards ambient temperature operation of Li metal batteries using UV-Crosslinked single-ion electrospun electrolytes.

In spite of the fact that lithium metal batteries (LMBs) facilitate the diversification of energy storage technologies, their electrochemical reversibility and stability have long been constrained by side reactions and lithium dendrite problems. While single-ion conducting polymer electrolytes (SICPEs) possess unique advantages of suppressing Li dendrite growth, they deal with difficulties in practical applications due to their slow ion transport in general application scenarios at âˆ¼25 °C. In this study, we develop novel bifunctional lithium salts with negative sulfonylimide (-SO2N(-)SO2-) anions mounted between two styrene reactive groups, which is capable of constructing 3D cross-linked networks with multiscale reticulated ion nanochannels, resulting in the uniform and rapid distribution of Li+ ions in the crosslinked electrolyte. To verify the feasibility of our strategy, we designed PVDF-HFP-based SICPEs and the obtained electrolyte exhibits high thermal stability, outstanding Li+ transference number (0.95), pleasing ionic conductivity (0.722 mS cm-1), and broad chemical window (greater than5.85 V) at ambient temperature. As a result of the electrolyte structural merits, the Li||LFP cells displayed excellent cycling stability (96.4% reversible capacities after 300 cycles at 0.2C) without additional auxiliary heating. This ingenious strategy is expected to providing a new perspective for advanced performance and high safety LMBs.

An Ultra-Stretchable Polyvinyl Alcohol Hydrogel Based on Tannic Acid Modified Aramid Nanofibers for Use as a Strain Sensor.

The mechanical performance is critical for hydrogels that are used as strain sensors. p-Aramid nanofiber (ANF) is preferable as an additive to the reinforce the mechanical performance of a poly(vinyl alcohol) (PVA). However, due to the limited hydrogen bond sites, the preparation of ultra-stretchable, ANF-based hydrogel strain sensor is still a challenge. Herein, we reported an ultra-stretchable PVA hydrogel sensor based on tea stain-inspired ANFs. Due to the presence of numerous phenol groups in the tannic acid (TA) layer, the interaction between PVA and the ANFs was significantly enhanced even though the mass ratio of TA@ANF in the hydrogel was 2.8 wt‱. The tensile breaking modulus of the PVA/TA@ANF/Ag hydrogel sensor was increased from 86 kPa to 326 kPa, and the tensile breaking elongation was increased from 356% to 602%. Meanwhile, the hydrogel became much softer, and no obvious deterioration of the flexibility was observed after repeated use. Moreover, Ag NPs were formed in situ on the surfaces of the ANFs, which imparted the sensor with electrical conductivity. The hydrogel-based strain sensor could be used to detect the joint movements of a finger, an elbow, a wrist, and a knee, respectively. This ultra-stretchable hydrogel described herein was a promising candidate for detecting large-scale motions.

Composite Aramid Membranes with High Strength and pH-Response.

The pH-responsive membrane is a new wastewater treatment technology developed in recent years. In this paper, a novel film with intelligent pH-responsiveness was first prepared by blending functional gates comprised of hydrolyzed aramid nanofibers (HANFs) into aramid nanofiber (ANF) membranes via a vacuum filtration method. Those as-prepared membranes exhibited dual pH-responsive characteristics, which were featured with a negative pH-responsiveness in an acidic environment and a positive pH-responsiveness in basic media. These dual pH-responsive membranes also exhibited a high tensile strength which could still reach 55.74 MPa (even when the HANFs content was as high as 50 wt%), a high decomposition temperature at ~363 °C, and good solvent resistance. The membranes described herein may be promising candidates for a myriad of applications, such as the controlled release of drugs, sensors, sewage treatment, etc.