Fabrication of chiral mesoporous carbonaceous nanofibers and their electrochemical energy storage

A highly conductive quasi-solid-state electrolyte based on helical silica nanofibers for lithium batteries

The replacement of flammable liquid electrolytes by inorganic solid ones is considered the most effective approach to enhancing the safety of Li batteries. However, solid electrolytes usually suffer from low ionic conductivity and poor rate capability. Here we report a unique quasi-solid-state electrolyte based on an inorganic matrix composed of helical tubular silica nanofibers (HSNFs) derived from the self-assembly of chiral low-molecular-weight amphiphiles. The HSNFs/ionic liquid quasi-solid-state electrolyte has high thermal stability (up to ∼370 °C) and good ionic conductivity (∼3.0 mS cm⁻¹ at room temperature). When tested as the electrolyte in a LiFePO₄/Li cell, excellent rate capability and good cycling stability are demonstrated, suggesting that it has potential be the electrolyte for a new generation of safer Li batteries.

A quasi-solid-state electrolyte of high-ionic conductivity is constructed from an inorganic matrix composed of helical silica nanofibers (HSNFs) derived from the self-assembly of chiral gelators.

Strong-Induced CPL Emission Promoted from Achiral Conjugated Polymer-Containing Emissive Nematic Liquid Crystals (P-N*-LCs)

With the rapid development on 3D printing technology, more and more works have been devoted to 3D display. 3D display will really come true by using circularly polarized luminescence (CPL)-active materials with both high quantum yield and dissymmetry factor (g_em ) in organic light-emitting diode or liquid crystals (LCs). But so far most of these CPL materials cannot meet the real application requirement because of the low g_em values in the range of 10^-5 -10^-2 . In this paper, ternary chiral emissive LCs (P-N*-LCs) is designed by doping chiral binaphthyl-based enantiomers as chiral dopant (Guest 1) and achiral conjugated polymer as induced CPL emitter (Guest 2) into nematic liquid crystal (N-LCs) Host 5CB. Both Guest 1 and Guest 2 show excellent compatibility with Host 5CB. The obtained ternary P-N*-LCs can emit strong-induced CPL signal with g_em up to 1.12 and Ф_FL up to 66.1%. This work first develops a new strategy for the smart design of excellent CPL materials from versatile achiral conjugation fluorescence polymers.

Boosting Ultra-Fast Charge Battery Performance: Filling Porous nanoLi4Ti5O12 Particles with 3D Network of N-doped Carbons

Lithium titanium oxide (Li₄Ti₅O₁₂)-based cells are a promising technology for ultra-fast charge-discharge and long life-cycle batteries. However, the surface reactivity of Li₄Ti₅O₁₂ and lack of electronic conductivity still remains problematic. One of the approaches toward mitigating these problems is the use of carbon-coated particles. In this study, we report the development of an economical, eco-friendly, and scalable method of making a homogenous 3D network coating of N-doped carbons. Our method makes it possible, for the first time, to fill the pores of secondary particles with carbons; we reveal that it is possible to cover each primary nanoparticle. This unique approach permits the creation of lithium-ion batteries with outstanding performances during ultra-fast charging (4C and 10C), and demonstrates an excellent ability to inhibit the degradation of cells over time at 1C and 45 °C. Furthermore, using this method, we can eliminate the addition of conductive carbons during electrode preparation, and significantly increase the energy density (by weight) of the anode.

Design of gradient nanopores in phenolics for ultrafast water permeation

Ultra-permeable and robust membranes are prepared by creating a gradient nanoporous structure in low-cost phenolics, enabled by the spontaneous assembly of gradually enlarged phenolic nanoparticles.

Membrane technology is playing a pivotal role in providing potable water to our thirsty planet. However, the strong demand for highly permeable and durable membranes with affordable costs remains. Such membranes are synthesized herein by designing gradient nanopores in low-cost phenolics. The gradient nanopores are achieved by spontaneous assembly of phenolic nanoparticles with gradually enlarged sizes. These particles nucleate and grow as a result of ZnCl₂-accelerated thermopolymerization of resol in the progressive downward gelating polymer. Subsequent removal of the gelated polymer and ZnCl₂ exposes the gradient nanopores. The gradient nanopores endow the phenolic structures with unprecedented permselectivity when used in membrane separation, totally rejecting fine particulates down to 5 nm dispersed in water or aggressive solvents while allowing water to permeate up to two orders of magnitude faster than other membranes with similar rejections. Our work opens up an avenue for the rational design and affordable synthesis of ultrafast membranes.

SiC Nanofibers as Long-Life Lithium-Ion Battery Anode Materials

The development of high energy lithium-ion batteries (LIBs) has spurred the designing and production of novel anode materials to substitute currently commercial using graphitic materials. Herein, twisted SiC nanofibers toward LIBs anode materials, containing 92.5 wt% cubic β-SiC and 7.5 wt% amorphous C, were successfully synthesized from resin-silica composites. The electrochemical measurements showed that the SiC-based electrode delivered a stable reversible capacity of 254.5 mAh g⁻¹ after 250 cycles at a current density of 0.1 A g⁻¹. It is interesting that a high discharge capacity of 540.1 mAh g⁻¹ was achieved after 500 cycles at an even higher current density of 0.3 A g⁻¹, which is higher than the theoretical capacity of graphite. The results imply that SiC nanomaterials are potential anode candidate for LIBs with high stability due to their high structure stability as supported with the transmission electron microscopy images.

Left-handed helical polymer resin nanotubes prepared by using N-palmitoyl glucosamine

Although the preparation of single-handed helical inorganic and hybrid organic-inorganic nanotubes is well developed, approaches to the formation of single-handed organopolymeric nanotubes are limited. Here, left-handed helical m-phenylenediamine-formaldehyde resin and 3-aminophenol-formaldehyde resin nanotubes were prepared by using N-palmitoyl glucosamine that can self-assemble into left-handed twisted nanoribbons in a mixture of methanol and water. In the reaction mixture, the helical pitch of the nanoribbons decreased with increasing reaction time. The resin nanotubes were obtained after removing the N-palmitoyl glucosamine template, and circular dichroism spectroscopy indicated that the organopolymeric nanotubes had optical activity. Carbonaceous nanotubes were then prepared by carbonization of the 3-aminophenol-formaldehyde resin nanotubes.

Single-Handed Helical Carbonaceous Nanotubes: Preparation, Optical Activity, and Applications

Carbon-based nanomaterials have been widely studied in the past decade. Three approaches have been developed for the preparation of single-handed helical carbonaceous nanotubes. The first approach uses the carbonization of organopolymeric nanotubes, where the organic polymers are polypyrrole, 3-aminophenol-formaldehyde resin, and m-diaminobenzene-formaldehyde resin. The second approach uses the carbonization of aromatic ring-bridged polybissilsesquioxane followed by the removal of silica. Micropores exist within the walls of the carbonaceous nanotubes. The third approach uses the carbonization of organic compounds within silica nanotubes. This hard-templating approach drives the formation of helical carbonaceous nanotubes containing twisted carbonaceous nanoribbons. All of these helical carbonaceous nanotubes exhibit optical activity, which is believed to originate from the chiral π-π stacking of aromatic rings. They can be used as chirality inducers, and for lithium-ion storage.

Doping-template approach of porous-walled graphitic nanocages for superior performance anodes of lithium ion batteries

Removal of the N-doped template creates nanopores in the shells of nanocages. The created nanopores enhance fast ion diffusion.