Free-Standing Sulfur-Carbon Nanotube Electrode with a Deposited Sulfur Layer for High-Energy Lithium-Sulfur Batteries.

To obtain a high S-loading cathode for a Li-S battery, we propose a free-standing carbon nanotube (CNT)-based S cathode, which consists of two layers: a pure S deposition layer with a thickness of 20 m, and a S-containing CNT film (S-CNT). Based on scanning electron microscopic (SEM) studies, it was observed that the S layer completely vanished when the cell with the S/S-CNT cathode was discharged to 2.1 V after cell assembly, indicating that the thick sulfur film dissolved in the form of polysulfide intermediates during discharge.

Carbon Nanotube-Based Sulfur Cathode with a Mesoporous Carbon-Silica Composite for Long Cycle Life Li-S Batteries.

The use of carbon nanotube (CNT) films as a sulfur host is a promising approach to improve the sulfur loading and energy density of Li-S batteries. However, the inability to durably incorporate polysulfides within the cathode structure results in a limited cycle life. Herein, we propose a CNTbased sulfur cathode with carbon-coated ordered mesoporous silica (c-OMS) to overcome the cycle performance issue.

Three-Layer Sulfur Cathode with a Conductive Material-Free Middle Layer.

An ingenious design for a three-layer sulfur cathode is demonstrated, in which the pure sulfur layer is sandwiched between carbon nanotube (CNT) films. The unique feature of this particular model is that the sulfur layer does not contain any conductive materials, and therefore, the top CNT film of the prepared three-layer CNT/S/CNT electrode is electrically isolated from the bottom CNT film. Scanning electron microscopy studies revealed that the three-layer cathode was transformed into a single CNT cathode, with proximate contact between the two CNT films in the upper plateau of the first discharge.

A Sulfur-Infused Separator for Boosting Areal Capacity of Li-S Batteries.

This study presents a new approach for enabling the development of high-performance lithium-sulfur (Li-S) cells by simply inserting a sulfur-infused separator (SIS) between a common S cathode and a Li metal anode. All solid sulfur electrically isolated from the cathode is electrochemically reduced to polysulfides during the first discharge. Notably, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) studies have demonstrated that the S in the separator disappears completely even when the cell is discharged to 2.

A Mesoporous Chelating Polymer-Carbon Composite for the Hyper-Efficient Separation of Heavy Metal Ions.

The removal of heavy-metal ions from wastewater is an important objective from a public-health perspective, and chelating agents can be used to achieve this aim. Herein, we report the synthesis of mesoporous carbon as a chelating polymer host using nanoarchitectonics approach. Carboxymethylated polyethyleneimine, a chelating polymer, was incorporated into the mesopore walls of mesoporous carbon to create a polymer-mesoporous-carbon composite.

A Novel Emulsion-Based Replica Method for the Synthesis of Mesoporous Carbon.

We present a novel approach for the synthesis of large-pore mesoporous carbon with a highly porous structure, based on an oil/water (O/W) emulsion templating method. For the formation of oil-in-water emulsions with nanoscale oil droplets, polyvinylpyrrolidone was used as an emulsifier. Mesoporous carbon materials with large mesopores were successfully synthesized via a three-step process: (1) polymerization in the oil-in-water emulsion, (2) filtration, and (3) carbonization.