Novel sulfur/polythiophene composites with core/shell structure composites were synthesized via an in situ chemical oxidative polymerization method with chloroform as a solvent, thiophene as a reagent, and iron chloride as an oxidant at 0 °C. Different ratios of the sulfur/polythiophene composites were characterized by elemental analysis, FTIR, XRD, SEM, TEM, and electrochemical methods. A suitable ratio for the composites was found to be 71.9% sulfur and 18.1% polythiophene as determined by CV and EIS results. Conductive polythiophene acts as a conducting additive and a porous adsorbing agent. It was uniformly coated onto the surface of the sulfur powder to form a core/shell structure, which effectively enhances the electrochemical performance and cycle life of the sulfur cells. The initial discharge capacity of the active material was 1119.3 mA h g−1, sulfur and the remaining capacity was 830.2 mA h g−1 sulfur after 80 cycles. After a rate test from 100 to 1600 mA g−1 sulfur, the cell remained at 811 mA h g−1 sulfur after 60 cycles when the current density returned to 100 mA g−1 sulfur. The sulfur utilization, the cycle life, and the rate performance of the S−PTh core/shell electrode in a lithium−sulfur battery improved significantly compared to that of the pure sulfur electrode. The pore and thickness of the shell affected the battery performance of the lithium ion diffusion channels.

A multiwalled carbon nanotube/sulfur (MWCNT@S) composite with core-shell structure was successfully embedded into the interlay galleries of graphene sheets (GS) through a facile two-step assembly process. Scanning and transmission electron microscopy images reveal a 3D hierarchical sandwich-type architecture of the composite GS-MWCNT@S. The thickness of the S layer on the MWCNTs is ~20 nm. Raman spectroscopy, X-ray diffraction, thermogravimetric analysis, and energy-dispersive X-ray analysis confirm that the sulfur in the composite is highly crystalline with a mass loading up to 70% of the composite. This composite is evaluated as a cathode material for Li/S batteries. The GS-MWCNT@S composite exhibits a high initial capacity of 1396 mAh/g at a current density of 0.2C (1C = 1672 mA/g), corresponding to 83% usage of the sulfur active material. Much improved cycling stability and rate capability are achieved for the GS-MWCNT@S composite cathode compared with the composite lacking GS or MWCNT. The superior electrochemical performance of the GS-MWCNT@S composite is mainly attributed to the synergistic effects of GS and MWCNTs, which provide a 3D conductive network for electron transfer, open channels for ion diffusion, strong confinement of soluble polysulfides, and effective buffer for volume expansion of the S cathode during discharge.

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This work describes the synthesis of Chevrel phase Mo6S8 nanocubes and its application as the anode material for rechargeable Zn-ion batteries. Mo6S8 can host Zn(2+) ions reversibly in both aqueous and nonaqueous electrolytes with specific capacities around 90 mAh/g, and exhibited remarkable intercalation kinetics and cyclic stability. In addition, we assembled full cells by integrating Mo6S8 anodes with zinc-polyiodide (I(-)/I3(-))-based catholytes, and demonstrated that such full cells were also able to deliver outstanding rate performance and cyclic stability. This first demonstration of a zinc-intercalating anode could inspire the design of advanced Zn-ion batteries.

Lithium-sulfur (Li-S) redox fl ow battery (RFB) is a promising candidate for high energy large-scale energy storage application due to good solubility of long-chain polysulfi de species and low cost of sulfur. Here, the fundamental understanding and control of lithium polysulfi de chemistry are studied to enable the development of liquid phase Li-S redox fl ow prototype cells. These differ signifi cantly from conventional static Li-S batteries targeting for vehicle electrifi cation. A high solubility of the different lithium polysulfi des generated at different depths of discharge and states of charge is required for a fl ow battery in order to take full advantage of the multiple electron transitions. A new dimethyl sulfoxide based electrolyte is proposed for Li-S RFBs, which not only enables the high solubility of lithium polysulfi de species, especially for the short-chain species, but also results in excellent cycling with a high Coulombic effi ciency. The challenges and opportunities for the Li-S redox fl ow concept have also been discussed in depth.

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Rapid in situ chemical oxidation polymerization of polyaniline was carried out to coat MWCNT-core/sulfurshell structures. The S-coated-MWCNTs were obtained by ballmilling and thermal treatment. The polymerization was carried out by adding 2.6 g of dispersed S/MWCNT and 0.65 g of aniline hydrochloride to ethanol, and then mixing in a certain amount of ammonium peroxydisulfate dissolved in 0.2 M HCl. The addition of S/MWCNT reduced the polymerization time from 60 to 21 min. The composites were characterized by elemental analysis, FTIR, XRD, SEM, TEM, and electrochemical methods. A 70.0% sulfur, 20.2% emeraldine PANi salt and 9.8% MWCNT composite gave the typical two reduction peaks and two oxidation peaks; these are due to three polysulfide species. The initial discharge capacity was 1334.4 mAh g À1 -S for the PANi-S/ MWCNT electrode and the remaining capacity was 932.4 mAh g À1 -S after 80 cycles. The columbic efficiency doubled to 92.4% compared to S-MWCNT-2. The rate of the reaction upon using PANi-S/MWCNT electrode was found to be almost twice that of the S/MWCNT composites. Because of the porous polymer, the diffusion distance of the lithium ion from the bulk liquid was reduced. The gel-like cathode composites and the higher conductivities improved the kinetics of the lithium sulfur redox reaction.