Carbon-sulfur cathode

The triple bond of the cyano group in benzonitrile is also affected by Sx anions thiobenzamide was formed in this case in a 40% yield [255,256]. An interesting example of a simultaneous introduction of both sulfur and carbon using a sacrificial carbon-sulfur cathode is the formation of 4-morpholino-a-thioxoethaneditioate from morpholine [264]. 

The rare 1,2,3-dithiazine ring system was prepared by the relatively unusual method of electrochemical synthesis <89BSF433,90BSF427). The electrolysis is performed using a carbon-sulfur cathode, which acts as a rich source of highly nucleophilic sulfur radical anions. These attack the substrate a,)S-unsaturated nitriles (166) or (168) to give radical intermediates which lead to the 1,2,3-dithiazine products by attack on the solvent (167) or by dimerization (169) (Scheme 17). 

Ji X, Lee KT, Nazar LF (2009) A highly ordered nanostructured carbon-sulfur cathode for lithium-sulphur batteries. Nat Mater 8 500-506... 

A recent report describes a cell derived from a highly ordered nanostractured carbon-sulfur cathode (Figure 23.1). This cell exhibits a high reversible capacity of up to 1.320 mAh g . This is an important improvement that suggests future pathways to further improve capacity and cyclability [25]. 

In applications where Nafion is not suitable, at temperatures above 200 °C with feed gas heavily contaminated with CO and sulfur species, a phosphoric acid fuel cell (PAFC)-based concentrator has been effective [15]. Treating the gas shown in Table 1, a H2 product containing 0.2% CO, 0.5%CO2 and only 6 ppm H2S was produced. The anode electrode was formed from a catalyst consisting basically of Pt-alloy mixed with 50% PTFE on a support of Vulcan XC-72 carbon. The cathode was... 

Also, intermolecular coupling with dienes has been satisfactorily accompHshed using a carbon fiber cathode. In the case of unsymmetrically substituted dienes, a high regioselectivity toward the less substituted terminal double bond was found [112]. Electroreduction of nonconjugated enones and ynones containing a sulfur or a nitrogen atom in the... 

The liquid (sulfur-based compounds) and sohd sulfur cathodes (items 6 and 7) do not develop surface chemistry that can be separated from their main electrochemical redox reactions. Hence, when the reduction of sulfur SO2 or SOCI2 produces insoluble species such as LiCl, LijS, and LijO, they precipitate on the current collector [9]. When formed, LijS can be reoxidized, up to elemental sulfur, via various LLS intermediate compounds [10]. Hence, the current collector, which may be aluminum (Al) plus carbon in the case of sulfur cathodes or carbon in the case of SOCI2 cathodes, does not develop intrinsic surface chemistry beyond the precipitation of the reduction products of the active mass. 

Huang J-Q, Zhang Q, Zhang S-M, Liu X-F, Zhu W, Qian W-Z, Wei F (2013) Aligned sulfur-coated carbon nanotubes with a polyethylene glyeol barrier at one end for use as a high efficiency sulfur cathode. Carbon 58 99-106... 

The sodium/sulfur battery operates around 570-620 K and consists of a molten sodium anode and a liquid sulfur cathode which contains a carbon fibre matrix for conduction. The anode and cathode are separated by a solid -alumina electrolyte (see Section 28.2). The cell reaction is ... 

Fig. 3b. This ceU used a graphite plate anode covered with Pd black nanoparticles and a porous carbon paper cathode covered with Pt black nanoparticles. Peak power density, 26 mWcm , was achieved with 1M formic acid in 0.5 M sulfuric acid anolyte and a blank 0.5 M sulfuric acid catholyte. The cathodic elecfrol)de stream was required to maintain an inter-diffusion zone with sufficient separation from the cathode and to facilitate ionic transport to the cathodic active sites.

A typical Li-S cell consists of a lithium metal anode and a sulfur-carbon composite cathode with an organic liquid electrolyte in between, which is shown in Fig. 1. The Li-S chemistry is based on the following conversion reaction ... 

Shortly after the discovery of mesoporous carbon (CMK-3)-sulfur cathode composites [31], many research activities on nanostmctured carbon materials for high-performance Li-S batteries have been conducted [32-57]. 

A comprehensive, systematic work related to Li-sulfur battery systems is described, beginning with the Li anode challenges, carbon-encapsulated sulfur cathodes, and various kinds of relevant electrolyte solutions (29). 

A catalyst that can prevent polysulfide anions from precipitating as solids would be highly desirable. While a catalyst still remains to be discovered, several approaches, common in catalysis, have been employed to improve the cycling performance of lithium-sulfur batteries. For example, new electrolytes [18-21], protective films [22], solubiHzed sulfides [23], and new cathodes [24] have been developed. However, the performance results have either not been reported or have been found to be inadequate for practical applications. For example, a disordered mesoporous carbon-sulfur composite in conjunction with ionic liquid electrolytes has been fabricated. This system achieves high initial capacity that deteriorates rapidly [20]. 

Choi YJ, Ahn JH, Ahn HJ (2008) Effects of carbon coating on the electrochemical properties of sulfur cathode for Uthium/sulfur cell. J Power Sourc 184 548-552... 

Sulfur dioxide is soluble in the electrolyte. Sulfur is soluble up to about 1 mol dm 3, but it precipitates in the cathode pores near the end of discharge. Lithium chloride is essentially insoluble and precipitates on the surfaces of the pores of the carbon cathode, forming an insulating layer which terminates the operation of cathode-limited cells [37],... 

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