13 Electrochemistry in Laboratory Flow Systems

Organic electrosynthesis in flow reactors is an area of increasing interest, with efficient mass transport and high electrode area to reactor volume present in many flow electrolysis cell designs facilitating higher rates of production with high selectivity. The controlled reaction environment available in flow cells also offers opportunities to develop new electrochemical processes. In this chapter, various types of electrochemical flow cells are reviewed in the context of laboratory synthesis, paying particular attention to how the different reactor environments impact upon the electrochemical processes, and the factors responsible for good cell performance. Coverage includes well-established plane-parallel-plate designs, reactors with small interelectrode gaps, extended-channel electrolysis cells, and highly sophisticated designs with rapidly rotating electrodes to enhance mass transport. In each case, illustrative electrosyntheses are presented.

15 Paired Electrolysis

While paired electrochemical reactions have a history that can be traced back to the 19th century and have been very effectively used for the production of commercial products, the larger synthetic community has only recently started to embrace the opportunities this approach offers to maximize the overall energy and atom efficiency of electrochemical processes. In this review, a summary of these efforts is presented in the context of four classes of paired electrochemical reactions. These classes of reaction involve parallel processing of products at the anode and cathode, divergent reactions that use a single starting material in different ways, convergent reactions that combine products made at the anode and cathode, and sequential reactions that pass a substrate between the electrodes.

Towards reliable three-electrode cells for lithium–sulfur batteries

Three-electrode measurements are valuable to the understanding of the electrochemical processes in a battery system. However, their application in lithium–sulfur chemistry is difficult due to the complexity of the system...

Impedance spectroscopy of capacitor systems based on saccharide-derived porous carbon materials.

The electrochemical processes in capacitor systems based on porous carbon materials (PCMs) derived from glucose, lactose, and saccharose at activation temperature of 800 and 1000°C are explored using impedance spectroscopy method. An equivalent electric circuit, which allows modeling of the impedance spectra in the frequency range from 10-2 to 105 Hz, is proposed, and a physical interpretation of each element of the electrical circuit is presented. It is set that in capacitor systems on the basis of the explored materials the accumulation of capacitance occurs due to the formation of a double electric layer at the electrode/electrolyte boundary, and Faradaic processes are minimized. The specific capacity of supercapacitors based on PCMs obtained at 800°C is 91-154 F/g due to the developed microporous structure of materials.