Diffusion layer streaming electrolyte

The electrical double-layer structure at Ga/DMF, In(Ga)/DMF, and Tl(Ga)/DMF interfaces upon the addition of various amounts of NaC104 as a surface-inactive electrolyte has been investigated by differential capacitance, as well as by the streaming electrode method.358 The capacitance of all the systems was found to be independent of the ac frequency, v. The potential of the diffuse layer minimum was independent of... 

Streaming potential The interface of a mineral (rock) in contact with an aqueous phase exhibits surface charge. The currently accepted model of this interface is the EDL model of Stem. Chemical reactions take place between the minerals and the electrolytes in the aqueous phase, which results in a net charge on the mineral. Water and electrolytes bound to the rock surface constitute the Stern (or Helmholtz) layer. In this region, the ions are tightly bound to the mineral, while away from this layer (the so-called diffuse layer), the ions are free to move about. 

Figure 5.21 Diffusion layer on a plate in a streaming electrolyte with thickness increasing from = 0 to...

Water produced at the electrode-electrolyte interfaces transports through the electrode-gas diffusion layers by diffusion and convection toward the gas flow channels where it may be transferred to the reactant gas flow streams by convection and diffusion if the gas streams are sufficiently dry. It is essential that water is removed from the electrolyte-electrode interface either by the flowing gas streams or by some external water collection system in order to prevent any accumulation or flooding of the electrode-electrolyte interface regions ftat blocks the pores of the electrode-gas diffusion layer and prevents reactant gas to reach reaction sites causing cell concentration polarization or mass tranter loss. Water flooding issue and mass transfer loss are... 

The interdigitated flow-field design consists of two sets of dead-ended gas flow channels as shown in Figure 10.16a. The first set of dead-ended inflow channels carries the gas stream from the inlet ports and transfers to the electrode gas diffusion layer. The gas stream is forced by advection through the porous gas diffusion layer toward the electrode-electrolyte interface and toward the second set of dead-ended outflow channels and moves toward the gas stream outlet port. 

As we can see, gas concentration drops sharply from the bulk gas stream to the electrode surface within the concentration boimdary layer by convection and then linearly decreases by diffusion to the electrode-electrolyte reaction interface. 

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