Half cell test

Lithium cycling on a lithium substrate (Li-on-Li cycling) is another frequently used Li half-cell test [28], in which an excess of lithium (Qex is plated on a metal working electrode, and then constant-capacity cycling (<2ps) Qps is smaller than Qex) is continued until all the excess lithium is consumed. The FOM can be evaluated as shown in Eq.(4). 

It should be noted that in practical batteries such as coin cell (parallel plate configuration) or AA, C, and D (jelly-roll configuration), there is a stack pressure on the electrodes (the Li anodes are pressed by the separator), and the ratio between the solution volume and the electrode s area is usually much lower than in laboratory testing. Both factors may considerably increase the Li cycling efficiency obtained in practical cells, compared with values measured for the same electrolyte solutions in the Li half-cell testing described above. It has already been proven that stack pressure suppresses Li dendrite formation and thus improves the uniformity of Li deposition-dissolution processes [107], The low ratio between the solution volume and the electrode area in practical batteries decreases the detrimental effects of contaminants such as Lewis acids, water, etc., on Li passivation. 

For use as PAFC catalysts a trimetallic colloidal (3.8 nm) precursor of composition Pt5oCo3oCr2o was prepared by co-reduction of the corresponding metal saks. " ] XRD examination showed that the particles consist of a trimetallic alloy with an ordered fee structure. In a standard half-cell test the electrocatalytic performance was compared with that of an industrial standard catalyst manufactured by co-precipitation and subsequent annealing to 900 °C, giving 5.7 nm trimetallic crystallites. Preliminary results have shown that the trimetallic colloid catalysts have advantages in respect of long-term stability - essential for PAFC catalysts. The decay of the potential after 22 h was found to be less than 10 mV. Further work is in progress. l... 

The synergistic effect between Pt and WC was demonstrated with Pt/WC powder catalysts. Thus, 7.5 wt% PtA 2C led to high specific activity of 156 mA/cm at 0.75 V (vs Ag/AgCl) in half cell test for methanol oxidation without Ru, which was commonly used with Pt for DMFC anodes (33). This specific activity represents higher electroactivity than that of commercial Pt-Ru/C electrocatalyst (20 wt% PtRu/C, E-Tek) imder the same experimental condition. Further improvement in the activity of methanol oxidation was observed when W2C was prepared to contain mesopores (34). There is also a report that 20 wt% Pt(W2C electrocatalysts show a higher mass current density (mA/mgpt) than 20 wt% Pt(C at the same potential under 0.5 M H2SO4 electrolyte, SCE reference electrode (155). 

Electrochemical leaching of Pt alloy catalysts has been deliberately applied to form core-shell materials with enhanced activities, either in half-cell tests [24, 25] or even... 

The single fuel cell test is one of the most direct and effective methods for the evaluation of catalyst layers and MEAs. Even if the results obtained by a half-cell test are very promising, the single-cell test is still a necessary step for performance validation of the developed catalyst layer and MEA. 

TECHNIQUES FOR PEM FUEL CELL TESTING 3.2.1. Half-Cell Testing... 

Half-Cell Testing for CO-Tolerant Anode Catalysts [31]... 

Fuel cell electrodes can be examined for their electrocatalytic behavior by ex situ or in situ voltammetry tests. In the case of ex situ tests, also known as half-cell tests, the properties of the electrode are evaluated using a standard three-electrode cell where an aqueous solution (e.g., perchloric acid) simulates the proton-conducting electrolyte in a PEMFC. Half-cell tests are a convenient and relatively fast method of screening electrocatalysts however. 

The other method that is used for catalyst electrochemical performance, is called half cell testing. Half cell apparatus can be used for different kinds of... 

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