High-voltage plateau

Cathode material High-voltage plateau redox couple Discharge voltage" (V vs. Li /Li ) Theoretical capacity (mAh g )... 

Lithium insertion in microporous hard carbons (region 3 in Fig. 2) is described in section 6. High capacity hard carbons can be made from many precursors, such as coal, wood, sugar, and different types of resins. Hard carbons made from resole and novolac resins at temperatures near 1000°C have a reversible capacity of about 550 mAh/g, show little hyteresis and have a large low voltage plateau on both discharge and charge. The analysis of powder X-ray diffraction. 

The majority of controlled-potential electrochemistry has been carried out at mercury-pool electrodes. This is because of the vast amount of reference data available from polarography. Furthermore, the uniform and reproducible surface, and the high voltage for solvent reduction make the mercury pool particularly attractive relative to solid electrodes. As with electrodeposition, controlled-potential electrolysis rates are dependent on electrode area, stirring rates, solution volume, solution temperature, and supporting electrolyte. If the diffusion layer is uniform and the applied potential is such that one is on the diffusion plateau, the electrolysis obeys the relation... 

From the current-voltage characteristic it is seen that the current is inversely proportional to the electrode spacing, since h. At low values of FV/RT the current is linear in the applied voltage, and at sufficiently high values it approaches the limiting current exponentially. This behavior is sketched in Fig. 6.1.2. The ideal electrolytic cell behavior will be modified with a real electrolyte as a consequence of dissociation of the solvent, say water, at sufficiently high voltages. This will result in a plateau and then a subsequent current increase, as sketched in Fig. 6.1.2. 

Immediately after the two solutions are in contact, the high-voltage power supply is turned on to induce electroosmotic flow. As the fluid in reservoir 1 displaces the existing fluid in the microchannel, the electric current draw changes. Initially the current is constant and then changes linearly until it reaches another plateau once the initial fluid is completely replaced. The time required for the displacement represents the time required for the solution to travel through... 

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