Real potentiostatic constraint

Diffusion-controlled lithium transport involves the following the system is so kinetically facile that the equilibrium concentration of lithium is quickly reached at the interface between the electrode and electrolyte at a moment of potential stepping for CT experiments. The instantaneous depletion and accumulation in the lithium concentration at the interface caused by the chemical diffusion away from and to the interface (and to and away from the bulk electrode) is completely compensated by the supply and release away from and into the electrolyte, respectively. This condition is referred to as real potentiostatic constraint at the interface between the electrode and the electrolyte. 

Serious efforts have been made to explain the atypical lithium transport behavior using modified diffusion control models. In these models the boundary conditions -that is, "real potentiostatic constraint at the electrode/electrolyte interface and impermeable constraint at the back of the electrode - remain valid, while lithium transport is strongly influenced by, for example (i) the geometry of the electrode surface [53-55] (ii) growth of a new phase in the electrode [56-63] and (iii) the electric field through the electrode [48, 56]. 

The above argument, along with the evidences presented in Sections 5.3.2.1-5.3.2.2, indicates that other transport mechanisms than diffusion-controlled lithium transport may dominate during the CT experiments. Furthermore, the Ohmic relationship between Jiiu and A indicates that internal cell resistance plays a critical role in lithium intercalation/deintercalation. If this is the case, it is reasonable to suggest that the interfacial flux of lithium ion is determined by the difference between the applied potential E pp and the actual instantaneous electrode potential (t), divided by the internal cell resistance Keen- Consequently, lithium ions barely undergo any real potentiostatic constraint at the electrode/electrolyte interface. This condition is designated as cell-impedance-controlled lithium transport. 

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