Solid-state redox reaction

Characteristic Features of Solid-State Redox Reactions in Li1 xNi02... 

According to our analytical results on the solid-state redox reaction of LiNi02 based on the phenomenological expression for solid-state redox potentials of insertion electrodes [23], the reaction consists of three redox systems characterized by potentials of 4.23, 3.93, and 3.63V with re-... 

Figure 9. Variation of E with the electrochemical density of states (dx/dE) for the solid-state redox reaction of LiNi02. The system described by (dy/d ), which is the sum of the (dx/dE) values, is characterized by three redox systems, (b) Comparison of the observed (O) and calculated E(y) curves for the reaction UNi02 + yLi —> LiyNi02. The E versus y curve was obtained by integrating (dy/dE) in (a) with respect to E from infinity to E.

Proton penetration into RUO2 has also been detected by other techniques, such as potential step (368, 377), current step (378, 379), membrane doublecell (366), and spectroelectrochemistry (380), and it has been attributed to bulk diffusion (permeation) in some cases (368,377) and regarded as unimportant for surface area measurement in other cases (372). In spite of the above, it is not clear why proton diffusion alone is assumed to be the reason for the effect observed it seems that a state of surface reaction involving increase or decrease of surface oxidation could account for the results equally well. Also, the connection between a solid state redox reaction (367,381) involving several Ru valence states in the oxide and the requirement (146,382) of proton intercalation to achieve charge balance at and OH sites as oxidation or reduction takes place was not noted. 

In this equation, A denotes the geometrical area of the electrode and T is the surface concentration of electroactive adsorption sites. This last parameter can be calculated from determination of the charge pass associated to solid-state redox reaction, q, because q, = nFAY, or from capacitance determination using the relationship (Brown and Anson, 1977 Smith et al., 1979) ... 

PANI/MnO nanocomposite, synthesized by a facile and effective one-step solid-state redox reaction between frozen aniline and solid KMnO, displayed reversible and highly efficient UV photoresponse properties [182]. Yu et al. [183,184] reported high photoelectrocatalytic activity of... 

The electrons for the radical anions are injected by the cathode, consisting of a metal with a low work function. Usually, calcium, a coevaporated magnesium-silver alloy with a Mg Ag ratio of 10 1, or aluminum can be used. The corresponding work functions are 2.9 eV, 3.7 eV, and 4.3 eV, respectively. The injection of the electrons can be facilitated by an additional layer of lithium fluoride [40]. Several mechanisms have been proposed to explain the electron injection improvement [41,42]. The most plausible mechanism is the dissociation of LiF toward metalHc hthium, which acts as a redox dopant for the electron-transport layer. From the cathode the electrons are then transported through the electron- transport layer on the LUMO level via hopping transport, which is in principle a mutual solid-state redox reaction. 

Ohzuku T, Ueda A (1994) Solid-state redox reactions of LiCo02 (R-3m) for 4 volt secondary lithium cells. J Electrochem Soc 141 2972-2977... 

As described above, LiNi02 is an attractive material for lithium-ion batteries. However, it is difficult to operate high-volume lithium-ion batteries consisting of LiNiOj and (natural) graphite (or other negative electrode materials) safely for thousands of cycles. The difficulty is associated with the formation of nickel dioxide, so that it is hopeless to cope with this problem in a usual manner. However, it may be possible using a characteristic feature of the solid-state redox reaction of... 

The equilibrium potential of a solid-state redox reaction associated with Li ions insertion and extraction usually shows subtle dependence on the reaction parameter, X (concentration of ions and electrons in the host matrix). This often makes... 

Fig. 13.8 (a) Voltage-composition profile for the solid-state redox reaction of an insertion compound Li < H > showing three potential region and (b) corresponding differential capacity (dx/dV) curve... 

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