Lithium redox reactions

Whatever the application, one of the main parameters characterizing an anode is its capacity, which can be defined as the number of Li-based charges that can be reversibly stored in a unit mass (specific capacity, traditionally expressed in Ah/g 1 Ah = 3600 C) or in a unit volume (volumetric capacity, expressed in Ah/cm ) of the active anode material. For instance, the specific capacity of an anode made of pure lithium is just the number of Li atoms/g in the metal multiplied by the elementary charge (since lithium redox reactions involve one electron only), i.e., 3.860 Ah/g or 3860 mAh/g (corresponding to 2046 mAh/cm ). For an alloy such as Li My, the specific capacity can he expressed as ... 

Nitromethane was treated with lithium aluminiumhydride in diethyl ether medium and at ambient temperature. This was followed by an explosion which pulverised the equipment. This accident can be explained by the fact that there was a redox reaction, but also by the formation of nitromethane lithium, unless... 

See Dibenzoyl peroxide Lithium tetrahydroaluminate Hydrazine Oxidants REDOX REACTIONS ROCKET PROPELLANTS... 

The reactions of azofurazans have been used to obtain the hydrazine and the amino derivatives. For example, reactions of azofurazans, including macrocyclic azofurazan 196, with BunLi and the lithium derivatives of methylfur-azans were studied. Several competitive processes were found to occur (1) the addition of a Li reagent at the N=N bond (2) the redox reaction giving rise to hydrazofurazans and (3) the reaction of the side chain of azofurazan (Scheme 44) <2004RCB615>. 

Lithium isotopes do not fractionate as a result of redox reactions, but Li is preferentially partitioned into the fluid phase, whereas Li prefers sites in alteration minerals such as micas. The Li/ Li ratios of mica and chlorite in alteration zones around uranium deposits are higher and decrease to lower values with distance from the ore relative to background mica in the Athabasca Group sandstones. In barren areas, high ratios are rare and background ratios are dominant. When used together, the isotopic composition of uranium and lithium can be utilized to refine both the genesis of uranium deposits and as exploration tools. 

This electrolyte provides the required conductivity to the solution, but its ions may themselves undergo redox reactions before the solvent does. The choice of the supporting electrolyte, in turn, depends not only on the resistance of its ions to being reduced or oxidized but also on its solubility in the solvent in question. Tetraalkylammonium ions are generally the preferred cations, otherwise alkali metal ions such as lithium or sodium may be employed, and perchlorate or hexafluorophosphate are commonly the anions of choice. 

The lithium alkyltelluroselenolates undergo internal redox reactions below room temperature to form dialkyl ditellurium and the diselenide anion. The phenyl derivative is stable under these conditions2. 

Intercalation reactions of the dichalcogenides with alkali metals are redox reactions in which the host lattice is reduced by electron transfer from the alkali metal. Lithium and sodium intercalation reactions, for example, have been studied using cells of the type Li/LiC104-dioxolane/MX2 andNa/Nal-propylene carbonate/MX2. The reactions proceed spontaneously to form the intercalation compound if the cell is short circuited alternatively, a reverse potential can be apphed to control the composition of the final product. Apart from their application in synthesis, such electrochemical cells can be used to obtain detailed thermodynamic information and to establish phase relations by measuring the dependence of the equilibrium cell voltage on composition (see Figure 4). 

Figure 10.6 shows the CV of a LiMn2O4 electrode on a cell with Li foil for both the reference and auxiliary electrodes in ethylene carbonate plus dimethyl carbonate solution of LiAsFg (1 M) (Sinha and Munichandraiah, 2008). The pair of peaks at larger potential corresponds to the deintercalation/intercalation of Li in the range 0 < X < 0.5 for Li Mn2O4, whereas the pair of peaks at lower potentials is attributable to this process for 0.5 < x < 1, both accompanied by reversible Mn(lV)/Mn(lll) redox reactions. Following Xia and Yoshio (1996), the later electrochemical process corresponds to the removal/addition of Li+ ions from/into half of the tetrahedral sites in which the lithium intercalation occurs. The former couple is then attributed to this process at the other tetrahedral sites where lithium intercalations do not occur. 

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