Lithium theoretical specific capacity

It is known about the existence of lithium silicide, Li6Si2, which is close to intermetallic compounds, and also that silicon is capable to form with lithium different alloys. We have calculated the theoretical specific capacity of such possible compounds, as well as pure silicon (Table 2). It is possible to explain from the Table 2 the noticeable increase of capacity for graphite electrodes (11%) even at the small content of Si (3wt%). We can suppose that some of such compounds (LixSiy) with high capacity may form... 

The high theoretical specific capacity (3862 Ah kg ) and capacity density (2047 Ah L" ) of the lithium-metal electrode, together with its promising redox potential, give the battery unique advantages in terms of specific energy and energy density. 

To avoid the problems associated with lithium metal, lithium insertion materials (e.g., graphitic carbons) are being investigated as negative electrodes. With respect to lithium metal, the use of negative insertion materials improves the cycle life and safety of the battery but lowers the cell voltage, the theoretical specific capacity, and the charge transfer rate [104]. 

The theoretical specific capacity of sulfur dioxide-lithium cells is 377 Ah/kg, the theoretical specific energy is 1170Wh/kg. In practice, the values of specific energy of up to 350 Wh/kg and power density of up to 100 W/kg are obtained. 

The current-producing reaction in manganese dioxide-lithium cells is described by Equation (11.2) here, indicator x is generally close to unity. In this case, the theoretical specific capacity of such a cell is 285 Ah/kg, which corresponds to the theoretical energy density of 998 Wh/kg at OCV of 3.5 V. The actual energy density for disk and cylindrical cells of a not too low capacity (above 0.1 Ah) is 200-350 Wh/kg and strongly depends on the discharge mode. 

C. Because of its initial discharge capacity (almost 93.5% of the theoretical specific capacity) and excellent cyclic ability, it may have great potential as a cathode for secondary lithium batteries. " ... 

Lithium-sulfur (Li-S) battery has a theoretical specific capacity of 1675 mAh/g and a theoretical energy density of 2500 Wh/kg (or 2800 Wh/L) according to the complete reduction from elemental sulfur to lithium sulfide (Li2S) by Eq. 7 ... 

Both nonaqueous and aqueous electrolyte-based Hthium-air batteries have similar theoretical specific energies ( 11000 Whkg based on Hthium alone), as shown in Table 22.1. Zheng et al. [39] simulated both aqueous and nonaqueous electrolyte-based Hthium-air batteries where the total weight of the Hthium, the carbon-based air electrode, and the electrolyte were considered. Their analysis showed that the maximum theoretical specific capacities of the cells are 435 and 940 mAh for lithium-air batteries with aqueous- and nonaqueous-based electrolytes, respectively. The main difference between these two kinds of Hthium-air batteries originates from the fact that the solvent is consumed in aqueous electrolyte-based lithium-air batteries, but it is not consumed in the nonaqueous electrolyte-based Hthium-air batteries. 

Table 2.1 Average voltage (vs. Li metal] and the theoretical specific capacity of a variety of possible lithium anodes. The theoretical specific capacities are given for the charge (llthiation] reaction except for lithium metal, which is given for the discharge (delithiation] reaction...

Fig. 2.2 Composition dependence of the experimental theoretical specific capacity of (CF c) cathode materials for primary lithium batteries. The theoretical capacity is calculated according to Eq. (2.11)...

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