Lithium specific capacity

Most commercial lithium-ion cells maufactured today use graphitic carbons from region 1 of Fig. 2. These are of several forms, with mesocarbon microspheres and natural graphites being the most commonly used. The specific capacity of these carbons is near 350 mAh/g. 

Main electrode features, which determine the energy density of an electrochemical storage cell, are the volumetric or specific capacity, i.e., the electric charge that electrodes can store per unit volume or weight, respectively, and the electrochemical potential they produce. Considering thermodynamic reasons, lithium, as being the most electropositive (-3.04 V vs. SHE) metal, is exceptional for use as... 

LiCo02, one of the most widely used cathode materials in lithium rechargeable batteries because of its high specific capacity, has been prepared in the form of... 

Lithium-Ion cell, graphite, specific capacity, irreversible capacity. 

The characteristics of a carbon material used as active reagent of the negative electrode (anode) of a Lithium-Ion cell considerably influence the power characteristics of the cell as a whole. Thus, the major parameters are the values of specific capacity per unit weight and volume, and also the... 

The specific capacity obtained in such Ams, actually corresponds to near theoretical limit of 372 mA-h/g, as calculated on a basis of classical LiC6 stoichiometry). Further increase of capacity is possible only via switching to new or modified materials, composites or alloys, which are capable for reversible and stable intercalation of lithium. 

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 properties of lithium metal were described in Chapter 4, where particular note was made of its high specific capacity and electrode potential. However, because of its highly electropositive nature, it is thermodynamically unstable in contact with a wide variety of reducible materials. In particular, lithium reacts with components of most electrolytes to form a passivating layer. Film formation of this type ensures long shelf life for primary lithium cells, but causes severe problems when the electrode is cycled in a secondary cell. 

The calcium-calcium chromate thermal cell has been established for many years. In the LiCl-KCl eutectic, the reaction product of this cell is a mixed lithium-calcium-chromium oxide. However,. this system cannot provide as high a specific capacity or energy density as the lithium-based systems described above. Furthermore, it suffers from parasitic chemical reactions which are exothermic and often uncontrolled. 

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