Irreversible specific charge

Figure 7. First- and second- cycle constant-current charge/discharge curves of graphite Timrex KS44 in LiN(S02CF3)2/ethylene carbonate/dimethyl carbonate as the electrolyte (CilT irreversible specific charge Crev =reversible specific charge) [2J.

Apart from reactions with the electrolyte at the carbon surface, the irreversible specific charge is furthermore strongly affected by the possible co-intercalation of polar solvent molecules between the graphene layers of highly graphitic matrices [139]. This so-called "solvated intercalation reaction" depends (i) on the crystallinity and the morphology of the parent carbonaceous material, which will be discussed in Sec. 

Both effects resulting from solvent cointercalation, the mechanical destruction and the higher irreversible specific charge losses, seriously complicate the operation... 

Since film formation on Li C is associated with the irreversible consumption of material (lithium and electrolyte), the corresponding charge loss is frequently called "irreversible specific charge" or "irreversible capacity". Reversible lithium intercalation, on the other hand, is called "reversible specific charge" or "reversible capacity". The losses have to be minimized because the losses of charge and of lithium are detrimental to the specific energy of the whole cell and, moreover, increase the material expenses because of the necessary excess of costly cathode material which is the lithium source in a lithium-ion cell after cell assembly. 

In conclusion, a high proportion of single-layer sheets and nanopores is beneficial for the hthium storage capabilities of hard carbons. On the other hand, heat treatment, above 1000 °C, leads to drastically increased irreversible specific charges of hard carbons [249, 275]. This may be related to the bum-off of material, which causes the opening of the nanopores. Electrolyte can penetrate in, and the sites... 

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