Electrode densities

Conductive paths through electrode higher compressibility causes higher electrode density and particle contacts Porosity control... 

Besides the electrical and thermal aspects, carbon conductive additives influence the mechanical properties of the electrodes. In particular, due to its compressibility, graphite improves the electrode density and mechanical stability. The generally lower DBPA of graphite is the reason for the lower amount of binder material necessary to achieve a suitable mechanical stability of the electrode. Further, a more facile spreadability of graphitic filaments in the electrode mass is reported for primary lithium cells.92... 

Very often a compromise has to be found between the achievable energy density and the power density of the cell. The energy density of the cell can be maximized by a high-electrode loading and density. This might be achieved by highly compressed electrode materials. However, the increase in the electrode density means a decrease of the porosity and, thus, it lowers the electrolyte retention. The decreased overall ionic conductivity deteriorates the high rate performance of the electrode and therefore the power density at the cell level. 

In addition to the beneficial effect on the electrochemical performance, the graphite conductive additives influence the electrode density positively. Typically, the graphitized mesocarbon or... 

FIGURE 7.23 Electrode density as a function of the compaction pressure of a pure MCMB electrode, a pure TIMREX SFG15 electrode, and an electrode containing MCMB blended with 20% graphite SFG15. 

FIGURE 12.12 Comparisons of discharge capacity variation of MAG and typical graphitic carbons as a function of current density (a) and apparent electrode density (b). In these curves discharge represents the deintercalation from the carbon host. (From Endo, M., et al., Carbon, 39, 1287, 2001. With permission.)... 

Fig. 2.22 Electrode resistance Ra versus the electrode thickness and the contact area ratio D = 50 nm, tp = t/3, gp = D, Ra — i t 1 fxm, f = 10%), where gp is the electrode density in terms of gap size between the inner particle cube. Reprinted from [Kim et al. (2007b)].

First, let us consider the matters required for LiCoO. The specification of LiCoOj supplied by a certain company is shown in Table 2.4 as an example. Naturally, the most important property is the electrode density, which is related to the packing density and the density of the sheet electrode. These data are important for the battery manufacturers in order to stuff the cathode active material, such as LiCoOj, into the battery case with constant volume as much as possible. Currently, it seems that 96 wt% of the cathode mixture is LiCoO and the residual 4 wt% is the binder and the conductor, such as carbon. Thus, it is important to stuff electroactive LiCoOj even 1% more. The electrode density within the battery case is increased by the increase in both cathode sheet density and packing density, which leads to the improvement of cell capacity. 

Miniaturization is required for the lithium-ion battery in the other words, an improvement in the volumetric energy density is important. Therefore, it is necessary to develop an anode material with high packing density. Finally, the increase in the electrode density without deterioration of electrochemical property is desirable. 

Figure 18.13 shows the relationship between the electrode density and the discharge capacity for three graphitic carbon anodes. The discharge capacity of all three electrodes decreases for every material with the increase in the electrode density. 

A high discharge capacity of MAG is attained by both its characteristic texture and ideal hexagonal crystal structure. It excels in high-rate discharge performance, cyclicity, and electrode density. 

Bakhshi and Ladik [173] calculated the electrode density of states of the various quasi-one-dimensional copolymers (superlattices) of the type (A B ) t numerically within the ab initio SCF tight-binding approximation. On the basis of the band positions of the homopolymers, these copolymers belong to the class of type-Il (staggered) superlattices. The paper discusses the trends in their electronic properties as a function of composition (m/n), block sizes m and n, and arrangements of blocks in the copolymer chain. 

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