Anode capacity

The anode capacity is the total coulombic charge (current x time) produced by unit mass of an anode as a result of electrochemical dissolution. It is normally expressed in ampere hours per kilogram (Ah/kg) although the inverse of anode capacity, i.e. the consumption rate (kg/Ay) is sometimes used. 

The theoretical anode capacity can be calculated according to Faraday s law. From this it can be shown that 1 kg of aluminium should provide 2981 Ah of charge. In practice, the realisable capacity of the anode is less than the theoretical value. The significance of the actual (as opposed to the theoretical) anode capacity is that it is a measure of the amount of cathodic current an anode can give. Since anode capacity varies amongst anode materials, it is the parameter against which the anode cost per unit anode weight should be evaluated. 

The anode efficiency is the percentage of the theoretical anode capacity that is achieved in practice ... 

The critical information required from testing may include one or all of the following tendency to passivation, anode operating potential and capacity. The tests, whilst all capable of producing information on the above, tend to be particularly suited to certain applications. For example potentiostatic testing is useful for evaluating passivation tendencies but not generally appropriate to anode capacity determination. 

Herreyre et al., it could be tentatively concluded that longer alkyl chains in the carboxylic acid section of the esters play a critical role in determining the cathodic stability of this component on a graphite anode. The tests in AA-size full lithium ion cells were only reported for EA- and MA-based quaternary electrolytes, and Figure 59 shows the discharging profiles of these cells at —40 °C. Despite their negative effect on anode capacity utilization at room temperature, MA and EA still improved the capacity significantly. 

FIGURE 12.9 Capacity transition of Li-ion batteries and change in their anode materials. The capacity of Li-ion batteries has increased by approximately 10% every year. Their anode capacities and densities have also increased. (From Ishii, Y., et al., Hitachi Chem. Tech. Rep., 47, 29, 2006.)... 

The major design changes made to primary alkaline cells were the use of improved cathode and anode formulations, the limitation of the anode capacity to approximately 1/3 of the cathode capacity to prevent overdischarge of the cathode, the application of improved separators and the integration of means to enable moderate cell abuse. Cell components (cans and closures) and raw materials (EMD, graphite, zinc) used are identical to the ones used in primary alkaline cells. The electrode capacity balance accounts for the reduced capacity of RAM cells when compared to primary alkaline cells of similar size. 

Fig. 11.1 Total capacity of LIB material presented as a function of anode capacity. Two possible cathodes with capacities of 140 and 200 mA h g respectively, are considered. As shown, a comparatively fast increase in the total capacity with an anode-specific capacity (C ) of 300-1,200 mA h g is followed by a tail with a smaller slope when exceeds ca. 1,200 mA h g" ...

To overcome this problem without using a metallic lithium layer, an active-active concept has been proposed. It also strove to avoid the presence of inactive solid phases that considerably reduce the overall anode capacity. Such an example is the multiphase system - Sn/SnSb - proposed by Besenhard s research group. It was revealed that this alloy reacts with LF according to the following scheme ... 

The Li-ion battery has already introduced the wireless revolution by powering the cell telephone and the laptop computer as well as their derivatives. Modest increases in anode capacity will improve the volume energy density for handheld electronic devices. 

Developing sensors that can sense remaining barrier properties, inhibitor or sacrificial anode capacity and... 

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