Batteries theoretical capacity

Table 1. Theoretical capacities, rechargeable capacities, average operating voltages, and energy densities of secondary lithium batteries with insertion materials...

In 1990, Takeuchi et al. investigated the low-temperature performance of Li/SVO batteries for potential nonmedical specialty applications [51], Twenty-three percent of theoretical capacity was obtained under constant resistive load at -40°C, and... 

Sn as well as Si was widely studied as an anodic material alternative to carbon for Li-ion batteries due to its much higher theoretical capacity of 991 mAh/g [167] than that of graphitic carbons. However, a pure Sn electrode suffers from poor cycle ability due to mechanical fatigue caused by volume change during Li insertion/deinsertion [168], Similar to the case of Si-based anode... 

Fig. 13.49. Discharge capacity vs. cycle number for representative cells (at 20 °C) that were charged to 130 and 85% of their theoretical capacity. (Reprinted from J. M. Pope, T. Sotomura, and N. Oyama, Characterization and Performance of Organosulfur Cathodes for Secondary Lithium Cells Composites of Organosulfur, Conducting Polymer, and Copper Ion, in Batteries for Portable Applications and Electric Vehicles, C. F. Holmes and A. R. Landgrebe, eds., Electrochemical Society Proc. 97-18, p. 122, 1997. Reproduced by permission of The Electrochemical Society.)...

Practical (actual) capacity— The amount of electricity (-> charge), usually expressed in Ah, that can be withdrawn from a battery at specific discharge conditions. Contrary to theoretical capacity and theoretical capacity of a practical battery, the practical capacity of a battery is a measured quantity, and intrinsically incorporates all the losses to the theoretical capacity due to the mass of the nonactive components of the cell, and the electrochemical and chemical limitations of the electrochemical system. The practical capacity of a cell is exceedingly dependent on the measurement conditions, e.g., temperature, cut-off voltage, discharge rate, etc. 

The calculated maximum amount of -> charge (in Ah kg-1) that can be withdrawn from a -> battery based on its theoretical capacity, and the minimum necessary nonactive components, i.e., electrolyte, separator, current-collectors, container, etc. Obviously, the theoretical capacity of a practical battery is considerably lower than its theoretical capacity, and is higher than the actual capacity. 

Theoretical capacity — A calculated amount of electricity (-> charge) involved in a specific electrochemical reaction (expressed for -> battery -> discharge), and usually expressed in terms of -> ampere-hours per kg or -> coulombs per kg. The theoretical capacity for one gram-equivalent weight of material amounts to 96,487 C (see -> Faraday constant) or 26.8 Ah. The general expression for the calculation of the theoretical capacity (in Ah kg-1) for a given -> anode material and - cathode material and their combination as full cell is given by... 

C h = in which n is the number of -> electrons involved in the electrochemical reaction, M is the molecular weight of the electroactive materials, and F stands for the Faraday constant. In calculating the theoretical capacity for a battery, only the cathode and anode material masses are taken into consideration, ignoring the electrolyte, separator (see diaphragm), current-collectors, container, etc. 

Carbon and graphite are used in batteries as electrodes or as additives in order to enhance the electronic conductivity of the electrodes. As electrodes, graphites and disordered carbons reversibly insert lithium, and hence they may serve as the anode material in -> lithium batteries. Graphitic carbons intercalate lithium in a reversible multi-stage process up to LiC6 (a theoretical capacity of 372 mAh g-1) and are used as the main anode material in commercial rechargeable Li ion batteries. As additives, carbon and graphite can be found in most of... 

Theoretical capacity (of batteries) - capacity Thermal battery - reserve battery Thermal cell - thermocell... 

The electrosynthesis of polythiophene (PT) from thiophene must be performed under extremely anhydrous conditions, quite in contrast to polypyrrole [334]. Polymerization of 3-methylthiophene and bithiophene is much less sensitive to water. The advantage of PT is a higher theoretical capacity and a very positive potential (cf. Table 7). It is for these reasons that its application as a positive electrode in rechargeable lithium batteries [335-338] and in a metal-free PPy/PT cell [339] has been considered. Derivatives such as dithienothiophene [340] or rra/is-l,2-di(2-thienyl)ethylene [341] have also been polymerized, but the polymer materials suffer from low theoretical capacities [337]. 

The procedure to calculate the theoretical capacity of batteries is given in Sect. 7.8. 

The capacity and voltage of the battery was discussed in Sect. 7.7. It was mentioned that the theoretical capacity and the theoretical voltage give the maximum capacity and voltage available in the battery and that they can be used to make an estimate of these values. This section presents more details about theoretical capacity and theoretical voltage, emphasizing the procedure to calculate them. 

As mentioned before, the theoretical capacity of the battery is the maximum battery capacity and depends only on... 

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