States of the battery

The Depth of Discharge (DOD or DoD) is an indication of the amoimt of electricity already extracted from a battery (section 2.3.3.10) in relation to its capacity. Thus, it is the ratio of the integral of discharge current idtsch, whether constant or variable, to the capacity. Consequently  

This is a dimensionless value, usually expressed as a percentage. For example, a DOD of 90% corresponds to a deep discharge, as the theoretical maximum is 100%. 

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A method based on the detection of end-of-discharge involves the measurement of the practical capacity of a battery by observing the Ah dilference between a full SoC and a fully discharged state of the battery during normal operation. This method is simple to implement if an Ah counter is available. The time between the full SoC and the discharged state should not be too high (i.e., less than 1 week). This method is only practical if the two reference points are reaehed within the application. 

When the battery is discharging, metallic lead oxidizes into lead sulfate and lead oxide is reduced to lead sulfate. Therefore, lead sulfate forms at both electrodes. At the same time, sulfuric acid is consumed and water is produced so that the density of sulfuric acid falls as discharging progresses. The state of the battery s charge can then be determined by this change of density. 

In almost all cases, the SOC of a battery cannot be directly determined from the measurement of a parameter, it is necessary to take accoimt of numerous electrical and electrochemical parameters of the battery (OCV, h, V(t), etc.) as well as the temperature in order to estimate the SOC of a battery. With regard to lithiitm batteries, we can use automated methods, such as Kalman filters [DO 10], to estimate the SOC. The SOC of batteries also gives us valuable information about the internal state of the battery, and can inform the user about the remaining lifetime [DEL 97]. 

The density of the electrolyte, measured by a hydrometer, forms a useful indicator of the state of charge or discharge of the battery. 

Sulfuric Acid. Sulfuric acid is a primary active material of the battery. It must be present to provide sufficient sulfate ions during discharge and to retain suitable conductivity. Lead—acid batteries generally use an aqueous solution of acid in either a free-flowing or in an immobilized state. 

It is characteristic for battery manufacture is that lead dioxide (Pb02) as the charged state of the active material is al-... 

The production of tubular positive plates is in principle similar to that of pasted plates. A number of manufacturers use the same gray oxide as the basic filling substance. Sometimes the share or red lead or minium (Pb304) is increased above 25 or even to 100wt.%. The latter is more economic when the manufacturer runs his own minium plant then the expense of the chemical oxidation of lead oxide (PbO) to minium (Pb304) may be compensated by reduced formation cost. Furthermore, curing is not required, because of the high oxidation state, and the battery starts with full capacity when formed. 

This section reviews the state-of-the-art in battery separator technology for lithium-ion cells, with a focus on separators for spirally wound batteries in particular, button cells are not considered. 

In the discharged state of ZEBRA batteries NaCl is formed in the positive electrode, which is beside the NaAlCl4. In abuse experiments, e.g., overheating, less volatile material will be released in the discharged state compared with the charged state where no NaCl is present. This is due to the lower vapor pressure of mixtures with increased NaCl content. 

The density of the electrolyte in a lead-acid battery is measured to assess its state of charge. Explain how the density indicates the state of charge of the battery. 

The description of the battery states that one electrode is Pb in contact with PbSOq, and the other electrode is Pb02 in contact with PbSOq. This information identifies the two half-reactions ... 

Skundin, A. M., O. N. Efimov, and O. V. Yarmolenko, The state-of-the-art and prospects for the development of rechargeable lithium batteries, Russ. Chem. Rev., 71, 329 (2002). Vincent, C. A., and B. Scrosati, Modem Batteries An Introduction to Electrochemical Power Sources, Edward Arnold, London, 1997. 

Ukraine s Y. Maletin et al. presented a comprehensive overview describing state of the art as well as future development trends in supercapacitors, as the fifth paper in this chapter. The authors establish key performance bars for supecapacitors upon meeting those, supercapacitors may start to compete with batteries. Also, this paper highlights so-called hybrid applications where supercapacitors complement operation of batteries and/or fuel cells. Optimization of supercapacitor performance through varying electrode thickness is contemplated in length. 

A battery is an electrochemical cell, and is defined as a device comprising two or more redox couples (where each couple comprises two redox states of the same material). An oxidation reaction occurs at the negative pole of the battery in tandem with a reduction reaction at the positive pole. Both reactions proceed with the passage of current. The two redox couples are separated physically by an electrolyte. 

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