Aging of batteries

The lifetime of a battery is strongly linked to the usage conditions. It depends on the number of cycles, the temperature, the state of charge, the charge/discharge current, etc. 

In general, the aging of a battery resrrlt in a deterioration in its energetic performances (decreased capacity, increased internal resistance, etc.). For vehicirlar applications, a battery is considered to be aged or no longer capable of fulfilling its function if its capacity drops by 20% or the resistance increases by a factor 2. 

F ure 5.9. Change in the internal resistance with the cycling of the lithium battery piOS 12] 

Consider a battery of accumulators with the following parameters  

2) Determine the energy that can be stored in this component. 

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Two thousand years passed before Volta s experiments ushered in the modem age of batteries and electrochemistry. Volta had... 

The golden age of batteries, and Indeed electrochemistry/started with Volta s experiments, and by the end of the 19th century tremendous progress had been made. Table I, shows the main milestones In the progress of battery evolution, and essentially by the end of the 19th century most of the rechargeable battery landmarks had been reached. These Includes the dry cells, the lead acid battery(, , the nickel cadmium battery(6, elements of the fuel cell CD and metal air batteries(8), nickel Iron (6,9) and even the nickel zinc ( ) battery concept. Progress has been slow ever since. 

Some of these began their work with electric cars. In Germany Ferdinand Porsche, built his first car, the Lohner Electric Chaise, in 1898 at the age of 23. The Lohner-Porsche was a first front-wheel drive car with four-wheel brakes and an automatic transmission. It used one electric motor in each of the four wheel hubs similar to today s hybrid cars, which have both gas and electric power. Porsche s second car was a hybrid, with an internal-combustion engine driving a generator to power the electric motors in the wheel hubs. On battery power alone, the car could travel 38 miles. 

Whereas the experimental design is quite standardized regarding maternal aspects, the duration of postnatal infant assessments is rather variable between studies, for example, from 7 days to 720 days in our experience. Evidently there is a need for standardization of the timing and type of test batteries for infants and of the time period the infant should be raised. For behavioral tests, a postnatal observation period of 9 months appears essential since these tests can only by applied from the age of 6 months onward. For evaluation of immune system development, a period of 6 months appears mandatory since from that age onward blood volume is sufficient to conduct several tests, such as the T cell dependent antibody response (TDAR), NK cell... 

Figure 18.1 Study design for the pre- and postnatal development evaluation in the cynomolgus monkey. Maternal treatment is either discontinued at term or is continued into the lactation period in order to investigate transfer of test item to the infant. Transfer of biopharmaceuticals via milk has been observed in this species. The duration of the postnatal observation period is variable and not yet standardized. In our laboratory the longest postnatal observation period covered 720 days. A variety of parameters is available for testing infant development (see also Table 18.4 for details). For biopharmaceuticals, a minimum period of 6 months appears appropriate. If the behavioral test battery comprises learning tests that are recommended from the age of 6 months onward, infants should be observed for at least 9 months.

Another common mode of failure of batteries is loss of electrical contact between the active material and the current collector. There are many other ways in which batteries can fail, such as the aging of separators and accidental contact between anode and cathode. These problems are not discussed here. 

Volta s discovery of the pile 200 years ago (1799) ushered in the age of electrochemistry. Today, while the battery remains the most widespread practical application of electrochemistry, it is perhaps just as true that the battery is also the most widespread application of electron transfer, the phenomenon at the basis of its operation. 

The internal resistance of a battery increases with battery age due to corrosion, sulfation, water loss, and loss of conductivity between grid and active mass. Therefore, the d.e. resistance or the complex admittanee are good indicators of battery age. As deseribed previously, battery resistanee is also influenced by the SoC and the temperature. 

During his Leipzig period, Nernst performed a series of electrochemical studies from which, at the age of twenty-five, he arrived at his well-known equations. These equations described the concentration dependence of the potential difference of galvanic cells, such as batteries, and were of both great theoretical and practical importance. Nernst started with the investigation of the diffusion of electrolytes in one solution. Then he turned to the diffusion at the boundary between two solutions with different electrolyte concentrations he determined that the osmotic pressure difference would result in an electric potential difference or electromotive force (emf). Next he divided both solutions into two concentration half-cells, connected to each other by a liquid junction, and measured the emf via electrodes dipped into both solutions. The data supported his first equation where the... 

In Sweden, for example, fees paid on Ni-Cd battery purchases in Sweden far exceed the costs of a collection and recycling system. Indeed, they appear to have been imposed by the government as a punitive tax in an attempt to force Ni-Cd batteries out of the market in favor of batteries utilizing other chemistries. In this age of internet commerce and rapid mail order delivery, consumers that are given a significant monetary incentive to do so can just as easily buy their batteries outside such a program and avoid paying the punitive fee. 

Manufacturers generally either stamp date codes on the base or side of the battery, or include a freshness code on the battery label. The age of each battery and hence the mercury content can be determined by recording the manufacturers code and converting this back to the year of manufacture. Some batteries can be assigned to manufacturing dates one year earlier than their actual year of manufacture as a result of using freshness codes, simply because the manufacturer will not replace his stocks of battery labels on January 1st each year. 

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