Aging mechanisms prediction

Accelerated tests usually require the application of a higher electrical stress (voltage) coupled sometimes with an increase in temperature as a second accelerating factor. As in all accelerated testing, care must be taken to ensure that this does not introduce ageing mechanisms different to those that occur in service. The most common relation used to predict insulation life in the presence of partial discharges is the power law ... 

Without proper knowledge of the circumstances in which degradation mechanisms are active and of how they interact, there is no firm base for reliable life prediction models. Products will be over-designed to compensate for the lack of accurate predictions. The models presently available for quantifying the degradation and ageing mechanisms presented in the previous section are reviewed here. 

Since 1993, much progress has been made in the knowledge of mechanisms of ageing. Mechanical tests at full scale (and scale 2/3) showed that there was no risk of break due to embrittlement. Some very limited tear of defects were observed, very far from instability or break, so no replacement is mandatory for safety reasons, nevertheless metallurgical examinations and gammagraphy control of elbows are planned for the ten-yearly inspections to check if the evolution of defects is in accordance with predictions. 

This chapter focuses on the nano-structured effects on electrode durabUity, i.e. ceU durability. Fundamental aging mechanisms of the electrode components are also summarized. Long-time performances of the nano-structured electrodes are introduced to reveal the nano-size effects on electrode durabUity. Furthermore, models ever reported for the prediction of durabUity are included for better understanding the influence from the nano-size scale. 

This implies that other ageing mechanisms are also involved. Thus, for the prediction of toughness retention, these procedures may be adequate for the comparison between different products, but fall short of providing quantitative service life prediction as they do for flexural strength. 

Aging Mechanisms and Calendar-Life Predictions. 393i... 

Yamaki presents an extensive review of the extensive efforts in various laboratories to improve the electrolyte solvent systems and studies of their reactivity with anodes and cathodes. This chapter, combined with Aurbach s opening chapter, the chapter on temperature effects in lithium-ion batteries (Salomon, Lin, Plichta, and Hendrickson) and Broussely s chapter on aging mechanisms and calendar life predictions gives a comprehensive insight into the reactivity of the systems that constitute commercial cells. 

Broussely M, Herreyre S, Biensan P, Kasztejna P, Nechev K, Staniewicz RJ (2001) Aging mechanism in Li ion cells and calendar life predictions. J Power Sourc 97-98 13-21... 

The period 1930-1980s may be the golden age for the growth of qualitative theories and conceptual models. As is well known, the frontier molecular orbital theory [1-3], Woodward-Hoffmann rules [4, 5], and the resonance theory [6] have equipped chemists well for rationalizing and predicting pericyclic reaction mechanisms or molecular properties with fundamental concepts such as orbital symmetry and hybridization. Remarkable advances in aeative synthesis and fine characterization during recent years appeal for new conceptual models. 

Besides the prediction of calcination temperatures during catalyst preparation, thermal analysis is also used to determine the composition of catalysts based on weight changes and thermal behavior during thermal decomposition and reduction, to characterize the aging and deactivation mechanisms of catalysts, and to investigate the acid-base properties of solid catalysts using probe molecules. However, these techniques lack chemical specificity, and require corroboration by other characterization methods. 

---