SECONDARY BATTERIES – LEAD– ACID SYSTEMS | Lifetime Determining Processes

Aging of lead–acid batteries is very complex and it needs to be admitted that it is still not fully understood in all cases. Changed operating conditions or new material additives still cause changes in the performance and lifetime of the battery, which are difficult to predict in advance owing to insufficient knowledge of the basic chemical and physical processes. This problem is even aggravated owing to the fact that aging appears in lead–acid batteries very inhomogeneously along the electrodes. This is due to the special role of the electrolyte, which takes part in the electrode reaction resulting in vertical concentration, potential, and current density gradients. Major aging effects are discussed in this chapter such as corrosion, sulfation, and drying out. Many processes are highly interlinked and it is always necessary to distinguish operating conditions that accelerate aging and aging processes that change the performance of the battery. The battery user can typically affect only the operating conditions such as current rates, depth of discharge (DOD), voltage, and temperature. It is the job of a good battery management to minimize the aging effects or to maximize the battery lifetime. It is impossible to avoid aging completely, but it can be minimized.